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all: add Pure Go build (pull request #114)

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Updates #94
This commit is contained in:
Roman Khavronenko 2019-07-23 17:26:39 +01:00 committed by Aliaksandr Valialkin
parent 8c3629a892
commit 5bf4e5ffb5
77 changed files with 14430 additions and 89 deletions
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8
Makefile
View file

@ -59,10 +59,18 @@ test:
test_full:
GO111MODULE=on go test -tags=integration -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
test-pure:
GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor ./lib/...
GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor ./app/...
benchmark:
GO111MODULE=on go test -mod=vendor -bench=. ./lib/...
GO111MODULE=on go test -mod=vendor -bench=. ./app/...
benchmark-pure:
GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor -bench=. ./lib/...
GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor -bench=. ./app/...
vendor-update:
GO111MODULE=on go get -u ./lib/...
GO111MODULE=on go get -u ./app/...

12
README.md
View file

@ -113,6 +113,18 @@ to your needs.
2. Run `make victoria-metrics-prod` from the root folder of the repository.
It will build `victoria-metrics-prod` binary and put it into the `bin` folder.
#### ARM build
1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.12.
2. Run `make victoria-metrics-arm` or `make victoria-metrics-arm64` from the root folder of the repository.
It will build `victoria-metrics-arm` or `victoria-metrics-arm64` binary respectively and put it into the `bin` folder.
#### Pure Go (CGO_ENABLED=0)
1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.12.
2. Run `make victoria-metrics-pure` from the root folder of the repository.
It will build `victoria-metrica-pure` binary and put it into the `bin` folder.
#### Building docker images
Run `make package-victoria-metrics`. It will build `victoriametrics/victoria-metrics:<PKG_TAG>` docker image locally.

7
app/victoria-metrics/Makefile
View file

@ -21,10 +21,13 @@ run-victoria-metrics:
$(MAKE) run-via-docker
victoria-metrics-arm:
CC=arm-linux-gnueabi-gcc CGO_ENABLED=1 GOARCH=arm GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-arm ./app/victoria-metrics
CGO_ENABLED=0 GOOS=linux GOARCH=arm GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-arm ./app/victoria-metrics
victoria-metrics-arm64:
CC=aarch64-linux-gnu-gcc CGO_ENABLED=1 GOARCH=arm64 GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-arm64 ./app/victoria-metrics
CGO_ENABLED=0 GOOS=linux GOARCH=arm64 GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-arm64 ./app/victoria-metrics
victoria-metrics-pure:
GO111MODULE=on CGO_ENABLED=0 go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-pure ./app/victoria-metrics
### Packaging for Debian - amd64
victoria-metrics-package-deb: victoria-metrics

1
go.mod
View file

@ -5,6 +5,7 @@ require (
github.com/VictoriaMetrics/metrics v1.7.0
github.com/cespare/xxhash/v2 v2.0.1-0.20190104013014-3767db7a7e18
github.com/golang/snappy v0.0.1
github.com/klauspost/compress v1.7.4
github.com/spaolacci/murmur3 v1.1.0 // indirect
github.com/valyala/fastjson v1.4.1
github.com/valyala/gozstd v1.5.1

2
go.sum
View file

@ -18,6 +18,8 @@ github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
github.com/klauspost/compress v1.4.0/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
github.com/klauspost/compress v1.4.1/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
github.com/klauspost/compress v1.7.4 h1:4UqAIzZ1Ns2epCTyJ1d2xMWvxtX+FNSCYWeOFogK9nc=
github.com/klauspost/compress v1.7.4/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
github.com/klauspost/cpuid v0.0.0-20180405133222-e7e905edc00e/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
github.com/klauspost/cpuid v1.2.0/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

6
lib/encoding/compress.go
View file

@ -1,8 +1,8 @@
package encoding
import (
"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding/zstd"
"github.com/VictoriaMetrics/metrics"
"github.com/valyala/gozstd"
)
// CompressZSTDLevel appends compressed src to dst and returns
@ -13,7 +13,7 @@ func CompressZSTDLevel(dst, src []byte, compressLevel int) []byte {
compressCalls.Inc()
originalBytes.Add(len(src))
dstLen := len(dst)
dst = gozstd.CompressLevel(dst, src, compressLevel)
dst = zstd.CompressLevel(dst, src, compressLevel)
compressedBytes.Add(len(dst) - dstLen)
return dst
}
@ -22,7 +22,7 @@ func CompressZSTDLevel(dst, src []byte, compressLevel int) []byte {
// the appended dst.
func DecompressZSTD(dst, src []byte) ([]byte, error) {
decompressCalls.Inc()
return gozstd.Decompress(dst, src)
return zstd.Decompress(dst, src)
}
var (

83
lib/encoding/encoding_cgo_test.go Normal file
View file

@ -0,0 +1,83 @@
// +build cgo
package encoding
import (
"math/rand"
"testing"
)
func TestMarshalUnmarshalInt64Array(t *testing.T) {
var va []int64
var v int64
// Verify nearest delta encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += int64(rand.NormFloat64() * 1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 23; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta)
}
for precisionBits := uint8(23); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += 30e6 + int64(rand.NormFloat64()*1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 24; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta2)
}
for precisionBits := uint8(24); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
// Verify nearest delta encoding.
va = va[:0]
v = 1000
for i := 0; i < 6; i++ {
v += int64(rand.NormFloat64() * 100)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 6; i++ {
v += 3000 + int64(rand.NormFloat64()*100)
va = append(va, v)
}
for precisionBits := uint8(5); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
}
func TestMarshalInt64ArraySize(t *testing.T) {
var va []int64
v := int64(rand.Float64() * 1e9)
for i := 0; i < 8*1024; i++ {
va = append(va, v)
v += 30e3 + int64(rand.NormFloat64()*1e3)
}
testMarshalInt64ArraySize(t, va, 1, 500, 1300)
testMarshalInt64ArraySize(t, va, 2, 600, 1400)
testMarshalInt64ArraySize(t, va, 3, 900, 1800)
testMarshalInt64ArraySize(t, va, 4, 1300, 2100)
testMarshalInt64ArraySize(t, va, 5, 2000, 3200)
testMarshalInt64ArraySize(t, va, 6, 3000, 4800)
testMarshalInt64ArraySize(t, va, 7, 4000, 6400)
testMarshalInt64ArraySize(t, va, 8, 6000, 8000)
testMarshalInt64ArraySize(t, va, 9, 7000, 8800)
testMarshalInt64ArraySize(t, va, 10, 8000, 10000)
}

83
lib/encoding/encoding_pure_test.go Normal file
View file

@ -0,0 +1,83 @@
// +build !cgo
package encoding
import (
"math/rand"
"testing"
)
func TestMarshalUnmarshalInt64Array(t *testing.T) {
var va []int64
var v int64
// Verify nearest delta encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += int64(rand.NormFloat64() * 1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 17; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta)
}
for precisionBits := uint8(23); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += 30e6 + int64(rand.NormFloat64()*1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 15; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta2)
}
for precisionBits := uint8(24); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
// Verify nearest delta encoding.
va = va[:0]
v = 1000
for i := 0; i < 6; i++ {
v += int64(rand.NormFloat64() * 100)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 6; i++ {
v += 3000 + int64(rand.NormFloat64()*100)
va = append(va, v)
}
for precisionBits := uint8(5); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
}
func TestMarshalInt64ArraySize(t *testing.T) {
var va []int64
v := int64(rand.Float64() * 1e9)
for i := 0; i < 8*1024; i++ {
va = append(va, v)
v += 30e3 + int64(rand.NormFloat64()*1e3)
}
testMarshalInt64ArraySize(t, va, 1, 500, 1700)
testMarshalInt64ArraySize(t, va, 2, 600, 1800)
testMarshalInt64ArraySize(t, va, 3, 900, 2100)
testMarshalInt64ArraySize(t, va, 4, 1300, 2200)
testMarshalInt64ArraySize(t, va, 5, 2000, 3300)
testMarshalInt64ArraySize(t, va, 6, 3000, 5000)
testMarshalInt64ArraySize(t, va, 7, 4000, 6500)
testMarshalInt64ArraySize(t, va, 8, 6000, 8000)
testMarshalInt64ArraySize(t, va, 9, 7000, 8800)
testMarshalInt64ArraySize(t, va, 10, 8000, 17000)
}

95
lib/encoding/encoding_test.go
View file

@ -89,73 +89,6 @@ func testEnsureNonDecreasingSequence(t *testing.T, a []int64, vMin, vMax int64,
}
}
func TestMarshalUnmarshalInt64Array(t *testing.T) {
testMarshalUnmarshalInt64Array(t, []int64{1, 20, 234}, 4, MarshalTypeNearestDelta2)
testMarshalUnmarshalInt64Array(t, []int64{1, 20, -2345, 678934, 342}, 4, MarshalTypeNearestDelta)
testMarshalUnmarshalInt64Array(t, []int64{1, 20, 2345, 6789, 12342}, 4, MarshalTypeNearestDelta2)
// Constant encoding
testMarshalUnmarshalInt64Array(t, []int64{1}, 4, MarshalTypeConst)
testMarshalUnmarshalInt64Array(t, []int64{1, 2}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{-1, 0, 1, 2, 3, 4, 5}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{-10, -1, 8, 17, 26}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{0, 0, 0, 0, 0, 0}, 4, MarshalTypeConst)
testMarshalUnmarshalInt64Array(t, []int64{100, 100, 100, 100}, 4, MarshalTypeConst)
var va []int64
var v int64
// Verify nearest delta encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += int64(rand.NormFloat64() * 1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 23; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta)
}
for precisionBits := uint8(23); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 8*1024; i++ {
v += 30e6 + int64(rand.NormFloat64()*1e6)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 24; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeZSTDNearestDelta2)
}
for precisionBits := uint8(24); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
// Verify nearest delta encoding.
va = va[:0]
v = 1000
for i := 0; i < 6; i++ {
v += int64(rand.NormFloat64() * 100)
va = append(va, v)
}
for precisionBits := uint8(1); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta)
}
// Verify nearest delta2 encoding.
va = va[:0]
v = 0
for i := 0; i < 6; i++ {
v += 3000 + int64(rand.NormFloat64()*100)
va = append(va, v)
}
for precisionBits := uint8(5); precisionBits < 65; precisionBits++ {
testMarshalUnmarshalInt64Array(t, va, precisionBits, MarshalTypeNearestDelta2)
}
}
func testMarshalUnmarshalInt64Array(t *testing.T, va []int64, precisionBits uint8, mtExpected MarshalType) {
t.Helper()
@ -259,24 +192,18 @@ func TestMarshalUnmarshalValues(t *testing.T) {
}
}
func TestMarshalInt64ArraySize(t *testing.T) {
var va []int64
v := int64(rand.Float64() * 1e9)
for i := 0; i < 8*1024; i++ {
va = append(va, v)
v += 30e3 + int64(rand.NormFloat64()*1e3)
}
func TestMarshalUnmarshalInt64ArrayConstant(t *testing.T) {
testMarshalUnmarshalInt64Array(t, []int64{1, 20, 234}, 4, MarshalTypeNearestDelta2)
testMarshalUnmarshalInt64Array(t, []int64{1, 20, -2345, 678934, 342}, 4, MarshalTypeNearestDelta)
testMarshalUnmarshalInt64Array(t, []int64{1, 20, 2345, 6789, 12342}, 4, MarshalTypeNearestDelta2)
testMarshalInt64ArraySize(t, va, 1, 500, 1300)
testMarshalInt64ArraySize(t, va, 2, 600, 1400)
testMarshalInt64ArraySize(t, va, 3, 900, 1800)
testMarshalInt64ArraySize(t, va, 4, 1300, 2100)
testMarshalInt64ArraySize(t, va, 5, 2000, 3200)
testMarshalInt64ArraySize(t, va, 6, 3000, 4800)
testMarshalInt64ArraySize(t, va, 7, 4000, 6400)
testMarshalInt64ArraySize(t, va, 8, 6000, 8000)
testMarshalInt64ArraySize(t, va, 9, 7000, 8800)
testMarshalInt64ArraySize(t, va, 10, 8000, 10000)
// Constant encoding
testMarshalUnmarshalInt64Array(t, []int64{1}, 4, MarshalTypeConst)
testMarshalUnmarshalInt64Array(t, []int64{1, 2}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{-1, 0, 1, 2, 3, 4, 5}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{-10, -1, 8, 17, 26}, 4, MarshalTypeDeltaConst)
testMarshalUnmarshalInt64Array(t, []int64{0, 0, 0, 0, 0, 0}, 4, MarshalTypeConst)
testMarshalUnmarshalInt64Array(t, []int64{100, 100, 100, 100}, 4, MarshalTypeConst)
}
func testMarshalInt64ArraySize(t *testing.T, va []int64, precisionBits uint8, minSizeExpected, maxSizeExpected int) {

19
lib/encoding/zstd/zstd_cgo.go Normal file
View file

@ -0,0 +1,19 @@
// +build cgo
package zstd
import (
"github.com/valyala/gozstd"
)
// Decompress appends decompressed src to dst and returns the result.
func Decompress(dst, src []byte) ([]byte, error) {
return gozstd.Decompress(dst, src)
}
// CompressLevel appends compressed src to dst and returns the result.
//
// The given compressionLevel is used for the compression.
func CompressLevel(dst, src []byte, compressionLevel int) []byte {
return gozstd.CompressLevel(dst, src, compressionLevel)
}

69
lib/encoding/zstd/zstd_pure.go Normal file
View file

@ -0,0 +1,69 @@
// +build !cgo
package zstd
import (
"sync"
"sync/atomic"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/klauspost/compress/zstd"
)
var (
decoder *zstd.Decoder
mu sync.Mutex
av atomic.Value
)
type registry map[int]*zstd.Encoder
func init() {
r := make(registry)
av.Store(r)
var err error
decoder, err = zstd.NewReader(nil)
if err != nil {
logger.Panicf("BUG: failed to create ZSTD reader: %s", err)
}
}
// Decompress appends decompressed src to dst and returns the result.
func Decompress(dst, src []byte) ([]byte, error) {
return decoder.DecodeAll(src, dst)
}
// CompressLevel appends compressed src to dst and returns the result.
//
// The given compressionLevel is used for the compression.
func CompressLevel(dst, src []byte, compressionLevel int) []byte {
e := getEncoder(compressionLevel)
return e.EncodeAll(src, dst)
}
func getEncoder(compressionLevel int) *zstd.Encoder {
r := av.Load().(registry)
if e, ok := r[compressionLevel]; ok {
return e
}
level := zstd.EncoderLevelFromZstd(compressionLevel)
e, err := zstd.NewWriter(nil, zstd.WithEncoderLevel(level))
if err != nil {
logger.Panicf("BUG: failed to create ZSTD writer: %s", err)
}
mu.Lock()
r1 := av.Load().(registry)
r2 := make(registry)
for k, v := range r1 {
r2[k] = v
}
r2[compressionLevel] = e
av.Store(r2)
mu.Unlock()
return e
}

94
lib/encoding/zstd/zstd_test.go Normal file
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@ -0,0 +1,94 @@
// +build cgo
package zstd
import (
"math/rand"
"testing"
pure "github.com/klauspost/compress/zstd"
cgo "github.com/valyala/gozstd"
)
func TestCompressDecompress(t *testing.T) {
testCrossCompressDecompress(t, []byte("a"))
testCrossCompressDecompress(t, []byte("foobarbaz"))
var b []byte
for i := 0; i < 64*1024; i++ {
b = append(b, byte(rand.Int31n(256)))
}
testCrossCompressDecompress(t, b)
}
func testCrossCompressDecompress(t *testing.T, b []byte) {
testCompressDecompress(t, pureCompress, pureDecompress, b)
testCompressDecompress(t, cgoCompress, cgoDecompress, b)
testCompressDecompress(t, pureCompress, cgoDecompress, b)
testCompressDecompress(t, cgoCompress, pureDecompress, b)
}
func testCompressDecompress(t *testing.T, compress compressFn, decompress decompressFn, b []byte) {
bc, err := compress(nil, b, 5)
if err != nil {
t.Fatalf("unexpected error when compressing b=%x: %s", b, err)
}
bNew, err := decompress(nil, bc)
if err != nil {
t.Fatalf("unexpected error when decompressing b=%x from bc=%x: %s", b, bc, err)
}
if string(bNew) != string(b) {
t.Fatalf("invalid bNew; got\n%x; expecting\n%x", bNew, b)
}
prefix := []byte{1, 2, 33}
bcNew, err := compress(prefix, b, 5)
if err != nil {
t.Fatalf("unexpected error when compressing b=%x: %s", bcNew, err)
}
if string(bcNew[:len(prefix)]) != string(prefix) {
t.Fatalf("invalid prefix for b=%x; got\n%x; expecting\n%x", b, bcNew[:len(prefix)], prefix)
}
if string(bcNew[len(prefix):]) != string(bc) {
t.Fatalf("invalid prefixed bcNew for b=%x; got\n%x; expecting\n%x", b, bcNew[len(prefix):], bc)
}
bNew, err = decompress(prefix, bc)
if err != nil {
t.Fatalf("unexpected error when decompressing b=%x from bc=%x with prefix: %s", b, bc, err)
}
if string(bNew[:len(prefix)]) != string(prefix) {
t.Fatalf("invalid bNew prefix when decompressing bc=%x; got\n%x; expecting\n%x", bc, bNew[:len(prefix)], prefix)
}
if string(bNew[len(prefix):]) != string(b) {
t.Fatalf("invalid prefixed bNew; got\n%x; expecting\n%x", bNew[len(prefix):], b)
}
}
type compressFn func(dst, src []byte, compressionLevel int) ([]byte, error)
func pureCompress(dst, src []byte, _ int) ([]byte, error) {
w, err := pure.NewWriter(nil, pure.WithEncoderLevel(pure.SpeedBestCompression))
if err != nil {
return nil, err
}
return w.EncodeAll(src, dst), nil
}
func cgoCompress(dst, src []byte, compressionLevel int) ([]byte, error) {
return cgo.CompressLevel(dst, src, compressionLevel), nil
}
type decompressFn func(dst, src []byte) ([]byte, error)
func pureDecompress(dst, src []byte) ([]byte, error) {
decoder, err := pure.NewReader(nil)
if err != nil {
return nil, err
}
return decoder.DecodeAll(src, dst)
}
func cgoDecompress(dst, src []byte) ([]byte, error) {
return cgo.Decompress(dst, src)
}

27
vendor/github.com/klauspost/compress/LICENSE generated vendored Normal file
View file

@ -0,0 +1,27 @@
Copyright (c) 2012 The Go Authors. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

79
vendor/github.com/klauspost/compress/fse/README.md generated vendored Normal file
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@ -0,0 +1,79 @@
# Finite State Entropy
This package provides Finite State Entropy encoding and decoding.
Finite State Entropy (also referenced as [tANS](https://en.wikipedia.org/wiki/Asymmetric_numeral_systems#tANS))
encoding provides a fast near-optimal symbol encoding/decoding
for byte blocks as implemented in [zstandard](https://github.com/facebook/zstd).
This can be used for compressing input with a lot of similar input values to the smallest number of bytes.
This does not perform any multi-byte [dictionary coding](https://en.wikipedia.org/wiki/Dictionary_coder) as LZ coders,
but it can be used as a secondary step to compressors (like Snappy) that does not do entropy encoding.
* [Godoc documentation](https://godoc.org/github.com/klauspost/compress/fse)
## News
* Feb 2018: First implementation released. Consider this beta software for now.
# Usage
This package provides a low level interface that allows to compress single independent blocks.
Each block is separate, and there is no built in integrity checks.
This means that the caller should keep track of block sizes and also do checksums if needed.
Compressing a block is done via the [`Compress`](https://godoc.org/github.com/klauspost/compress/fse#Compress) function.
You must provide input and will receive the output and maybe an error.
These error values can be returned:
| Error | Description |
|---------------------|-----------------------------------------------------------------------------|
| `<nil>` | Everything ok, output is returned |
| `ErrIncompressible` | Returned when input is judged to be too hard to compress |
| `ErrUseRLE` | Returned from the compressor when the input is a single byte value repeated |
| `(error)` | An internal error occurred. |
As can be seen above there are errors that will be returned even under normal operation so it is important to handle these.
To reduce allocations you can provide a [`Scratch`](https://godoc.org/github.com/klauspost/compress/fse#Scratch) object
that can be re-used for successive calls. Both compression and decompression accepts a `Scratch` object, and the same
object can be used for both.
Be aware, that when re-using a `Scratch` object that the *output* buffer is also re-used, so if you are still using this
you must set the `Out` field in the scratch to nil. The same buffer is used for compression and decompression output.
Decompressing is done by calling the [`Decompress`](https://godoc.org/github.com/klauspost/compress/fse#Decompress) function.
You must provide the output from the compression stage, at exactly the size you got back. If you receive an error back
your input was likely corrupted.
It is important to note that a successful decoding does *not* mean your output matches your original input.
There are no integrity checks, so relying on errors from the decompressor does not assure your data is valid.
For more detailed usage, see examples in the [godoc documentation](https://godoc.org/github.com/klauspost/compress/fse#pkg-examples).
# Performance
A lot of factors are affecting speed. Block sizes and compressibility of the material are primary factors.
All compression functions are currently only running on the calling goroutine so only one core will be used per block.
The compressor is significantly faster if symbols are kept as small as possible. The highest byte value of the input
is used to reduce some of the processing, so if all your input is above byte value 64 for instance, it may be
beneficial to transpose all your input values down by 64.
With moderate block sizes around 64k speed are typically 200MB/s per core for compression and
around 300MB/s decompression speed.
The same hardware typically does Huffman (deflate) encoding at 125MB/s and decompression at 100MB/s.
# Plans
At one point, more internals will be exposed to facilitate more "expert" usage of the components.
A streaming interface is also likely to be implemented. Likely compatible with [FSE stream format](https://github.com/Cyan4973/FiniteStateEntropy/blob/dev/programs/fileio.c#L261).
# Contributing
Contributions are always welcome. Be aware that adding public functions will require good justification and breaking
changes will likely not be accepted. If in doubt open an issue before writing the PR.

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import (
"errors"
"io"
)
// bitReader reads a bitstream in reverse.
// The last set bit indicates the start of the stream and is used
// for aligning the input.
type bitReader struct {
in []byte
off uint // next byte to read is at in[off - 1]
value uint64
bitsRead uint8
}
// init initializes and resets the bit reader.
func (b *bitReader) init(in []byte) error {
if len(in) < 1 {
return errors.New("corrupt stream: too short")
}
b.in = in
b.off = uint(len(in))
// The highest bit of the last byte indicates where to start
v := in[len(in)-1]
if v == 0 {
return errors.New("corrupt stream, did not find end of stream")
}
b.bitsRead = 64
b.value = 0
b.fill()
b.fill()
b.bitsRead += 8 - uint8(highBits(uint32(v)))
return nil
}
// getBits will return n bits. n can be 0.
func (b *bitReader) getBits(n uint8) uint16 {
if n == 0 || b.bitsRead >= 64 {
return 0
}
return b.getBitsFast(n)
}
// getBitsFast requires that at least one bit is requested every time.
// There are no checks if the buffer is filled.
func (b *bitReader) getBitsFast(n uint8) uint16 {
const regMask = 64 - 1
v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
b.bitsRead += n
return v
}
// fillFast() will make sure at least 32 bits are available.
// There must be at least 4 bytes available.
func (b *bitReader) fillFast() {
if b.bitsRead < 32 {
return
}
// Do single re-slice to avoid bounds checks.
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
}
// fill() will make sure at least 32 bits are available.
func (b *bitReader) fill() {
if b.bitsRead < 32 {
return
}
if b.off > 4 {
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
return
}
for b.off > 0 {
b.value = (b.value << 8) | uint64(b.in[b.off-1])
b.bitsRead -= 8
b.off--
}
}
// finished returns true if all bits have been read from the bit stream.
func (b *bitReader) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReader) close() error {
// Release reference.
b.in = nil
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}
return nil
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import "fmt"
// bitWriter will write bits.
// First bit will be LSB of the first byte of output.
type bitWriter struct {
bitContainer uint64
nBits uint8
out []byte
}
// bitMask16 is bitmasks. Has extra to avoid bounds check.
var bitMask16 = [32]uint16{
0, 1, 3, 7, 0xF, 0x1F,
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF} /* up to 16 bits */
// addBits16NC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
b.nBits += bits
}
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// addBits16ZeroNC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
// This is fastest if bits can be zero.
func (b *bitWriter) addBits16ZeroNC(value uint16, bits uint8) {
if bits == 0 {
return
}
value <<= (16 - bits) & 15
value >>= (16 - bits) & 15
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// flush will flush all pending full bytes.
// There will be at least 56 bits available for writing when this has been called.
// Using flush32 is faster, but leaves less space for writing.
func (b *bitWriter) flush() {
v := b.nBits >> 3
switch v {
case 0:
case 1:
b.out = append(b.out,
byte(b.bitContainer),
)
case 2:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
)
case 3:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
)
case 4:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
)
case 5:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
)
case 6:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
)
case 7:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
)
case 8:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
byte(b.bitContainer>>56),
)
default:
panic(fmt.Errorf("bits (%d) > 64", b.nBits))
}
b.bitContainer >>= v << 3
b.nBits &= 7
}
// flush32 will flush out, so there are at least 32 bits available for writing.
func (b *bitWriter) flush32() {
if b.nBits < 32 {
return
}
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24))
b.nBits -= 32
b.bitContainer >>= 32
}
// flushAlign will flush remaining full bytes and align to next byte boundary.
func (b *bitWriter) flushAlign() {
nbBytes := (b.nBits + 7) >> 3
for i := uint8(0); i < nbBytes; i++ {
b.out = append(b.out, byte(b.bitContainer>>(i*8)))
}
b.nBits = 0
b.bitContainer = 0
}
// close will write the alignment bit and write the final byte(s)
// to the output.
func (b *bitWriter) close() error {
// End mark
b.addBits16Clean(1, 1)
// flush until next byte.
b.flushAlign()
return nil
}
// reset and continue writing by appending to out.
func (b *bitWriter) reset(out []byte) {
b.bitContainer = 0
b.nBits = 0
b.out = out
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
// byteReader provides a byte reader that reads
// little endian values from a byte stream.
// The input stream is manually advanced.
// The reader performs no bounds checks.
type byteReader struct {
b []byte
off int
}
// init will initialize the reader and set the input.
func (b *byteReader) init(in []byte) {
b.b = in
b.off = 0
}
// advance the stream b n bytes.
func (b *byteReader) advance(n uint) {
b.off += int(n)
}
// Int32 returns a little endian int32 starting at current offset.
func (b byteReader) Int32() int32 {
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := int32(b2[3])
v2 := int32(b2[2])
v1 := int32(b2[1])
v0 := int32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// Uint32 returns a little endian uint32 starting at current offset.
func (b byteReader) Uint32() uint32 {
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := uint32(b2[3])
v2 := uint32(b2[2])
v1 := uint32(b2[1])
v0 := uint32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// unread returns the unread portion of the input.
func (b byteReader) unread() []byte {
return b.b[b.off:]
}
// remain will return the number of bytes remaining.
func (b byteReader) remain() int {
return len(b.b) - b.off
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import (
"errors"
"fmt"
)
// Compress the input bytes. Input must be < 2GB.
// Provide a Scratch buffer to avoid memory allocations.
// Note that the output is also kept in the scratch buffer.
// If input is too hard to compress, ErrIncompressible is returned.
// If input is a single byte value repeated ErrUseRLE is returned.
func Compress(in []byte, s *Scratch) ([]byte, error) {
if len(in) <= 1 {
return nil, ErrIncompressible
}
if len(in) > (2<<30)-1 {
return nil, errors.New("input too big, must be < 2GB")
}
s, err := s.prepare(in)
if err != nil {
return nil, err
}
// Create histogram, if none was provided.
maxCount := s.maxCount
if maxCount == 0 {
maxCount = s.countSimple(in)
}
// Reset for next run.
s.clearCount = true
s.maxCount = 0
if maxCount == len(in) {
// One symbol, use RLE
return nil, ErrUseRLE
}
if maxCount == 1 || maxCount < (len(in)>>7) {
// Each symbol present maximum once or too well distributed.
return nil, ErrIncompressible
}
s.optimalTableLog()
err = s.normalizeCount()
if err != nil {
return nil, err
}
err = s.writeCount()
if err != nil {
return nil, err
}
if false {
err = s.validateNorm()
if err != nil {
return nil, err
}
}
err = s.buildCTable()
if err != nil {
return nil, err
}
err = s.compress(in)
if err != nil {
return nil, err
}
s.Out = s.bw.out
// Check if we compressed.
if len(s.Out) >= len(in) {
return nil, ErrIncompressible
}
return s.Out, nil
}
// cState contains the compression state of a stream.
type cState struct {
bw *bitWriter
stateTable []uint16
state uint16
}
// init will initialize the compression state to the first symbol of the stream.
func (c *cState) init(bw *bitWriter, ct *cTable, tableLog uint8, first symbolTransform) {
c.bw = bw
c.stateTable = ct.stateTable
nbBitsOut := (first.deltaNbBits + (1 << 15)) >> 16
im := int32((nbBitsOut << 16) - first.deltaNbBits)
lu := (im >> nbBitsOut) + first.deltaFindState
c.state = c.stateTable[lu]
return
}
// encode the output symbol provided and write it to the bitstream.
func (c *cState) encode(symbolTT symbolTransform) {
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
c.bw.addBits16NC(c.state, uint8(nbBitsOut))
c.state = c.stateTable[dstState]
}
// encode the output symbol provided and write it to the bitstream.
func (c *cState) encodeZero(symbolTT symbolTransform) {
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
c.bw.addBits16ZeroNC(c.state, uint8(nbBitsOut))
c.state = c.stateTable[dstState]
}
// flush will write the tablelog to the output and flush the remaining full bytes.
func (c *cState) flush(tableLog uint8) {
c.bw.flush32()
c.bw.addBits16NC(c.state, tableLog)
c.bw.flush()
}
// compress is the main compression loop that will encode the input from the last byte to the first.
func (s *Scratch) compress(src []byte) error {
if len(src) <= 2 {
return errors.New("compress: src too small")
}
tt := s.ct.symbolTT[:256]
s.bw.reset(s.Out)
// Our two states each encodes every second byte.
// Last byte encoded (first byte decoded) will always be encoded by c1.
var c1, c2 cState
// Encode so remaining size is divisible by 4.
ip := len(src)
if ip&1 == 1 {
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
c1.encodeZero(tt[src[ip-3]])
ip -= 3
} else {
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
ip -= 2
}
if ip&2 != 0 {
c2.encodeZero(tt[src[ip-1]])
c1.encodeZero(tt[src[ip-2]])
ip -= 2
}
// Main compression loop.
switch {
case !s.zeroBits && s.actualTableLog <= 8:
// We can encode 4 symbols without requiring a flush.
// We do not need to check if any output is 0 bits.
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encode(tt[v0])
c1.encode(tt[v1])
c2.encode(tt[v2])
c1.encode(tt[v3])
ip -= 4
}
case !s.zeroBits:
// We do not need to check if any output is 0 bits.
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encode(tt[v0])
c1.encode(tt[v1])
s.bw.flush32()
c2.encode(tt[v2])
c1.encode(tt[v3])
ip -= 4
}
case s.actualTableLog <= 8:
// We can encode 4 symbols without requiring a flush
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encodeZero(tt[v0])
c1.encodeZero(tt[v1])
c2.encodeZero(tt[v2])
c1.encodeZero(tt[v3])
ip -= 4
}
default:
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encodeZero(tt[v0])
c1.encodeZero(tt[v1])
s.bw.flush32()
c2.encodeZero(tt[v2])
c1.encodeZero(tt[v3])
ip -= 4
}
}
// Flush final state.
// Used to initialize state when decoding.
c2.flush(s.actualTableLog)
c1.flush(s.actualTableLog)
return s.bw.close()
}
// writeCount will write the normalized histogram count to header.
// This is read back by readNCount.
func (s *Scratch) writeCount() error {
var (
tableLog = s.actualTableLog
tableSize = 1 << tableLog
previous0 bool
charnum uint16
maxHeaderSize = ((int(s.symbolLen) * int(tableLog)) >> 3) + 3
// Write Table Size
bitStream = uint32(tableLog - minTablelog)
bitCount = uint(4)
remaining = int16(tableSize + 1) /* +1 for extra accuracy */
threshold = int16(tableSize)
nbBits = uint(tableLog + 1)
)
if cap(s.Out) < maxHeaderSize {
s.Out = make([]byte, 0, s.br.remain()+maxHeaderSize)
}
outP := uint(0)
out := s.Out[:maxHeaderSize]
// stops at 1
for remaining > 1 {
if previous0 {
start := charnum
for s.norm[charnum] == 0 {
charnum++
}
for charnum >= start+24 {
start += 24
bitStream += uint32(0xFFFF) << bitCount
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
}
for charnum >= start+3 {
start += 3
bitStream += 3 << bitCount
bitCount += 2
}
bitStream += uint32(charnum-start) << bitCount
bitCount += 2
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
count := s.norm[charnum]
charnum++
max := (2*threshold - 1) - remaining
if count < 0 {
remaining += count
} else {
remaining -= count
}
count++ // +1 for extra accuracy
if count >= threshold {
count += max // [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[
}
bitStream += uint32(count) << bitCount
bitCount += nbBits
if count < max {
bitCount--
}
previous0 = count == 1
if remaining < 1 {
return errors.New("internal error: remaining<1")
}
for remaining < threshold {
nbBits--
threshold >>= 1
}
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += (bitCount + 7) / 8
if uint16(charnum) > s.symbolLen {
return errors.New("internal error: charnum > s.symbolLen")
}
s.Out = out[:outP]
return nil
}
// symbolTransform contains the state transform for a symbol.
type symbolTransform struct {
deltaFindState int32
deltaNbBits uint32
}
// String prints values as a human readable string.
func (s symbolTransform) String() string {
return fmt.Sprintf("dnbits: %08x, fs:%d", s.deltaNbBits, s.deltaFindState)
}
// cTable contains tables used for compression.
type cTable struct {
tableSymbol []byte
stateTable []uint16
symbolTT []symbolTransform
}
// allocCtable will allocate tables needed for compression.
// If existing tables a re big enough, they are simply re-used.
func (s *Scratch) allocCtable() {
tableSize := 1 << s.actualTableLog
// get tableSymbol that is big enough.
if cap(s.ct.tableSymbol) < int(tableSize) {
s.ct.tableSymbol = make([]byte, tableSize)
}
s.ct.tableSymbol = s.ct.tableSymbol[:tableSize]
ctSize := tableSize
if cap(s.ct.stateTable) < ctSize {
s.ct.stateTable = make([]uint16, ctSize)
}
s.ct.stateTable = s.ct.stateTable[:ctSize]
if cap(s.ct.symbolTT) < 256 {
s.ct.symbolTT = make([]symbolTransform, 256)
}
s.ct.symbolTT = s.ct.symbolTT[:256]
}
// buildCTable will populate the compression table so it is ready to be used.
func (s *Scratch) buildCTable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
var cumul [maxSymbolValue + 2]int16
s.allocCtable()
tableSymbol := s.ct.tableSymbol[:tableSize]
// symbol start positions
{
cumul[0] = 0
for ui, v := range s.norm[:s.symbolLen-1] {
u := byte(ui) // one less than reference
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = u
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
}
// Encode last symbol separately to avoid overflowing u
u := int(s.symbolLen - 1)
v := s.norm[s.symbolLen-1]
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = byte(u)
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
if uint32(cumul[s.symbolLen]) != tableSize {
return fmt.Errorf("internal error: expected cumul[s.symbolLen] (%d) == tableSize (%d)", cumul[s.symbolLen], tableSize)
}
cumul[s.symbolLen] = int16(tableSize) + 1
}
// Spread symbols
s.zeroBits = false
{
step := tableStep(tableSize)
tableMask := tableSize - 1
var position uint32
// if any symbol > largeLimit, we may have 0 bits output.
largeLimit := int16(1 << (s.actualTableLog - 1))
for ui, v := range s.norm[:s.symbolLen] {
symbol := byte(ui)
if v > largeLimit {
s.zeroBits = true
}
for nbOccurrences := int16(0); nbOccurrences < v; nbOccurrences++ {
tableSymbol[position] = symbol
position = (position + step) & tableMask
for position > highThreshold {
position = (position + step) & tableMask
} /* Low proba area */
}
}
// Check if we have gone through all positions
if position != 0 {
return errors.New("position!=0")
}
}
// Build table
table := s.ct.stateTable
{
tsi := int(tableSize)
for u, v := range tableSymbol {
// TableU16 : sorted by symbol order; gives next state value
table[cumul[v]] = uint16(tsi + u)
cumul[v]++
}
}
// Build Symbol Transformation Table
{
total := int16(0)
symbolTT := s.ct.symbolTT[:s.symbolLen]
tableLog := s.actualTableLog
tl := (uint32(tableLog) << 16) - (1 << tableLog)
for i, v := range s.norm[:s.symbolLen] {
switch v {
case 0:
case -1, 1:
symbolTT[i].deltaNbBits = tl
symbolTT[i].deltaFindState = int32(total - 1)
total++
default:
maxBitsOut := uint32(tableLog) - highBits(uint32(v-1))
minStatePlus := uint32(v) << maxBitsOut
symbolTT[i].deltaNbBits = (maxBitsOut << 16) - minStatePlus
symbolTT[i].deltaFindState = int32(total - v)
total += v
}
}
if total != int16(tableSize) {
return fmt.Errorf("total mismatch %d (got) != %d (want)", total, tableSize)
}
}
return nil
}
// countSimple will create a simple histogram in s.count.
// Returns the biggest count.
// Does not update s.clearCount.
func (s *Scratch) countSimple(in []byte) (max int) {
for _, v := range in {
s.count[v]++
}
m := uint32(0)
for i, v := range s.count[:] {
if v > m {
m = v
}
if v > 0 {
s.symbolLen = uint16(i) + 1
}
}
return int(m)
}
// minTableLog provides the minimum logSize to safely represent a distribution.
func (s *Scratch) minTableLog() uint8 {
minBitsSrc := highBits(uint32(s.br.remain()-1)) + 1
minBitsSymbols := highBits(uint32(s.symbolLen-1)) + 2
if minBitsSrc < minBitsSymbols {
return uint8(minBitsSrc)
}
return uint8(minBitsSymbols)
}
// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
func (s *Scratch) optimalTableLog() {
tableLog := s.TableLog
minBits := s.minTableLog()
maxBitsSrc := uint8(highBits(uint32(s.br.remain()-1))) - 2
if maxBitsSrc < tableLog {
// Accuracy can be reduced
tableLog = maxBitsSrc
}
if minBits > tableLog {
tableLog = minBits
}
// Need a minimum to safely represent all symbol values
if tableLog < minTablelog {
tableLog = minTablelog
}
if tableLog > maxTableLog {
tableLog = maxTableLog
}
s.actualTableLog = tableLog
}
var rtbTable = [...]uint32{0, 473195, 504333, 520860, 550000, 700000, 750000, 830000}
// normalizeCount will normalize the count of the symbols so
// the total is equal to the table size.
func (s *Scratch) normalizeCount() error {
var (
tableLog = s.actualTableLog
scale = 62 - uint64(tableLog)
step = (1 << 62) / uint64(s.br.remain())
vStep = uint64(1) << (scale - 20)
stillToDistribute = int16(1 << tableLog)
largest int
largestP int16
lowThreshold = (uint32)(s.br.remain() >> tableLog)
)
for i, cnt := range s.count[:s.symbolLen] {
// already handled
// if (count[s] == s.length) return 0; /* rle special case */
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
stillToDistribute--
} else {
proba := (int16)((uint64(cnt) * step) >> scale)
if proba < 8 {
restToBeat := vStep * uint64(rtbTable[proba])
v := uint64(cnt)*step - (uint64(proba) << scale)
if v > restToBeat {
proba++
}
}
if proba > largestP {
largestP = proba
largest = i
}
s.norm[i] = proba
stillToDistribute -= proba
}
}
if -stillToDistribute >= (s.norm[largest] >> 1) {
// corner case, need another normalization method
return s.normalizeCount2()
}
s.norm[largest] += stillToDistribute
return nil
}
// Secondary normalization method.
// To be used when primary method fails.
func (s *Scratch) normalizeCount2() error {
const notYetAssigned = -2
var (
distributed uint32
total = uint32(s.br.remain())
tableLog = s.actualTableLog
lowThreshold = uint32(total >> tableLog)
lowOne = uint32((total * 3) >> (tableLog + 1))
)
for i, cnt := range s.count[:s.symbolLen] {
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
distributed++
total -= cnt
continue
}
if cnt <= lowOne {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
s.norm[i] = notYetAssigned
}
toDistribute := (1 << tableLog) - distributed
if (total / toDistribute) > lowOne {
// risk of rounding to zero
lowOne = uint32((total * 3) / (toDistribute * 2))
for i, cnt := range s.count[:s.symbolLen] {
if (s.norm[i] == notYetAssigned) && (cnt <= lowOne) {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
}
toDistribute = (1 << tableLog) - distributed
}
if distributed == uint32(s.symbolLen)+1 {
// all values are pretty poor;
// probably incompressible data (should have already been detected);
// find max, then give all remaining points to max
var maxV int
var maxC uint32
for i, cnt := range s.count[:s.symbolLen] {
if cnt > maxC {
maxV = i
maxC = cnt
}
}
s.norm[maxV] += int16(toDistribute)
return nil
}
if total == 0 {
// all of the symbols were low enough for the lowOne or lowThreshold
for i := uint32(0); toDistribute > 0; i = (i + 1) % (uint32(s.symbolLen)) {
if s.norm[i] > 0 {
toDistribute--
s.norm[i]++
}
}
return nil
}
var (
vStepLog = 62 - uint64(tableLog)
mid = uint64((1 << (vStepLog - 1)) - 1)
rStep = (((1 << vStepLog) * uint64(toDistribute)) + mid) / uint64(total) // scale on remaining
tmpTotal = mid
)
for i, cnt := range s.count[:s.symbolLen] {
if s.norm[i] == notYetAssigned {
var (
end = tmpTotal + uint64(cnt)*rStep
sStart = uint32(tmpTotal >> vStepLog)
sEnd = uint32(end >> vStepLog)
weight = sEnd - sStart
)
if weight < 1 {
return errors.New("weight < 1")
}
s.norm[i] = int16(weight)
tmpTotal = end
}
}
return nil
}
// validateNorm validates the normalized histogram table.
func (s *Scratch) validateNorm() (err error) {
var total int
for _, v := range s.norm[:s.symbolLen] {
if v >= 0 {
total += int(v)
} else {
total -= int(v)
}
}
defer func() {
if err == nil {
return
}
fmt.Printf("selected TableLog: %d, Symbol length: %d\n", s.actualTableLog, s.symbolLen)
for i, v := range s.norm[:s.symbolLen] {
fmt.Printf("%3d: %5d -> %4d \n", i, s.count[i], v)
}
}()
if total != (1 << s.actualTableLog) {
return fmt.Errorf("warning: Total == %d != %d", total, 1<<s.actualTableLog)
}
for i, v := range s.count[s.symbolLen:] {
if v != 0 {
return fmt.Errorf("warning: Found symbol out of range, %d after cut", i)
}
}
return nil
}

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package fse
import (
"errors"
"fmt"
)
const (
tablelogAbsoluteMax = 15
)
// Decompress a block of data.
// You can provide a scratch buffer to avoid allocations.
// If nil is provided a temporary one will be allocated.
// It is possible, but by no way guaranteed that corrupt data will
// return an error.
// It is up to the caller to verify integrity of the returned data.
// Use a predefined Scrach to set maximum acceptable output size.
func Decompress(b []byte, s *Scratch) ([]byte, error) {
s, err := s.prepare(b)
if err != nil {
return nil, err
}
s.Out = s.Out[:0]
err = s.readNCount()
if err != nil {
return nil, err
}
err = s.buildDtable()
if err != nil {
return nil, err
}
err = s.decompress()
if err != nil {
return nil, err
}
return s.Out, nil
}
// readNCount will read the symbol distribution so decoding tables can be constructed.
func (s *Scratch) readNCount() error {
var (
charnum uint16
previous0 bool
b = &s.br
)
iend := b.remain()
if iend < 4 {
return errors.New("input too small")
}
bitStream := b.Uint32()
nbBits := uint((bitStream & 0xF) + minTablelog) // extract tableLog
if nbBits > tablelogAbsoluteMax {
return errors.New("tableLog too large")
}
bitStream >>= 4
bitCount := uint(4)
s.actualTableLog = uint8(nbBits)
remaining := int32((1 << nbBits) + 1)
threshold := int32(1 << nbBits)
gotTotal := int32(0)
nbBits++
for remaining > 1 {
if previous0 {
n0 := charnum
for (bitStream & 0xFFFF) == 0xFFFF {
n0 += 24
if b.off < iend-5 {
b.advance(2)
bitStream = b.Uint32() >> bitCount
} else {
bitStream >>= 16
bitCount += 16
}
}
for (bitStream & 3) == 3 {
n0 += 3
bitStream >>= 2
bitCount += 2
}
n0 += uint16(bitStream & 3)
bitCount += 2
if n0 > maxSymbolValue {
return errors.New("maxSymbolValue too small")
}
for charnum < n0 {
s.norm[charnum&0xff] = 0
charnum++
}
if b.off <= iend-7 || b.off+int(bitCount>>3) <= iend-4 {
b.advance(bitCount >> 3)
bitCount &= 7
bitStream = b.Uint32() >> bitCount
} else {
bitStream >>= 2
}
}
max := (2*(threshold) - 1) - (remaining)
var count int32
if (int32(bitStream) & (threshold - 1)) < max {
count = int32(bitStream) & (threshold - 1)
bitCount += nbBits - 1
} else {
count = int32(bitStream) & (2*threshold - 1)
if count >= threshold {
count -= max
}
bitCount += nbBits
}
count-- // extra accuracy
if count < 0 {
// -1 means +1
remaining += count
gotTotal -= count
} else {
remaining -= count
gotTotal += count
}
s.norm[charnum&0xff] = int16(count)
charnum++
previous0 = count == 0
for remaining < threshold {
nbBits--
threshold >>= 1
}
if b.off <= iend-7 || b.off+int(bitCount>>3) <= iend-4 {
b.advance(bitCount >> 3)
bitCount &= 7
} else {
bitCount -= (uint)(8 * (len(b.b) - 4 - b.off))
b.off = len(b.b) - 4
}
bitStream = b.Uint32() >> (bitCount & 31)
}
s.symbolLen = charnum
if s.symbolLen <= 1 {
return fmt.Errorf("symbolLen (%d) too small", s.symbolLen)
}
if s.symbolLen > maxSymbolValue+1 {
return fmt.Errorf("symbolLen (%d) too big", s.symbolLen)
}
if remaining != 1 {
return fmt.Errorf("corruption detected (remaining %d != 1)", remaining)
}
if bitCount > 32 {
return fmt.Errorf("corruption detected (bitCount %d > 32)", bitCount)
}
if gotTotal != 1<<s.actualTableLog {
return fmt.Errorf("corruption detected (total %d != %d)", gotTotal, 1<<s.actualTableLog)
}
b.advance((bitCount + 7) >> 3)
return nil
}
// decSymbol contains information about a state entry,
// Including the state offset base, the output symbol and
// the number of bits to read for the low part of the destination state.
type decSymbol struct {
newState uint16
symbol uint8
nbBits uint8
}
// allocDtable will allocate decoding tables if they are not big enough.
func (s *Scratch) allocDtable() {
tableSize := 1 << s.actualTableLog
if cap(s.decTable) < int(tableSize) {
s.decTable = make([]decSymbol, tableSize)
}
s.decTable = s.decTable[:tableSize]
if cap(s.ct.tableSymbol) < 256 {
s.ct.tableSymbol = make([]byte, 256)
}
s.ct.tableSymbol = s.ct.tableSymbol[:256]
if cap(s.ct.stateTable) < 256 {
s.ct.stateTable = make([]uint16, 256)
}
s.ct.stateTable = s.ct.stateTable[:256]
}
// buildDtable will build the decoding table.
func (s *Scratch) buildDtable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
s.allocDtable()
symbolNext := s.ct.stateTable[:256]
// Init, lay down lowprob symbols
s.zeroBits = false
{
largeLimit := int16(1 << (s.actualTableLog - 1))
for i, v := range s.norm[:s.symbolLen] {
if v == -1 {
s.decTable[highThreshold].symbol = uint8(i)
highThreshold--
symbolNext[i] = 1
} else {
if v >= largeLimit {
s.zeroBits = true
}
symbolNext[i] = uint16(v)
}
}
}
// Spread symbols
{
tableMask := tableSize - 1
step := tableStep(tableSize)
position := uint32(0)
for ss, v := range s.norm[:s.symbolLen] {
for i := 0; i < int(v); i++ {
s.decTable[position].symbol = uint8(ss)
position = (position + step) & tableMask
for position > highThreshold {
// lowprob area
position = (position + step) & tableMask
}
}
}
if position != 0 {
// position must reach all cells once, otherwise normalizedCounter is incorrect
return errors.New("corrupted input (position != 0)")
}
}
// Build Decoding table
{
tableSize := uint16(1 << s.actualTableLog)
for u, v := range s.decTable {
symbol := v.symbol
nextState := symbolNext[symbol]
symbolNext[symbol] = nextState + 1
nBits := s.actualTableLog - byte(highBits(uint32(nextState)))
s.decTable[u].nbBits = nBits
newState := (nextState << nBits) - tableSize
if newState > tableSize {
return fmt.Errorf("newState (%d) outside table size (%d)", newState, tableSize)
}
if newState == uint16(u) && nBits == 0 {
// Seems weird that this is possible with nbits > 0.
return fmt.Errorf("newState (%d) == oldState (%d) and no bits", newState, u)
}
s.decTable[u].newState = newState
}
}
return nil
}
// decompress will decompress the bitstream.
// If the buffer is over-read an error is returned.
func (s *Scratch) decompress() error {
br := &s.bits
br.init(s.br.unread())
var s1, s2 decoder
// Initialize and decode first state and symbol.
s1.init(br, s.decTable, s.actualTableLog)
s2.init(br, s.decTable, s.actualTableLog)
// Use temp table to avoid bound checks/append penalty.
var tmp = s.ct.tableSymbol[:256]
var off uint8
// Main part
if !s.zeroBits {
for br.off >= 8 {
br.fillFast()
tmp[off+0] = s1.nextFast()
tmp[off+1] = s2.nextFast()
br.fillFast()
tmp[off+2] = s1.nextFast()
tmp[off+3] = s2.nextFast()
off += 4
if off == 0 {
s.Out = append(s.Out, tmp...)
}
}
} else {
for br.off >= 8 {
br.fillFast()
tmp[off+0] = s1.next()
tmp[off+1] = s2.next()
br.fillFast()
tmp[off+2] = s1.next()
tmp[off+3] = s2.next()
off += 4
if off == 0 {
s.Out = append(s.Out, tmp...)
off = 0
if len(s.Out) >= s.DecompressLimit {
return fmt.Errorf("output size (%d) > DecompressLimit (%d)", len(s.Out), s.DecompressLimit)
}
}
}
}
s.Out = append(s.Out, tmp[:off]...)
// Final bits, a bit more expensive check
for {
if s1.finished() {
s.Out = append(s.Out, s1.final(), s2.final())
break
}
br.fill()
s.Out = append(s.Out, s1.next())
if s2.finished() {
s.Out = append(s.Out, s2.final(), s1.final())
break
}
s.Out = append(s.Out, s2.next())
if len(s.Out) >= s.DecompressLimit {
return fmt.Errorf("output size (%d) > DecompressLimit (%d)", len(s.Out), s.DecompressLimit)
}
}
return br.close()
}
// decoder keeps track of the current state and updates it from the bitstream.
type decoder struct {
state uint16
br *bitReader
dt []decSymbol
}
// init will initialize the decoder and read the first state from the stream.
func (d *decoder) init(in *bitReader, dt []decSymbol, tableLog uint8) {
d.dt = dt
d.br = in
d.state = uint16(in.getBits(tableLog))
}
// next returns the next symbol and sets the next state.
// At least tablelog bits must be available in the bit reader.
func (d *decoder) next() uint8 {
n := &d.dt[d.state]
lowBits := d.br.getBits(n.nbBits)
d.state = n.newState + lowBits
return n.symbol
}
// finished returns true if all bits have been read from the bitstream
// and the next state would require reading bits from the input.
func (d *decoder) finished() bool {
return d.br.finished() && d.dt[d.state].nbBits > 0
}
// final returns the current state symbol without decoding the next.
func (d *decoder) final() uint8 {
return d.dt[d.state].symbol
}
// nextFast returns the next symbol and sets the next state.
// This can only be used if no symbols are 0 bits.
// At least tablelog bits must be available in the bit reader.
func (d *decoder) nextFast() uint8 {
n := d.dt[d.state]
lowBits := d.br.getBitsFast(n.nbBits)
d.state = n.newState + lowBits
return n.symbol
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
// Package fse provides Finite State Entropy encoding and decoding.
//
// Finite State Entropy encoding provides a fast near-optimal symbol encoding/decoding
// for byte blocks as implemented in zstd.
//
// See https://github.com/klauspost/compress/tree/master/fse for more information.
package fse
import (
"errors"
"fmt"
"math/bits"
)
const (
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
maxMemoryUsage = 14
defaultMemoryUsage = 13
maxTableLog = maxMemoryUsage - 2
maxTablesize = 1 << maxTableLog
defaultTablelog = defaultMemoryUsage - 2
minTablelog = 5
maxSymbolValue = 255
)
var (
// ErrIncompressible is returned when input is judged to be too hard to compress.
ErrIncompressible = errors.New("input is not compressible")
// ErrUseRLE is returned from the compressor when the input is a single byte value repeated.
ErrUseRLE = errors.New("input is single value repeated")
)
// Scratch provides temporary storage for compression and decompression.
type Scratch struct {
// Private
count [maxSymbolValue + 1]uint32
norm [maxSymbolValue + 1]int16
symbolLen uint16 // Length of active part of the symbol table.
actualTableLog uint8 // Selected tablelog.
br byteReader
bits bitReader
bw bitWriter
ct cTable // Compression tables.
decTable []decSymbol // Decompression table.
zeroBits bool // no bits has prob > 50%.
clearCount bool // clear count
maxCount int // count of the most probable symbol
// Per block parameters.
// These can be used to override compression parameters of the block.
// Do not touch, unless you know what you are doing.
// Out is output buffer.
// If the scratch is re-used before the caller is done processing the output,
// set this field to nil.
// Otherwise the output buffer will be re-used for next Compression/Decompression step
// and allocation will be avoided.
Out []byte
// MaxSymbolValue will override the maximum symbol value of the next block.
MaxSymbolValue uint8
// TableLog will attempt to override the tablelog for the next block.
TableLog uint8
// DecompressLimit limits the maximum decoded size acceptable.
// If > 0 decompression will stop when approximately this many bytes
// has been decoded.
// If 0, maximum size will be 2GB.
DecompressLimit int
}
// Histogram allows to populate the histogram and skip that step in the compression,
// It otherwise allows to inspect the histogram when compression is done.
// To indicate that you have populated the histogram call HistogramFinished
// with the value of the highest populated symbol, as well as the number of entries
// in the most populated entry. These are accepted at face value.
// The returned slice will always be length 256.
func (s *Scratch) Histogram() []uint32 {
return s.count[:]
}
// HistogramFinished can be called to indicate that the histogram has been populated.
// maxSymbol is the index of the highest set symbol of the next data segment.
// maxCount is the number of entries in the most populated entry.
// These are accepted at face value.
func (s *Scratch) HistogramFinished(maxSymbol uint8, maxCount int) {
s.maxCount = maxCount
s.symbolLen = uint16(maxSymbol) + 1
s.clearCount = maxCount != 0
}
// prepare will prepare and allocate scratch tables used for both compression and decompression.
func (s *Scratch) prepare(in []byte) (*Scratch, error) {
if s == nil {
s = &Scratch{}
}
if s.MaxSymbolValue == 0 {
s.MaxSymbolValue = 255
}
if s.TableLog == 0 {
s.TableLog = defaultTablelog
}
if s.TableLog > maxTableLog {
return nil, fmt.Errorf("tableLog (%d) > maxTableLog (%d)", s.TableLog, maxTableLog)
}
if cap(s.Out) == 0 {
s.Out = make([]byte, 0, len(in))
}
if s.clearCount && s.maxCount == 0 {
for i := range s.count {
s.count[i] = 0
}
s.clearCount = false
}
s.br.init(in)
if s.DecompressLimit == 0 {
// Max size 2GB.
s.DecompressLimit = (2 << 30) - 1
}
return s, nil
}
// tableStep returns the next table index.
func tableStep(tableSize uint32) uint32 {
return (tableSize >> 1) + (tableSize >> 3) + 3
}
func highBits(val uint32) (n uint32) {
return uint32(bits.Len32(val) - 1)
}

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/huff0-fuzz.zip

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# Huff0 entropy compression
This package provides Huff0 encoding and decoding as used in zstd.
[Huff0](https://github.com/Cyan4973/FiniteStateEntropy#new-generation-entropy-coders),
a Huffman codec designed for modern CPU, featuring OoO (Out of Order) operations on multiple ALU
(Arithmetic Logic Unit), achieving extremely fast compression and decompression speeds.
This can be used for compressing input with a lot of similar input values to the smallest number of bytes.
This does not perform any multi-byte [dictionary coding](https://en.wikipedia.org/wiki/Dictionary_coder) as LZ coders,
but it can be used as a secondary step to compressors (like Snappy) that does not do entropy encoding.
* [Godoc documentation](https://godoc.org/github.com/klauspost/compress/huff0)
THIS PACKAGE IS NOT CONSIDERED STABLE AND API OR ENCODING MAY CHANGE IN THE FUTURE.
## News
* Mar 2018: First implementation released. Consider this beta software for now.
# Usage
This package provides a low level interface that allows to compress single independent blocks.
Each block is separate, and there is no built in integrity checks.
This means that the caller should keep track of block sizes and also do checksums if needed.
Compressing a block is done via the [`Compress1X`](https://godoc.org/github.com/klauspost/compress/huff0#Compress1X) and
[`Compress4X`](https://godoc.org/github.com/klauspost/compress/huff0#Compress4X) functions.
You must provide input and will receive the output and maybe an error.
These error values can be returned:
| Error | Description |
|---------------------|-----------------------------------------------------------------------------|
| `<nil>` | Everything ok, output is returned |
| `ErrIncompressible` | Returned when input is judged to be too hard to compress |
| `ErrUseRLE` | Returned from the compressor when the input is a single byte value repeated |
| `ErrTooBig` | Returned if the input block exceeds the maximum allowed size (128 Kib) |
| `(error)` | An internal error occurred. |
As can be seen above some of there are errors that will be returned even under normal operation so it is important to handle these.
To reduce allocations you can provide a [`Scratch`](https://godoc.org/github.com/klauspost/compress/huff0#Scratch) object
that can be re-used for successive calls. Both compression and decompression accepts a `Scratch` object, and the same
object can be used for both.
Be aware, that when re-using a `Scratch` object that the *output* buffer is also re-used, so if you are still using this
you must set the `Out` field in the scratch to nil. The same buffer is used for compression and decompression output.
The `Scratch` object will retain state that allows to re-use previous tables for encoding and decoding.
## Tables and re-use
Huff0 allows for reusing tables from the previous block to save space if that is expected to give better/faster results.
The Scratch object allows you to set a [`ReusePolicy`](https://godoc.org/github.com/klauspost/compress/huff0#ReusePolicy)
that controls this behaviour. See the documentation for details. This can be altered between each block.
Do however note that this information is *not* stored in the output block and it is up to the users of the package to
record whether [`ReadTable`](https://godoc.org/github.com/klauspost/compress/huff0#ReadTable) should be called,
based on the boolean reported back from the CompressXX call.
If you want to store the table separate from the data, you can access them as `OutData` and `OutTable` on the
[`Scratch`](https://godoc.org/github.com/klauspost/compress/huff0#Scratch) object.
## Decompressing
The first part of decoding is to initialize the decoding table through [`ReadTable`](https://godoc.org/github.com/klauspost/compress/huff0#ReadTable).
This will initialize the decoding tables.
You can supply the complete block to `ReadTable` and it will return the data part of the block
which can be given to the decompressor.
Decompressing is done by calling the [`Decompress1X`](https://godoc.org/github.com/klauspost/compress/huff0#Scratch.Decompress1X)
or [`Decompress4X`](https://godoc.org/github.com/klauspost/compress/huff0#Scratch.Decompress4X) function.
You must provide the output from the compression stage, at exactly the size you got back. If you receive an error back
your input was likely corrupted.
It is important to note that a successful decoding does *not* mean your output matches your original input.
There are no integrity checks, so relying on errors from the decompressor does not assure your data is valid.
# Contributing
Contributions are always welcome. Be aware that adding public functions will require good justification and breaking
changes will likely not be accepted. If in doubt open an issue before writing the PR.

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package huff0
import (
"errors"
"io"
)
// bitReader reads a bitstream in reverse.
// The last set bit indicates the start of the stream and is used
// for aligning the input.
type bitReader struct {
in []byte
off uint // next byte to read is at in[off - 1]
value uint64
bitsRead uint8
}
// init initializes and resets the bit reader.
func (b *bitReader) init(in []byte) error {
if len(in) < 1 {
return errors.New("corrupt stream: too short")
}
b.in = in
b.off = uint(len(in))
// The highest bit of the last byte indicates where to start
v := in[len(in)-1]
if v == 0 {
return errors.New("corrupt stream, did not find end of stream")
}
b.bitsRead = 64
b.value = 0
b.fill()
b.fill()
b.bitsRead += 8 - uint8(highBit32(uint32(v)))
return nil
}
// getBits will return n bits. n can be 0.
func (b *bitReader) getBits(n uint8) uint16 {
if n == 0 || b.bitsRead >= 64 {
return 0
}
return b.getBitsFast(n)
}
// getBitsFast requires that at least one bit is requested every time.
// There are no checks if the buffer is filled.
func (b *bitReader) getBitsFast(n uint8) uint16 {
const regMask = 64 - 1
v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
b.bitsRead += n
return v
}
// peekBitsFast requires that at least one bit is requested every time.
// There are no checks if the buffer is filled.
func (b *bitReader) peekBitsFast(n uint8) uint16 {
const regMask = 64 - 1
v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
return v
}
// fillFast() will make sure at least 32 bits are available.
// There must be at least 4 bytes available.
func (b *bitReader) fillFast() {
if b.bitsRead < 32 {
return
}
// Do single re-slice to avoid bounds checks.
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
}
// fill() will make sure at least 32 bits are available.
func (b *bitReader) fill() {
if b.bitsRead < 32 {
return
}
if b.off > 4 {
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
return
}
for b.off > 0 {
b.value = (b.value << 8) | uint64(b.in[b.off-1])
b.bitsRead -= 8
b.off--
}
}
// finished returns true if all bits have been read from the bit stream.
func (b *bitReader) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReader) close() error {
// Release reference.
b.in = nil
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}
return nil
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package huff0
import "fmt"
// bitWriter will write bits.
// First bit will be LSB of the first byte of output.
type bitWriter struct {
bitContainer uint64
nBits uint8
out []byte
}
// bitMask16 is bitmasks. Has extra to avoid bounds check.
var bitMask16 = [32]uint16{
0, 1, 3, 7, 0xF, 0x1F,
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF} /* up to 16 bits */
// addBits16NC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
b.nBits += bits
}
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
func (b *bitWriter) encSymbol(ct cTable, symbol byte) {
enc := ct[symbol]
b.bitContainer |= uint64(enc.val) << (b.nBits & 63)
b.nBits += enc.nBits
}
// addBits16ZeroNC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
// This is fastest if bits can be zero.
func (b *bitWriter) addBits16ZeroNC(value uint16, bits uint8) {
if bits == 0 {
return
}
value <<= (16 - bits) & 15
value >>= (16 - bits) & 15
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// flush will flush all pending full bytes.
// There will be at least 56 bits available for writing when this has been called.
// Using flush32 is faster, but leaves less space for writing.
func (b *bitWriter) flush() {
v := b.nBits >> 3
switch v {
case 0:
return
case 1:
b.out = append(b.out,
byte(b.bitContainer),
)
b.bitContainer >>= 1 << 3
case 2:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
)
b.bitContainer >>= 2 << 3
case 3:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
)
b.bitContainer >>= 3 << 3
case 4:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
)
b.bitContainer >>= 4 << 3
case 5:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
)
b.bitContainer >>= 5 << 3
case 6:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
)
b.bitContainer >>= 6 << 3
case 7:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
)
b.bitContainer >>= 7 << 3
case 8:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
byte(b.bitContainer>>56),
)
b.bitContainer = 0
b.nBits = 0
return
default:
panic(fmt.Errorf("bits (%d) > 64", b.nBits))
}
b.nBits &= 7
}
// flush32 will flush out, so there are at least 32 bits available for writing.
func (b *bitWriter) flush32() {
if b.nBits < 32 {
return
}
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24))
b.nBits -= 32
b.bitContainer >>= 32
}
// flushAlign will flush remaining full bytes and align to next byte boundary.
func (b *bitWriter) flushAlign() {
nbBytes := (b.nBits + 7) >> 3
for i := uint8(0); i < nbBytes; i++ {
b.out = append(b.out, byte(b.bitContainer>>(i*8)))
}
b.nBits = 0
b.bitContainer = 0
}
// close will write the alignment bit and write the final byte(s)
// to the output.
func (b *bitWriter) close() error {
// End mark
b.addBits16Clean(1, 1)
// flush until next byte.
b.flushAlign()
return nil
}
// reset and continue writing by appending to out.
func (b *bitWriter) reset(out []byte) {
b.bitContainer = 0
b.nBits = 0
b.out = out
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package huff0
// byteReader provides a byte reader that reads
// little endian values from a byte stream.
// The input stream is manually advanced.
// The reader performs no bounds checks.
type byteReader struct {
b []byte
off int
}
// init will initialize the reader and set the input.
func (b *byteReader) init(in []byte) {
b.b = in
b.off = 0
}
// advance the stream b n bytes.
func (b *byteReader) advance(n uint) {
b.off += int(n)
}
// Int32 returns a little endian int32 starting at current offset.
func (b byteReader) Int32() int32 {
v3 := int32(b.b[b.off+3])
v2 := int32(b.b[b.off+2])
v1 := int32(b.b[b.off+1])
v0 := int32(b.b[b.off])
return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
}
// Uint32 returns a little endian uint32 starting at current offset.
func (b byteReader) Uint32() uint32 {
v3 := uint32(b.b[b.off+3])
v2 := uint32(b.b[b.off+2])
v1 := uint32(b.b[b.off+1])
v0 := uint32(b.b[b.off])
return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
}
// unread returns the unread portion of the input.
func (b byteReader) unread() []byte {
return b.b[b.off:]
}
// remain will return the number of bytes remaining.
func (b byteReader) remain() int {
return len(b.b) - b.off
}

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package huff0
import (
"fmt"
"runtime"
"sync"
)
// Compress1X will compress the input.
// The output can be decoded using Decompress1X.
// Supply a Scratch object. The scratch object contains state about re-use,
// So when sharing across independent encodes, be sure to set the re-use policy.
func Compress1X(in []byte, s *Scratch) (out []byte, reUsed bool, err error) {
s, err = s.prepare(in)
if err != nil {
return nil, false, err
}
return compress(in, s, s.compress1X)
}
// Compress4X will compress the input. The input is split into 4 independent blocks
// and compressed similar to Compress1X.
// The output can be decoded using Decompress4X.
// Supply a Scratch object. The scratch object contains state about re-use,
// So when sharing across independent encodes, be sure to set the re-use policy.
func Compress4X(in []byte, s *Scratch) (out []byte, reUsed bool, err error) {
s, err = s.prepare(in)
if err != nil {
return nil, false, err
}
if false {
// TODO: compress4Xp only slightly faster.
const parallelThreshold = 8 << 10
if len(in) < parallelThreshold || runtime.GOMAXPROCS(0) == 1 {
return compress(in, s, s.compress4X)
}
return compress(in, s, s.compress4Xp)
}
return compress(in, s, s.compress4X)
}
func compress(in []byte, s *Scratch, compressor func(src []byte) ([]byte, error)) (out []byte, reUsed bool, err error) {
// Nuke previous table if we cannot reuse anyway.
if s.Reuse == ReusePolicyNone {
s.prevTable = s.prevTable[:0]
}
// Create histogram, if none was provided.
maxCount := s.maxCount
var canReuse = false
if maxCount == 0 {
maxCount, canReuse = s.countSimple(in)
} else {
canReuse = s.canUseTable(s.prevTable)
}
// Reset for next run.
s.clearCount = true
s.maxCount = 0
if maxCount >= len(in) {
if maxCount > len(in) {
return nil, false, fmt.Errorf("maxCount (%d) > length (%d)", maxCount, len(in))
}
if len(in) == 1 {
return nil, false, ErrIncompressible
}
// One symbol, use RLE
return nil, false, ErrUseRLE
}
if maxCount == 1 || maxCount < (len(in)>>7) {
// Each symbol present maximum once or too well distributed.
return nil, false, ErrIncompressible
}
if s.Reuse == ReusePolicyPrefer && canReuse {
keepTable := s.cTable
s.cTable = s.prevTable
s.Out, err = compressor(in)
s.cTable = keepTable
if err == nil && len(s.Out) < len(in) {
s.OutData = s.Out
return s.Out, true, nil
}
// Do not attempt to re-use later.
s.prevTable = s.prevTable[:0]
}
// Calculate new table.
s.optimalTableLog()
err = s.buildCTable()
if err != nil {
return nil, false, err
}
if false && !s.canUseTable(s.cTable) {
panic("invalid table generated")
}
if s.Reuse == ReusePolicyAllow && canReuse {
hSize := len(s.Out)
oldSize := s.prevTable.estimateSize(s.count[:s.symbolLen])
newSize := s.cTable.estimateSize(s.count[:s.symbolLen])
if oldSize <= hSize+newSize || hSize+12 >= len(in) {
// Retain cTable even if we re-use.
keepTable := s.cTable
s.cTable = s.prevTable
s.Out, err = compressor(in)
s.cTable = keepTable
if len(s.Out) >= len(in) {
return nil, false, ErrIncompressible
}
s.OutData = s.Out
return s.Out, true, nil
}
}
// Use new table
err = s.cTable.write(s)
if err != nil {
s.OutTable = nil
return nil, false, err
}
s.OutTable = s.Out
// Compress using new table
s.Out, err = compressor(in)
if err != nil {
s.OutTable = nil
return nil, false, err
}
if len(s.Out) >= len(in) {
s.OutTable = nil
return nil, false, ErrIncompressible
}
// Move current table into previous.
s.prevTable, s.cTable = s.cTable, s.prevTable[:0]
s.OutData = s.Out[len(s.OutTable):]
return s.Out, false, nil
}
func (s *Scratch) compress1X(src []byte) ([]byte, error) {
return s.compress1xDo(s.Out, src)
}
func (s *Scratch) compress1xDo(dst, src []byte) ([]byte, error) {
var bw = bitWriter{out: dst}
// N is length divisible by 4.
n := len(src)
n -= n & 3
cTable := s.cTable[:256]
// Encode last bytes.
for i := len(src) & 3; i > 0; i-- {
bw.encSymbol(cTable, src[n+i-1])
}
if s.actualTableLog <= 8 {
n -= 4
for ; n >= 0; n -= 4 {
tmp := src[n : n+4]
// tmp should be len 4
bw.flush32()
bw.encSymbol(cTable, tmp[3])
bw.encSymbol(cTable, tmp[2])
bw.encSymbol(cTable, tmp[1])
bw.encSymbol(cTable, tmp[0])
}
} else {
n -= 4
for ; n >= 0; n -= 4 {
tmp := src[n : n+4]
// tmp should be len 4
bw.flush32()
bw.encSymbol(cTable, tmp[3])
bw.encSymbol(cTable, tmp[2])
bw.flush32()
bw.encSymbol(cTable, tmp[1])
bw.encSymbol(cTable, tmp[0])
}
}
err := bw.close()
return bw.out, err
}
var sixZeros [6]byte
func (s *Scratch) compress4X(src []byte) ([]byte, error) {
if len(src) < 12 {
return nil, ErrIncompressible
}
segmentSize := (len(src) + 3) / 4
// Add placeholder for output length
offsetIdx := len(s.Out)
s.Out = append(s.Out, sixZeros[:]...)
for i := 0; i < 4; i++ {
toDo := src
if len(toDo) > segmentSize {
toDo = toDo[:segmentSize]
}
src = src[len(toDo):]
var err error
idx := len(s.Out)
s.Out, err = s.compress1xDo(s.Out, toDo)
if err != nil {
return nil, err
}
// Write compressed length as little endian before block.
if i < 3 {
// Last length is not written.
length := len(s.Out) - idx
s.Out[i*2+offsetIdx] = byte(length)
s.Out[i*2+offsetIdx+1] = byte(length >> 8)
}
}
return s.Out, nil
}
// compress4Xp will compress 4 streams using separate goroutines.
func (s *Scratch) compress4Xp(src []byte) ([]byte, error) {
if len(src) < 12 {
return nil, ErrIncompressible
}
// Add placeholder for output length
s.Out = s.Out[:6]
segmentSize := (len(src) + 3) / 4
var wg sync.WaitGroup
var errs [4]error
wg.Add(4)
for i := 0; i < 4; i++ {
toDo := src
if len(toDo) > segmentSize {
toDo = toDo[:segmentSize]
}
src = src[len(toDo):]
// Separate goroutine for each block.
go func(i int) {
s.tmpOut[i], errs[i] = s.compress1xDo(s.tmpOut[i][:0], toDo)
wg.Done()
}(i)
}
wg.Wait()
for i := 0; i < 4; i++ {
if errs[i] != nil {
return nil, errs[i]
}
o := s.tmpOut[i]
// Write compressed length as little endian before block.
if i < 3 {
// Last length is not written.
s.Out[i*2] = byte(len(o))
s.Out[i*2+1] = byte(len(o) >> 8)
}
// Write output.
s.Out = append(s.Out, o...)
}
return s.Out, nil
}
// countSimple will create a simple histogram in s.count.
// Returns the biggest count.
// Does not update s.clearCount.
func (s *Scratch) countSimple(in []byte) (max int, reuse bool) {
reuse = true
for _, v := range in {
s.count[v]++
}
m := uint32(0)
if len(s.prevTable) > 0 {
for i, v := range s.count[:] {
if v > m {
m = v
}
if v > 0 {
s.symbolLen = uint16(i) + 1
if i >= len(s.prevTable) {
reuse = false
} else {
if s.prevTable[i].nBits == 0 {
reuse = false
}
}
}
}
return int(m), reuse
}
for i, v := range s.count[:] {
if v > m {
m = v
}
if v > 0 {
s.symbolLen = uint16(i) + 1
}
}
return int(m), false
}
func (s *Scratch) canUseTable(c cTable) bool {
if len(c) < int(s.symbolLen) {
return false
}
for i, v := range s.count[:s.symbolLen] {
if v != 0 && c[i].nBits == 0 {
return false
}
}
return true
}
// minTableLog provides the minimum logSize to safely represent a distribution.
func (s *Scratch) minTableLog() uint8 {
minBitsSrc := highBit32(uint32(s.br.remain()-1)) + 1
minBitsSymbols := highBit32(uint32(s.symbolLen-1)) + 2
if minBitsSrc < minBitsSymbols {
return uint8(minBitsSrc)
}
return uint8(minBitsSymbols)
}
// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
func (s *Scratch) optimalTableLog() {
tableLog := s.TableLog
minBits := s.minTableLog()
maxBitsSrc := uint8(highBit32(uint32(s.br.remain()-1))) - 2
if maxBitsSrc < tableLog {
// Accuracy can be reduced
tableLog = maxBitsSrc
}
if minBits > tableLog {
tableLog = minBits
}
// Need a minimum to safely represent all symbol values
if tableLog < minTablelog {
tableLog = minTablelog
}
if tableLog > tableLogMax {
tableLog = tableLogMax
}
s.actualTableLog = tableLog
}
type cTableEntry struct {
val uint16
nBits uint8
// We have 8 bits extra
}
const huffNodesMask = huffNodesLen - 1
func (s *Scratch) buildCTable() error {
s.huffSort()
if cap(s.cTable) < maxSymbolValue+1 {
s.cTable = make([]cTableEntry, s.symbolLen, maxSymbolValue+1)
} else {
s.cTable = s.cTable[:s.symbolLen]
for i := range s.cTable {
s.cTable[i] = cTableEntry{}
}
}
var startNode = int16(s.symbolLen)
nonNullRank := s.symbolLen - 1
nodeNb := int16(startNode)
huffNode := s.nodes[1 : huffNodesLen+1]
// This overlays the slice above, but allows "-1" index lookups.
// Different from reference implementation.
huffNode0 := s.nodes[0 : huffNodesLen+1]
for huffNode[nonNullRank].count == 0 {
nonNullRank--
}
lowS := int16(nonNullRank)
nodeRoot := nodeNb + lowS - 1
lowN := nodeNb
huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS-1].count
huffNode[lowS].parent, huffNode[lowS-1].parent = uint16(nodeNb), uint16(nodeNb)
nodeNb++
lowS -= 2
for n := nodeNb; n <= nodeRoot; n++ {
huffNode[n].count = 1 << 30
}
// fake entry, strong barrier
huffNode0[0].count = 1 << 31
// create parents
for nodeNb <= nodeRoot {
var n1, n2 int16
if huffNode0[lowS+1].count < huffNode0[lowN+1].count {
n1 = lowS
lowS--
} else {
n1 = lowN
lowN++
}
if huffNode0[lowS+1].count < huffNode0[lowN+1].count {
n2 = lowS
lowS--
} else {
n2 = lowN
lowN++
}
huffNode[nodeNb].count = huffNode0[n1+1].count + huffNode0[n2+1].count
huffNode0[n1+1].parent, huffNode0[n2+1].parent = uint16(nodeNb), uint16(nodeNb)
nodeNb++
}
// distribute weights (unlimited tree height)
huffNode[nodeRoot].nbBits = 0
for n := nodeRoot - 1; n >= startNode; n-- {
huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1
}
for n := uint16(0); n <= nonNullRank; n++ {
huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1
}
s.actualTableLog = s.setMaxHeight(int(nonNullRank))
maxNbBits := s.actualTableLog
// fill result into tree (val, nbBits)
if maxNbBits > tableLogMax {
return fmt.Errorf("internal error: maxNbBits (%d) > tableLogMax (%d)", maxNbBits, tableLogMax)
}
var nbPerRank [tableLogMax + 1]uint16
var valPerRank [tableLogMax + 1]uint16
for _, v := range huffNode[:nonNullRank+1] {
nbPerRank[v.nbBits]++
}
// determine stating value per rank
{
min := uint16(0)
for n := maxNbBits; n > 0; n-- {
// get starting value within each rank
valPerRank[n] = min
min += nbPerRank[n]
min >>= 1
}
}
// push nbBits per symbol, symbol order
// TODO: changed `s.symbolLen` -> `nonNullRank+1` (micro-opt)
for _, v := range huffNode[:nonNullRank+1] {
s.cTable[v.symbol].nBits = v.nbBits
}
// assign value within rank, symbol order
for n, val := range s.cTable[:s.symbolLen] {
v := valPerRank[val.nBits]
s.cTable[n].val = v
valPerRank[val.nBits] = v + 1
}
return nil
}
// huffSort will sort symbols, decreasing order.
func (s *Scratch) huffSort() {
type rankPos struct {
base uint32
current uint32
}
// Clear nodes
nodes := s.nodes[:huffNodesLen+1]
s.nodes = nodes
nodes = nodes[1 : huffNodesLen+1]
// Sort into buckets based on length of symbol count.
var rank [32]rankPos
for _, v := range s.count[:s.symbolLen] {
r := highBit32(v+1) & 31
rank[r].base++
}
for n := 30; n > 0; n-- {
rank[n-1].base += rank[n].base
}
for n := range rank[:] {
rank[n].current = rank[n].base
}
for n, c := range s.count[:s.symbolLen] {
r := (highBit32(c+1) + 1) & 31
pos := rank[r].current
rank[r].current++
prev := nodes[(pos-1)&huffNodesMask]
for pos > rank[r].base && c > prev.count {
nodes[pos&huffNodesMask] = prev
pos--
prev = nodes[(pos-1)&huffNodesMask]
}
nodes[pos&huffNodesMask] = nodeElt{count: c, symbol: byte(n)}
}
return
}
func (s *Scratch) setMaxHeight(lastNonNull int) uint8 {
maxNbBits := s.TableLog
huffNode := s.nodes[1 : huffNodesLen+1]
//huffNode = huffNode[: huffNodesLen]
largestBits := huffNode[lastNonNull].nbBits
// early exit : no elt > maxNbBits
if largestBits <= maxNbBits {
return largestBits
}
totalCost := int(0)
baseCost := int(1) << (largestBits - maxNbBits)
n := uint32(lastNonNull)
for huffNode[n].nbBits > maxNbBits {
totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits))
huffNode[n].nbBits = maxNbBits
n--
}
// n stops at huffNode[n].nbBits <= maxNbBits
for huffNode[n].nbBits == maxNbBits {
n--
}
// n end at index of smallest symbol using < maxNbBits
// renorm totalCost
totalCost >>= largestBits - maxNbBits /* note : totalCost is necessarily a multiple of baseCost */
// repay normalized cost
{
const noSymbol = 0xF0F0F0F0
var rankLast [tableLogMax + 2]uint32
for i := range rankLast[:] {
rankLast[i] = noSymbol
}
// Get pos of last (smallest) symbol per rank
{
currentNbBits := uint8(maxNbBits)
for pos := int(n); pos >= 0; pos-- {
if huffNode[pos].nbBits >= currentNbBits {
continue
}
currentNbBits = huffNode[pos].nbBits // < maxNbBits
rankLast[maxNbBits-currentNbBits] = uint32(pos)
}
}
for totalCost > 0 {
nBitsToDecrease := uint8(highBit32(uint32(totalCost))) + 1
for ; nBitsToDecrease > 1; nBitsToDecrease-- {
highPos := rankLast[nBitsToDecrease]
lowPos := rankLast[nBitsToDecrease-1]
if highPos == noSymbol {
continue
}
if lowPos == noSymbol {
break
}
highTotal := huffNode[highPos].count
lowTotal := 2 * huffNode[lowPos].count
if highTotal <= lowTotal {
break
}
}
// only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !)
// HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary
// FIXME: try to remove
for (nBitsToDecrease <= tableLogMax) && (rankLast[nBitsToDecrease] == noSymbol) {
nBitsToDecrease++
}
totalCost -= 1 << (nBitsToDecrease - 1)
if rankLast[nBitsToDecrease-1] == noSymbol {
// this rank is no longer empty
rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease]
}
huffNode[rankLast[nBitsToDecrease]].nbBits++
if rankLast[nBitsToDecrease] == 0 {
/* special case, reached largest symbol */
rankLast[nBitsToDecrease] = noSymbol
} else {
rankLast[nBitsToDecrease]--
if huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease {
rankLast[nBitsToDecrease] = noSymbol /* this rank is now empty */
}
}
}
for totalCost < 0 { /* Sometimes, cost correction overshoot */
if rankLast[1] == noSymbol { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0 (using maxNbBits) */
for huffNode[n].nbBits == maxNbBits {
n--
}
huffNode[n+1].nbBits--
rankLast[1] = n + 1
totalCost++
continue
}
huffNode[rankLast[1]+1].nbBits--
rankLast[1]++
totalCost++
}
}
return maxNbBits
}
type nodeElt struct {
count uint32
parent uint16
symbol byte
nbBits uint8
}

397
vendor/github.com/klauspost/compress/huff0/decompress.go generated vendored Normal file
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@ -0,0 +1,397 @@
package huff0
import (
"errors"
"fmt"
"io"
"github.com/klauspost/compress/fse"
)
type dTable struct {
single []dEntrySingle
double []dEntryDouble
}
// single-symbols decoding
type dEntrySingle struct {
byte uint8
nBits uint8
}
// double-symbols decoding
type dEntryDouble struct {
seq uint16
nBits uint8
len uint8
}
// ReadTable will read a table from the input.
// The size of the input may be larger than the table definition.
// Any content remaining after the table definition will be returned.
// If no Scratch is provided a new one is allocated.
// The returned Scratch can be used for decoding input using this table.
func ReadTable(in []byte, s *Scratch) (s2 *Scratch, remain []byte, err error) {
s, err = s.prepare(in)
if err != nil {
return s, nil, err
}
if len(in) <= 1 {
return s, nil, errors.New("input too small for table")
}
iSize := in[0]
in = in[1:]
if iSize >= 128 {
// Uncompressed
oSize := iSize - 127
iSize = (oSize + 1) / 2
if int(iSize) > len(in) {
return s, nil, errors.New("input too small for table")
}
for n := uint8(0); n < oSize; n += 2 {
v := in[n/2]
s.huffWeight[n] = v >> 4
s.huffWeight[n+1] = v & 15
}
s.symbolLen = uint16(oSize)
in = in[iSize:]
} else {
if len(in) <= int(iSize) {
return s, nil, errors.New("input too small for table")
}
// FSE compressed weights
s.fse.DecompressLimit = 255
hw := s.huffWeight[:]
s.fse.Out = hw
b, err := fse.Decompress(in[:iSize], s.fse)
s.fse.Out = nil
if err != nil {
return s, nil, err
}
if len(b) > 255 {
return s, nil, errors.New("corrupt input: output table too large")
}
s.symbolLen = uint16(len(b))
in = in[iSize:]
}
// collect weight stats
var rankStats [tableLogMax + 1]uint32
weightTotal := uint32(0)
for _, v := range s.huffWeight[:s.symbolLen] {
if v > tableLogMax {
return s, nil, errors.New("corrupt input: weight too large")
}
rankStats[v]++
weightTotal += (1 << (v & 15)) >> 1
}
if weightTotal == 0 {
return s, nil, errors.New("corrupt input: weights zero")
}
// get last non-null symbol weight (implied, total must be 2^n)
{
tableLog := highBit32(weightTotal) + 1
if tableLog > tableLogMax {
return s, nil, errors.New("corrupt input: tableLog too big")
}
s.actualTableLog = uint8(tableLog)
// determine last weight
{
total := uint32(1) << tableLog
rest := total - weightTotal
verif := uint32(1) << highBit32(rest)
lastWeight := highBit32(rest) + 1
if verif != rest {
// last value must be a clean power of 2
return s, nil, errors.New("corrupt input: last value not power of two")
}
s.huffWeight[s.symbolLen] = uint8(lastWeight)
s.symbolLen++
rankStats[lastWeight]++
}
}
if (rankStats[1] < 2) || (rankStats[1]&1 != 0) {
// by construction : at least 2 elts of rank 1, must be even
return s, nil, errors.New("corrupt input: min elt size, even check failed ")
}
// TODO: Choose between single/double symbol decoding
// Calculate starting value for each rank
{
var nextRankStart uint32
for n := uint8(1); n < s.actualTableLog+1; n++ {
current := nextRankStart
nextRankStart += rankStats[n] << (n - 1)
rankStats[n] = current
}
}
// fill DTable (always full size)
tSize := 1 << tableLogMax
if len(s.dt.single) != tSize {
s.dt.single = make([]dEntrySingle, tSize)
}
for n, w := range s.huffWeight[:s.symbolLen] {
length := (uint32(1) << w) >> 1
d := dEntrySingle{
byte: uint8(n),
nBits: s.actualTableLog + 1 - w,
}
for u := rankStats[w]; u < rankStats[w]+length; u++ {
s.dt.single[u] = d
}
rankStats[w] += length
}
return s, in, nil
}
// Decompress1X will decompress a 1X encoded stream.
// The length of the supplied input must match the end of a block exactly.
// Before this is called, the table must be initialized with ReadTable unless
// the encoder re-used the table.
func (s *Scratch) Decompress1X(in []byte) (out []byte, err error) {
if len(s.dt.single) == 0 {
return nil, errors.New("no table loaded")
}
var br bitReader
err = br.init(in)
if err != nil {
return nil, err
}
s.Out = s.Out[:0]
decode := func() byte {
val := br.peekBitsFast(s.actualTableLog) /* note : actualTableLog >= 1 */
v := s.dt.single[val]
br.bitsRead += v.nBits
return v.byte
}
hasDec := func(v dEntrySingle) byte {
br.bitsRead += v.nBits
return v.byte
}
// Avoid bounds check by always having full sized table.
const tlSize = 1 << tableLogMax
const tlMask = tlSize - 1
dt := s.dt.single[:tlSize]
// Use temp table to avoid bound checks/append penalty.
var tmp = s.huffWeight[:256]
var off uint8
for br.off >= 8 {
br.fillFast()
tmp[off+0] = hasDec(dt[br.peekBitsFast(s.actualTableLog)&tlMask])
tmp[off+1] = hasDec(dt[br.peekBitsFast(s.actualTableLog)&tlMask])
br.fillFast()
tmp[off+2] = hasDec(dt[br.peekBitsFast(s.actualTableLog)&tlMask])
tmp[off+3] = hasDec(dt[br.peekBitsFast(s.actualTableLog)&tlMask])
off += 4
if off == 0 {
s.Out = append(s.Out, tmp...)
}
}
s.Out = append(s.Out, tmp[:off]...)
for !br.finished() {
br.fill()
s.Out = append(s.Out, decode())
}
return s.Out, br.close()
}
// Decompress4X will decompress a 4X encoded stream.
// Before this is called, the table must be initialized with ReadTable unless
// the encoder re-used the table.
// The length of the supplied input must match the end of a block exactly.
// The destination size of the uncompressed data must be known and provided.
func (s *Scratch) Decompress4X(in []byte, dstSize int) (out []byte, err error) {
if len(s.dt.single) == 0 {
return nil, errors.New("no table loaded")
}
if len(in) < 6+(4*1) {
return nil, errors.New("input too small")
}
// TODO: We do not detect when we overrun a buffer, except if the last one does.
var br [4]bitReader
start := 6
for i := 0; i < 3; i++ {
length := int(in[i*2]) | (int(in[i*2+1]) << 8)
if start+length >= len(in) {
return nil, errors.New("truncated input (or invalid offset)")
}
err = br[i].init(in[start : start+length])
if err != nil {
return nil, err
}
start += length
}
err = br[3].init(in[start:])
if err != nil {
return nil, err
}
// Prepare output
if cap(s.Out) < dstSize {
s.Out = make([]byte, 0, dstSize)
}
s.Out = s.Out[:dstSize]
// destination, offset to match first output
dstOut := s.Out
dstEvery := (dstSize + 3) / 4
decode := func(br *bitReader) byte {
val := br.peekBitsFast(s.actualTableLog) /* note : actualTableLog >= 1 */
v := s.dt.single[val]
br.bitsRead += v.nBits
return v.byte
}
// Use temp table to avoid bound checks/append penalty.
var tmp = s.huffWeight[:256]
var off uint8
// Decode 2 values from each decoder/loop.
const bufoff = 256 / 4
bigloop:
for {
for i := range br {
if br[i].off < 4 {
break bigloop
}
br[i].fillFast()
}
tmp[off] = decode(&br[0])
tmp[off+bufoff] = decode(&br[1])
tmp[off+bufoff*2] = decode(&br[2])
tmp[off+bufoff*3] = decode(&br[3])
tmp[off+1] = decode(&br[0])
tmp[off+1+bufoff] = decode(&br[1])
tmp[off+1+bufoff*2] = decode(&br[2])
tmp[off+1+bufoff*3] = decode(&br[3])
off += 2
if off == bufoff {
if bufoff > dstEvery {
return nil, errors.New("corruption detected: stream overrun")
}
copy(dstOut, tmp[:bufoff])
copy(dstOut[dstEvery:], tmp[bufoff:bufoff*2])
copy(dstOut[dstEvery*2:], tmp[bufoff*2:bufoff*3])
copy(dstOut[dstEvery*3:], tmp[bufoff*3:bufoff*4])
off = 0
dstOut = dstOut[bufoff:]
// There must at least be 3 buffers left.
if len(dstOut) < dstEvery*3+3 {
return nil, errors.New("corruption detected: stream overrun")
}
}
}
if off > 0 {
ioff := int(off)
if len(dstOut) < dstEvery*3+ioff {
return nil, errors.New("corruption detected: stream overrun")
}
copy(dstOut, tmp[:off])
copy(dstOut[dstEvery:dstEvery+ioff], tmp[bufoff:bufoff*2])
copy(dstOut[dstEvery*2:dstEvery*2+ioff], tmp[bufoff*2:bufoff*3])
copy(dstOut[dstEvery*3:dstEvery*3+ioff], tmp[bufoff*3:bufoff*4])
dstOut = dstOut[off:]
}
for i := range br {
offset := dstEvery * i
br := &br[i]
for !br.finished() {
br.fill()
if offset >= len(dstOut) {
return nil, errors.New("corruption detected: stream overrun")
}
dstOut[offset] = decode(br)
offset++
}
err = br.close()
if err != nil {
return nil, err
}
}
return s.Out, nil
}
// matches will compare a decoding table to a coding table.
// Errors are written to the writer.
// Nothing will be written if table is ok.
func (s *Scratch) matches(ct cTable, w io.Writer) {
if s == nil || len(s.dt.single) == 0 {
return
}
dt := s.dt.single[:1<<s.actualTableLog]
tablelog := s.actualTableLog
ok := 0
broken := 0
for sym, enc := range ct {
errs := 0
broken++
if enc.nBits == 0 {
for _, dec := range dt {
if dec.byte == byte(sym) {
fmt.Fprintf(w, "symbol %x has decoder, but no encoder\n", sym)
errs++
break
}
}
if errs == 0 {
broken--
}
continue
}
// Unused bits in input
ub := tablelog - enc.nBits
top := enc.val << ub
// decoder looks at top bits.
dec := dt[top]
if dec.nBits != enc.nBits {
fmt.Fprintf(w, "symbol 0x%x bit size mismatch (enc: %d, dec:%d).\n", sym, enc.nBits, dec.nBits)
errs++
}
if dec.byte != uint8(sym) {
fmt.Fprintf(w, "symbol 0x%x decoder output mismatch (enc: %d, dec:%d).\n", sym, sym, dec.byte)
errs++
}
if errs > 0 {
fmt.Fprintf(w, "%d errros in base, stopping\n", errs)
continue
}
// Ensure that all combinations are covered.
for i := uint16(0); i < (1 << ub); i++ {
vval := top | i
dec := dt[vval]
if dec.nBits != enc.nBits {
fmt.Fprintf(w, "symbol 0x%x bit size mismatch (enc: %d, dec:%d).\n", vval, enc.nBits, dec.nBits)
errs++
}
if dec.byte != uint8(sym) {
fmt.Fprintf(w, "symbol 0x%x decoder output mismatch (enc: %d, dec:%d).\n", vval, sym, dec.byte)
errs++
}
if errs > 20 {
fmt.Fprintf(w, "%d errros, stopping\n", errs)
break
}
}
if errs == 0 {
ok++
broken--
}
}
if broken > 0 {
fmt.Fprintf(w, "%d broken, %d ok\n", broken, ok)
}
}

241
vendor/github.com/klauspost/compress/huff0/huff0.go generated vendored Normal file
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@ -0,0 +1,241 @@
// Package huff0 provides fast huffman encoding as used in zstd.
//
// See README.md at https://github.com/klauspost/compress/tree/master/huff0 for details.
package huff0
import (
"errors"
"fmt"
"math"
"math/bits"
"github.com/klauspost/compress/fse"
)
const (
maxSymbolValue = 255
// zstandard limits tablelog to 11, see:
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#huffman-tree-description
tableLogMax = 11
tableLogDefault = 11
minTablelog = 5
huffNodesLen = 512
// BlockSizeMax is maximum input size for a single block uncompressed.
BlockSizeMax = 1<<18 - 1
)
var (
// ErrIncompressible is returned when input is judged to be too hard to compress.
ErrIncompressible = errors.New("input is not compressible")
// ErrUseRLE is returned from the compressor when the input is a single byte value repeated.
ErrUseRLE = errors.New("input is single value repeated")
// ErrTooBig is return if input is too large for a single block.
ErrTooBig = errors.New("input too big")
)
type ReusePolicy uint8
const (
// ReusePolicyAllow will allow reuse if it produces smaller output.
ReusePolicyAllow ReusePolicy = iota
// ReusePolicyPrefer will re-use aggressively if possible.
// This will not check if a new table will produce smaller output,
// except if the current table is impossible to use or
// compressed output is bigger than input.
ReusePolicyPrefer
// ReusePolicyNone will disable re-use of tables.
// This is slightly faster than ReusePolicyAllow but may produce larger output.
ReusePolicyNone
)
type Scratch struct {
count [maxSymbolValue + 1]uint32
// Per block parameters.
// These can be used to override compression parameters of the block.
// Do not touch, unless you know what you are doing.
// Out is output buffer.
// If the scratch is re-used before the caller is done processing the output,
// set this field to nil.
// Otherwise the output buffer will be re-used for next Compression/Decompression step
// and allocation will be avoided.
Out []byte
// OutTable will contain the table data only, if a new table has been generated.
// Slice of the returned data.
OutTable []byte
// OutData will contain the compressed data.
// Slice of the returned data.
OutData []byte
// MaxSymbolValue will override the maximum symbol value of the next block.
MaxSymbolValue uint8
// TableLog will attempt to override the tablelog for the next block.
// Must be <= 11.
TableLog uint8
// Reuse will specify the reuse policy
Reuse ReusePolicy
br byteReader
symbolLen uint16 // Length of active part of the symbol table.
maxCount int // count of the most probable symbol
clearCount bool // clear count
actualTableLog uint8 // Selected tablelog.
prevTable cTable // Table used for previous compression.
cTable cTable // compression table
dt dTable // decompression table
nodes []nodeElt
tmpOut [4][]byte
fse *fse.Scratch
huffWeight [maxSymbolValue + 1]byte
}
func (s *Scratch) prepare(in []byte) (*Scratch, error) {
if len(in) > BlockSizeMax {
return nil, ErrTooBig
}
if s == nil {
s = &Scratch{}
}
if s.MaxSymbolValue == 0 {
s.MaxSymbolValue = maxSymbolValue
}
if s.TableLog == 0 {
s.TableLog = tableLogDefault
}
if s.TableLog > tableLogMax {
return nil, fmt.Errorf("tableLog (%d) > maxTableLog (%d)", s.TableLog, tableLogMax)
}
if s.clearCount && s.maxCount == 0 {
for i := range s.count {
s.count[i] = 0
}
s.clearCount = false
}
if cap(s.Out) == 0 {
s.Out = make([]byte, 0, len(in))
}
s.Out = s.Out[:0]
s.OutTable = nil
s.OutData = nil
if cap(s.nodes) < huffNodesLen+1 {
s.nodes = make([]nodeElt, 0, huffNodesLen+1)
}
s.nodes = s.nodes[:0]
if s.fse == nil {
s.fse = &fse.Scratch{}
}
s.br.init(in)
return s, nil
}
type cTable []cTableEntry
func (c cTable) write(s *Scratch) error {
var (
// precomputed conversion table
bitsToWeight [tableLogMax + 1]byte
huffLog = s.actualTableLog
// last weight is not saved.
maxSymbolValue = uint8(s.symbolLen - 1)
huffWeight = s.huffWeight[:256]
)
const (
maxFSETableLog = 6
)
// convert to weight
bitsToWeight[0] = 0
for n := uint8(1); n < huffLog+1; n++ {
bitsToWeight[n] = huffLog + 1 - n
}
// Acquire histogram for FSE.
hist := s.fse.Histogram()
hist = hist[:256]
for i := range hist[:16] {
hist[i] = 0
}
for n := uint8(0); n < maxSymbolValue; n++ {
v := bitsToWeight[c[n].nBits] & 15
huffWeight[n] = v
hist[v]++
}
// FSE compress if feasible.
if maxSymbolValue >= 2 {
huffMaxCnt := uint32(0)
huffMax := uint8(0)
for i, v := range hist[:16] {
if v == 0 {
continue
}
huffMax = byte(i)
if v > huffMaxCnt {
huffMaxCnt = v
}
}
s.fse.HistogramFinished(huffMax, int(huffMaxCnt))
s.fse.TableLog = maxFSETableLog
b, err := fse.Compress(huffWeight[:maxSymbolValue], s.fse)
if err == nil && len(b) < int(s.symbolLen>>1) {
s.Out = append(s.Out, uint8(len(b)))
s.Out = append(s.Out, b...)
return nil
}
// Unable to compress (RLE/uncompressible)
}
// write raw values as 4-bits (max : 15)
if maxSymbolValue > (256 - 128) {
// should not happen : likely means source cannot be compressed
return ErrIncompressible
}
op := s.Out
// special case, pack weights 4 bits/weight.
op = append(op, 128|(maxSymbolValue-1))
// be sure it doesn't cause msan issue in final combination
huffWeight[maxSymbolValue] = 0
for n := uint16(0); n < uint16(maxSymbolValue); n += 2 {
op = append(op, (huffWeight[n]<<4)|huffWeight[n+1])
}
s.Out = op
return nil
}
// estimateSize returns the estimated size in bytes of the input represented in the
// histogram supplied.
func (c cTable) estimateSize(hist []uint32) int {
nbBits := uint32(7)
for i, v := range c[:len(hist)] {
nbBits += uint32(v.nBits) * hist[i]
}
return int(nbBits >> 3)
}
// minSize returns the minimum possible size considering the shannon limit.
func (s *Scratch) minSize(total int) int {
nbBits := float64(7)
fTotal := float64(total)
for _, v := range s.count[:s.symbolLen] {
n := float64(v)
if n > 0 {
nbBits += math.Log2(fTotal/n) * n
}
}
return int(nbBits) >> 3
}
func highBit32(val uint32) (n uint32) {
return uint32(bits.Len32(val) - 1)
}

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vendor/github.com/klauspost/compress/snappy/.gitignore generated vendored Normal file
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cmd/snappytool/snappytool
testdata/bench
# These explicitly listed benchmark data files are for an obsolete version of
# snappy_test.go.
testdata/alice29.txt
testdata/asyoulik.txt
testdata/fireworks.jpeg
testdata/geo.protodata
testdata/html
testdata/html_x_4
testdata/kppkn.gtb
testdata/lcet10.txt
testdata/paper-100k.pdf
testdata/plrabn12.txt
testdata/urls.10K

15
vendor/github.com/klauspost/compress/snappy/AUTHORS generated vendored Normal file
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# This is the official list of Snappy-Go authors for copyright purposes.
# This file is distinct from the CONTRIBUTORS files.
# See the latter for an explanation.
# Names should be added to this file as
# Name or Organization <email address>
# The email address is not required for organizations.
# Please keep the list sorted.
Damian Gryski <dgryski@gmail.com>
Google Inc.
Jan Mercl <0xjnml@gmail.com>
Rodolfo Carvalho <rhcarvalho@gmail.com>
Sebastien Binet <seb.binet@gmail.com>

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# This is the official list of people who can contribute
# (and typically have contributed) code to the Snappy-Go repository.
# The AUTHORS file lists the copyright holders; this file
# lists people. For example, Google employees are listed here
# but not in AUTHORS, because Google holds the copyright.
#
# The submission process automatically checks to make sure
# that people submitting code are listed in this file (by email address).
#
# Names should be added to this file only after verifying that
# the individual or the individual's organization has agreed to
# the appropriate Contributor License Agreement, found here:
#
# http://code.google.com/legal/individual-cla-v1.0.html
# http://code.google.com/legal/corporate-cla-v1.0.html
#
# The agreement for individuals can be filled out on the web.
#
# When adding J Random Contributor's name to this file,
# either J's name or J's organization's name should be
# added to the AUTHORS file, depending on whether the
# individual or corporate CLA was used.
# Names should be added to this file like so:
# Name <email address>
# Please keep the list sorted.
Damian Gryski <dgryski@gmail.com>
Jan Mercl <0xjnml@gmail.com>
Kai Backman <kaib@golang.org>
Marc-Antoine Ruel <maruel@chromium.org>
Nigel Tao <nigeltao@golang.org>
Rob Pike <r@golang.org>
Rodolfo Carvalho <rhcarvalho@gmail.com>
Russ Cox <rsc@golang.org>
Sebastien Binet <seb.binet@gmail.com>

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Copyright (c) 2011 The Snappy-Go Authors. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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The Snappy compression format in the Go programming language.
To download and install from source:
$ go get github.com/golang/snappy
Unless otherwise noted, the Snappy-Go source files are distributed
under the BSD-style license found in the LICENSE file.
Benchmarks.
The golang/snappy benchmarks include compressing (Z) and decompressing (U) ten
or so files, the same set used by the C++ Snappy code (github.com/google/snappy
and note the "google", not "golang"). On an "Intel(R) Core(TM) i7-3770 CPU @
3.40GHz", Go's GOARCH=amd64 numbers as of 2016-05-29:
"go test -test.bench=."
_UFlat0-8 2.19GB/s ± 0% html
_UFlat1-8 1.41GB/s ± 0% urls
_UFlat2-8 23.5GB/s ± 2% jpg
_UFlat3-8 1.91GB/s ± 0% jpg_200
_UFlat4-8 14.0GB/s ± 1% pdf
_UFlat5-8 1.97GB/s ± 0% html4
_UFlat6-8 814MB/s ± 0% txt1
_UFlat7-8 785MB/s ± 0% txt2
_UFlat8-8 857MB/s ± 0% txt3
_UFlat9-8 719MB/s ± 1% txt4
_UFlat10-8 2.84GB/s ± 0% pb
_UFlat11-8 1.05GB/s ± 0% gaviota
_ZFlat0-8 1.04GB/s ± 0% html
_ZFlat1-8 534MB/s ± 0% urls
_ZFlat2-8 15.7GB/s ± 1% jpg
_ZFlat3-8 740MB/s ± 3% jpg_200
_ZFlat4-8 9.20GB/s ± 1% pdf
_ZFlat5-8 991MB/s ± 0% html4
_ZFlat6-8 379MB/s ± 0% txt1
_ZFlat7-8 352MB/s ± 0% txt2
_ZFlat8-8 396MB/s ± 1% txt3
_ZFlat9-8 327MB/s ± 1% txt4
_ZFlat10-8 1.33GB/s ± 1% pb
_ZFlat11-8 605MB/s ± 1% gaviota
"go test -test.bench=. -tags=noasm"
_UFlat0-8 621MB/s ± 2% html
_UFlat1-8 494MB/s ± 1% urls
_UFlat2-8 23.2GB/s ± 1% jpg
_UFlat3-8 1.12GB/s ± 1% jpg_200
_UFlat4-8 4.35GB/s ± 1% pdf
_UFlat5-8 609MB/s ± 0% html4
_UFlat6-8 296MB/s ± 0% txt1
_UFlat7-8 288MB/s ± 0% txt2
_UFlat8-8 309MB/s ± 1% txt3
_UFlat9-8 280MB/s ± 1% txt4
_UFlat10-8 753MB/s ± 0% pb
_UFlat11-8 400MB/s ± 0% gaviota
_ZFlat0-8 409MB/s ± 1% html
_ZFlat1-8 250MB/s ± 1% urls
_ZFlat2-8 12.3GB/s ± 1% jpg
_ZFlat3-8 132MB/s ± 0% jpg_200
_ZFlat4-8 2.92GB/s ± 0% pdf
_ZFlat5-8 405MB/s ± 1% html4
_ZFlat6-8 179MB/s ± 1% txt1
_ZFlat7-8 170MB/s ± 1% txt2
_ZFlat8-8 189MB/s ± 1% txt3
_ZFlat9-8 164MB/s ± 1% txt4
_ZFlat10-8 479MB/s ± 1% pb
_ZFlat11-8 270MB/s ± 1% gaviota
For comparison (Go's encoded output is byte-for-byte identical to C++'s), here
are the numbers from C++ Snappy's
make CXXFLAGS="-O2 -DNDEBUG -g" clean snappy_unittest.log && cat snappy_unittest.log
BM_UFlat/0 2.4GB/s html
BM_UFlat/1 1.4GB/s urls
BM_UFlat/2 21.8GB/s jpg
BM_UFlat/3 1.5GB/s jpg_200
BM_UFlat/4 13.3GB/s pdf
BM_UFlat/5 2.1GB/s html4
BM_UFlat/6 1.0GB/s txt1
BM_UFlat/7 959.4MB/s txt2
BM_UFlat/8 1.0GB/s txt3
BM_UFlat/9 864.5MB/s txt4
BM_UFlat/10 2.9GB/s pb
BM_UFlat/11 1.2GB/s gaviota
BM_ZFlat/0 944.3MB/s html (22.31 %)
BM_ZFlat/1 501.6MB/s urls (47.78 %)
BM_ZFlat/2 14.3GB/s jpg (99.95 %)
BM_ZFlat/3 538.3MB/s jpg_200 (73.00 %)
BM_ZFlat/4 8.3GB/s pdf (83.30 %)
BM_ZFlat/5 903.5MB/s html4 (22.52 %)
BM_ZFlat/6 336.0MB/s txt1 (57.88 %)
BM_ZFlat/7 312.3MB/s txt2 (61.91 %)
BM_ZFlat/8 353.1MB/s txt3 (54.99 %)
BM_ZFlat/9 289.9MB/s txt4 (66.26 %)
BM_ZFlat/10 1.2GB/s pb (19.68 %)
BM_ZFlat/11 527.4MB/s gaviota (37.72 %)

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// Copyright 2011 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package snappy
import (
"encoding/binary"
"errors"
"io"
)
var (
// ErrCorrupt reports that the input is invalid.
ErrCorrupt = errors.New("snappy: corrupt input")
// ErrTooLarge reports that the uncompressed length is too large.
ErrTooLarge = errors.New("snappy: decoded block is too large")
// ErrUnsupported reports that the input isn't supported.
ErrUnsupported = errors.New("snappy: unsupported input")
errUnsupportedLiteralLength = errors.New("snappy: unsupported literal length")
)
// DecodedLen returns the length of the decoded block.
func DecodedLen(src []byte) (int, error) {
v, _, err := decodedLen(src)
return v, err
}
// decodedLen returns the length of the decoded block and the number of bytes
// that the length header occupied.
func decodedLen(src []byte) (blockLen, headerLen int, err error) {
v, n := binary.Uvarint(src)
if n <= 0 || v > 0xffffffff {
return 0, 0, ErrCorrupt
}
const wordSize = 32 << (^uint(0) >> 32 & 1)
if wordSize == 32 && v > 0x7fffffff {
return 0, 0, ErrTooLarge
}
return int(v), n, nil
}
const (
decodeErrCodeCorrupt = 1
decodeErrCodeUnsupportedLiteralLength = 2
)
// Decode returns the decoded form of src. The returned slice may be a sub-
// slice of dst if dst was large enough to hold the entire decoded block.
// Otherwise, a newly allocated slice will be returned.
//
// The dst and src must not overlap. It is valid to pass a nil dst.
func Decode(dst, src []byte) ([]byte, error) {
dLen, s, err := decodedLen(src)
if err != nil {
return nil, err
}
if dLen <= len(dst) {
dst = dst[:dLen]
} else {
dst = make([]byte, dLen)
}
switch decode(dst, src[s:]) {
case 0:
return dst, nil
case decodeErrCodeUnsupportedLiteralLength:
return nil, errUnsupportedLiteralLength
}
return nil, ErrCorrupt
}
// NewReader returns a new Reader that decompresses from r, using the framing
// format described at
// https://github.com/google/snappy/blob/master/framing_format.txt
func NewReader(r io.Reader) *Reader {
return &Reader{
r: r,
decoded: make([]byte, maxBlockSize),
buf: make([]byte, maxEncodedLenOfMaxBlockSize+checksumSize),
}
}
// Reader is an io.Reader that can read Snappy-compressed bytes.
type Reader struct {
r io.Reader
err error
decoded []byte
buf []byte
// decoded[i:j] contains decoded bytes that have not yet been passed on.
i, j int
readHeader bool
}
// Reset discards any buffered data, resets all state, and switches the Snappy
// reader to read from r. This permits reusing a Reader rather than allocating
// a new one.
func (r *Reader) Reset(reader io.Reader) {
r.r = reader
r.err = nil
r.i = 0
r.j = 0
r.readHeader = false
}
func (r *Reader) readFull(p []byte, allowEOF bool) (ok bool) {
if _, r.err = io.ReadFull(r.r, p); r.err != nil {
if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
r.err = ErrCorrupt
}
return false
}
return true
}
// Read satisfies the io.Reader interface.
func (r *Reader) Read(p []byte) (int, error) {
if r.err != nil {
return 0, r.err
}
for {
if r.i < r.j {
n := copy(p, r.decoded[r.i:r.j])
r.i += n
return n, nil
}
if !r.readFull(r.buf[:4], true) {
return 0, r.err
}
chunkType := r.buf[0]
if !r.readHeader {
if chunkType != chunkTypeStreamIdentifier {
r.err = ErrCorrupt
return 0, r.err
}
r.readHeader = true
}
chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
if chunkLen > len(r.buf) {
r.err = ErrUnsupported
return 0, r.err
}
// The chunk types are specified at
// https://github.com/google/snappy/blob/master/framing_format.txt
switch chunkType {
case chunkTypeCompressedData:
// Section 4.2. Compressed data (chunk type 0x00).
if chunkLen < checksumSize {
r.err = ErrCorrupt
return 0, r.err
}
buf := r.buf[:chunkLen]
if !r.readFull(buf, false) {
return 0, r.err
}
checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
buf = buf[checksumSize:]
n, err := DecodedLen(buf)
if err != nil {
r.err = err
return 0, r.err
}
if n > len(r.decoded) {
r.err = ErrCorrupt
return 0, r.err
}
if _, err := Decode(r.decoded, buf); err != nil {
r.err = err
return 0, r.err
}
if crc(r.decoded[:n]) != checksum {
r.err = ErrCorrupt
return 0, r.err
}
r.i, r.j = 0, n
continue
case chunkTypeUncompressedData:
// Section 4.3. Uncompressed data (chunk type 0x01).
if chunkLen < checksumSize {
r.err = ErrCorrupt
return 0, r.err
}
buf := r.buf[:checksumSize]
if !r.readFull(buf, false) {
return 0, r.err
}
checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
// Read directly into r.decoded instead of via r.buf.
n := chunkLen - checksumSize
if n > len(r.decoded) {
r.err = ErrCorrupt
return 0, r.err
}
if !r.readFull(r.decoded[:n], false) {
return 0, r.err
}
if crc(r.decoded[:n]) != checksum {
r.err = ErrCorrupt
return 0, r.err
}
r.i, r.j = 0, n
continue
case chunkTypeStreamIdentifier:
// Section 4.1. Stream identifier (chunk type 0xff).
if chunkLen != len(magicBody) {
r.err = ErrCorrupt
return 0, r.err
}
if !r.readFull(r.buf[:len(magicBody)], false) {
return 0, r.err
}
for i := 0; i < len(magicBody); i++ {
if r.buf[i] != magicBody[i] {
r.err = ErrCorrupt
return 0, r.err
}
}
continue
}
if chunkType <= 0x7f {
// Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
r.err = ErrUnsupported
return 0, r.err
}
// Section 4.4 Padding (chunk type 0xfe).
// Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
if !r.readFull(r.buf[:chunkLen], false) {
return 0, r.err
}
}
}

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vendor/github.com/klauspost/compress/snappy/decode_amd64.go generated vendored Normal file
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// Copyright 2016 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !appengine
// +build gc
// +build !noasm
package snappy
// decode has the same semantics as in decode_other.go.
//
//go:noescape
func decode(dst, src []byte) int

490
vendor/github.com/klauspost/compress/snappy/decode_amd64.s generated vendored Normal file
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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !appengine
// +build gc
// +build !noasm
#include "textflag.h"
// The asm code generally follows the pure Go code in decode_other.go, except
// where marked with a "!!!".
// func decode(dst, src []byte) int
//
// All local variables fit into registers. The non-zero stack size is only to
// spill registers and push args when issuing a CALL. The register allocation:
// - AX scratch
// - BX scratch
// - CX length or x
// - DX offset
// - SI &src[s]
// - DI &dst[d]
// + R8 dst_base
// + R9 dst_len
// + R10 dst_base + dst_len
// + R11 src_base
// + R12 src_len
// + R13 src_base + src_len
// - R14 used by doCopy
// - R15 used by doCopy
//
// The registers R8-R13 (marked with a "+") are set at the start of the
// function, and after a CALL returns, and are not otherwise modified.
//
// The d variable is implicitly DI - R8, and len(dst)-d is R10 - DI.
// The s variable is implicitly SI - R11, and len(src)-s is R13 - SI.
TEXT ·decode(SB), NOSPLIT, $48-56
// Initialize SI, DI and R8-R13.
MOVQ dst_base+0(FP), R8
MOVQ dst_len+8(FP), R9
MOVQ R8, DI
MOVQ R8, R10
ADDQ R9, R10
MOVQ src_base+24(FP), R11
MOVQ src_len+32(FP), R12
MOVQ R11, SI
MOVQ R11, R13
ADDQ R12, R13
loop:
// for s < len(src)
CMPQ SI, R13
JEQ end
// CX = uint32(src[s])
//
// switch src[s] & 0x03
MOVBLZX (SI), CX
MOVL CX, BX
ANDL $3, BX
CMPL BX, $1
JAE tagCopy
// ----------------------------------------
// The code below handles literal tags.
// case tagLiteral:
// x := uint32(src[s] >> 2)
// switch
SHRL $2, CX
CMPL CX, $60
JAE tagLit60Plus
// case x < 60:
// s++
INCQ SI
doLit:
// This is the end of the inner "switch", when we have a literal tag.
//
// We assume that CX == x and x fits in a uint32, where x is the variable
// used in the pure Go decode_other.go code.
// length = int(x) + 1
//
// Unlike the pure Go code, we don't need to check if length <= 0 because
// CX can hold 64 bits, so the increment cannot overflow.
INCQ CX
// Prepare to check if copying length bytes will run past the end of dst or
// src.
//
// AX = len(dst) - d
// BX = len(src) - s
MOVQ R10, AX
SUBQ DI, AX
MOVQ R13, BX
SUBQ SI, BX
// !!! Try a faster technique for short (16 or fewer bytes) copies.
//
// if length > 16 || len(dst)-d < 16 || len(src)-s < 16 {
// goto callMemmove // Fall back on calling runtime·memmove.
// }
//
// The C++ snappy code calls this TryFastAppend. It also checks len(src)-s
// against 21 instead of 16, because it cannot assume that all of its input
// is contiguous in memory and so it needs to leave enough source bytes to
// read the next tag without refilling buffers, but Go's Decode assumes
// contiguousness (the src argument is a []byte).
CMPQ CX, $16
JGT callMemmove
CMPQ AX, $16
JLT callMemmove
CMPQ BX, $16
JLT callMemmove
// !!! Implement the copy from src to dst as a 16-byte load and store.
// (Decode's documentation says that dst and src must not overlap.)
//
// This always copies 16 bytes, instead of only length bytes, but that's
// OK. If the input is a valid Snappy encoding then subsequent iterations
// will fix up the overrun. Otherwise, Decode returns a nil []byte (and a
// non-nil error), so the overrun will be ignored.
//
// Note that on amd64, it is legal and cheap to issue unaligned 8-byte or
// 16-byte loads and stores. This technique probably wouldn't be as
// effective on architectures that are fussier about alignment.
MOVOU 0(SI), X0
MOVOU X0, 0(DI)
// d += length
// s += length
ADDQ CX, DI
ADDQ CX, SI
JMP loop
callMemmove:
// if length > len(dst)-d || length > len(src)-s { etc }
CMPQ CX, AX
JGT errCorrupt
CMPQ CX, BX
JGT errCorrupt
// copy(dst[d:], src[s:s+length])
//
// This means calling runtime·memmove(&dst[d], &src[s], length), so we push
// DI, SI and CX as arguments. Coincidentally, we also need to spill those
// three registers to the stack, to save local variables across the CALL.
MOVQ DI, 0(SP)
MOVQ SI, 8(SP)
MOVQ CX, 16(SP)
MOVQ DI, 24(SP)
MOVQ SI, 32(SP)
MOVQ CX, 40(SP)
CALL runtime·memmove(SB)
// Restore local variables: unspill registers from the stack and
// re-calculate R8-R13.
MOVQ 24(SP), DI
MOVQ 32(SP), SI
MOVQ 40(SP), CX
MOVQ dst_base+0(FP), R8
MOVQ dst_len+8(FP), R9
MOVQ R8, R10
ADDQ R9, R10
MOVQ src_base+24(FP), R11
MOVQ src_len+32(FP), R12
MOVQ R11, R13
ADDQ R12, R13
// d += length
// s += length
ADDQ CX, DI
ADDQ CX, SI
JMP loop
tagLit60Plus:
// !!! This fragment does the
//
// s += x - 58; if uint(s) > uint(len(src)) { etc }
//
// checks. In the asm version, we code it once instead of once per switch case.
ADDQ CX, SI
SUBQ $58, SI
MOVQ SI, BX
SUBQ R11, BX
CMPQ BX, R12
JA errCorrupt
// case x == 60:
CMPL CX, $61
JEQ tagLit61
JA tagLit62Plus
// x = uint32(src[s-1])
MOVBLZX -1(SI), CX
JMP doLit
tagLit61:
// case x == 61:
// x = uint32(src[s-2]) | uint32(src[s-1])<<8
MOVWLZX -2(SI), CX
JMP doLit
tagLit62Plus:
CMPL CX, $62
JA tagLit63
// case x == 62:
// x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
MOVWLZX -3(SI), CX
MOVBLZX -1(SI), BX
SHLL $16, BX
ORL BX, CX
JMP doLit
tagLit63:
// case x == 63:
// x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
MOVL -4(SI), CX
JMP doLit
// The code above handles literal tags.
// ----------------------------------------
// The code below handles copy tags.
tagCopy4:
// case tagCopy4:
// s += 5
ADDQ $5, SI
// if uint(s) > uint(len(src)) { etc }
MOVQ SI, BX
SUBQ R11, BX
CMPQ BX, R12
JA errCorrupt
// length = 1 + int(src[s-5])>>2
SHRQ $2, CX
INCQ CX
// offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
MOVLQZX -4(SI), DX
JMP doCopy
tagCopy2:
// case tagCopy2:
// s += 3
ADDQ $3, SI
// if uint(s) > uint(len(src)) { etc }
MOVQ SI, BX
SUBQ R11, BX
CMPQ BX, R12
JA errCorrupt
// length = 1 + int(src[s-3])>>2
SHRQ $2, CX
INCQ CX
// offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
MOVWQZX -2(SI), DX
JMP doCopy
tagCopy:
// We have a copy tag. We assume that:
// - BX == src[s] & 0x03
// - CX == src[s]
CMPQ BX, $2
JEQ tagCopy2
JA tagCopy4
// case tagCopy1:
// s += 2
ADDQ $2, SI
// if uint(s) > uint(len(src)) { etc }
MOVQ SI, BX
SUBQ R11, BX
CMPQ BX, R12
JA errCorrupt
// offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
MOVQ CX, DX
ANDQ $0xe0, DX
SHLQ $3, DX
MOVBQZX -1(SI), BX
ORQ BX, DX
// length = 4 + int(src[s-2])>>2&0x7
SHRQ $2, CX
ANDQ $7, CX
ADDQ $4, CX
doCopy:
// This is the end of the outer "switch", when we have a copy tag.
//
// We assume that:
// - CX == length && CX > 0
// - DX == offset
// if offset <= 0 { etc }
CMPQ DX, $0
JLE errCorrupt
// if d < offset { etc }
MOVQ DI, BX
SUBQ R8, BX
CMPQ BX, DX
JLT errCorrupt
// if length > len(dst)-d { etc }
MOVQ R10, BX
SUBQ DI, BX
CMPQ CX, BX
JGT errCorrupt
// forwardCopy(dst[d:d+length], dst[d-offset:]); d += length
//
// Set:
// - R14 = len(dst)-d
// - R15 = &dst[d-offset]
MOVQ R10, R14
SUBQ DI, R14
MOVQ DI, R15
SUBQ DX, R15
// !!! Try a faster technique for short (16 or fewer bytes) forward copies.
//
// First, try using two 8-byte load/stores, similar to the doLit technique
// above. Even if dst[d:d+length] and dst[d-offset:] can overlap, this is
// still OK if offset >= 8. Note that this has to be two 8-byte load/stores
// and not one 16-byte load/store, and the first store has to be before the
// second load, due to the overlap if offset is in the range [8, 16).
//
// if length > 16 || offset < 8 || len(dst)-d < 16 {
// goto slowForwardCopy
// }
// copy 16 bytes
// d += length
CMPQ CX, $16
JGT slowForwardCopy
CMPQ DX, $8
JLT slowForwardCopy
CMPQ R14, $16
JLT slowForwardCopy
MOVQ 0(R15), AX
MOVQ AX, 0(DI)
MOVQ 8(R15), BX
MOVQ BX, 8(DI)
ADDQ CX, DI
JMP loop
slowForwardCopy:
// !!! If the forward copy is longer than 16 bytes, or if offset < 8, we
// can still try 8-byte load stores, provided we can overrun up to 10 extra
// bytes. As above, the overrun will be fixed up by subsequent iterations
// of the outermost loop.
//
// The C++ snappy code calls this technique IncrementalCopyFastPath. Its
// commentary says:
//
// ----
//
// The main part of this loop is a simple copy of eight bytes at a time
// until we've copied (at least) the requested amount of bytes. However,
// if d and d-offset are less than eight bytes apart (indicating a
// repeating pattern of length < 8), we first need to expand the pattern in
// order to get the correct results. For instance, if the buffer looks like
// this, with the eight-byte <d-offset> and <d> patterns marked as
// intervals:
//
// abxxxxxxxxxxxx
// [------] d-offset
// [------] d
//
// a single eight-byte copy from <d-offset> to <d> will repeat the pattern
// once, after which we can move <d> two bytes without moving <d-offset>:
//
// ababxxxxxxxxxx
// [------] d-offset
// [------] d
//
// and repeat the exercise until the two no longer overlap.
//
// This allows us to do very well in the special case of one single byte
// repeated many times, without taking a big hit for more general cases.
//
// The worst case of extra writing past the end of the match occurs when
// offset == 1 and length == 1; the last copy will read from byte positions
// [0..7] and write to [4..11], whereas it was only supposed to write to
// position 1. Thus, ten excess bytes.
//
// ----
//
// That "10 byte overrun" worst case is confirmed by Go's
// TestSlowForwardCopyOverrun, which also tests the fixUpSlowForwardCopy
// and finishSlowForwardCopy algorithm.
//
// if length > len(dst)-d-10 {
// goto verySlowForwardCopy
// }
SUBQ $10, R14
CMPQ CX, R14
JGT verySlowForwardCopy
makeOffsetAtLeast8:
// !!! As above, expand the pattern so that offset >= 8 and we can use
// 8-byte load/stores.
//
// for offset < 8 {
// copy 8 bytes from dst[d-offset:] to dst[d:]
// length -= offset
// d += offset
// offset += offset
// // The two previous lines together means that d-offset, and therefore
// // R15, is unchanged.
// }
CMPQ DX, $8
JGE fixUpSlowForwardCopy
MOVQ (R15), BX
MOVQ BX, (DI)
SUBQ DX, CX
ADDQ DX, DI
ADDQ DX, DX
JMP makeOffsetAtLeast8
fixUpSlowForwardCopy:
// !!! Add length (which might be negative now) to d (implied by DI being
// &dst[d]) so that d ends up at the right place when we jump back to the
// top of the loop. Before we do that, though, we save DI to AX so that, if
// length is positive, copying the remaining length bytes will write to the
// right place.
MOVQ DI, AX
ADDQ CX, DI
finishSlowForwardCopy:
// !!! Repeat 8-byte load/stores until length <= 0. Ending with a negative
// length means that we overrun, but as above, that will be fixed up by
// subsequent iterations of the outermost loop.
CMPQ CX, $0
JLE loop
MOVQ (R15), BX
MOVQ BX, (AX)
ADDQ $8, R15
ADDQ $8, AX
SUBQ $8, CX
JMP finishSlowForwardCopy
verySlowForwardCopy:
// verySlowForwardCopy is a simple implementation of forward copy. In C
// parlance, this is a do/while loop instead of a while loop, since we know
// that length > 0. In Go syntax:
//
// for {
// dst[d] = dst[d - offset]
// d++
// length--
// if length == 0 {
// break
// }
// }
MOVB (R15), BX
MOVB BX, (DI)
INCQ R15
INCQ DI
DECQ CX
JNZ verySlowForwardCopy
JMP loop
// The code above handles copy tags.
// ----------------------------------------
end:
// This is the end of the "for s < len(src)".
//
// if d != len(dst) { etc }
CMPQ DI, R10
JNE errCorrupt
// return 0
MOVQ $0, ret+48(FP)
RET
errCorrupt:
// return decodeErrCodeCorrupt
MOVQ $1, ret+48(FP)
RET

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vendor/github.com/klauspost/compress/snappy/decode_other.go generated vendored Normal file
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// Copyright 2016 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !amd64 appengine !gc noasm
package snappy
// decode writes the decoding of src to dst. It assumes that the varint-encoded
// length of the decompressed bytes has already been read, and that len(dst)
// equals that length.
//
// It returns 0 on success or a decodeErrCodeXxx error code on failure.
func decode(dst, src []byte) int {
var d, s, offset, length int
for s < len(src) {
switch src[s] & 0x03 {
case tagLiteral:
x := uint32(src[s] >> 2)
switch {
case x < 60:
s++
case x == 60:
s += 2
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
x = uint32(src[s-1])
case x == 61:
s += 3
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
x = uint32(src[s-2]) | uint32(src[s-1])<<8
case x == 62:
s += 4
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
case x == 63:
s += 5
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
}
length = int(x) + 1
if length <= 0 {
return decodeErrCodeUnsupportedLiteralLength
}
if length > len(dst)-d || length > len(src)-s {
return decodeErrCodeCorrupt
}
copy(dst[d:], src[s:s+length])
d += length
s += length
continue
case tagCopy1:
s += 2
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
length = 4 + int(src[s-2])>>2&0x7
offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
case tagCopy2:
s += 3
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
length = 1 + int(src[s-3])>>2
offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
case tagCopy4:
s += 5
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
return decodeErrCodeCorrupt
}
length = 1 + int(src[s-5])>>2
offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
}
if offset <= 0 || d < offset || length > len(dst)-d {
return decodeErrCodeCorrupt
}
// Copy from an earlier sub-slice of dst to a later sub-slice. Unlike
// the built-in copy function, this byte-by-byte copy always runs
// forwards, even if the slices overlap. Conceptually, this is:
//
// d += forwardCopy(dst[d:d+length], dst[d-offset:])
for end := d + length; d != end; d++ {
dst[d] = dst[d-offset]
}
}
if d != len(dst) {
return decodeErrCodeCorrupt
}
return 0
}

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vendor/github.com/klauspost/compress/snappy/encode.go generated vendored Normal file
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// Copyright 2011 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package snappy
import (
"encoding/binary"
"errors"
"io"
)
// Encode returns the encoded form of src. The returned slice may be a sub-
// slice of dst if dst was large enough to hold the entire encoded block.
// Otherwise, a newly allocated slice will be returned.
//
// The dst and src must not overlap. It is valid to pass a nil dst.
func Encode(dst, src []byte) []byte {
if n := MaxEncodedLen(len(src)); n < 0 {
panic(ErrTooLarge)
} else if len(dst) < n {
dst = make([]byte, n)
}
// The block starts with the varint-encoded length of the decompressed bytes.
d := binary.PutUvarint(dst, uint64(len(src)))
for len(src) > 0 {
p := src
src = nil
if len(p) > maxBlockSize {
p, src = p[:maxBlockSize], p[maxBlockSize:]
}
if len(p) < minNonLiteralBlockSize {
d += emitLiteral(dst[d:], p)
} else {
d += encodeBlock(dst[d:], p)
}
}
return dst[:d]
}
// inputMargin is the minimum number of extra input bytes to keep, inside
// encodeBlock's inner loop. On some architectures, this margin lets us
// implement a fast path for emitLiteral, where the copy of short (<= 16 byte)
// literals can be implemented as a single load to and store from a 16-byte
// register. That literal's actual length can be as short as 1 byte, so this
// can copy up to 15 bytes too much, but that's OK as subsequent iterations of
// the encoding loop will fix up the copy overrun, and this inputMargin ensures
// that we don't overrun the dst and src buffers.
const inputMargin = 16 - 1
// minNonLiteralBlockSize is the minimum size of the input to encodeBlock that
// could be encoded with a copy tag. This is the minimum with respect to the
// algorithm used by encodeBlock, not a minimum enforced by the file format.
//
// The encoded output must start with at least a 1 byte literal, as there are
// no previous bytes to copy. A minimal (1 byte) copy after that, generated
// from an emitCopy call in encodeBlock's main loop, would require at least
// another inputMargin bytes, for the reason above: we want any emitLiteral
// calls inside encodeBlock's main loop to use the fast path if possible, which
// requires being able to overrun by inputMargin bytes. Thus,
// minNonLiteralBlockSize equals 1 + 1 + inputMargin.
//
// The C++ code doesn't use this exact threshold, but it could, as discussed at
// https://groups.google.com/d/topic/snappy-compression/oGbhsdIJSJ8/discussion
// The difference between Go (2+inputMargin) and C++ (inputMargin) is purely an
// optimization. It should not affect the encoded form. This is tested by
// TestSameEncodingAsCppShortCopies.
const minNonLiteralBlockSize = 1 + 1 + inputMargin
// MaxEncodedLen returns the maximum length of a snappy block, given its
// uncompressed length.
//
// It will return a negative value if srcLen is too large to encode.
func MaxEncodedLen(srcLen int) int {
n := uint64(srcLen)
if n > 0xffffffff {
return -1
}
// Compressed data can be defined as:
// compressed := item* literal*
// item := literal* copy
//
// The trailing literal sequence has a space blowup of at most 62/60
// since a literal of length 60 needs one tag byte + one extra byte
// for length information.
//
// Item blowup is trickier to measure. Suppose the "copy" op copies
// 4 bytes of data. Because of a special check in the encoding code,
// we produce a 4-byte copy only if the offset is < 65536. Therefore
// the copy op takes 3 bytes to encode, and this type of item leads
// to at most the 62/60 blowup for representing literals.
//
// Suppose the "copy" op copies 5 bytes of data. If the offset is big
// enough, it will take 5 bytes to encode the copy op. Therefore the
// worst case here is a one-byte literal followed by a five-byte copy.
// That is, 6 bytes of input turn into 7 bytes of "compressed" data.
//
// This last factor dominates the blowup, so the final estimate is:
n = 32 + n + n/6
if n > 0xffffffff {
return -1
}
return int(n)
}
var errClosed = errors.New("snappy: Writer is closed")
// NewWriter returns a new Writer that compresses to w.
//
// The Writer returned does not buffer writes. There is no need to Flush or
// Close such a Writer.
//
// Deprecated: the Writer returned is not suitable for many small writes, only
// for few large writes. Use NewBufferedWriter instead, which is efficient
// regardless of the frequency and shape of the writes, and remember to Close
// that Writer when done.
func NewWriter(w io.Writer) *Writer {
return &Writer{
w: w,
obuf: make([]byte, obufLen),
}
}
// NewBufferedWriter returns a new Writer that compresses to w, using the
// framing format described at
// https://github.com/google/snappy/blob/master/framing_format.txt
//
// The Writer returned buffers writes. Users must call Close to guarantee all
// data has been forwarded to the underlying io.Writer. They may also call
// Flush zero or more times before calling Close.
func NewBufferedWriter(w io.Writer) *Writer {
return &Writer{
w: w,
ibuf: make([]byte, 0, maxBlockSize),
obuf: make([]byte, obufLen),
}
}
// Writer is an io.Writer that can write Snappy-compressed bytes.
type Writer struct {
w io.Writer
err error
// ibuf is a buffer for the incoming (uncompressed) bytes.
//
// Its use is optional. For backwards compatibility, Writers created by the
// NewWriter function have ibuf == nil, do not buffer incoming bytes, and
// therefore do not need to be Flush'ed or Close'd.
ibuf []byte
// obuf is a buffer for the outgoing (compressed) bytes.
obuf []byte
// wroteStreamHeader is whether we have written the stream header.
wroteStreamHeader bool
}
// Reset discards the writer's state and switches the Snappy writer to write to
// w. This permits reusing a Writer rather than allocating a new one.
func (w *Writer) Reset(writer io.Writer) {
w.w = writer
w.err = nil
if w.ibuf != nil {
w.ibuf = w.ibuf[:0]
}
w.wroteStreamHeader = false
}
// Write satisfies the io.Writer interface.
func (w *Writer) Write(p []byte) (nRet int, errRet error) {
if w.ibuf == nil {
// Do not buffer incoming bytes. This does not perform or compress well
// if the caller of Writer.Write writes many small slices. This
// behavior is therefore deprecated, but still supported for backwards
// compatibility with code that doesn't explicitly Flush or Close.
return w.write(p)
}
// The remainder of this method is based on bufio.Writer.Write from the
// standard library.
for len(p) > (cap(w.ibuf)-len(w.ibuf)) && w.err == nil {
var n int
if len(w.ibuf) == 0 {
// Large write, empty buffer.
// Write directly from p to avoid copy.
n, _ = w.write(p)
} else {
n = copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
w.ibuf = w.ibuf[:len(w.ibuf)+n]
w.Flush()
}
nRet += n
p = p[n:]
}
if w.err != nil {
return nRet, w.err
}
n := copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
w.ibuf = w.ibuf[:len(w.ibuf)+n]
nRet += n
return nRet, nil
}
func (w *Writer) write(p []byte) (nRet int, errRet error) {
if w.err != nil {
return 0, w.err
}
for len(p) > 0 {
obufStart := len(magicChunk)
if !w.wroteStreamHeader {
w.wroteStreamHeader = true
copy(w.obuf, magicChunk)
obufStart = 0
}
var uncompressed []byte
if len(p) > maxBlockSize {
uncompressed, p = p[:maxBlockSize], p[maxBlockSize:]
} else {
uncompressed, p = p, nil
}
checksum := crc(uncompressed)
// Compress the buffer, discarding the result if the improvement
// isn't at least 12.5%.
compressed := Encode(w.obuf[obufHeaderLen:], uncompressed)
chunkType := uint8(chunkTypeCompressedData)
chunkLen := 4 + len(compressed)
obufEnd := obufHeaderLen + len(compressed)
if len(compressed) >= len(uncompressed)-len(uncompressed)/8 {
chunkType = chunkTypeUncompressedData
chunkLen = 4 + len(uncompressed)
obufEnd = obufHeaderLen
}
// Fill in the per-chunk header that comes before the body.
w.obuf[len(magicChunk)+0] = chunkType
w.obuf[len(magicChunk)+1] = uint8(chunkLen >> 0)
w.obuf[len(magicChunk)+2] = uint8(chunkLen >> 8)
w.obuf[len(magicChunk)+3] = uint8(chunkLen >> 16)
w.obuf[len(magicChunk)+4] = uint8(checksum >> 0)
w.obuf[len(magicChunk)+5] = uint8(checksum >> 8)
w.obuf[len(magicChunk)+6] = uint8(checksum >> 16)
w.obuf[len(magicChunk)+7] = uint8(checksum >> 24)
if _, err := w.w.Write(w.obuf[obufStart:obufEnd]); err != nil {
w.err = err
return nRet, err
}
if chunkType == chunkTypeUncompressedData {
if _, err := w.w.Write(uncompressed); err != nil {
w.err = err
return nRet, err
}
}
nRet += len(uncompressed)
}
return nRet, nil
}
// Flush flushes the Writer to its underlying io.Writer.
func (w *Writer) Flush() error {
if w.err != nil {
return w.err
}
if len(w.ibuf) == 0 {
return nil
}
w.write(w.ibuf)
w.ibuf = w.ibuf[:0]
return w.err
}
// Close calls Flush and then closes the Writer.
func (w *Writer) Close() error {
w.Flush()
ret := w.err
if w.err == nil {
w.err = errClosed
}
return ret
}

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vendor/github.com/klauspost/compress/snappy/encode_amd64.go generated vendored Normal file
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// Copyright 2016 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !appengine
// +build gc
// +build !noasm
package snappy
// emitLiteral has the same semantics as in encode_other.go.
//
//go:noescape
func emitLiteral(dst, lit []byte) int
// emitCopy has the same semantics as in encode_other.go.
//
//go:noescape
func emitCopy(dst []byte, offset, length int) int
// extendMatch has the same semantics as in encode_other.go.
//
//go:noescape
func extendMatch(src []byte, i, j int) int
// encodeBlock has the same semantics as in encode_other.go.
//
//go:noescape
func encodeBlock(dst, src []byte) (d int)

730
vendor/github.com/klauspost/compress/snappy/encode_amd64.s generated vendored Normal file
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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !appengine
// +build gc
// +build !noasm
#include "textflag.h"
// The XXX lines assemble on Go 1.4, 1.5 and 1.7, but not 1.6, due to a
// Go toolchain regression. See https://github.com/golang/go/issues/15426 and
// https://github.com/golang/snappy/issues/29
//
// As a workaround, the package was built with a known good assembler, and
// those instructions were disassembled by "objdump -d" to yield the
// 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
// style comments, in AT&T asm syntax. Note that rsp here is a physical
// register, not Go/asm's SP pseudo-register (see https://golang.org/doc/asm).
// The instructions were then encoded as "BYTE $0x.." sequences, which assemble
// fine on Go 1.6.
// The asm code generally follows the pure Go code in encode_other.go, except
// where marked with a "!!!".
// ----------------------------------------------------------------------------
// func emitLiteral(dst, lit []byte) int
//
// All local variables fit into registers. The register allocation:
// - AX len(lit)
// - BX n
// - DX return value
// - DI &dst[i]
// - R10 &lit[0]
//
// The 24 bytes of stack space is to call runtime·memmove.
//
// The unusual register allocation of local variables, such as R10 for the
// source pointer, matches the allocation used at the call site in encodeBlock,
// which makes it easier to manually inline this function.
TEXT ·emitLiteral(SB), NOSPLIT, $24-56
MOVQ dst_base+0(FP), DI
MOVQ lit_base+24(FP), R10
MOVQ lit_len+32(FP), AX
MOVQ AX, DX
MOVL AX, BX
SUBL $1, BX
CMPL BX, $60
JLT oneByte
CMPL BX, $256
JLT twoBytes
threeBytes:
MOVB $0xf4, 0(DI)
MOVW BX, 1(DI)
ADDQ $3, DI
ADDQ $3, DX
JMP memmove
twoBytes:
MOVB $0xf0, 0(DI)
MOVB BX, 1(DI)
ADDQ $2, DI
ADDQ $2, DX
JMP memmove
oneByte:
SHLB $2, BX
MOVB BX, 0(DI)
ADDQ $1, DI
ADDQ $1, DX
memmove:
MOVQ DX, ret+48(FP)
// copy(dst[i:], lit)
//
// This means calling runtime·memmove(&dst[i], &lit[0], len(lit)), so we push
// DI, R10 and AX as arguments.
MOVQ DI, 0(SP)
MOVQ R10, 8(SP)
MOVQ AX, 16(SP)
CALL runtime·memmove(SB)
RET
// ----------------------------------------------------------------------------
// func emitCopy(dst []byte, offset, length int) int
//
// All local variables fit into registers. The register allocation:
// - AX length
// - SI &dst[0]
// - DI &dst[i]
// - R11 offset
//
// The unusual register allocation of local variables, such as R11 for the
// offset, matches the allocation used at the call site in encodeBlock, which
// makes it easier to manually inline this function.
TEXT ·emitCopy(SB), NOSPLIT, $0-48
MOVQ dst_base+0(FP), DI
MOVQ DI, SI
MOVQ offset+24(FP), R11
MOVQ length+32(FP), AX
loop0:
// for length >= 68 { etc }
CMPL AX, $68
JLT step1
// Emit a length 64 copy, encoded as 3 bytes.
MOVB $0xfe, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
SUBL $64, AX
JMP loop0
step1:
// if length > 64 { etc }
CMPL AX, $64
JLE step2
// Emit a length 60 copy, encoded as 3 bytes.
MOVB $0xee, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
SUBL $60, AX
step2:
// if length >= 12 || offset >= 2048 { goto step3 }
CMPL AX, $12
JGE step3
CMPL R11, $2048
JGE step3
// Emit the remaining copy, encoded as 2 bytes.
MOVB R11, 1(DI)
SHRL $8, R11
SHLB $5, R11
SUBB $4, AX
SHLB $2, AX
ORB AX, R11
ORB $1, R11
MOVB R11, 0(DI)
ADDQ $2, DI
// Return the number of bytes written.
SUBQ SI, DI
MOVQ DI, ret+40(FP)
RET
step3:
// Emit the remaining copy, encoded as 3 bytes.
SUBL $1, AX
SHLB $2, AX
ORB $2, AX
MOVB AX, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
// Return the number of bytes written.
SUBQ SI, DI
MOVQ DI, ret+40(FP)
RET
// ----------------------------------------------------------------------------
// func extendMatch(src []byte, i, j int) int
//
// All local variables fit into registers. The register allocation:
// - DX &src[0]
// - SI &src[j]
// - R13 &src[len(src) - 8]
// - R14 &src[len(src)]
// - R15 &src[i]
//
// The unusual register allocation of local variables, such as R15 for a source
// pointer, matches the allocation used at the call site in encodeBlock, which
// makes it easier to manually inline this function.
TEXT ·extendMatch(SB), NOSPLIT, $0-48
MOVQ src_base+0(FP), DX
MOVQ src_len+8(FP), R14
MOVQ i+24(FP), R15
MOVQ j+32(FP), SI
ADDQ DX, R14
ADDQ DX, R15
ADDQ DX, SI
MOVQ R14, R13
SUBQ $8, R13
cmp8:
// As long as we are 8 or more bytes before the end of src, we can load and
// compare 8 bytes at a time. If those 8 bytes are equal, repeat.
CMPQ SI, R13
JA cmp1
MOVQ (R15), AX
MOVQ (SI), BX
CMPQ AX, BX
JNE bsf
ADDQ $8, R15
ADDQ $8, SI
JMP cmp8
bsf:
// If those 8 bytes were not equal, XOR the two 8 byte values, and return
// the index of the first byte that differs. The BSF instruction finds the
// least significant 1 bit, the amd64 architecture is little-endian, and
// the shift by 3 converts a bit index to a byte index.
XORQ AX, BX
BSFQ BX, BX
SHRQ $3, BX
ADDQ BX, SI
// Convert from &src[ret] to ret.
SUBQ DX, SI
MOVQ SI, ret+40(FP)
RET
cmp1:
// In src's tail, compare 1 byte at a time.
CMPQ SI, R14
JAE extendMatchEnd
MOVB (R15), AX
MOVB (SI), BX
CMPB AX, BX
JNE extendMatchEnd
ADDQ $1, R15
ADDQ $1, SI
JMP cmp1
extendMatchEnd:
// Convert from &src[ret] to ret.
SUBQ DX, SI
MOVQ SI, ret+40(FP)
RET
// ----------------------------------------------------------------------------
// func encodeBlock(dst, src []byte) (d int)
//
// All local variables fit into registers, other than "var table". The register
// allocation:
// - AX . .
// - BX . .
// - CX 56 shift (note that amd64 shifts by non-immediates must use CX).
// - DX 64 &src[0], tableSize
// - SI 72 &src[s]
// - DI 80 &dst[d]
// - R9 88 sLimit
// - R10 . &src[nextEmit]
// - R11 96 prevHash, currHash, nextHash, offset
// - R12 104 &src[base], skip
// - R13 . &src[nextS], &src[len(src) - 8]
// - R14 . len(src), bytesBetweenHashLookups, &src[len(src)], x
// - R15 112 candidate
//
// The second column (56, 64, etc) is the stack offset to spill the registers
// when calling other functions. We could pack this slightly tighter, but it's
// simpler to have a dedicated spill map independent of the function called.
//
// "var table [maxTableSize]uint16" takes up 32768 bytes of stack space. An
// extra 56 bytes, to call other functions, and an extra 64 bytes, to spill
// local variables (registers) during calls gives 32768 + 56 + 64 = 32888.
TEXT ·encodeBlock(SB), 0, $32888-56
MOVQ dst_base+0(FP), DI
MOVQ src_base+24(FP), SI
MOVQ src_len+32(FP), R14
// shift, tableSize := uint32(32-8), 1<<8
MOVQ $24, CX
MOVQ $256, DX
calcShift:
// for ; tableSize < maxTableSize && tableSize < len(src); tableSize *= 2 {
// shift--
// }
CMPQ DX, $16384
JGE varTable
CMPQ DX, R14
JGE varTable
SUBQ $1, CX
SHLQ $1, DX
JMP calcShift
varTable:
// var table [maxTableSize]uint16
//
// In the asm code, unlike the Go code, we can zero-initialize only the
// first tableSize elements. Each uint16 element is 2 bytes and each MOVOU
// writes 16 bytes, so we can do only tableSize/8 writes instead of the
// 2048 writes that would zero-initialize all of table's 32768 bytes.
SHRQ $3, DX
LEAQ table-32768(SP), BX
PXOR X0, X0
memclr:
MOVOU X0, 0(BX)
ADDQ $16, BX
SUBQ $1, DX
JNZ memclr
// !!! DX = &src[0]
MOVQ SI, DX
// sLimit := len(src) - inputMargin
MOVQ R14, R9
SUBQ $15, R9
// !!! Pre-emptively spill CX, DX and R9 to the stack. Their values don't
// change for the rest of the function.
MOVQ CX, 56(SP)
MOVQ DX, 64(SP)
MOVQ R9, 88(SP)
// nextEmit := 0
MOVQ DX, R10
// s := 1
ADDQ $1, SI
// nextHash := hash(load32(src, s), shift)
MOVL 0(SI), R11
IMULL $0x1e35a7bd, R11
SHRL CX, R11
outer:
// for { etc }
// skip := 32
MOVQ $32, R12
// nextS := s
MOVQ SI, R13
// candidate := 0
MOVQ $0, R15
inner0:
// for { etc }
// s := nextS
MOVQ R13, SI
// bytesBetweenHashLookups := skip >> 5
MOVQ R12, R14
SHRQ $5, R14
// nextS = s + bytesBetweenHashLookups
ADDQ R14, R13
// skip += bytesBetweenHashLookups
ADDQ R14, R12
// if nextS > sLimit { goto emitRemainder }
MOVQ R13, AX
SUBQ DX, AX
CMPQ AX, R9
JA emitRemainder
// candidate = int(table[nextHash])
// XXX: MOVWQZX table-32768(SP)(R11*2), R15
// XXX: 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
BYTE $0x4e
BYTE $0x0f
BYTE $0xb7
BYTE $0x7c
BYTE $0x5c
BYTE $0x78
// table[nextHash] = uint16(s)
MOVQ SI, AX
SUBQ DX, AX
// XXX: MOVW AX, table-32768(SP)(R11*2)
// XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
BYTE $0x66
BYTE $0x42
BYTE $0x89
BYTE $0x44
BYTE $0x5c
BYTE $0x78
// nextHash = hash(load32(src, nextS), shift)
MOVL 0(R13), R11
IMULL $0x1e35a7bd, R11
SHRL CX, R11
// if load32(src, s) != load32(src, candidate) { continue } break
MOVL 0(SI), AX
MOVL (DX)(R15*1), BX
CMPL AX, BX
JNE inner0
fourByteMatch:
// As per the encode_other.go code:
//
// A 4-byte match has been found. We'll later see etc.
// !!! Jump to a fast path for short (<= 16 byte) literals. See the comment
// on inputMargin in encode.go.
MOVQ SI, AX
SUBQ R10, AX
CMPQ AX, $16
JLE emitLiteralFastPath
// ----------------------------------------
// Begin inline of the emitLiteral call.
//
// d += emitLiteral(dst[d:], src[nextEmit:s])
MOVL AX, BX
SUBL $1, BX
CMPL BX, $60
JLT inlineEmitLiteralOneByte
CMPL BX, $256
JLT inlineEmitLiteralTwoBytes
inlineEmitLiteralThreeBytes:
MOVB $0xf4, 0(DI)
MOVW BX, 1(DI)
ADDQ $3, DI
JMP inlineEmitLiteralMemmove
inlineEmitLiteralTwoBytes:
MOVB $0xf0, 0(DI)
MOVB BX, 1(DI)
ADDQ $2, DI
JMP inlineEmitLiteralMemmove
inlineEmitLiteralOneByte:
SHLB $2, BX
MOVB BX, 0(DI)
ADDQ $1, DI
inlineEmitLiteralMemmove:
// Spill local variables (registers) onto the stack; call; unspill.
//
// copy(dst[i:], lit)
//
// This means calling runtime·memmove(&dst[i], &lit[0], len(lit)), so we push
// DI, R10 and AX as arguments.
MOVQ DI, 0(SP)
MOVQ R10, 8(SP)
MOVQ AX, 16(SP)
ADDQ AX, DI // Finish the "d +=" part of "d += emitLiteral(etc)".
MOVQ SI, 72(SP)
MOVQ DI, 80(SP)
MOVQ R15, 112(SP)
CALL runtime·memmove(SB)
MOVQ 56(SP), CX
MOVQ 64(SP), DX
MOVQ 72(SP), SI
MOVQ 80(SP), DI
MOVQ 88(SP), R9
MOVQ 112(SP), R15
JMP inner1
inlineEmitLiteralEnd:
// End inline of the emitLiteral call.
// ----------------------------------------
emitLiteralFastPath:
// !!! Emit the 1-byte encoding "uint8(len(lit)-1)<<2".
MOVB AX, BX
SUBB $1, BX
SHLB $2, BX
MOVB BX, (DI)
ADDQ $1, DI
// !!! Implement the copy from lit to dst as a 16-byte load and store.
// (Encode's documentation says that dst and src must not overlap.)
//
// This always copies 16 bytes, instead of only len(lit) bytes, but that's
// OK. Subsequent iterations will fix up the overrun.
//
// Note that on amd64, it is legal and cheap to issue unaligned 8-byte or
// 16-byte loads and stores. This technique probably wouldn't be as
// effective on architectures that are fussier about alignment.
MOVOU 0(R10), X0
MOVOU X0, 0(DI)
ADDQ AX, DI
inner1:
// for { etc }
// base := s
MOVQ SI, R12
// !!! offset := base - candidate
MOVQ R12, R11
SUBQ R15, R11
SUBQ DX, R11
// ----------------------------------------
// Begin inline of the extendMatch call.
//
// s = extendMatch(src, candidate+4, s+4)
// !!! R14 = &src[len(src)]
MOVQ src_len+32(FP), R14
ADDQ DX, R14
// !!! R13 = &src[len(src) - 8]
MOVQ R14, R13
SUBQ $8, R13
// !!! R15 = &src[candidate + 4]
ADDQ $4, R15
ADDQ DX, R15
// !!! s += 4
ADDQ $4, SI
inlineExtendMatchCmp8:
// As long as we are 8 or more bytes before the end of src, we can load and
// compare 8 bytes at a time. If those 8 bytes are equal, repeat.
CMPQ SI, R13
JA inlineExtendMatchCmp1
MOVQ (R15), AX
MOVQ (SI), BX
CMPQ AX, BX
JNE inlineExtendMatchBSF
ADDQ $8, R15
ADDQ $8, SI
JMP inlineExtendMatchCmp8
inlineExtendMatchBSF:
// If those 8 bytes were not equal, XOR the two 8 byte values, and return
// the index of the first byte that differs. The BSF instruction finds the
// least significant 1 bit, the amd64 architecture is little-endian, and
// the shift by 3 converts a bit index to a byte index.
XORQ AX, BX
BSFQ BX, BX
SHRQ $3, BX
ADDQ BX, SI
JMP inlineExtendMatchEnd
inlineExtendMatchCmp1:
// In src's tail, compare 1 byte at a time.
CMPQ SI, R14
JAE inlineExtendMatchEnd
MOVB (R15), AX
MOVB (SI), BX
CMPB AX, BX
JNE inlineExtendMatchEnd
ADDQ $1, R15
ADDQ $1, SI
JMP inlineExtendMatchCmp1
inlineExtendMatchEnd:
// End inline of the extendMatch call.
// ----------------------------------------
// ----------------------------------------
// Begin inline of the emitCopy call.
//
// d += emitCopy(dst[d:], base-candidate, s-base)
// !!! length := s - base
MOVQ SI, AX
SUBQ R12, AX
inlineEmitCopyLoop0:
// for length >= 68 { etc }
CMPL AX, $68
JLT inlineEmitCopyStep1
// Emit a length 64 copy, encoded as 3 bytes.
MOVB $0xfe, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
SUBL $64, AX
JMP inlineEmitCopyLoop0
inlineEmitCopyStep1:
// if length > 64 { etc }
CMPL AX, $64
JLE inlineEmitCopyStep2
// Emit a length 60 copy, encoded as 3 bytes.
MOVB $0xee, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
SUBL $60, AX
inlineEmitCopyStep2:
// if length >= 12 || offset >= 2048 { goto inlineEmitCopyStep3 }
CMPL AX, $12
JGE inlineEmitCopyStep3
CMPL R11, $2048
JGE inlineEmitCopyStep3
// Emit the remaining copy, encoded as 2 bytes.
MOVB R11, 1(DI)
SHRL $8, R11
SHLB $5, R11
SUBB $4, AX
SHLB $2, AX
ORB AX, R11
ORB $1, R11
MOVB R11, 0(DI)
ADDQ $2, DI
JMP inlineEmitCopyEnd
inlineEmitCopyStep3:
// Emit the remaining copy, encoded as 3 bytes.
SUBL $1, AX
SHLB $2, AX
ORB $2, AX
MOVB AX, 0(DI)
MOVW R11, 1(DI)
ADDQ $3, DI
inlineEmitCopyEnd:
// End inline of the emitCopy call.
// ----------------------------------------
// nextEmit = s
MOVQ SI, R10
// if s >= sLimit { goto emitRemainder }
MOVQ SI, AX
SUBQ DX, AX
CMPQ AX, R9
JAE emitRemainder
// As per the encode_other.go code:
//
// We could immediately etc.
// x := load64(src, s-1)
MOVQ -1(SI), R14
// prevHash := hash(uint32(x>>0), shift)
MOVL R14, R11
IMULL $0x1e35a7bd, R11
SHRL CX, R11
// table[prevHash] = uint16(s-1)
MOVQ SI, AX
SUBQ DX, AX
SUBQ $1, AX
// XXX: MOVW AX, table-32768(SP)(R11*2)
// XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
BYTE $0x66
BYTE $0x42
BYTE $0x89
BYTE $0x44
BYTE $0x5c
BYTE $0x78
// currHash := hash(uint32(x>>8), shift)
SHRQ $8, R14
MOVL R14, R11
IMULL $0x1e35a7bd, R11
SHRL CX, R11
// candidate = int(table[currHash])
// XXX: MOVWQZX table-32768(SP)(R11*2), R15
// XXX: 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
BYTE $0x4e
BYTE $0x0f
BYTE $0xb7
BYTE $0x7c
BYTE $0x5c
BYTE $0x78
// table[currHash] = uint16(s)
ADDQ $1, AX
// XXX: MOVW AX, table-32768(SP)(R11*2)
// XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
BYTE $0x66
BYTE $0x42
BYTE $0x89
BYTE $0x44
BYTE $0x5c
BYTE $0x78
// if uint32(x>>8) == load32(src, candidate) { continue }
MOVL (DX)(R15*1), BX
CMPL R14, BX
JEQ inner1
// nextHash = hash(uint32(x>>16), shift)
SHRQ $8, R14
MOVL R14, R11
IMULL $0x1e35a7bd, R11
SHRL CX, R11
// s++
ADDQ $1, SI
// break out of the inner1 for loop, i.e. continue the outer loop.
JMP outer
emitRemainder:
// if nextEmit < len(src) { etc }
MOVQ src_len+32(FP), AX
ADDQ DX, AX
CMPQ R10, AX
JEQ encodeBlockEnd
// d += emitLiteral(dst[d:], src[nextEmit:])
//
// Push args.
MOVQ DI, 0(SP)
MOVQ $0, 8(SP) // Unnecessary, as the callee ignores it, but conservative.
MOVQ $0, 16(SP) // Unnecessary, as the callee ignores it, but conservative.
MOVQ R10, 24(SP)
SUBQ R10, AX
MOVQ AX, 32(SP)
MOVQ AX, 40(SP) // Unnecessary, as the callee ignores it, but conservative.
// Spill local variables (registers) onto the stack; call; unspill.
MOVQ DI, 80(SP)
CALL ·emitLiteral(SB)
MOVQ 80(SP), DI
// Finish the "d +=" part of "d += emitLiteral(etc)".
ADDQ 48(SP), DI
encodeBlockEnd:
MOVQ dst_base+0(FP), AX
SUBQ AX, DI
MOVQ DI, d+48(FP)
RET

238
vendor/github.com/klauspost/compress/snappy/encode_other.go generated vendored Normal file
View file

@ -0,0 +1,238 @@
// Copyright 2016 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !amd64 appengine !gc noasm
package snappy
func load32(b []byte, i int) uint32 {
b = b[i : i+4 : len(b)] // Help the compiler eliminate bounds checks on the next line.
return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
}
func load64(b []byte, i int) uint64 {
b = b[i : i+8 : len(b)] // Help the compiler eliminate bounds checks on the next line.
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}
// emitLiteral writes a literal chunk and returns the number of bytes written.
//
// It assumes that:
// dst is long enough to hold the encoded bytes
// 1 <= len(lit) && len(lit) <= 65536
func emitLiteral(dst, lit []byte) int {
i, n := 0, uint(len(lit)-1)
switch {
case n < 60:
dst[0] = uint8(n)<<2 | tagLiteral
i = 1
case n < 1<<8:
dst[0] = 60<<2 | tagLiteral
dst[1] = uint8(n)
i = 2
default:
dst[0] = 61<<2 | tagLiteral
dst[1] = uint8(n)
dst[2] = uint8(n >> 8)
i = 3
}
return i + copy(dst[i:], lit)
}
// emitCopy writes a copy chunk and returns the number of bytes written.
//
// It assumes that:
// dst is long enough to hold the encoded bytes
// 1 <= offset && offset <= 65535
// 4 <= length && length <= 65535
func emitCopy(dst []byte, offset, length int) int {
i := 0
// The maximum length for a single tagCopy1 or tagCopy2 op is 64 bytes. The
// threshold for this loop is a little higher (at 68 = 64 + 4), and the
// length emitted down below is is a little lower (at 60 = 64 - 4), because
// it's shorter to encode a length 67 copy as a length 60 tagCopy2 followed
// by a length 7 tagCopy1 (which encodes as 3+2 bytes) than to encode it as
// a length 64 tagCopy2 followed by a length 3 tagCopy2 (which encodes as
// 3+3 bytes). The magic 4 in the 64±4 is because the minimum length for a
// tagCopy1 op is 4 bytes, which is why a length 3 copy has to be an
// encodes-as-3-bytes tagCopy2 instead of an encodes-as-2-bytes tagCopy1.
for length >= 68 {
// Emit a length 64 copy, encoded as 3 bytes.
dst[i+0] = 63<<2 | tagCopy2
dst[i+1] = uint8(offset)
dst[i+2] = uint8(offset >> 8)
i += 3
length -= 64
}
if length > 64 {
// Emit a length 60 copy, encoded as 3 bytes.
dst[i+0] = 59<<2 | tagCopy2
dst[i+1] = uint8(offset)
dst[i+2] = uint8(offset >> 8)
i += 3
length -= 60
}
if length >= 12 || offset >= 2048 {
// Emit the remaining copy, encoded as 3 bytes.
dst[i+0] = uint8(length-1)<<2 | tagCopy2
dst[i+1] = uint8(offset)
dst[i+2] = uint8(offset >> 8)
return i + 3
}
// Emit the remaining copy, encoded as 2 bytes.
dst[i+0] = uint8(offset>>8)<<5 | uint8(length-4)<<2 | tagCopy1
dst[i+1] = uint8(offset)
return i + 2
}
// extendMatch returns the largest k such that k <= len(src) and that
// src[i:i+k-j] and src[j:k] have the same contents.
//
// It assumes that:
// 0 <= i && i < j && j <= len(src)
func extendMatch(src []byte, i, j int) int {
for ; j < len(src) && src[i] == src[j]; i, j = i+1, j+1 {
}
return j
}
func hash(u, shift uint32) uint32 {
return (u * 0x1e35a7bd) >> shift
}
// encodeBlock encodes a non-empty src to a guaranteed-large-enough dst. It
// assumes that the varint-encoded length of the decompressed bytes has already
// been written.
//
// It also assumes that:
// len(dst) >= MaxEncodedLen(len(src)) &&
// minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize
func encodeBlock(dst, src []byte) (d int) {
// Initialize the hash table. Its size ranges from 1<<8 to 1<<14 inclusive.
// The table element type is uint16, as s < sLimit and sLimit < len(src)
// and len(src) <= maxBlockSize and maxBlockSize == 65536.
const (
maxTableSize = 1 << 14
// tableMask is redundant, but helps the compiler eliminate bounds
// checks.
tableMask = maxTableSize - 1
)
shift := uint32(32 - 8)
for tableSize := 1 << 8; tableSize < maxTableSize && tableSize < len(src); tableSize *= 2 {
shift--
}
// In Go, all array elements are zero-initialized, so there is no advantage
// to a smaller tableSize per se. However, it matches the C++ algorithm,
// and in the asm versions of this code, we can get away with zeroing only
// the first tableSize elements.
var table [maxTableSize]uint16
// sLimit is when to stop looking for offset/length copies. The inputMargin
// lets us use a fast path for emitLiteral in the main loop, while we are
// looking for copies.
sLimit := len(src) - inputMargin
// nextEmit is where in src the next emitLiteral should start from.
nextEmit := 0
// The encoded form must start with a literal, as there are no previous
// bytes to copy, so we start looking for hash matches at s == 1.
s := 1
nextHash := hash(load32(src, s), shift)
for {
// Copied from the C++ snappy implementation:
//
// Heuristic match skipping: If 32 bytes are scanned with no matches
// found, start looking only at every other byte. If 32 more bytes are
// scanned (or skipped), look at every third byte, etc.. When a match
// is found, immediately go back to looking at every byte. This is a
// small loss (~5% performance, ~0.1% density) for compressible data
// due to more bookkeeping, but for non-compressible data (such as
// JPEG) it's a huge win since the compressor quickly "realizes" the
// data is incompressible and doesn't bother looking for matches
// everywhere.
//
// The "skip" variable keeps track of how many bytes there are since
// the last match; dividing it by 32 (ie. right-shifting by five) gives
// the number of bytes to move ahead for each iteration.
skip := 32
nextS := s
candidate := 0
for {
s = nextS
bytesBetweenHashLookups := skip >> 5
nextS = s + bytesBetweenHashLookups
skip += bytesBetweenHashLookups
if nextS > sLimit {
goto emitRemainder
}
candidate = int(table[nextHash&tableMask])
table[nextHash&tableMask] = uint16(s)
nextHash = hash(load32(src, nextS), shift)
if load32(src, s) == load32(src, candidate) {
break
}
}
// A 4-byte match has been found. We'll later see if more than 4 bytes
// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
// them as literal bytes.
d += emitLiteral(dst[d:], src[nextEmit:s])
// Call emitCopy, and then see if another emitCopy could be our next
// move. Repeat until we find no match for the input immediately after
// what was consumed by the last emitCopy call.
//
// If we exit this loop normally then we need to call emitLiteral next,
// though we don't yet know how big the literal will be. We handle that
// by proceeding to the next iteration of the main loop. We also can
// exit this loop via goto if we get close to exhausting the input.
for {
// Invariant: we have a 4-byte match at s, and no need to emit any
// literal bytes prior to s.
base := s
// Extend the 4-byte match as long as possible.
//
// This is an inlined version of:
// s = extendMatch(src, candidate+4, s+4)
s += 4
for i := candidate + 4; s < len(src) && src[i] == src[s]; i, s = i+1, s+1 {
}
d += emitCopy(dst[d:], base-candidate, s-base)
nextEmit = s
if s >= sLimit {
goto emitRemainder
}
// We could immediately start working at s now, but to improve
// compression we first update the hash table at s-1 and at s. If
// another emitCopy is not our next move, also calculate nextHash
// at s+1. At least on GOARCH=amd64, these three hash calculations
// are faster as one load64 call (with some shifts) instead of
// three load32 calls.
x := load64(src, s-1)
prevHash := hash(uint32(x>>0), shift)
table[prevHash&tableMask] = uint16(s - 1)
currHash := hash(uint32(x>>8), shift)
candidate = int(table[currHash&tableMask])
table[currHash&tableMask] = uint16(s)
if uint32(x>>8) != load32(src, candidate) {
nextHash = hash(uint32(x>>16), shift)
s++
break
}
}
}
emitRemainder:
if nextEmit < len(src) {
d += emitLiteral(dst[d:], src[nextEmit:])
}
return d
}

2
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del old.txt
go test -bench=. >>old.txt && go test -bench=. >>old.txt && go test -bench=. >>old.txt && benchstat -delta-test=ttest old.txt new.txt

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// Copyright 2011 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package snappy implements the Snappy compression format. It aims for very
// high speeds and reasonable compression.
//
// There are actually two Snappy formats: block and stream. They are related,
// but different: trying to decompress block-compressed data as a Snappy stream
// will fail, and vice versa. The block format is the Decode and Encode
// functions and the stream format is the Reader and Writer types.
//
// The block format, the more common case, is used when the complete size (the
// number of bytes) of the original data is known upfront, at the time
// compression starts. The stream format, also known as the framing format, is
// for when that isn't always true.
//
// The canonical, C++ implementation is at https://github.com/google/snappy and
// it only implements the block format.
package snappy
import (
"hash/crc32"
)
/*
Each encoded block begins with the varint-encoded length of the decoded data,
followed by a sequence of chunks. Chunks begin and end on byte boundaries. The
first byte of each chunk is broken into its 2 least and 6 most significant bits
called l and m: l ranges in [0, 4) and m ranges in [0, 64). l is the chunk tag.
Zero means a literal tag. All other values mean a copy tag.
For literal tags:
- If m < 60, the next 1 + m bytes are literal bytes.
- Otherwise, let n be the little-endian unsigned integer denoted by the next
m - 59 bytes. The next 1 + n bytes after that are literal bytes.
For copy tags, length bytes are copied from offset bytes ago, in the style of
Lempel-Ziv compression algorithms. In particular:
- For l == 1, the offset ranges in [0, 1<<11) and the length in [4, 12).
The length is 4 + the low 3 bits of m. The high 3 bits of m form bits 8-10
of the offset. The next byte is bits 0-7 of the offset.
- For l == 2, the offset ranges in [0, 1<<16) and the length in [1, 65).
The length is 1 + m. The offset is the little-endian unsigned integer
denoted by the next 2 bytes.
- For l == 3, this tag is a legacy format that is no longer issued by most
encoders. Nonetheless, the offset ranges in [0, 1<<32) and the length in
[1, 65). The length is 1 + m. The offset is the little-endian unsigned
integer denoted by the next 4 bytes.
*/
const (
tagLiteral = 0x00
tagCopy1 = 0x01
tagCopy2 = 0x02
tagCopy4 = 0x03
)
const (
checksumSize = 4
chunkHeaderSize = 4
magicChunk = "\xff\x06\x00\x00" + magicBody
magicBody = "sNaPpY"
// maxBlockSize is the maximum size of the input to encodeBlock. It is not
// part of the wire format per se, but some parts of the encoder assume
// that an offset fits into a uint16.
//
// Also, for the framing format (Writer type instead of Encode function),
// https://github.com/google/snappy/blob/master/framing_format.txt says
// that "the uncompressed data in a chunk must be no longer than 65536
// bytes".
maxBlockSize = 65536
// maxEncodedLenOfMaxBlockSize equals MaxEncodedLen(maxBlockSize), but is
// hard coded to be a const instead of a variable, so that obufLen can also
// be a const. Their equivalence is confirmed by
// TestMaxEncodedLenOfMaxBlockSize.
maxEncodedLenOfMaxBlockSize = 76490
obufHeaderLen = len(magicChunk) + checksumSize + chunkHeaderSize
obufLen = obufHeaderLen + maxEncodedLenOfMaxBlockSize
)
const (
chunkTypeCompressedData = 0x00
chunkTypeUncompressedData = 0x01
chunkTypePadding = 0xfe
chunkTypeStreamIdentifier = 0xff
)
var crcTable = crc32.MakeTable(crc32.Castagnoli)
// crc implements the checksum specified in section 3 of
// https://github.com/google/snappy/blob/master/framing_format.txt
func crc(b []byte) uint32 {
c := crc32.Update(0, crcTable, b)
return uint32(c>>15|c<<17) + 0xa282ead8
}

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# zstd
[Zstandard](https://facebook.github.io/zstd/) is a real-time compression algorithm, providing high compression ratios.
It offers a very wide range of compression / speed trade-off, while being backed by a very fast decoder.
A high performance compression algorithm is implemented. For now focused on speed.
This package provides [compression](#Compressor) to and [decompression](#Decompressor) of Zstandard content.
Note that custom dictionaries are not supported yet, so if your code relies on that,
you cannot use the package as-is.
This package is pure Go and without use of "unsafe".
If a significant speedup can be achieved using "unsafe", it may be added as an option later.
The `zstd` package is provided as open source software using a Go standard license.
Currently the package is heavily optimized for 64 bit processors and will be significantly slower on 32 bit processors.
## Installation
Install using `go get -u github.com/klauspost/compress`. The package is located in `github.com/klauspost/compress/zstd`.
Godoc Documentation: https://godoc.org/github.com/klauspost/compress/zstd
## Compressor
### Status:
BETA - there may still be subtle bugs, but a wide variety of content has been tested.
There may still be implementation specific stuff in regards to error handling that could lead to edge cases.
For now, a high speed (fastest) and medium-fast (default) compressor has been implemented.
The "Fastest" compression ratio is roughly equivalent to zstd level 1.
The "Default" compression ration is roughly equivalent to zstd level 3 (default).
In terms of speed, it is typically 2x as fast as the stdlib deflate/gzip in its fastest mode. The compression ratio compared to stdlib is around level 3, but usually 3x as fast.
Compared to cgo zstd, the speed is around level 3 (default), but compression slightly worse, between level 1&2.
### Usage
An Encoder can be used for either compressing a stream via the
`io.WriteCloser` interface supported by the Encoder or as multiple independent
tasks via the `EncodeAll` function.
Smaller encodes are encouraged to use the EncodeAll function.
Use `NewWriter` to create a new instance that can be used for both.
To create a writer with default options, do like this:
```Go
// Compress input to output.
func Compress(in io.Reader, out io.Writer) error {
w, err := NewWriter(output)
if err != nil {
return err
}
_, err := io.Copy(w, input)
if err != nil {
enc.Close()
return err
}
return enc.Close()
}
```
Now you can encode by writing data to `enc`. The output will be finished writing when `Close()` is called.
Even if your encode fails, you should still call `Close()` to release any resources that may be held up.
The above is fine for big encodes. However, whenever possible try to *reuse* the writer.
To reuse the encoder, you can use the `Reset(io.Writer)` function to change to another output.
This will allow the encoder to reuse all resources and avoid wasteful allocations.
Currently stream encoding has 'light' concurrency, meaning up to 2 goroutines can be working on part
of a stream. This is independent of the `WithEncoderConcurrency(n)`, but that is likely to change
in the future. So if you want to limit concurrency for future updates, specify the concurrency
you would like.
You can specify your desired compression level using `WithEncoderLevel()` option. Currently only pre-defined
compression settings can be specified.
#### Future Compatibility Guarantees
This will be an evolving project. When using this package it is important to note that both the compression efficiency and speed may change.
The goal will be to keep the default efficiency at the default zstd (level 3).
However the encoding should never be assumed to remain the same,
and you should not use hashes of compressed output for similarity checks.
The Encoder can be assumed to produce the same output from the exact same code version.
However, the may be modes in the future that break this,
although they will not be enabled without an explicit option.
This encoder is not designed to (and will probably never) output the exact same bitstream as the reference encoder.
Also note, that the cgo decompressor currently does not [report all errors on invalid input](https://github.com/DataDog/zstd/issues/59),
[omits error checks](https://github.com/DataDog/zstd/issues/61), [ignores checksums](https://github.com/DataDog/zstd/issues/43)
and seems to ignore concatenated streams, even though [it is part of the spec](https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#frames).
#### Blocks
For compressing small blocks, the returned encoder has a function called `EncodeAll(src, dst []byte) []byte`.
`EncodeAll` will encode all input in src and append it to dst.
This function can be called concurrently, but each call will only run on a single goroutine.
Encoded blocks can be concatenated and the result will be the combined input stream.
Data compressed with EncodeAll can be decoded with the Decoder, using either a stream or `DecodeAll`.
Especially when encoding blocks you should take special care to reuse the encoder.
This will effectively make it run without allocations after a warmup period.
To make it run completely without allocations, supply a destination buffer with space for all content.
```Go
import "github.com/klauspost/compress/zstd"
// Create a writer that caches compressors.
// For this operation type we supply a nil Reader.
var encoder, _ = zstd.NewWriter(nil)
// Compress a buffer.
// If you have a destination buffer, the allocation in the call can also be eliminated.
func Compress(src []byte) []byte {
return encoder.EncodeAll(src, make([]byte, 0, len(src)))
}
```
You can control the maximum number of concurrent encodes using the `WithEncoderConcurrency(n)`
option when creating the writer.
Using the Encoder for both a stream and individual blocks concurrently is safe.
### Performance
I have collected some speed examples to compare speed and compression against other compressors.
* `file` is the input file.
* `out` is the compressor used. `zskp` is this package. `gzstd` is gzip standard library. `zstd` is the Datadog cgo library.
* `level` is the compression level used. For `zskp` level 1 is "fastest", level 2 is "default".
* `insize`/`outsize` is the input/output size.
* `millis` is the number of milliseconds used for compression.
* `mb/s` is megabytes (2^20 bytes) per second.
```
The test data for the Large Text Compression Benchmark is the first
10^9 bytes of the English Wikipedia dump on Mar. 3, 2006.
http://mattmahoney.net/dc/textdata.html
file out level insize outsize millis mb/s
enwik9 zskp 1 1000000000 343833033 5840 163.30
enwik9 zskp 2 1000000000 317822183 8449 112.87
enwik9 gzstd 1 1000000000 382578136 13627 69.98
enwik9 gzstd 3 1000000000 349139651 22344 42.68
enwik9 zstd 1 1000000000 357416379 4838 197.12
enwik9 zstd 3 1000000000 313734522 7556 126.21
GOB stream of binary data. Highly compressible.
https://files.klauspost.com/compress/gob-stream.7z
file out level insize outsize millis mb/s
gob-stream zskp 1 1911399616 234981983 5100 357.42
gob-stream zskp 2 1911399616 208674003 6698 272.15
gob-stream gzstd 1 1911399616 357382641 14727 123.78
gob-stream gzstd 3 1911399616 327835097 17005 107.19
gob-stream zstd 1 1911399616 250787165 4075 447.22
gob-stream zstd 3 1911399616 208191888 5511 330.77
Highly compressible JSON file. Similar to logs in a lot of ways.
https://files.klauspost.com/compress/adresser.001.gz
file out level insize outsize millis mb/s
adresser.001 zskp 1 1073741824 18510122 1477 692.83
adresser.001 zskp 2 1073741824 19831697 1705 600.59
adresser.001 gzstd 1 1073741824 47755503 3079 332.47
adresser.001 gzstd 3 1073741824 40052381 3051 335.63
adresser.001 zstd 1 1073741824 16135896 994 1030.18
adresser.001 zstd 3 1073741824 17794465 905 1131.49
VM Image, Linux mint with a few installed applications:
https://files.klauspost.com/compress/rawstudio-mint14.7z
file out level insize outsize millis mb/s
rawstudio-mint14.tar zskp 1 8558382592 3648168838 33398 244.38
rawstudio-mint14.tar zskp 2 8558382592 3376721436 50962 160.16
rawstudio-mint14.tar gzstd 1 8558382592 3926257486 84712 96.35
rawstudio-mint14.tar gzstd 3 8558382592 3740711978 176344 46.28
rawstudio-mint14.tar zstd 1 8558382592 3607859742 27903 292.51
rawstudio-mint14.tar zstd 3 8558382592 3341710879 46700 174.77
The test data is designed to test archivers in realistic backup scenarios.
http://mattmahoney.net/dc/10gb.html
file out level insize outsize millis mb/s
10gb.tar zskp 1 10065157632 4883149814 45715 209.97
10gb.tar zskp 2 10065157632 4638110010 60970 157.44
10gb.tar gzstd 1 10065157632 5198296126 97769 98.18
10gb.tar gzstd 3 10065157632 4932665487 313427 30.63
10gb.tar zstd 1 10065157632 4940796535 40391 237.65
10gb.tar zstd 3 10065157632 4638618579 52911 181.42
Silesia Corpus:
http://sun.aei.polsl.pl/~sdeor/corpus/silesia.zip
file out level insize outsize millis mb/s
silesia.tar zskp 1 211947520 73025800 1108 182.26
silesia.tar zskp 2 211947520 67674684 1599 126.41
silesia.tar gzstd 1 211947520 80007735 2515 80.37
silesia.tar gzstd 3 211947520 73133380 4259 47.45
silesia.tar zstd 1 211947520 73513991 933 216.64
silesia.tar zstd 3 211947520 66793301 1377 146.79
```
### Converters
As part of the development process a *Snappy* -> *Zstandard* converter was also built.
This can convert a *framed* [Snappy Stream](https://godoc.org/github.com/golang/snappy#Writer) to a zstd stream. Note that a single block is not framed.
Conversion is done by converting the stream directly from Snappy without intermediate full decoding.
Therefore the compression ratio is much less than what can be done by a full decompression
and compression, and a faulty Snappy stream may lead to a faulty Zstandard stream without
any errors being generated.
No CRC value is being generated and not all CRC values of the Snappy stream are checked.
However, it provides really fast re-compression of Snappy streams.
```
BenchmarkSnappy_ConvertSilesia-8 1 1156001600 ns/op 183.35 MB/s
Snappy len 103008711 -> zstd len 82687318
BenchmarkSnappy_Enwik9-8 1 6472998400 ns/op 154.49 MB/s
Snappy len 508028601 -> zstd len 390921079
```
```Go
s := zstd.SnappyConverter{}
n, err = s.Convert(input, output)
if err != nil {
fmt.Println("Re-compressed stream to", n, "bytes")
}
```
The converter `s` can be reused to avoid allocations, even after errors.
## Decompressor
STATUS: Release Candidate - there may still be subtle bugs, but a wide variety of content has been tested.
### Usage
The package has been designed for two main usages, big streams of data and smaller in-memory buffers.
There are two main usages of the package for these. Both of them are accessed by creating a `Decoder`.
For streaming use a simple setup could look like this:
```Go
import "github.com/klauspost/compress/zstd"
func Decompress(in io.Reader, out io.Writer) error {
d, err := zstd.NewReader(input)
if err != nil {
return err
}
defer d.Close()
// Copy content...
_, err := io.Copy(out, d)
return err
}
```
It is important to use the "Close" function when you no longer need the Reader to stop running goroutines.
See "Allocation-less operation" below.
For decoding buffers, it could look something like this:
```Go
import "github.com/klauspost/compress/zstd"
// Create a reader that caches decompressors.
// For this operation type we supply a nil Reader.
var decoder, _ = zstd.NewReader(nil)
// Decompress a buffer. We don't supply a destination buffer,
// so it will be allocated by the decoder.
func Decompress(src []byte) ([]byte, error) {
return decoder.DecodeAll(src, nil)
}
```
Both of these cases should provide the functionality needed.
The decoder can be used for *concurrent* decompression of multiple buffers.
It will only allow a certain number of concurrent operations to run.
To tweak that yourself use the `WithDecoderConcurrency(n)` option when creating the decoder.
### Allocation-less operation
The decoder has been designed to operate without allocations after a warmup.
This means that you should *store* the decoder for best performance.
To re-use a stream decoder, use the `Reset(r io.Reader) error` to switch to another stream.
A decoder can safely be re-used even if the previous stream failed.
To release the resources, you must call the `Close()` function on a decoder.
After this it can *no longer be reused*, but all running goroutines will be stopped.
So you *must* use this if you will no longer need the Reader.
For decompressing smaller buffers a single decoder can be used.
When decoding buffers, you can supply a destination slice with length 0 and your expected capacity.
In this case no unneeded allocations should be made.
### Concurrency
The buffer decoder does everything on the same goroutine and does nothing concurrently.
It can however decode several buffers concurrently. Use `WithDecoderConcurrency(n)` to limit that.
The stream decoder operates on
* One goroutine reads input and splits the input to several block decoders.
* A number of decoders will decode blocks.
* A goroutine coordinates these blocks and sends history from one to the next.
So effectively this also means the decoder will "read ahead" and prepare data to always be available for output.
Since "blocks" are quite dependent on the output of the previous block stream decoding will only have limited concurrency.
In practice this means that concurrency is often limited to utilizing about 2 cores effectively.
### Benchmarks
These are some examples of performance compared to [datadog cgo library](https://github.com/DataDog/zstd).
The first two are streaming decodes and the last are smaller inputs.
```
BenchmarkDecoderSilesia-8 20 642550210 ns/op 329.85 MB/s 3101 B/op 8 allocs/op
BenchmarkDecoderSilesiaCgo-8 100 384930000 ns/op 550.61 MB/s 451878 B/op 9713 allocs/op
BenchmarkDecoderEnwik9-2 10 3146000080 ns/op 317.86 MB/s 2649 B/op 9 allocs/op
BenchmarkDecoderEnwik9Cgo-2 20 1905900000 ns/op 524.69 MB/s 1125120 B/op 45785 allocs/op
BenchmarkDecoder_DecodeAll/z000000.zst-8 200 7049994 ns/op 138.26 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000001.zst-8 100000 19560 ns/op 97.49 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000002.zst-8 5000 297599 ns/op 236.99 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000003.zst-8 2000 725502 ns/op 141.17 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000004.zst-8 200000 9314 ns/op 54.54 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000005.zst-8 10000 137500 ns/op 104.72 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000006.zst-8 500 2316009 ns/op 206.06 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000007.zst-8 20000 64499 ns/op 344.90 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000008.zst-8 50000 24900 ns/op 219.56 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAll/z000009.zst-8 1000 2348999 ns/op 154.01 MB/s 40 B/op 2 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000000.zst-8 500 4268005 ns/op 228.38 MB/s 1228849 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000001.zst-8 100000 15250 ns/op 125.05 MB/s 2096 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000002.zst-8 10000 147399 ns/op 478.49 MB/s 73776 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000003.zst-8 5000 320798 ns/op 319.27 MB/s 139312 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000004.zst-8 200000 10004 ns/op 50.77 MB/s 560 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000005.zst-8 20000 73599 ns/op 195.64 MB/s 19120 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000006.zst-8 1000 1119003 ns/op 426.48 MB/s 557104 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000007.zst-8 20000 103450 ns/op 215.04 MB/s 71296 B/op 9 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000008.zst-8 100000 20130 ns/op 271.58 MB/s 6192 B/op 3 allocs/op
BenchmarkDecoder_DecodeAllCgo/z000009.zst-8 2000 1123500 ns/op 322.00 MB/s 368688 B/op 3 allocs/op
```
This reflects the performance around May 2019, but this may be out of date.
# Contributions
Contributions are always welcome.
For new features/fixes, remember to add tests and for performance enhancements include benchmarks.
For sending files for reproducing errors use a service like [goobox](https://goobox.io/#/upload) or similar to share your files.
For general feedback and experience reports, feel free to open an issue or write me on [Twitter](https://twitter.com/sh0dan).
This package includes the excellent [`github.com/cespare/xxhash`](https://github.com/cespare/xxhash) package Copyright (c) 2016 Caleb Spare.

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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"io"
"math/bits"
)
// bitReader reads a bitstream in reverse.
// The last set bit indicates the start of the stream and is used
// for aligning the input.
type bitReader struct {
in []byte
off uint // next byte to read is at in[off - 1]
value uint64 // Maybe use [16]byte, but shifting is awkward.
bitsRead uint8
}
// init initializes and resets the bit reader.
func (b *bitReader) init(in []byte) error {
if len(in) < 1 {
return errors.New("corrupt stream: too short")
}
b.in = in
b.off = uint(len(in))
// The highest bit of the last byte indicates where to start
v := in[len(in)-1]
if v == 0 {
return errors.New("corrupt stream, did not find end of stream")
}
b.bitsRead = 64
b.value = 0
b.fill()
b.fill()
b.bitsRead += 8 - uint8(highBits(uint32(v)))
return nil
}
// getBits will return n bits. n can be 0.
func (b *bitReader) getBits(n uint8) int {
if n == 0 /*|| b.bitsRead >= 64 */ {
return 0
}
return b.getBitsFast(n)
}
// getBitsFast requires that at least one bit is requested every time.
// There are no checks if the buffer is filled.
func (b *bitReader) getBitsFast(n uint8) int {
const regMask = 64 - 1
v := uint32((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
b.bitsRead += n
return int(v)
}
// fillFast() will make sure at least 32 bits are available.
// There must be at least 4 bytes available.
func (b *bitReader) fillFast() {
if b.bitsRead < 32 {
return
}
// Do single re-slice to avoid bounds checks.
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
}
// fill() will make sure at least 32 bits are available.
func (b *bitReader) fill() {
if b.bitsRead < 32 {
return
}
if b.off >= 4 {
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
return
}
for b.off > 0 {
b.value = (b.value << 8) | uint64(b.in[b.off-1])
b.bitsRead -= 8
b.off--
}
}
// finished returns true if all bits have been read from the bit stream.
func (b *bitReader) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
// overread returns true if more bits have been requested than is on the stream.
func (b *bitReader) overread() bool {
return b.bitsRead > 64
}
// remain returns the number of bits remaining.
func (b *bitReader) remain() uint {
return b.off*8 + 64 - uint(b.bitsRead)
}
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReader) close() error {
// Release reference.
b.in = nil
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}
return nil
}
func highBits(val uint32) (n uint32) {
return uint32(bits.Len32(val) - 1)
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package zstd
import "fmt"
// bitWriter will write bits.
// First bit will be LSB of the first byte of output.
type bitWriter struct {
bitContainer uint64
nBits uint8
out []byte
}
// bitMask16 is bitmasks. Has extra to avoid bounds check.
var bitMask16 = [32]uint16{
0, 1, 3, 7, 0xF, 0x1F,
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF} /* up to 16 bits */
var bitMask32 = [32]uint32{
0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF,
0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF,
0x1ffff, 0x3ffff, 0x7FFFF, 0xfFFFF, 0x1fFFFF, 0x3fFFFF, 0x7fFFFF, 0xffFFFF,
0x1ffFFFF, 0x3ffFFFF, 0x7ffFFFF, 0xfffFFFF, 0x1fffFFFF, 0x3fffFFFF, 0x7fffFFFF,
} // up to 32 bits
// addBits16NC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
b.nBits += bits
}
// addBits32NC will add up to 32 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits32NC(value uint32, bits uint8) {
b.bitContainer |= uint64(value&bitMask32[bits&31]) << (b.nBits & 63)
b.nBits += bits
}
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// flush will flush all pending full bytes.
// There will be at least 56 bits available for writing when this has been called.
// Using flush32 is faster, but leaves less space for writing.
func (b *bitWriter) flush() {
v := b.nBits >> 3
switch v {
case 0:
case 1:
b.out = append(b.out,
byte(b.bitContainer),
)
case 2:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
)
case 3:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
)
case 4:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
)
case 5:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
)
case 6:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
)
case 7:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
)
case 8:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
byte(b.bitContainer>>56),
)
default:
panic(fmt.Errorf("bits (%d) > 64", b.nBits))
}
b.bitContainer >>= v << 3
b.nBits &= 7
}
// flush32 will flush out, so there are at least 32 bits available for writing.
func (b *bitWriter) flush32() {
if b.nBits < 32 {
return
}
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24))
b.nBits -= 32
b.bitContainer >>= 32
}
// flushAlign will flush remaining full bytes and align to next byte boundary.
func (b *bitWriter) flushAlign() {
nbBytes := (b.nBits + 7) >> 3
for i := uint8(0); i < nbBytes; i++ {
b.out = append(b.out, byte(b.bitContainer>>(i*8)))
}
b.nBits = 0
b.bitContainer = 0
}
// close will write the alignment bit and write the final byte(s)
// to the output.
func (b *bitWriter) close() error {
// End mark
b.addBits16Clean(1, 1)
// flush until next byte.
b.flushAlign()
return nil
}
// reset and continue writing by appending to out.
func (b *bitWriter) reset(out []byte) {
b.bitContainer = 0
b.nBits = 0
b.out = out
}

709
vendor/github.com/klauspost/compress/zstd/blockdec.go generated vendored Normal file
View file

@ -0,0 +1,709 @@
// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"io"
"sync"
"github.com/klauspost/compress/huff0"
)
type blockType uint8
//go:generate stringer -type=blockType,literalsBlockType,seqCompMode,tableIndex
const (
blockTypeRaw blockType = iota
blockTypeRLE
blockTypeCompressed
blockTypeReserved
)
type literalsBlockType uint8
const (
literalsBlockRaw literalsBlockType = iota
literalsBlockRLE
literalsBlockCompressed
literalsBlockTreeless
)
const (
// maxCompressedBlockSize is the biggest allowed compressed block size (128KB)
maxCompressedBlockSize = 128 << 10
// Maximum possible block size (all Raw+Uncompressed).
maxBlockSize = (1 << 21) - 1
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#literals_section_header
maxCompressedLiteralSize = 1 << 18
maxRLELiteralSize = 1 << 20
maxMatchLen = 131074
maxSequences = 0x7f00 + 0xffff
// We support slightly less than the reference decoder to be able to
// use ints on 32 bit archs.
maxOffsetBits = 30
)
var (
huffDecoderPool = sync.Pool{New: func() interface{} {
return &huff0.Scratch{}
}}
fseDecoderPool = sync.Pool{New: func() interface{} {
return &fseDecoder{}
}}
)
type blockDec struct {
// Raw source data of the block.
data []byte
dataStorage []byte
// Destination of the decoded data.
dst []byte
// Buffer for literals data.
literalBuf []byte
// Window size of the block.
WindowSize uint64
Type blockType
RLESize uint32
// Is this the last block of a frame?
Last bool
// Use less memory
lowMem bool
history chan *history
input chan struct{}
result chan decodeOutput
sequenceBuf []seq
tmp [4]byte
err error
}
func (b *blockDec) String() string {
if b == nil {
return "<nil>"
}
return fmt.Sprintf("Steam Size: %d, Type: %v, Last: %t, Window: %d", len(b.data), b.Type, b.Last, b.WindowSize)
}
func newBlockDec(lowMem bool) *blockDec {
b := blockDec{
lowMem: lowMem,
result: make(chan decodeOutput, 1),
input: make(chan struct{}, 1),
history: make(chan *history, 1),
}
go b.startDecoder()
return &b
}
// reset will reset the block.
// Input must be a start of a block and will be at the end of the block when returned.
func (b *blockDec) reset(br byteBuffer, windowSize uint64) error {
b.WindowSize = windowSize
tmp := br.readSmall(3)
if tmp == nil {
if debug {
println("Reading block header:", io.ErrUnexpectedEOF)
}
return io.ErrUnexpectedEOF
}
bh := uint32(tmp[0]) | (uint32(tmp[1]) << 8) | (uint32(tmp[2]) << 16)
b.Last = bh&1 != 0
b.Type = blockType((bh >> 1) & 3)
// find size.
cSize := int(bh >> 3)
switch b.Type {
case blockTypeReserved:
return ErrReservedBlockType
case blockTypeRLE:
b.RLESize = uint32(cSize)
cSize = 1
case blockTypeCompressed:
if debug {
println("Data size on stream:", cSize)
}
b.RLESize = 0
if cSize > maxCompressedBlockSize || uint64(cSize) > b.WindowSize {
if debug {
printf("compressed block too big: csize:%d block: %+v\n", uint64(cSize), b)
}
return ErrCompressedSizeTooBig
}
default:
b.RLESize = 0
}
// Read block data.
if cap(b.dataStorage) < cSize {
if b.lowMem {
b.dataStorage = make([]byte, 0, cSize)
} else {
b.dataStorage = make([]byte, 0, maxBlockSize)
}
}
if cap(b.dst) <= maxBlockSize {
b.dst = make([]byte, 0, maxBlockSize+1)
}
var err error
b.data, err = br.readBig(cSize, b.dataStorage)
if err != nil {
if debug {
println("Reading block:", err)
}
return err
}
return nil
}
// sendEOF will make the decoder send EOF on this frame.
func (b *blockDec) sendErr(err error) {
b.Last = true
b.Type = blockTypeReserved
b.err = err
b.input <- struct{}{}
}
// Close will release resources.
// Closed blockDec cannot be reset.
func (b *blockDec) Close() {
close(b.input)
close(b.history)
close(b.result)
}
// decodeAsync will prepare decoding the block when it receives input.
// This will separate output and history.
func (b *blockDec) startDecoder() {
for range b.input {
//println("blockDec: Got block input")
switch b.Type {
case blockTypeRLE:
if cap(b.dst) < int(b.RLESize) {
if b.lowMem {
b.dst = make([]byte, b.RLESize)
} else {
b.dst = make([]byte, maxBlockSize)
}
}
o := decodeOutput{
d: b,
b: b.dst[:b.RLESize],
err: nil,
}
v := b.data[0]
for i := range o.b {
o.b[i] = v
}
hist := <-b.history
hist.append(o.b)
b.result <- o
case blockTypeRaw:
o := decodeOutput{
d: b,
b: b.data,
err: nil,
}
hist := <-b.history
hist.append(o.b)
b.result <- o
case blockTypeCompressed:
b.dst = b.dst[:0]
err := b.decodeCompressed(nil)
o := decodeOutput{
d: b,
b: b.dst,
err: err,
}
if debug {
println("Decompressed to", len(b.dst), "bytes, error:", err)
}
b.result <- o
case blockTypeReserved:
// Used for returning errors.
<-b.history
b.result <- decodeOutput{
d: b,
b: nil,
err: b.err,
}
default:
panic("Invalid block type")
}
if debug {
println("blockDec: Finished block")
}
}
}
// decodeAsync will prepare decoding the block when it receives the history.
// If history is provided, it will not fetch it from the channel.
func (b *blockDec) decodeBuf(hist *history) error {
switch b.Type {
case blockTypeRLE:
if cap(b.dst) < int(b.RLESize) {
if b.lowMem {
b.dst = make([]byte, b.RLESize)
} else {
b.dst = make([]byte, maxBlockSize)
}
}
b.dst = b.dst[:b.RLESize]
v := b.data[0]
for i := range b.dst {
b.dst[i] = v
}
hist.appendKeep(b.dst)
return nil
case blockTypeRaw:
hist.appendKeep(b.data)
return nil
case blockTypeCompressed:
saved := b.dst
b.dst = hist.b
hist.b = nil
err := b.decodeCompressed(hist)
if debug {
println("Decompressed to total", len(b.dst), "bytes, error:", err)
}
hist.b = b.dst
b.dst = saved
return err
case blockTypeReserved:
// Used for returning errors.
return b.err
default:
panic("Invalid block type")
}
}
// decodeCompressed will start decompressing a block.
// If no history is supplied the decoder will decodeAsync as much as possible
// before fetching from blockDec.history
func (b *blockDec) decodeCompressed(hist *history) error {
in := b.data
delayedHistory := hist == nil
if delayedHistory {
// We must always grab history.
defer func() {
if hist == nil {
<-b.history
}
}()
}
// There must be at least one byte for Literals_Block_Type and one for Sequences_Section_Header
if len(in) < 2 {
return ErrBlockTooSmall
}
litType := literalsBlockType(in[0] & 3)
var litRegenSize int
var litCompSize int
sizeFormat := (in[0] >> 2) & 3
var fourStreams bool
switch litType {
case literalsBlockRaw, literalsBlockRLE:
switch sizeFormat {
case 0, 2:
// Regenerated_Size uses 5 bits (0-31). Literals_Section_Header uses 1 byte.
litRegenSize = int(in[0] >> 3)
in = in[1:]
case 1:
// Regenerated_Size uses 12 bits (0-4095). Literals_Section_Header uses 2 bytes.
litRegenSize = int(in[0]>>4) + (int(in[1]) << 4)
in = in[2:]
case 3:
// Regenerated_Size uses 20 bits (0-1048575). Literals_Section_Header uses 3 bytes.
if len(in) < 3 {
println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
return ErrBlockTooSmall
}
litRegenSize = int(in[0]>>4) + (int(in[1]) << 4) + (int(in[2]) << 12)
in = in[3:]
}
case literalsBlockCompressed, literalsBlockTreeless:
switch sizeFormat {
case 0, 1:
// Both Regenerated_Size and Compressed_Size use 10 bits (0-1023).
if len(in) < 3 {
println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
return ErrBlockTooSmall
}
n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12)
litRegenSize = int(n & 1023)
litCompSize = int(n >> 10)
fourStreams = sizeFormat == 1
in = in[3:]
case 2:
fourStreams = true
if len(in) < 4 {
println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
return ErrBlockTooSmall
}
n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20)
litRegenSize = int(n & 16383)
litCompSize = int(n >> 14)
in = in[4:]
case 3:
fourStreams = true
if len(in) < 5 {
println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
return ErrBlockTooSmall
}
n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20) + (uint64(in[4]) << 28)
litRegenSize = int(n & 262143)
litCompSize = int(n >> 18)
in = in[5:]
}
}
if debug {
println("literals type:", litType, "litRegenSize:", litRegenSize, "litCompSize", litCompSize)
}
var literals []byte
var huff *huff0.Scratch
switch litType {
case literalsBlockRaw:
if len(in) < litRegenSize {
println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litRegenSize)
return ErrBlockTooSmall
}
literals = in[:litRegenSize]
in = in[litRegenSize:]
//printf("Found %d uncompressed literals\n", litRegenSize)
case literalsBlockRLE:
if len(in) < 1 {
println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", 1)
return ErrBlockTooSmall
}
if cap(b.literalBuf) < litRegenSize {
if b.lowMem {
b.literalBuf = make([]byte, litRegenSize)
} else {
if litRegenSize > maxCompressedLiteralSize {
// Exceptional
b.literalBuf = make([]byte, litRegenSize)
} else {
b.literalBuf = make([]byte, litRegenSize, maxCompressedLiteralSize)
}
}
}
literals = b.literalBuf[:litRegenSize]
v := in[0]
for i := range literals {
literals[i] = v
}
in = in[1:]
if debug {
printf("Found %d RLE compressed literals\n", litRegenSize)
}
case literalsBlockTreeless:
if len(in) < litCompSize {
println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
return ErrBlockTooSmall
}
// Store compressed literals, so we defer decoding until we get history.
literals = in[:litCompSize]
in = in[litCompSize:]
if debug {
printf("Found %d compressed literals\n", litCompSize)
}
case literalsBlockCompressed:
if len(in) < litCompSize {
println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
return ErrBlockTooSmall
}
literals = in[:litCompSize]
in = in[litCompSize:]
huff = huffDecoderPool.Get().(*huff0.Scratch)
var err error
// Ensure we have space to store it.
if cap(b.literalBuf) < litRegenSize {
if b.lowMem {
b.literalBuf = make([]byte, 0, litRegenSize)
} else {
b.literalBuf = make([]byte, 0, maxCompressedLiteralSize)
}
}
if huff == nil {
huff = &huff0.Scratch{}
}
huff.Out = b.literalBuf[:0]
huff, literals, err = huff0.ReadTable(literals, huff)
if err != nil {
println("reading huffman table:", err)
return err
}
// Use our out buffer.
huff.Out = b.literalBuf[:0]
if fourStreams {
literals, err = huff.Decompress4X(literals, litRegenSize)
} else {
literals, err = huff.Decompress1X(literals)
}
if err != nil {
println("decoding compressed literals:", err)
return err
}
// Make sure we don't leak our literals buffer
huff.Out = nil
if len(literals) != litRegenSize {
return fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
}
if debug {
printf("Decompressed %d literals into %d bytes\n", litCompSize, litRegenSize)
}
}
// Decode Sequences
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#sequences-section
if len(in) < 1 {
return ErrBlockTooSmall
}
seqHeader := in[0]
nSeqs := 0
switch {
case seqHeader == 0:
in = in[1:]
case seqHeader < 128:
nSeqs = int(seqHeader)
in = in[1:]
case seqHeader < 255:
if len(in) < 2 {
return ErrBlockTooSmall
}
nSeqs = int(seqHeader-128)<<8 | int(in[1])
in = in[2:]
case seqHeader == 255:
if len(in) < 3 {
return ErrBlockTooSmall
}
nSeqs = 0x7f00 + int(in[1]) + (int(in[2]) << 8)
in = in[3:]
}
// Allocate sequences
if cap(b.sequenceBuf) < nSeqs {
if b.lowMem {
b.sequenceBuf = make([]seq, nSeqs)
} else {
// Allocate max
b.sequenceBuf = make([]seq, nSeqs, maxSequences)
}
} else {
// Reuse buffer
b.sequenceBuf = b.sequenceBuf[:nSeqs]
}
var seqs = &sequenceDecs{}
if nSeqs > 0 {
if len(in) < 1 {
return ErrBlockTooSmall
}
br := byteReader{b: in, off: 0}
compMode := br.Uint8()
br.advance(1)
if debug {
printf("Compression modes: 0b%b", compMode)
}
for i := uint(0); i < 3; i++ {
mode := seqCompMode((compMode >> (6 - i*2)) & 3)
if debug {
println("Table", tableIndex(i), "is", mode)
}
var seq *sequenceDec
switch tableIndex(i) {
case tableLiteralLengths:
seq = &seqs.litLengths
case tableOffsets:
seq = &seqs.offsets
case tableMatchLengths:
seq = &seqs.matchLengths
default:
panic("unknown table")
}
switch mode {
case compModePredefined:
seq.fse = &fsePredef[i]
case compModeRLE:
if br.remain() < 1 {
return ErrBlockTooSmall
}
v := br.Uint8()
br.advance(1)
dec := fseDecoderPool.Get().(*fseDecoder)
symb, err := decSymbolValue(v, symbolTableX[i])
if err != nil {
printf("RLE Transform table (%v) error: %v", tableIndex(i), err)
return err
}
dec.setRLE(symb)
seq.fse = dec
if debug {
printf("RLE set to %+v, code: %v", symb, v)
}
case compModeFSE:
println("Reading table for", tableIndex(i))
dec := fseDecoderPool.Get().(*fseDecoder)
err := dec.readNCount(&br, uint16(maxTableSymbol[i]))
if err != nil {
println("Read table error:", err)
return err
}
err = dec.transform(symbolTableX[i])
if err != nil {
println("Transform table error:", err)
return err
}
if debug {
println("Read table ok", "symbolLen:", dec.symbolLen)
}
seq.fse = dec
case compModeRepeat:
seq.repeat = true
}
if br.overread() {
return io.ErrUnexpectedEOF
}
}
in = br.unread()
}
// Wait for history.
// All time spent after this is critical since it is strictly sequential.
if hist == nil {
hist = <-b.history
if hist.error {
return ErrDecoderClosed
}
}
// Decode treeless literal block.
if litType == literalsBlockTreeless {
// TODO: We could send the history early WITHOUT the stream history.
// This would allow decoding treeless literials before the byte history is available.
// Silencia stats: Treeless 4393, with: 32775, total: 37168, 11% treeless.
// So not much obvious gain here.
if hist.huffTree == nil {
return errors.New("literal block was treeless, but no history was defined")
}
// Ensure we have space to store it.
if cap(b.literalBuf) < litRegenSize {
if b.lowMem {
b.literalBuf = make([]byte, 0, litRegenSize)
} else {
b.literalBuf = make([]byte, 0, maxCompressedLiteralSize)
}
}
var err error
// Use our out buffer.
huff = hist.huffTree
huff.Out = b.literalBuf[:0]
if fourStreams {
literals, err = huff.Decompress4X(literals, litRegenSize)
} else {
literals, err = huff.Decompress1X(literals)
}
// Make sure we don't leak our literals buffer
huff.Out = nil
if err != nil {
println("decompressing literals:", err)
return err
}
if len(literals) != litRegenSize {
return fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
}
} else {
if hist.huffTree != nil && huff != nil {
huffDecoderPool.Put(hist.huffTree)
hist.huffTree = nil
}
}
if huff != nil {
huff.Out = nil
hist.huffTree = huff
}
if debug {
println("Final literals:", len(literals), "and", nSeqs, "sequences.")
}
if nSeqs == 0 {
// Decompressed content is defined entirely as Literals Section content.
b.dst = append(b.dst, literals...)
if delayedHistory {
hist.append(literals)
}
return nil
}
seqs, err := seqs.mergeHistory(&hist.decoders)
if err != nil {
return err
}
if debug {
println("History merged ok")
}
br := &bitReader{}
if err := br.init(in); err != nil {
return err
}
// TODO: Investigate if sending history without decoders are faster.
// This would allow the sequences to be decoded async and only have to construct stream history.
// If only recent offsets were not transferred, this would be an obvious win.
// Also, if first 3 sequences don't reference recent offsets, all sequences can be decoded.
if err := seqs.initialize(br, hist, literals, b.dst); err != nil {
println("initializing sequences:", err)
return err
}
err = seqs.decode(nSeqs, br, hist.b)
if err != nil {
return err
}
if !br.finished() {
return fmt.Errorf("%d extra bits on block, should be 0", br.remain())
}
err = br.close()
if err != nil {
printf("Closing sequences: %v, %+v\n", err, *br)
}
if len(b.data) > maxCompressedBlockSize {
return fmt.Errorf("compressed block size too large (%d)", len(b.data))
}
// Set output and release references.
b.dst = seqs.out
seqs.out, seqs.literals, seqs.hist = nil, nil, nil
if !delayedHistory {
// If we don't have delayed history, no need to update.
hist.recentOffsets = seqs.prevOffset
return nil
}
if b.Last {
// if last block we don't care about history.
println("Last block, no history returned")
hist.b = hist.b[:0]
return nil
}
hist.append(b.dst)
hist.recentOffsets = seqs.prevOffset
if debug {
println("Finished block with literals:", len(literals), "and", nSeqs, "sequences.")
}
return nil
}

754
vendor/github.com/klauspost/compress/zstd/blockenc.go generated vendored Normal file
View file

@ -0,0 +1,754 @@
// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"math"
"math/bits"
"github.com/klauspost/compress/huff0"
)
type blockEnc struct {
size int
literals []byte
sequences []seq
coders seqCoders
litEnc *huff0.Scratch
wr bitWriter
extraLits int
last bool
output []byte
recentOffsets [3]uint32
prevRecentOffsets [3]uint32
}
// init should be used once the block has been created.
// If called more than once, the effect is the same as calling reset.
func (b *blockEnc) init() {
if cap(b.literals) < maxCompressedLiteralSize {
b.literals = make([]byte, 0, maxCompressedLiteralSize)
}
const defSeqs = 200
b.literals = b.literals[:0]
if cap(b.sequences) < defSeqs {
b.sequences = make([]seq, 0, defSeqs)
}
if cap(b.output) < maxCompressedBlockSize {
b.output = make([]byte, 0, maxCompressedBlockSize)
}
if b.coders.mlEnc == nil {
b.coders.mlEnc = &fseEncoder{}
b.coders.mlPrev = &fseEncoder{}
b.coders.ofEnc = &fseEncoder{}
b.coders.ofPrev = &fseEncoder{}
b.coders.llEnc = &fseEncoder{}
b.coders.llPrev = &fseEncoder{}
}
b.litEnc = &huff0.Scratch{}
b.reset(nil)
}
// initNewEncode can be used to reset offsets and encoders to the initial state.
func (b *blockEnc) initNewEncode() {
b.recentOffsets = [3]uint32{1, 4, 8}
b.litEnc.Reuse = huff0.ReusePolicyNone
b.coders.setPrev(nil, nil, nil)
}
// reset will reset the block for a new encode, but in the same stream,
// meaning that state will be carried over, but the block content is reset.
// If a previous block is provided, the recent offsets are carried over.
func (b *blockEnc) reset(prev *blockEnc) {
b.extraLits = 0
b.literals = b.literals[:0]
b.size = 0
b.sequences = b.sequences[:0]
b.output = b.output[:0]
b.last = false
if prev != nil {
b.recentOffsets = prev.prevRecentOffsets
}
}
// reset will reset the block for a new encode, but in the same stream,
// meaning that state will be carried over, but the block content is reset.
// If a previous block is provided, the recent offsets are carried over.
func (b *blockEnc) swapEncoders(prev *blockEnc) {
b.coders.swap(&prev.coders)
b.litEnc, prev.litEnc = prev.litEnc, b.litEnc
}
// blockHeader contains the information for a block header.
type blockHeader uint32
// setLast sets the 'last' indicator on a block.
func (h *blockHeader) setLast(b bool) {
if b {
*h = *h | 1
} else {
const mask = (1 << 24) - 2
*h = *h & mask
}
}
// setSize will store the compressed size of a block.
func (h *blockHeader) setSize(v uint32) {
const mask = 7
*h = (*h)&mask | blockHeader(v<<3)
}
// setType sets the block type.
func (h *blockHeader) setType(t blockType) {
const mask = 1 | (((1 << 24) - 1) ^ 7)
*h = (*h & mask) | blockHeader(t<<1)
}
// appendTo will append the block header to a slice.
func (h blockHeader) appendTo(b []byte) []byte {
return append(b, uint8(h), uint8(h>>8), uint8(h>>16))
}
// String returns a string representation of the block.
func (h blockHeader) String() string {
return fmt.Sprintf("Type: %d, Size: %d, Last:%t", (h>>1)&3, h>>3, h&1 == 1)
}
// literalsHeader contains literals header information.
type literalsHeader uint64
// setType can be used to set the type of literal block.
func (h *literalsHeader) setType(t literalsBlockType) {
const mask = math.MaxUint64 - 3
*h = (*h & mask) | literalsHeader(t)
}
// setSize can be used to set a single size, for uncompressed and RLE content.
func (h *literalsHeader) setSize(regenLen int) {
inBits := bits.Len32(uint32(regenLen))
// Only retain 2 bits
const mask = 3
lh := uint64(*h & mask)
switch {
case inBits < 5:
lh |= (uint64(regenLen) << 3) | (1 << 60)
if debug {
got := int(lh>>3) & 0xff
if got != regenLen {
panic(fmt.Sprint("litRegenSize = ", regenLen, "(want) != ", got, "(got)"))
}
}
case inBits < 12:
lh |= (1 << 2) | (uint64(regenLen) << 4) | (2 << 60)
case inBits < 20:
lh |= (3 << 2) | (uint64(regenLen) << 4) | (3 << 60)
default:
panic(fmt.Errorf("internal error: block too big (%d)", regenLen))
}
*h = literalsHeader(lh)
}
// setSizes will set the size of a compressed literals section and the input length.
func (h *literalsHeader) setSizes(compLen, inLen int) {
compBits, inBits := bits.Len32(uint32(compLen)), bits.Len32(uint32(inLen))
// Only retain 2 bits
const mask = 3
lh := uint64(*h & mask)
switch {
case compBits <= 10 && inBits <= 10:
lh |= (1 << 2) | (uint64(inLen) << 4) | (uint64(compLen) << (10 + 4)) | (3 << 60)
if debug {
const mmask = (1 << 24) - 1
n := (lh >> 4) & mmask
if int(n&1023) != inLen {
panic(fmt.Sprint("regensize:", int(n&1023), "!=", inLen, inBits))
}
if int(n>>10) != compLen {
panic(fmt.Sprint("compsize:", int(n>>10), "!=", compLen, compBits))
}
}
case compBits <= 14 && inBits <= 14:
lh |= (2 << 2) | (uint64(inLen) << 4) | (uint64(compLen) << (14 + 4)) | (4 << 60)
case compBits <= 18 && inBits <= 18:
lh |= (3 << 2) | (uint64(inLen) << 4) | (uint64(compLen) << (18 + 4)) | (5 << 60)
default:
panic("internal error: block too big")
}
*h = literalsHeader(lh)
}
// appendTo will append the literals header to a byte slice.
func (h literalsHeader) appendTo(b []byte) []byte {
size := uint8(h >> 60)
switch size {
case 1:
b = append(b, uint8(h))
case 2:
b = append(b, uint8(h), uint8(h>>8))
case 3:
b = append(b, uint8(h), uint8(h>>8), uint8(h>>16))
case 4:
b = append(b, uint8(h), uint8(h>>8), uint8(h>>16), uint8(h>>24))
case 5:
b = append(b, uint8(h), uint8(h>>8), uint8(h>>16), uint8(h>>24), uint8(h>>32))
default:
panic(fmt.Errorf("internal error: literalsHeader has invalid size (%d)", size))
}
return b
}
// size returns the output size with currently set values.
func (h literalsHeader) size() int {
return int(h >> 60)
}
func (h literalsHeader) String() string {
return fmt.Sprintf("Type: %d, SizeFormat: %d, Size: 0x%d, Bytes:%d", literalsBlockType(h&3), (h>>2)&3, h&((1<<60)-1)>>4, h>>60)
}
// pushOffsets will push the recent offsets to the backup store.
func (b *blockEnc) pushOffsets() {
b.prevRecentOffsets = b.recentOffsets
}
// pushOffsets will push the recent offsets to the backup store.
func (b *blockEnc) popOffsets() {
b.recentOffsets = b.prevRecentOffsets
}
// matchOffset will adjust recent offsets and return the adjusted one,
// if it matches a previous offset.
func (b *blockEnc) matchOffset(offset, lits uint32) uint32 {
// Check if offset is one of the recent offsets.
// Adjusts the output offset accordingly.
// Gives a tiny bit of compression, typically around 1%.
if true {
if lits > 0 {
switch offset {
case b.recentOffsets[0]:
offset = 1
case b.recentOffsets[1]:
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset = 2
case b.recentOffsets[2]:
b.recentOffsets[2] = b.recentOffsets[1]
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset = 3
default:
b.recentOffsets[2] = b.recentOffsets[1]
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset += 3
}
} else {
switch offset {
case b.recentOffsets[1]:
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset = 1
case b.recentOffsets[2]:
b.recentOffsets[2] = b.recentOffsets[1]
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset = 2
case b.recentOffsets[0] - 1:
b.recentOffsets[2] = b.recentOffsets[1]
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset = 3
default:
b.recentOffsets[2] = b.recentOffsets[1]
b.recentOffsets[1] = b.recentOffsets[0]
b.recentOffsets[0] = offset
offset += 3
}
}
} else {
offset += 3
}
return offset
}
// encodeRaw can be used to set the output to a raw representation of supplied bytes.
func (b *blockEnc) encodeRaw(a []byte) {
var bh blockHeader
bh.setLast(b.last)
bh.setSize(uint32(len(a)))
bh.setType(blockTypeRaw)
b.output = bh.appendTo(b.output[:0])
b.output = append(b.output, a...)
if debug {
println("Adding RAW block, length", len(a))
}
}
// encodeLits can be used if the block is only litLen.
func (b *blockEnc) encodeLits() error {
var bh blockHeader
bh.setLast(b.last)
bh.setSize(uint32(len(b.literals)))
// Don't compress extremely small blocks
if len(b.literals) < 32 {
if debug {
println("Adding RAW block, length", len(b.literals))
}
bh.setType(blockTypeRaw)
b.output = bh.appendTo(b.output)
b.output = append(b.output, b.literals...)
return nil
}
// TODO: Switch to 1X when less than x bytes.
out, reUsed, err := huff0.Compress4X(b.literals, b.litEnc)
// Bail out of compression is too little.
if len(out) > (len(b.literals) - len(b.literals)>>4) {
err = huff0.ErrIncompressible
}
switch err {
case huff0.ErrIncompressible:
if debug {
println("Adding RAW block, length", len(b.literals))
}
bh.setType(blockTypeRaw)
b.output = bh.appendTo(b.output)
b.output = append(b.output, b.literals...)
return nil
case huff0.ErrUseRLE:
if debug {
println("Adding RLE block, length", len(b.literals))
}
bh.setType(blockTypeRLE)
b.output = bh.appendTo(b.output)
b.output = append(b.output, b.literals[0])
return nil
default:
return err
case nil:
}
// Compressed...
// Now, allow reuse
b.litEnc.Reuse = huff0.ReusePolicyAllow
bh.setType(blockTypeCompressed)
var lh literalsHeader
if reUsed {
if debug {
println("Reused tree, compressed to", len(out))
}
lh.setType(literalsBlockTreeless)
} else {
if debug {
println("New tree, compressed to", len(out), "tree size:", len(b.litEnc.OutTable))
}
lh.setType(literalsBlockCompressed)
}
// Set sizes
lh.setSizes(len(out), len(b.literals))
bh.setSize(uint32(len(out) + lh.size() + 1))
// Write block headers.
b.output = bh.appendTo(b.output)
b.output = lh.appendTo(b.output)
// Add compressed data.
b.output = append(b.output, out...)
// No sequences.
b.output = append(b.output, 0)
return nil
}
// encode will encode the block and put the output in b.output.
func (b *blockEnc) encode() error {
if len(b.sequences) == 0 {
return b.encodeLits()
}
// We want some difference
if len(b.literals) > (b.size - (b.size >> 5)) {
return errIncompressible
}
var bh blockHeader
var lh literalsHeader
bh.setLast(b.last)
bh.setType(blockTypeCompressed)
b.output = bh.appendTo(b.output)
var (
out []byte
reUsed bool
err error
)
if len(b.literals) > 32 {
// TODO: Switch to 1X on small blocks.
out, reUsed, err = huff0.Compress4X(b.literals, b.litEnc)
if len(out) > len(b.literals)-len(b.literals)>>4 {
err = huff0.ErrIncompressible
}
} else {
err = huff0.ErrIncompressible
}
switch err {
case huff0.ErrIncompressible:
lh.setType(literalsBlockRaw)
lh.setSize(len(b.literals))
b.output = lh.appendTo(b.output)
b.output = append(b.output, b.literals...)
if debug {
println("Adding literals RAW, length", len(b.literals))
}
case huff0.ErrUseRLE:
lh.setType(literalsBlockRLE)
lh.setSize(len(b.literals))
b.output = lh.appendTo(b.output)
b.output = append(b.output, b.literals[0])
if debug {
println("Adding literals RLE")
}
default:
if debug {
println("Adding literals ERROR:", err)
}
return err
case nil:
// Compressed litLen...
if reUsed {
if debug {
println("reused tree")
}
lh.setType(literalsBlockTreeless)
} else {
if debug {
println("new tree, size:", len(b.litEnc.OutTable))
}
lh.setType(literalsBlockCompressed)
if debug {
_, _, err := huff0.ReadTable(out, nil)
if err != nil {
panic(err)
}
}
}
lh.setSizes(len(out), len(b.literals))
if debug {
printf("Compressed %d literals to %d bytes", len(b.literals), len(out))
println("Adding literal header:", lh)
}
b.output = lh.appendTo(b.output)
b.output = append(b.output, out...)
b.litEnc.Reuse = huff0.ReusePolicyAllow
if debug {
println("Adding literals compressed")
}
}
// Sequence compression
// Write the number of sequences
switch {
case len(b.sequences) < 128:
b.output = append(b.output, uint8(len(b.sequences)))
case len(b.sequences) < 0x7f00: // TODO: this could be wrong
n := len(b.sequences)
b.output = append(b.output, 128+uint8(n>>8), uint8(n))
default:
n := len(b.sequences) - 0x7f00
b.output = append(b.output, 255, uint8(n), uint8(n>>8))
}
if debug {
println("Encoding", len(b.sequences), "sequences")
}
b.genCodes()
llEnc := b.coders.llEnc
ofEnc := b.coders.ofEnc
mlEnc := b.coders.mlEnc
err = llEnc.normalizeCount(len(b.sequences))
if err != nil {
return err
}
err = ofEnc.normalizeCount(len(b.sequences))
if err != nil {
return err
}
err = mlEnc.normalizeCount(len(b.sequences))
if err != nil {
return err
}
// Choose the best compression mode for each type.
// Will evaluate the new vs predefined and previous.
chooseComp := func(cur, prev, preDef *fseEncoder) (*fseEncoder, seqCompMode) {
// See if predefined/previous is better
hist := cur.count[:cur.symbolLen]
nSize := cur.approxSize(hist) + cur.maxHeaderSize()
predefSize := preDef.approxSize(hist)
prevSize := prev.approxSize(hist)
// Add a small penalty for new encoders.
// Don't bother with extremely small (<2 byte gains).
nSize = nSize + (nSize+2*8*16)>>4
switch {
case predefSize <= prevSize && predefSize <= nSize || forcePreDef:
if debug {
println("Using predefined", predefSize>>3, "<=", nSize>>3)
}
return preDef, compModePredefined
case prevSize <= nSize:
if debug {
println("Using previous", prevSize>>3, "<=", nSize>>3)
}
return prev, compModeRepeat
default:
if debug {
println("Using new, predef", predefSize>>3, ". previous:", prevSize>>3, ">", nSize>>3, "header max:", cur.maxHeaderSize()>>3, "bytes")
println("tl:", cur.actualTableLog, "symbolLen:", cur.symbolLen, "norm:", cur.norm[:cur.symbolLen], "hist", cur.count[:cur.symbolLen])
}
return cur, compModeFSE
}
}
// Write compression mode
var mode uint8
if llEnc.useRLE {
mode |= uint8(compModeRLE) << 6
llEnc.setRLE(b.sequences[0].llCode)
if debug {
println("llEnc.useRLE")
}
} else {
var m seqCompMode
llEnc, m = chooseComp(llEnc, b.coders.llPrev, &fsePredefEnc[tableLiteralLengths])
mode |= uint8(m) << 6
}
if ofEnc.useRLE {
mode |= uint8(compModeRLE) << 4
ofEnc.setRLE(b.sequences[0].ofCode)
if debug {
println("ofEnc.useRLE")
}
} else {
var m seqCompMode
ofEnc, m = chooseComp(ofEnc, b.coders.ofPrev, &fsePredefEnc[tableOffsets])
mode |= uint8(m) << 4
}
if mlEnc.useRLE {
mode |= uint8(compModeRLE) << 2
mlEnc.setRLE(b.sequences[0].mlCode)
if debug {
println("mlEnc.useRLE, code: ", b.sequences[0].mlCode, "value", b.sequences[0].matchLen)
}
} else {
var m seqCompMode
mlEnc, m = chooseComp(mlEnc, b.coders.mlPrev, &fsePredefEnc[tableMatchLengths])
mode |= uint8(m) << 2
}
b.output = append(b.output, mode)
if debug {
printf("Compression modes: 0b%b", mode)
}
b.output, err = llEnc.writeCount(b.output)
if err != nil {
return err
}
start := len(b.output)
b.output, err = ofEnc.writeCount(b.output)
if err != nil {
return err
}
if false {
println("block:", b.output[start:], "tablelog", ofEnc.actualTableLog, "maxcount:", ofEnc.maxCount)
fmt.Printf("selected TableLog: %d, Symbol length: %d\n", ofEnc.actualTableLog, ofEnc.symbolLen)
for i, v := range ofEnc.norm[:ofEnc.symbolLen] {
fmt.Printf("%3d: %5d -> %4d \n", i, ofEnc.count[i], v)
}
}
b.output, err = mlEnc.writeCount(b.output)
if err != nil {
return err
}
// Maybe in block?
wr := &b.wr
wr.reset(b.output)
var ll, of, ml cState
// Current sequence
seq := len(b.sequences) - 1
s := b.sequences[seq]
llEnc.setBits(llBitsTable[:])
mlEnc.setBits(mlBitsTable[:])
ofEnc.setBits(nil)
llTT, ofTT, mlTT := llEnc.ct.symbolTT[:256], ofEnc.ct.symbolTT[:256], mlEnc.ct.symbolTT[:256]
// We have 3 bounds checks here (and in the loop).
// Since we are iterating backwards it is kinda hard to avoid.
llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
ll.init(wr, &llEnc.ct, llB)
of.init(wr, &ofEnc.ct, ofB)
wr.flush32()
ml.init(wr, &mlEnc.ct, mlB)
// Each of these lookups also generates a bounds check.
wr.addBits32NC(s.litLen, llB.outBits)
wr.addBits32NC(s.matchLen, mlB.outBits)
wr.flush32()
wr.addBits32NC(s.offset, ofB.outBits)
if debugSequences {
println("Encoded seq", seq, s, "codes:", s.llCode, s.mlCode, s.ofCode, "states:", ll.state, ml.state, of.state, "bits:", llB, mlB, ofB)
}
seq--
if llEnc.maxBits+mlEnc.maxBits+ofEnc.maxBits <= 32 {
// No need to flush (common)
for seq >= 0 {
s = b.sequences[seq]
wr.flush32()
llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
// tabelog max is 8 for all.
of.encode(ofB)
ml.encode(mlB)
ll.encode(llB)
wr.flush32()
// We checked that all can stay within 32 bits
wr.addBits32NC(s.litLen, llB.outBits)
wr.addBits32NC(s.matchLen, mlB.outBits)
wr.addBits32NC(s.offset, ofB.outBits)
if debugSequences {
println("Encoded seq", seq, s)
}
seq--
}
} else {
for seq >= 0 {
s = b.sequences[seq]
wr.flush32()
llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
// tabelog max is below 8 for each.
of.encode(ofB)
ml.encode(mlB)
ll.encode(llB)
wr.flush32()
// ml+ll = max 32 bits total
wr.addBits32NC(s.litLen, llB.outBits)
wr.addBits32NC(s.matchLen, mlB.outBits)
wr.flush32()
wr.addBits32NC(s.offset, ofB.outBits)
if debugSequences {
println("Encoded seq", seq, s)
}
seq--
}
}
ml.flush(mlEnc.actualTableLog)
of.flush(ofEnc.actualTableLog)
ll.flush(llEnc.actualTableLog)
err = wr.close()
if err != nil {
return err
}
b.output = wr.out
if len(b.output)-3 >= b.size {
// Maybe even add a bigger margin.
b.litEnc.Reuse = huff0.ReusePolicyNone
return errIncompressible
}
// Size is output minus block header.
bh.setSize(uint32(len(b.output)) - 3)
if debug {
println("Rewriting block header", bh)
}
_ = bh.appendTo(b.output[:0])
b.coders.setPrev(llEnc, mlEnc, ofEnc)
return nil
}
var errIncompressible = errors.New("uncompressible")
func (b *blockEnc) genCodes() {
if len(b.sequences) == 0 {
// nothing to do
return
}
if len(b.sequences) > math.MaxUint16 {
panic("can only encode up to 64K sequences")
}
// No bounds checks after here:
llH := b.coders.llEnc.Histogram()[:256]
ofH := b.coders.ofEnc.Histogram()[:256]
mlH := b.coders.mlEnc.Histogram()[:256]
for i := range llH {
llH[i] = 0
}
for i := range ofH {
ofH[i] = 0
}
for i := range mlH {
mlH[i] = 0
}
var llMax, ofMax, mlMax uint8
for i, seq := range b.sequences {
v := llCode(seq.litLen)
seq.llCode = v
llH[v]++
if v > llMax {
llMax = v
}
v = ofCode(seq.offset)
seq.ofCode = v
ofH[v]++
if v > ofMax {
ofMax = v
}
v = mlCode(seq.matchLen)
seq.mlCode = v
mlH[v]++
if v > mlMax {
mlMax = v
if debug && mlMax > maxMatchLengthSymbol {
panic(fmt.Errorf("mlMax > maxMatchLengthSymbol (%d), matchlen: %d", mlMax, seq.matchLen))
}
}
b.sequences[i] = seq
}
maxCount := func(a []uint32) int {
var max uint32
for _, v := range a {
if v > max {
max = v
}
}
return int(max)
}
if mlMax > maxMatchLengthSymbol {
panic(fmt.Errorf("mlMax > maxMatchLengthSymbol (%d)", mlMax))
}
if ofMax > maxOffsetBits {
panic(fmt.Errorf("ofMax > maxOffsetBits (%d)", ofMax))
}
if llMax > maxLiteralLengthSymbol {
panic(fmt.Errorf("llMax > maxLiteralLengthSymbol (%d)", llMax))
}
b.coders.mlEnc.HistogramFinished(mlMax, maxCount(mlH[:mlMax+1]))
b.coders.ofEnc.HistogramFinished(ofMax, maxCount(ofH[:ofMax+1]))
b.coders.llEnc.HistogramFinished(llMax, maxCount(llH[:llMax+1]))
}

85
vendor/github.com/klauspost/compress/zstd/blocktype_string.go generated vendored Normal file
View file

@ -0,0 +1,85 @@
// Code generated by "stringer -type=blockType,literalsBlockType,seqCompMode,tableIndex"; DO NOT EDIT.
package zstd
import "strconv"
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[blockTypeRaw-0]
_ = x[blockTypeRLE-1]
_ = x[blockTypeCompressed-2]
_ = x[blockTypeReserved-3]
}
const _blockType_name = "blockTypeRawblockTypeRLEblockTypeCompressedblockTypeReserved"
var _blockType_index = [...]uint8{0, 12, 24, 43, 60}
func (i blockType) String() string {
if i >= blockType(len(_blockType_index)-1) {
return "blockType(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _blockType_name[_blockType_index[i]:_blockType_index[i+1]]
}
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[literalsBlockRaw-0]
_ = x[literalsBlockRLE-1]
_ = x[literalsBlockCompressed-2]
_ = x[literalsBlockTreeless-3]
}
const _literalsBlockType_name = "literalsBlockRawliteralsBlockRLEliteralsBlockCompressedliteralsBlockTreeless"
var _literalsBlockType_index = [...]uint8{0, 16, 32, 55, 76}
func (i literalsBlockType) String() string {
if i >= literalsBlockType(len(_literalsBlockType_index)-1) {
return "literalsBlockType(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _literalsBlockType_name[_literalsBlockType_index[i]:_literalsBlockType_index[i+1]]
}
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[compModePredefined-0]
_ = x[compModeRLE-1]
_ = x[compModeFSE-2]
_ = x[compModeRepeat-3]
}
const _seqCompMode_name = "compModePredefinedcompModeRLEcompModeFSEcompModeRepeat"
var _seqCompMode_index = [...]uint8{0, 18, 29, 40, 54}
func (i seqCompMode) String() string {
if i >= seqCompMode(len(_seqCompMode_index)-1) {
return "seqCompMode(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _seqCompMode_name[_seqCompMode_index[i]:_seqCompMode_index[i+1]]
}
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[tableLiteralLengths-0]
_ = x[tableOffsets-1]
_ = x[tableMatchLengths-2]
}
const _tableIndex_name = "tableLiteralLengthstableOffsetstableMatchLengths"
var _tableIndex_index = [...]uint8{0, 19, 31, 48}
func (i tableIndex) String() string {
if i >= tableIndex(len(_tableIndex_index)-1) {
return "tableIndex(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _tableIndex_name[_tableIndex_index[i]:_tableIndex_index[i+1]]
}

121
vendor/github.com/klauspost/compress/zstd/bytebuf.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"fmt"
"io"
"io/ioutil"
)
type byteBuffer interface {
// Read up to 8 bytes.
// Returns nil if no more input is available.
readSmall(n int) []byte
// Read >8 bytes.
// MAY use the destination slice.
readBig(n int, dst []byte) ([]byte, error)
// Read a single byte.
readByte() (byte, error)
// Skip n bytes.
skipN(n int) error
}
// in-memory buffer
type byteBuf []byte
func (b *byteBuf) readSmall(n int) []byte {
if debug && n > 8 {
panic(fmt.Errorf("small read > 8 (%d). use readBig", n))
}
bb := *b
if len(bb) < n {
return nil
}
r := bb[:n]
*b = bb[n:]
return r
}
func (b *byteBuf) readBig(n int, dst []byte) ([]byte, error) {
bb := *b
if len(bb) < n {
return nil, io.ErrUnexpectedEOF
}
r := bb[:n]
*b = bb[n:]
return r, nil
}
func (b *byteBuf) remain() []byte {
return *b
}
func (b *byteBuf) readByte() (byte, error) {
bb := *b
if len(bb) < 1 {
return 0, nil
}
r := bb[0]
*b = bb[1:]
return r, nil
}
func (b *byteBuf) skipN(n int) error {
bb := *b
if len(bb) < n {
return io.ErrUnexpectedEOF
}
*b = bb[n:]
return nil
}
// wrapper around a reader.
type readerWrapper struct {
r io.Reader
tmp [8]byte
}
func (r *readerWrapper) readSmall(n int) []byte {
if debug && n > 8 {
panic(fmt.Errorf("small read > 8 (%d). use readBig", n))
}
n2, err := io.ReadFull(r.r, r.tmp[:n])
// We only really care about the actual bytes read.
if n2 != n {
if debug {
println("readSmall: got", n2, "want", n, "err", err)
}
return nil
}
return r.tmp[:n]
}
func (r *readerWrapper) readBig(n int, dst []byte) ([]byte, error) {
if cap(dst) < n {
dst = make([]byte, n)
}
n2, err := io.ReadFull(r.r, dst[:n])
return dst[:n2], err
}
func (r *readerWrapper) readByte() (byte, error) {
n2, err := r.r.Read(r.tmp[:1])
if err != nil {
return 0, err
}
if n2 != 1 {
return 0, io.ErrUnexpectedEOF
}
return r.tmp[0], nil
}
func (r *readerWrapper) skipN(n int) error {
_, err := io.CopyN(ioutil.Discard, r.r, int64(n))
return err
}

74
vendor/github.com/klauspost/compress/zstd/bytereader.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
// byteReader provides a byte reader that reads
// little endian values from a byte stream.
// The input stream is manually advanced.
// The reader performs no bounds checks.
type byteReader struct {
b []byte
off int
}
// init will initialize the reader and set the input.
func (b *byteReader) init(in []byte) {
b.b = in
b.off = 0
}
// advance the stream b n bytes.
func (b *byteReader) advance(n uint) {
b.off += int(n)
}
// overread returns whether we have advanced too far.
func (b *byteReader) overread() bool {
return b.off > len(b.b)
}
// Int32 returns a little endian int32 starting at current offset.
func (b byteReader) Int32() int32 {
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := int32(b2[3])
v2 := int32(b2[2])
v1 := int32(b2[1])
v0 := int32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// Uint8 returns the next byte
func (b *byteReader) Uint8() uint8 {
v := b.b[b.off]
return v
}
// Uint32 returns a little endian uint32 starting at current offset.
func (b byteReader) Uint32() uint32 {
if r := b.remain(); r < 4 {
// Very rare
v := uint32(0)
for i := 1; i <= r; i++ {
v = (v << 8) | uint32(b.b[len(b.b)-i])
}
return v
}
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := uint32(b2[3])
v2 := uint32(b2[2])
v1 := uint32(b2[1])
v0 := uint32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// unread returns the unread portion of the input.
func (b byteReader) unread() []byte {
return b.b[b.off:]
}
// remain will return the number of bytes remaining.
func (b byteReader) remain() int {
return len(b.b) - b.off
}

462
vendor/github.com/klauspost/compress/zstd/decoder.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"bytes"
"errors"
"io"
"sync"
)
// Decoder provides decoding of zstandard streams.
// The decoder has been designed to operate without allocations after a warmup.
// This means that you should store the decoder for best performance.
// To re-use a stream decoder, use the Reset(r io.Reader) error to switch to another stream.
// A decoder can safely be re-used even if the previous stream failed.
// To release the resources, you must call the Close() function on a decoder.
type Decoder struct {
o decoderOptions
// Unreferenced decoders, ready for use.
decoders chan *blockDec
// Unreferenced decoders, ready for use.
frames chan *frameDec
// Streams ready to be decoded.
stream chan decodeStream
// Current read position used for Reader functionality.
current decoderState
// Custom dictionaries
dicts map[uint32]struct{}
// streamWg is the waitgroup for all streams
streamWg sync.WaitGroup
}
// decoderState is used for maintaining state when the decoder
// is used for streaming.
type decoderState struct {
// current block being written to stream.
decodeOutput
// output in order to be written to stream.
output chan decodeOutput
// cancel remaining output.
cancel chan struct{}
flushed bool
}
var (
// Check the interfaces we want to support.
_ = io.WriterTo(&Decoder{})
_ = io.Reader(&Decoder{})
)
// NewReader creates a new decoder.
// A nil Reader can be provided in which case Reset can be used to start a decode.
//
// A Decoder can be used in two modes:
//
// 1) As a stream, or
// 2) For stateless decoding using DecodeAll or DecodeBuffer.
//
// Only a single stream can be decoded concurrently, but the same decoder
// can run multiple concurrent stateless decodes. It is even possible to
// use stateless decodes while a stream is being decoded.
//
// The Reset function can be used to initiate a new stream, which is will considerably
// reduce the allocations normally caused by NewReader.
func NewReader(r io.Reader, opts ...DOption) (*Decoder, error) {
var d Decoder
d.o.setDefault()
for _, o := range opts {
err := o(&d.o)
if err != nil {
return nil, err
}
}
d.current.output = make(chan decodeOutput, d.o.concurrent)
d.current.flushed = true
// Create decoders
d.decoders = make(chan *blockDec, d.o.concurrent)
d.frames = make(chan *frameDec, d.o.concurrent)
for i := 0; i < d.o.concurrent; i++ {
d.frames <- newFrameDec(d.o)
d.decoders <- newBlockDec(d.o.lowMem)
}
if r == nil {
return &d, nil
}
return &d, d.Reset(r)
}
// Read bytes from the decompressed stream into p.
// Returns the number of bytes written and any error that occurred.
// When the stream is done, io.EOF will be returned.
func (d *Decoder) Read(p []byte) (int, error) {
if d.stream == nil {
return 0, errors.New("no input has been initialized")
}
var n int
for {
if len(d.current.b) > 0 {
filled := copy(p, d.current.b)
p = p[filled:]
d.current.b = d.current.b[filled:]
n += filled
}
if len(p) == 0 {
break
}
if len(d.current.b) == 0 {
// We have an error and no more data
if d.current.err != nil {
break
}
d.nextBlock()
}
}
if len(d.current.b) > 0 {
if debug {
println("returning", n, "still bytes left:", len(d.current.b))
}
// Only return error at end of block
return n, nil
}
if d.current.err != nil {
d.drainOutput()
}
if debug {
println("returning", n, d.current.err, len(d.decoders))
}
return n, d.current.err
}
// Reset will reset the decoder the supplied stream after the current has finished processing.
// Note that this functionality cannot be used after Close has been called.
func (d *Decoder) Reset(r io.Reader) error {
if d.current.err == ErrDecoderClosed {
return d.current.err
}
if r == nil {
return errors.New("nil Reader sent as input")
}
if d.stream == nil {
d.stream = make(chan decodeStream, 1)
d.streamWg.Add(1)
go d.startStreamDecoder(d.stream)
}
d.drainOutput()
// If bytes buffer and < 1MB, do sync decoding anyway.
if bb, ok := r.(*bytes.Buffer); ok && bb.Len() < 1<<20 {
if debug {
println("*bytes.Buffer detected, doing sync decode, len:", bb.Len())
}
b := bb.Bytes()
dst, err := d.DecodeAll(b, nil)
if err == nil {
err = io.EOF
}
d.current.b = dst
d.current.err = err
d.current.flushed = true
if debug {
println("sync decode to ", len(dst), "bytes, err:", err)
}
return nil
}
// Remove current block.
d.current.decodeOutput = decodeOutput{}
d.current.err = nil
d.current.cancel = make(chan struct{})
d.current.flushed = false
d.current.d = nil
d.stream <- decodeStream{
r: r,
output: d.current.output,
cancel: d.current.cancel,
}
return nil
}
// drainOutput will drain the output until errEndOfStream is sent.
func (d *Decoder) drainOutput() {
if d.current.cancel != nil {
println("cancelling current")
close(d.current.cancel)
d.current.cancel = nil
}
if d.current.d != nil {
if debug {
printf("re-adding current decoder %p, decoders: %d", d.current.d, len(d.decoders))
}
d.decoders <- d.current.d
d.current.d = nil
d.current.b = nil
}
if d.current.output == nil || d.current.flushed {
println("current already flushed")
return
}
for {
select {
case v := <-d.current.output:
if v.d != nil {
if debug {
printf("re-adding decoder %p", v.d)
}
d.decoders <- v.d
}
if v.err == errEndOfStream {
println("current flushed")
d.current.flushed = true
return
}
}
}
}
// WriteTo writes data to w until there's no more data to write or when an error occurs.
// The return value n is the number of bytes written.
// Any error encountered during the write is also returned.
func (d *Decoder) WriteTo(w io.Writer) (int64, error) {
if d.stream == nil {
return 0, errors.New("no input has been initialized")
}
var n int64
for {
if len(d.current.b) > 0 {
n2, err2 := w.Write(d.current.b)
n += int64(n2)
if err2 != nil && d.current.err == nil {
d.current.err = err2
break
}
}
if d.current.err != nil {
break
}
d.nextBlock()
}
err := d.current.err
if err != nil {
d.drainOutput()
}
if err == io.EOF {
err = nil
}
return n, err
}
// DecodeAll allows stateless decoding of a blob of bytes.
// Output will be appended to dst, so if the destination size is known
// you can pre-allocate the destination slice to avoid allocations.
// DecodeAll can be used concurrently.
// The Decoder concurrency limits will be respected.
func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
if d.current.err == ErrDecoderClosed {
return dst, ErrDecoderClosed
}
// Grab a block decoder and frame decoder.
block, frame := <-d.decoders, <-d.frames
defer func() {
if debug {
printf("re-adding decoder: %p", block)
}
d.decoders <- block
frame.rawInput = nil
d.frames <- frame
}()
if cap(dst) == 0 {
// Allocate 1MB by default if nothing is provided.
dst = make([]byte, 0, 1<<20)
}
// Allocation here:
br := byteBuf(input)
for {
err := frame.reset(&br)
if err == io.EOF {
return dst, nil
}
if err != nil {
return dst, err
}
if frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
return dst, ErrDecoderSizeExceeded
}
if frame.FrameContentSize > 0 && frame.FrameContentSize < 1<<30 {
// Never preallocate moe than 1 GB up front.
if uint64(cap(dst)) < frame.FrameContentSize {
dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
copy(dst2, dst)
dst = dst2
}
}
dst, err = frame.runDecoder(dst, block)
if err != nil {
return dst, err
}
if len(br) == 0 {
break
}
}
return dst, nil
}
// nextBlock returns the next block.
// If an error occurs d.err will be set.
func (d *Decoder) nextBlock() {
if d.current.d != nil {
if debug {
printf("re-adding current decoder %p", d.current.d)
}
d.decoders <- d.current.d
d.current.d = nil
}
if d.current.err != nil {
// Keep error state.
return
}
d.current.decodeOutput = <-d.current.output
if debug {
println("got", len(d.current.b), "bytes, error:", d.current.err)
}
}
// Close will release all resources.
// It is NOT possible to reuse the decoder after this.
func (d *Decoder) Close() {
if d.current.err == ErrDecoderClosed {
return
}
d.drainOutput()
if d.stream != nil {
close(d.stream)
d.streamWg.Wait()
d.stream = nil
}
if d.decoders != nil {
close(d.decoders)
for dec := range d.decoders {
dec.Close()
}
d.decoders = nil
}
if d.current.d != nil {
d.current.d.Close()
d.current.d = nil
}
d.current.err = ErrDecoderClosed
}
type decodeOutput struct {
d *blockDec
b []byte
err error
}
type decodeStream struct {
r io.Reader
// Blocks ready to be written to output.
output chan decodeOutput
// cancel reading from the input
cancel chan struct{}
}
// errEndOfStream indicates that everything from the stream was read.
var errEndOfStream = errors.New("end-of-stream")
// Create Decoder:
// Spawn n block decoders. These accept tasks to decode a block.
// Create goroutine that handles stream processing, this will send history to decoders as they are available.
// Decoders update the history as they decode.
// When a block is returned:
// a) history is sent to the next decoder,
// b) content written to CRC.
// c) return data to WRITER.
// d) wait for next block to return data.
// Once WRITTEN, the decoders reused by the writer frame decoder for re-use.
func (d *Decoder) startStreamDecoder(inStream chan decodeStream) {
defer d.streamWg.Done()
frame := newFrameDec(d.o)
for stream := range inStream {
if debug {
println("got new stream")
}
br := readerWrapper{r: stream.r}
decodeStream:
for {
err := frame.reset(&br)
if debug && err != nil {
println("Frame decoder returned", err)
}
if err != nil {
stream.output <- decodeOutput{
err: err,
}
break
}
if debug {
println("starting frame decoder")
}
// This goroutine will forward history between frames.
frame.frameDone.Add(1)
frame.initAsync()
go frame.startDecoder(stream.output)
decodeFrame:
// Go through all blocks of the frame.
for {
dec := <-d.decoders
select {
case <-stream.cancel:
if !frame.sendErr(dec, io.EOF) {
// To not let the decoder dangle, send it back.
stream.output <- decodeOutput{d: dec}
}
break decodeStream
default:
}
err := frame.next(dec)
switch err {
case io.EOF:
// End of current frame, no error
println("EOF on next block")
break decodeFrame
case nil:
continue
default:
println("block decoder returned", err)
break decodeStream
}
}
// All blocks have started decoding, check if there are more frames.
println("waiting for done")
frame.frameDone.Wait()
println("done waiting...")
}
frame.frameDone.Wait()
println("Sending EOS")
stream.output <- decodeOutput{err: errEndOfStream}
}
}

66
vendor/github.com/klauspost/compress/zstd/decoder_options.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"runtime"
)
// DOption is an option for creating a decoder.
type DOption func(*decoderOptions) error
// options retains accumulated state of multiple options.
type decoderOptions struct {
lowMem bool
concurrent int
maxDecodedSize uint64
}
func (o *decoderOptions) setDefault() {
*o = decoderOptions{
// use less ram: true for now, but may change.
lowMem: true,
concurrent: runtime.GOMAXPROCS(0),
}
o.maxDecodedSize = 1 << 63
}
// WithDecoderLowmem will set whether to use a lower amount of memory,
// but possibly have to allocate more while running.
func WithDecoderLowmem(b bool) DOption {
return func(o *decoderOptions) error { o.lowMem = b; return nil }
}
// WithDecoderConcurrency will set the concurrency,
// meaning the maximum number of decoders to run concurrently.
// The value supplied must be at least 1.
// By default this will be set to GOMAXPROCS.
func WithDecoderConcurrency(n int) DOption {
return func(o *decoderOptions) error {
if n <= 0 {
return fmt.Errorf("Concurrency must be at least 1")
}
o.concurrent = n
return nil
}
}
// WithDecoderMaxMemory allows to set a maximum decoded size for in-memory
// (non-streaming) operations.
// Maxmimum and default is 1 << 63 bytes.
func WithDecoderMaxMemory(n uint64) DOption {
return func(o *decoderOptions) error {
if n == 0 {
return errors.New("WithDecoderMaxmemory must be at least 1")
}
if n > 1<<63 {
return fmt.Errorf("WithDecoderMaxmemorymust be less than 1 << 63")
}
o.maxDecodedSize = n
return nil
}
}

425
vendor/github.com/klauspost/compress/zstd/enc_dfast.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
const (
dFastLongTableBits = 17 // Bits used in the long match table
dFastLongTableSize = 1 << dFastLongTableBits // Size of the table
dFastLongTableMask = dFastLongTableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
dFastShortTableBits = tableBits // Bits used in the short match table
dFastShortTableSize = 1 << dFastShortTableBits // Size of the table
dFastShortTableMask = dFastShortTableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
)
type doubleFastEncoder struct {
fastEncoder
longTable [dFastLongTableSize]tableEntry
}
// Encode mimmics functionality in zstd_dfast.c
func (e *doubleFastEncoder) Encode(blk *blockEnc, src []byte) {
const (
// Input margin is the number of bytes we read (8)
// and the maximum we will read ahead (2)
inputMargin = 8 + 2
minNonLiteralBlockSize = 16
)
// Protect against e.cur wraparound.
for e.cur > (1<<30)+e.maxMatchOff {
if len(e.hist) == 0 {
for i := range e.table[:] {
e.table[i] = tableEntry{}
}
for i := range e.longTable[:] {
e.longTable[i] = tableEntry{}
}
e.cur = e.maxMatchOff
break
}
// Shift down everything in the table that isn't already too far away.
minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
for i := range e.table[:] {
v := e.table[i].offset
if v < minOff {
v = 0
} else {
v = v - e.cur + e.maxMatchOff
}
e.table[i].offset = v
}
for i := range e.longTable[:] {
v := e.longTable[i].offset
if v < minOff {
v = 0
} else {
v = v - e.cur + e.maxMatchOff
}
e.longTable[i].offset = v
}
e.cur = e.maxMatchOff
}
s := e.addBlock(src)
blk.size = len(src)
if len(src) < minNonLiteralBlockSize {
blk.extraLits = len(src)
blk.literals = blk.literals[:len(src)]
copy(blk.literals, src)
return
}
// Override src
src = e.hist
sLimit := int32(len(src)) - inputMargin
// stepSize is the number of bytes to skip on every main loop iteration.
// It should be >= 1.
stepSize := int32(e.o.targetLength)
if stepSize == 0 {
stepSize++
}
// TEMPLATE
const kSearchStrength = 8
// nextEmit is where in src the next emitLiteral should start from.
nextEmit := s
cv := load6432(src, s)
// nextHash is the hash at s
nextHashS := hash5(cv, dFastShortTableBits)
nextHashL := hash8(cv, dFastLongTableBits)
// Relative offsets
offset1 := int32(blk.recentOffsets[0])
offset2 := int32(blk.recentOffsets[1])
addLiterals := func(s *seq, until int32) {
if until == nextEmit {
return
}
blk.literals = append(blk.literals, src[nextEmit:until]...)
s.litLen = uint32(until - nextEmit)
}
if debug {
println("recent offsets:", blk.recentOffsets)
}
encodeLoop:
for {
var t int32
// We allow the encoder to optionally turn off repeat offsets across blocks
canRepeat := len(blk.sequences) > 2
for {
if debug && canRepeat && offset1 == 0 {
panic("offset0 was 0")
}
nextHashS = nextHashS & dFastShortTableMask
nextHashL = nextHashL & dFastLongTableMask
candidateL := e.longTable[nextHashL]
candidateS := e.table[nextHashS]
const repOff = 1
repIndex := s - offset1 + repOff
entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
e.longTable[nextHashL] = entry
e.table[nextHashS] = entry
if canRepeat {
if repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
// Consider history as well.
var seq seq
lenght := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
seq.matchLen = uint32(lenght - zstdMinMatch)
// We might be able to match backwards.
// Extend as long as we can.
start := s + repOff
// We end the search early, so we don't risk 0 literals
// and have to do special offset treatment.
startLimit := nextEmit + 1
tMin := s - e.maxMatchOff
if tMin < 0 {
tMin = 0
}
for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
repIndex--
start--
seq.matchLen++
}
addLiterals(&seq, start)
// rep 0
seq.offset = 1
if debugSequences {
println("repeat sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
s += lenght + repOff
nextEmit = s
if s >= sLimit {
if debug {
println("repeat ended", s, lenght)
}
break encodeLoop
}
cv = load6432(src, s)
nextHashS = hash5(cv, dFastShortTableBits)
nextHashL = hash8(cv, dFastLongTableBits)
continue
}
const repOff2 = 1
// We deviate from the reference encoder and also check offset 2.
// Slower and not consistently better, so disabled.
// repIndex = s - offset2 + repOff2
if false && repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff2*8)) {
// Consider history as well.
var seq seq
lenght := 4 + e.matchlen(s+4+repOff2, repIndex+4, src)
seq.matchLen = uint32(lenght - zstdMinMatch)
// We might be able to match backwards.
// Extend as long as we can.
start := s + repOff2
// We end the search early, so we don't risk 0 literals
// and have to do special offset treatment.
startLimit := nextEmit + 1
tMin := s - e.maxMatchOff
if tMin < 0 {
tMin = 0
}
for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
repIndex--
start--
seq.matchLen++
}
addLiterals(&seq, start)
// rep 2
seq.offset = 2
if debugSequences {
println("repeat sequence 2", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
s += lenght + repOff2
nextEmit = s
if s >= sLimit {
if debug {
println("repeat ended", s, lenght)
}
break encodeLoop
}
cv = load6432(src, s)
nextHashS = hash5(cv, dFastShortTableBits)
nextHashL = hash8(cv, dFastLongTableBits)
// Swap offsets
offset1, offset2 = offset2, offset1
continue
}
}
// Find the offsets of our two matches.
coffsetL := s - (candidateL.offset - e.cur)
coffsetS := s - (candidateS.offset - e.cur)
// Check if we have a long match.
if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
// Found a long match, likely at least 8 bytes.
// Reference encoder checks all 8 bytes, we only check 4,
// but the likelihood of both the first 4 bytes and the hash matching should be enough.
t = candidateL.offset - e.cur
if debug && s <= t {
panic("s <= t")
}
if debug && s-t > e.maxMatchOff {
panic("s - t >e.maxMatchOff")
}
if debug {
println("long match")
}
break
}
// Check if we have a short match.
if coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
// found a regular match
// See if we can find a long match at s+1
const checkAt = 1
cv := load6432(src, s+checkAt)
nextHashL = hash8(cv, dFastLongTableBits)
candidateL = e.longTable[nextHashL]
coffsetL = s - (candidateL.offset - e.cur) + checkAt
// We can store it, since we have at least a 4 byte match.
e.longTable[nextHashL] = tableEntry{offset: s + checkAt + e.cur, val: uint32(cv)}
if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
// Found a long match, likely at least 8 bytes.
// Reference encoder checks all 8 bytes, we only check 4,
// but the likelihood of both the first 4 bytes and the hash matching should be enough.
t = candidateL.offset - e.cur
s += checkAt
if debug {
println("long match (after short)")
}
break
}
t = candidateS.offset - e.cur
if debug && s <= t {
panic("s <= t")
}
if debug && s-t > e.maxMatchOff {
panic("s - t >e.maxMatchOff")
}
if debug && t < 0 {
panic("t<0")
}
if debug {
println("short match")
}
break
}
// No match found, move forward in input.
s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
if s >= sLimit {
break encodeLoop
}
cv = load6432(src, s)
nextHashS = hash5(cv, dFastShortTableBits)
nextHashL = hash8(cv, dFastLongTableBits)
}
// A 4-byte match has been found. Update recent offsets.
// We'll later see if more than 4 bytes.
offset2 = offset1
offset1 = s - t
if debug && s <= t {
panic("s <= t")
}
if debug && canRepeat && int(offset1) > len(src) {
panic("invalid offset")
}
// Extend the 4-byte match as long as possible.
l := e.matchlen(s+4, t+4, src) + 4
// Extend backwards
tMin := s - e.maxMatchOff
if tMin < 0 {
tMin = 0
}
for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
s--
t--
l++
}
// Write our sequence
var seq seq
seq.litLen = uint32(s - nextEmit)
seq.matchLen = uint32(l - zstdMinMatch)
if seq.litLen > 0 {
blk.literals = append(blk.literals, src[nextEmit:s]...)
}
seq.offset = uint32(s-t) + 3
s += l
if debugSequences {
println("sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
nextEmit = s
if s >= sLimit {
break encodeLoop
}
// Index match start+1 (long) and start+2 (short)
index0 := s - l + 1
// Index match end-2 (long) and end-1 (short)
index1 := s - 2
cv0 := load6432(src, index0)
cv1 := load6432(src, index1)
te0 := tableEntry{offset: index0 + e.cur, val: uint32(cv0)}
te1 := tableEntry{offset: index1 + e.cur, val: uint32(cv1)}
e.longTable[hash8(cv0, dFastLongTableBits)&dFastLongTableMask] = te0
e.longTable[hash8(cv1, dFastLongTableBits)&dFastLongTableMask] = te1
cv0 >>= 8
cv1 >>= 8
te0.offset++
te1.offset++
te0.val = uint32(cv0)
te1.val = uint32(cv1)
e.table[hash5(cv0, dFastShortTableBits)&dFastShortTableMask] = te0
e.table[hash5(cv1, dFastShortTableBits)&dFastShortTableMask] = te1
cv = load6432(src, s)
nextHashS = hash5(cv1>>8, dFastShortTableBits)
nextHashL = hash8(cv, dFastLongTableBits)
if !canRepeat {
continue
}
// Check offset 2
for {
o2 := s - offset2
if load3232(src, o2) != uint32(cv) {
// Do regular search
break
}
// We have at least 4 byte match.
// No need to check backwards. We come straight from a match
l := 4 + e.matchlen(s+4, o2+4, src)
// Store this, since we have it.
entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
e.longTable[nextHashL&dFastLongTableMask] = entry
e.table[nextHashS&dFastShortTableMask] = entry
seq.matchLen = uint32(l) - zstdMinMatch
seq.litLen = 0
// Since litlen is always 0, this is offset 1.
seq.offset = 1
s += l
nextEmit = s
if debugSequences {
println("sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
// Swap offset 1 and 2.
offset1, offset2 = offset2, offset1
if s >= sLimit {
// Finished
break encodeLoop
}
cv = load6432(src, s)
nextHashS = hash5(cv, dFastShortTableBits)
nextHashL = hash8(cv, dFastLongTableBits)
}
}
if int(nextEmit) < len(src) {
blk.literals = append(blk.literals, src[nextEmit:]...)
blk.extraLits = len(src) - int(nextEmit)
}
blk.recentOffsets[0] = uint32(offset1)
blk.recentOffsets[1] = uint32(offset2)
if debug {
println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
}
}

416
vendor/github.com/klauspost/compress/zstd/enc_fast.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"math/bits"
"github.com/klauspost/compress/zstd/internal/xxhash"
)
const (
tableBits = 15 // Bits used in the table
tableSize = 1 << tableBits // Size of the table
tableMask = tableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
maxMatchLength = 131074
)
type tableEntry struct {
val uint32
offset int32
}
type fastEncoder struct {
o encParams
// cur is the offset at the start of hist
cur int32
// maximum offset. Should be at least 2x block size.
maxMatchOff int32
hist []byte
crc *xxhash.Digest
table [tableSize]tableEntry
tmp [8]byte
blk *blockEnc
}
// CRC returns the underlying CRC writer.
func (e *fastEncoder) CRC() *xxhash.Digest {
return e.crc
}
// AppendCRC will append the CRC to the destination slice and return it.
func (e *fastEncoder) AppendCRC(dst []byte) []byte {
crc := e.crc.Sum(e.tmp[:0])
dst = append(dst, crc[7], crc[6], crc[5], crc[4])
return dst
}
// WindowSize returns the window size of the encoder,
// or a window size small enough to contain the input size, if > 0.
func (e *fastEncoder) WindowSize(size int) int32 {
if size > 0 && size < int(e.maxMatchOff) {
b := int32(1) << uint(bits.Len(uint(size)))
// Keep minimum window.
if b < 1024 {
b = 1024
}
return b
}
return e.maxMatchOff
}
// Block returns the current block.
func (e *fastEncoder) Block() *blockEnc {
return e.blk
}
// Encode mimmics functionality in zstd_fast.c
func (e *fastEncoder) Encode(blk *blockEnc, src []byte) {
const (
inputMargin = 8
minNonLiteralBlockSize = 1 + 1 + inputMargin
)
// Protect against e.cur wraparound.
for e.cur > (1<<30)+e.maxMatchOff {
if len(e.hist) == 0 {
for i := range e.table[:] {
e.table[i] = tableEntry{}
}
e.cur = e.maxMatchOff
break
}
// Shift down everything in the table that isn't already too far away.
minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
for i := range e.table[:] {
v := e.table[i].offset
if v < minOff {
v = 0
} else {
v = v - e.cur + e.maxMatchOff
}
e.table[i].offset = v
}
e.cur = e.maxMatchOff
}
s := e.addBlock(src)
blk.size = len(src)
if len(src) < minNonLiteralBlockSize {
blk.extraLits = len(src)
blk.literals = blk.literals[:len(src)]
copy(blk.literals, src)
return
}
// Override src
src = e.hist
sLimit := int32(len(src)) - inputMargin
// stepSize is the number of bytes to skip on every main loop iteration.
// It should be >= 2.
stepSize := int32(e.o.targetLength)
if stepSize == 0 {
stepSize++
}
stepSize++
// TEMPLATE
const hashLog = tableBits
// seems global, but would be nice to tweak.
const kSearchStrength = 8
// nextEmit is where in src the next emitLiteral should start from.
nextEmit := s
cv := load6432(src, s)
// nextHash is the hash at s
nextHash := hash6(cv, hashLog)
// Relative offsets
offset1 := int32(blk.recentOffsets[0])
offset2 := int32(blk.recentOffsets[1])
addLiterals := func(s *seq, until int32) {
if until == nextEmit {
return
}
blk.literals = append(blk.literals, src[nextEmit:until]...)
s.litLen = uint32(until - nextEmit)
}
if debug {
println("recent offsets:", blk.recentOffsets)
}
encodeLoop:
for {
// t will contain the match offset when we find one.
// When existing the search loop, we have already checked 4 bytes.
var t int32
// We will not use repeat offsets across blocks.
// By not using them for the first 3 matches
canRepeat := len(blk.sequences) > 2
for {
if debug && canRepeat && offset1 == 0 {
panic("offset0 was 0")
}
nextHash2 := hash6(cv>>8, hashLog) & tableMask
nextHash = nextHash & tableMask
candidate := e.table[nextHash]
candidate2 := e.table[nextHash2]
repIndex := s - offset1 + 2
e.table[nextHash] = tableEntry{offset: s + e.cur, val: uint32(cv)}
e.table[nextHash2] = tableEntry{offset: s + e.cur + 1, val: uint32(cv >> 8)}
if canRepeat && repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>16) {
// Consider history as well.
var seq seq
lenght := 4 + e.matchlen(s+6, repIndex+4, src)
seq.matchLen = uint32(lenght - zstdMinMatch)
// We might be able to match backwards.
// Extend as long as we can.
start := s + 2
// We end the search early, so we don't risk 0 literals
// and have to do special offset treatment.
startLimit := nextEmit + 1
sMin := s - e.maxMatchOff
if sMin < 0 {
sMin = 0
}
for repIndex > sMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch {
repIndex--
start--
seq.matchLen++
}
addLiterals(&seq, start)
// rep 0
seq.offset = 1
if debugSequences {
println("repeat sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
s += lenght + 2
nextEmit = s
if s >= sLimit {
if debug {
println("repeat ended", s, lenght)
}
break encodeLoop
}
cv = load6432(src, s)
//nextHash = hashLen(cv, hashLog, mls)
nextHash = hash6(cv, hashLog)
continue
}
coffset0 := s - (candidate.offset - e.cur)
coffset1 := s - (candidate2.offset - e.cur) + 1
if coffset0 < e.maxMatchOff && uint32(cv) == candidate.val {
// found a regular match
t = candidate.offset - e.cur
if debug && s <= t {
panic("s <= t")
}
if debug && s-t > e.maxMatchOff {
panic("s - t >e.maxMatchOff")
}
break
}
if coffset1 < e.maxMatchOff && uint32(cv>>8) == candidate2.val {
// found a regular match
t = candidate2.offset - e.cur
s++
if debug && s <= t {
panic("s <= t")
}
if debug && s-t > e.maxMatchOff {
panic("s - t >e.maxMatchOff")
}
if debug && t < 0 {
panic("t<0")
}
break
}
s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
if s >= sLimit {
break encodeLoop
}
cv = load6432(src, s)
nextHash = hash6(cv, hashLog)
}
// A 4-byte match has been found. We'll later see if more than 4 bytes.
offset2 = offset1
offset1 = s - t
if debug && s <= t {
panic("s <= t")
}
if debug && canRepeat && int(offset1) > len(src) {
panic("invalid offset")
}
// Extend the 4-byte match as long as possible.
l := e.matchlen(s+4, t+4, src) + 4
// Extend backwards
tMin := s - e.maxMatchOff
if tMin < 0 {
tMin = 0
}
for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
s--
t--
l++
}
// Write our sequence.
var seq seq
seq.litLen = uint32(s - nextEmit)
seq.matchLen = uint32(l - zstdMinMatch)
if seq.litLen > 0 {
blk.literals = append(blk.literals, src[nextEmit:s]...)
}
// Don't use repeat offsets
seq.offset = uint32(s-t) + 3
s += l
if debugSequences {
println("sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
nextEmit = s
if s >= sLimit {
break encodeLoop
}
cv = load6432(src, s)
nextHash = hash6(cv, hashLog)
// Check offset 2
if o2 := s - offset2; canRepeat && o2 > 0 && load3232(src, o2) == uint32(cv) {
// We have at least 4 byte match.
// No need to check backwards. We come straight from a match
l := 4 + e.matchlen(s+4, o2+4, src)
// Store this, since we have it.
e.table[nextHash&tableMask] = tableEntry{offset: s + e.cur, val: uint32(cv)}
seq.matchLen = uint32(l) - zstdMinMatch
seq.litLen = 0
// Since litlen is always 0, this is offset 1.
seq.offset = 1
s += l
nextEmit = s
if debugSequences {
println("sequence", seq, "next s:", s)
}
blk.sequences = append(blk.sequences, seq)
// Swap offset 1 and 2.
offset1, offset2 = offset2, offset1
if s >= sLimit {
break encodeLoop
}
// Prepare next loop.
cv = load6432(src, s)
nextHash = hash6(cv, hashLog)
}
}
if int(nextEmit) < len(src) {
blk.literals = append(blk.literals, src[nextEmit:]...)
blk.extraLits = len(src) - int(nextEmit)
}
blk.recentOffsets[0] = uint32(offset1)
blk.recentOffsets[1] = uint32(offset2)
if debug {
println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
}
}
func (e *fastEncoder) addBlock(src []byte) int32 {
// check if we have space already
if len(e.hist)+len(src) > cap(e.hist) {
if cap(e.hist) == 0 {
l := e.maxMatchOff * 2
// Make it at least 1MB.
if l < 1<<20 {
l = 1 << 20
}
e.hist = make([]byte, 0, l)
} else {
if cap(e.hist) < int(e.maxMatchOff*2) {
panic("unexpected buffer size")
}
// Move down
offset := int32(len(e.hist)) - e.maxMatchOff
copy(e.hist[0:e.maxMatchOff], e.hist[offset:])
e.cur += offset
e.hist = e.hist[:e.maxMatchOff]
}
}
s := int32(len(e.hist))
e.hist = append(e.hist, src...)
return s
}
// useBlock will replace the block with the provided one,
// but transfer recent offsets from the previous.
func (e *fastEncoder) UseBlock(enc *blockEnc) {
enc.reset(e.blk)
e.blk = enc
}
func (e *fastEncoder) matchlen(s, t int32, src []byte) int32 {
if debug {
if s < 0 {
panic("s<0")
}
if t < 0 {
panic("t<0")
}
if s-t > e.maxMatchOff {
panic(s - t)
}
}
s1 := int(s) + maxMatchLength - 4
if s1 > len(src) {
s1 = len(src)
}
// Extend the match to be as long as possible.
return int32(matchLen(src[s:s1], src[t:]))
}
// Reset the encoding table.
func (e *fastEncoder) Reset() {
if e.blk == nil {
e.blk = &blockEnc{}
e.blk.init()
} else {
e.blk.reset(nil)
}
e.blk.initNewEncode()
if e.crc == nil {
e.crc = xxhash.New()
} else {
e.crc.Reset()
}
if cap(e.hist) < int(e.maxMatchOff*2) {
l := e.maxMatchOff * 2
// Make it at least 1MB.
if l < 1<<20 {
l = 1 << 20
}
e.hist = make([]byte, 0, l)
}
// We offset current position so everything will be out of reach
e.cur += e.maxMatchOff + int32(len(e.hist))
e.hist = e.hist[:0]
}

154
vendor/github.com/klauspost/compress/zstd/enc_params.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
type encParams struct {
// largest match distance : larger == more compression, more memory needed during decompression
windowLog uint8
// fully searched segment : larger == more compression, slower, more memory (useless for fast)
chainLog uint8
// dispatch table : larger == faster, more memory
hashLog uint8
// < nb of searches : larger == more compression, slower
searchLog uint8
// < match length searched : larger == faster decompression, sometimes less compression
minMatch uint8
// acceptable match size for optimal parser (only) : larger == more compression, slower
targetLength uint32
// see ZSTD_strategy definition above
strategy strategy
}
// strategy defines the algorithm to use when generating sequences.
type strategy uint8
const (
// Compression strategies, listed from fastest to strongest
strategyFast strategy = iota + 1
strategyDfast
strategyGreedy
strategyLazy
strategyLazy2
strategyBtlazy2
strategyBtopt
strategyBtultra
strategyBtultra2
// note : new strategies _might_ be added in the future.
// Only the order (from fast to strong) is guaranteed
)
var defEncParams = [4][]encParams{
{ // "default" - for any srcSize > 256 KB
// W, C, H, S, L, TL, strat
{19, 12, 13, 1, 6, 1, strategyFast}, // base for negative levels
{19, 13, 14, 1, 7, 0, strategyFast}, // level 1
{20, 15, 16, 1, 6, 0, strategyFast}, // level 2
{21, 16, 17, 1, 5, 1, strategyDfast}, // level 3
{21, 18, 18, 1, 5, 1, strategyDfast}, // level 4
{21, 18, 19, 2, 5, 2, strategyGreedy}, // level 5
{21, 19, 19, 3, 5, 4, strategyGreedy}, // level 6
{21, 19, 19, 3, 5, 8, strategyLazy}, // level 7
{21, 19, 19, 3, 5, 16, strategyLazy2}, // level 8
{21, 19, 20, 4, 5, 16, strategyLazy2}, // level 9
{22, 20, 21, 4, 5, 16, strategyLazy2}, // level 10
{22, 21, 22, 4, 5, 16, strategyLazy2}, // level 11
{22, 21, 22, 5, 5, 16, strategyLazy2}, // level 12
{22, 21, 22, 5, 5, 32, strategyBtlazy2}, // level 13
{22, 22, 23, 5, 5, 32, strategyBtlazy2}, // level 14
{22, 23, 23, 6, 5, 32, strategyBtlazy2}, // level 15
{22, 22, 22, 5, 5, 48, strategyBtopt}, // level 16
{23, 23, 22, 5, 4, 64, strategyBtopt}, // level 17
{23, 23, 22, 6, 3, 64, strategyBtultra}, // level 18
{23, 24, 22, 7, 3, 256, strategyBtultra2}, // level 19
{25, 25, 23, 7, 3, 256, strategyBtultra2}, // level 20
{26, 26, 24, 7, 3, 512, strategyBtultra2}, // level 21
{27, 27, 25, 9, 3, 999, strategyBtultra2}, // level 22
},
{ // for srcSize <= 256 KB
// W, C, H, S, L, T, strat
{18, 12, 13, 1, 5, 1, strategyFast}, // base for negative levels
{18, 13, 14, 1, 6, 0, strategyFast}, // level 1
{18, 14, 14, 1, 5, 1, strategyDfast}, // level 2
{18, 16, 16, 1, 4, 1, strategyDfast}, // level 3
{18, 16, 17, 2, 5, 2, strategyGreedy}, // level 4.
{18, 18, 18, 3, 5, 2, strategyGreedy}, // level 5.
{18, 18, 19, 3, 5, 4, strategyLazy}, // level 6.
{18, 18, 19, 4, 4, 4, strategyLazy}, // level 7
{18, 18, 19, 4, 4, 8, strategyLazy2}, // level 8
{18, 18, 19, 5, 4, 8, strategyLazy2}, // level 9
{18, 18, 19, 6, 4, 8, strategyLazy2}, // level 10
{18, 18, 19, 5, 4, 12, strategyBtlazy2}, // level 11.
{18, 19, 19, 7, 4, 12, strategyBtlazy2}, // level 12.
{18, 18, 19, 4, 4, 16, strategyBtopt}, // level 13
{18, 18, 19, 4, 3, 32, strategyBtopt}, // level 14.
{18, 18, 19, 6, 3, 128, strategyBtopt}, // level 15.
{18, 19, 19, 6, 3, 128, strategyBtultra}, // level 16.
{18, 19, 19, 8, 3, 256, strategyBtultra}, // level 17.
{18, 19, 19, 6, 3, 128, strategyBtultra2}, // level 18.
{18, 19, 19, 8, 3, 256, strategyBtultra2}, // level 19.
{18, 19, 19, 10, 3, 512, strategyBtultra2}, // level 20.
{18, 19, 19, 12, 3, 512, strategyBtultra2}, // level 21.
{18, 19, 19, 13, 3, 999, strategyBtultra2}, // level 22.
},
{ // for srcSize <= 128 KB
// W, C, H, S, L, T, strat
{17, 12, 12, 1, 5, 1, strategyFast}, // base for negative levels
{17, 12, 13, 1, 6, 0, strategyFast}, // level 1
{17, 13, 15, 1, 5, 0, strategyFast}, // level 2
{17, 15, 16, 2, 5, 1, strategyDfast}, // level 3
{17, 17, 17, 2, 4, 1, strategyDfast}, // level 4
{17, 16, 17, 3, 4, 2, strategyGreedy}, // level 5
{17, 17, 17, 3, 4, 4, strategyLazy}, // level 6
{17, 17, 17, 3, 4, 8, strategyLazy2}, // level 7
{17, 17, 17, 4, 4, 8, strategyLazy2}, // level 8
{17, 17, 17, 5, 4, 8, strategyLazy2}, // level 9
{17, 17, 17, 6, 4, 8, strategyLazy2}, // level 10
{17, 17, 17, 5, 4, 8, strategyBtlazy2}, // level 11
{17, 18, 17, 7, 4, 12, strategyBtlazy2}, // level 12
{17, 18, 17, 3, 4, 12, strategyBtopt}, // level 13.
{17, 18, 17, 4, 3, 32, strategyBtopt}, // level 14.
{17, 18, 17, 6, 3, 256, strategyBtopt}, // level 15.
{17, 18, 17, 6, 3, 128, strategyBtultra}, // level 16.
{17, 18, 17, 8, 3, 256, strategyBtultra}, // level 17.
{17, 18, 17, 10, 3, 512, strategyBtultra}, // level 18.
{17, 18, 17, 5, 3, 256, strategyBtultra2}, // level 19.
{17, 18, 17, 7, 3, 512, strategyBtultra2}, // level 20.
{17, 18, 17, 9, 3, 512, strategyBtultra2}, // level 21.
{17, 18, 17, 11, 3, 999, strategyBtultra2}, // level 22.
},
{ // for srcSize <= 16 KB
// W, C, H, S, L, T, strat
{14, 12, 13, 1, 5, 1, strategyFast}, // base for negative levels
{14, 14, 15, 1, 5, 0, strategyFast}, // level 1
{14, 14, 15, 1, 4, 0, strategyFast}, // level 2
{14, 14, 15, 2, 4, 1, strategyDfast}, // level 3
{14, 14, 14, 4, 4, 2, strategyGreedy}, // level 4
{14, 14, 14, 3, 4, 4, strategyLazy}, // level 5.
{14, 14, 14, 4, 4, 8, strategyLazy2}, // level 6
{14, 14, 14, 6, 4, 8, strategyLazy2}, // level 7
{14, 14, 14, 8, 4, 8, strategyLazy2}, // level 8.
{14, 15, 14, 5, 4, 8, strategyBtlazy2}, // level 9.
{14, 15, 14, 9, 4, 8, strategyBtlazy2}, // level 10.
{14, 15, 14, 3, 4, 12, strategyBtopt}, // level 11.
{14, 15, 14, 4, 3, 24, strategyBtopt}, // level 12.
{14, 15, 14, 5, 3, 32, strategyBtultra}, // level 13.
{14, 15, 15, 6, 3, 64, strategyBtultra}, // level 14.
{14, 15, 15, 7, 3, 256, strategyBtultra}, // level 15.
{14, 15, 15, 5, 3, 48, strategyBtultra2}, // level 16.
{14, 15, 15, 6, 3, 128, strategyBtultra2}, // level 17.
{14, 15, 15, 7, 3, 256, strategyBtultra2}, // level 18.
{14, 15, 15, 8, 3, 256, strategyBtultra2}, // level 19.
{14, 15, 15, 8, 3, 512, strategyBtultra2}, // level 20.
{14, 15, 15, 9, 3, 512, strategyBtultra2}, // level 21.
{14, 15, 15, 10, 3, 999, strategyBtultra2}, // level 22.
},
}

473
vendor/github.com/klauspost/compress/zstd/encoder.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"crypto/rand"
"fmt"
"io"
rdebug "runtime/debug"
"sync"
"github.com/klauspost/compress/zstd/internal/xxhash"
)
// Encoder provides encoding to Zstandard.
// An Encoder can be used for either compressing a stream via the
// io.WriteCloser interface supported by the Encoder or as multiple independent
// tasks via the EncodeAll function.
// Smaller encodes are encouraged to use the EncodeAll function.
// Use NewWriter to create a new instance.
type Encoder struct {
o encoderOptions
encoders chan encoder
state encoderState
init sync.Once
}
type encoder interface {
Encode(blk *blockEnc, src []byte)
Block() *blockEnc
CRC() *xxhash.Digest
AppendCRC([]byte) []byte
WindowSize(size int) int32
UseBlock(*blockEnc)
Reset()
}
type encoderState struct {
w io.Writer
filling []byte
current []byte
previous []byte
encoder encoder
writing *blockEnc
err error
writeErr error
nWritten int64
headerWritten bool
eofWritten bool
// This waitgroup indicates an encode is running.
wg sync.WaitGroup
// This waitgroup indicates we have a block encoding/writing.
wWg sync.WaitGroup
}
// NewWriter will create a new Zstandard encoder.
// If the encoder will be used for encoding blocks a nil writer can be used.
func NewWriter(w io.Writer, opts ...EOption) (*Encoder, error) {
var e Encoder
e.o.setDefault()
for _, o := range opts {
err := o(&e.o)
if err != nil {
return nil, err
}
}
if w != nil {
e.Reset(w)
} else {
e.init.Do(func() {
e.initialize()
})
}
return &e, nil
}
func (e *Encoder) initialize() {
e.encoders = make(chan encoder, e.o.concurrent)
for i := 0; i < e.o.concurrent; i++ {
e.encoders <- e.o.encoder()
}
}
// Reset will re-initialize the writer and new writes will encode to the supplied writer
// as a new, independent stream.
func (e *Encoder) Reset(w io.Writer) {
e.init.Do(func() {
e.initialize()
})
s := &e.state
s.wg.Wait()
s.wWg.Wait()
if cap(s.filling) == 0 {
s.filling = make([]byte, 0, e.o.blockSize)
}
if cap(s.current) == 0 {
s.current = make([]byte, 0, e.o.blockSize)
}
if cap(s.previous) == 0 {
s.previous = make([]byte, 0, e.o.blockSize)
}
if s.encoder == nil {
s.encoder = e.o.encoder()
}
if s.writing == nil {
s.writing = &blockEnc{}
s.writing.init()
}
s.writing.initNewEncode()
s.filling = s.filling[:0]
s.current = s.current[:0]
s.previous = s.previous[:0]
s.encoder.Reset()
s.headerWritten = false
s.eofWritten = false
s.w = w
s.err = nil
s.nWritten = 0
s.writeErr = nil
}
// Write data to the encoder.
// Input data will be buffered and as the buffer fills up
// content will be compressed and written to the output.
// When done writing, use Close to flush the remaining output
// and write CRC if requested.
func (e *Encoder) Write(p []byte) (n int, err error) {
s := &e.state
for len(p) > 0 {
if len(p)+len(s.filling) < e.o.blockSize {
if e.o.crc {
_, _ = s.encoder.CRC().Write(p)
}
s.filling = append(s.filling, p...)
return n + len(p), nil
}
add := p
if len(p)+len(s.filling) > e.o.blockSize {
add = add[:e.o.blockSize-len(s.filling)]
}
if e.o.crc {
_, _ = s.encoder.CRC().Write(add)
}
s.filling = append(s.filling, add...)
p = p[len(add):]
n += len(add)
if len(s.filling) < e.o.blockSize {
return n, nil
}
err := e.nextBlock(false)
if err != nil {
return n, err
}
if debug && len(s.filling) > 0 {
panic(len(s.filling))
}
}
return n, nil
}
// nextBlock will synchronize and start compressing input in e.state.filling.
// If an error has occurred during encoding it will be returned.
func (e *Encoder) nextBlock(final bool) error {
s := &e.state
// Wait for current block.
s.wg.Wait()
if s.err != nil {
return s.err
}
if len(s.filling) > e.o.blockSize {
return fmt.Errorf("block > maxStoreBlockSize")
}
if !s.headerWritten {
var tmp [maxHeaderSize]byte
fh := frameHeader{
ContentSize: 0,
WindowSize: uint32(s.encoder.WindowSize(0)),
SingleSegment: false,
Checksum: e.o.crc,
DictID: 0,
}
dst, err := fh.appendTo(tmp[:0])
if err != nil {
return err
}
s.headerWritten = true
s.wWg.Wait()
var n2 int
n2, s.err = s.w.Write(dst)
if s.err != nil {
return s.err
}
s.nWritten += int64(n2)
}
if s.eofWritten {
// Ensure we only write it once.
final = false
}
if len(s.filling) == 0 {
// Final block, but no data.
if final {
enc := s.encoder
blk := enc.Block()
blk.reset(nil)
blk.last = true
blk.encodeRaw(nil)
s.wWg.Wait()
_, s.err = s.w.Write(blk.output)
s.nWritten += int64(len(blk.output))
s.eofWritten = true
}
return s.err
}
// Move blocks forward.
s.filling, s.current, s.previous = s.previous[:0], s.filling, s.current
s.wg.Add(1)
go func(src []byte) {
if debug {
println("Adding block,", len(src), "bytes, final:", final)
}
defer func() {
if r := recover(); r != nil {
s.err = fmt.Errorf("panic while encoding: %v", r)
rdebug.PrintStack()
}
s.wg.Done()
}()
enc := s.encoder
blk := enc.Block()
enc.Encode(blk, src)
blk.last = final
if final {
s.eofWritten = true
}
// Wait for pending writes.
s.wWg.Wait()
if s.writeErr != nil {
s.err = s.writeErr
return
}
// Transfer encoders from previous write block.
blk.swapEncoders(s.writing)
// Transfer recent offsets to next.
enc.UseBlock(s.writing)
s.writing = blk
s.wWg.Add(1)
go func() {
defer func() {
if r := recover(); r != nil {
s.writeErr = fmt.Errorf("panic while encoding/writing: %v", r)
rdebug.PrintStack()
}
s.wWg.Done()
}()
err := blk.encode()
switch err {
case errIncompressible:
if debug {
println("Storing incompressible block as raw")
}
blk.encodeRaw(src)
// In fast mode, we do not transfer offsets, so we don't have to deal with changing the.
case nil:
default:
s.writeErr = err
return
}
_, s.writeErr = s.w.Write(blk.output)
s.nWritten += int64(len(blk.output))
}()
}(s.current)
return nil
}
// ReadFrom reads data from r until EOF or error.
// The return value n is the number of bytes read.
// Any error except io.EOF encountered during the read is also returned.
//
// The Copy function uses ReaderFrom if available.
func (e *Encoder) ReadFrom(r io.Reader) (n int64, err error) {
if debug {
println("Using ReadFrom")
}
// Maybe handle stuff queued?
e.state.filling = e.state.filling[:e.o.blockSize]
src := e.state.filling
for {
n2, err := r.Read(src)
_, _ = e.state.encoder.CRC().Write(src[:n2])
// src is now the unfilled part...
src = src[n2:]
n += int64(n2)
switch err {
case io.EOF:
e.state.filling = e.state.filling[:len(e.state.filling)-len(src)]
if debug {
println("ReadFrom: got EOF final block:", len(e.state.filling))
}
return n, e.nextBlock(true)
default:
if debug {
println("ReadFrom: got error:", err)
}
e.state.err = err
return n, err
case nil:
}
if len(src) > 0 {
if debug {
println("ReadFrom: got space left in source:", len(src))
}
continue
}
err = e.nextBlock(false)
if err != nil {
return n, err
}
e.state.filling = e.state.filling[:e.o.blockSize]
src = e.state.filling
}
}
// Flush will send the currently written data to output
// and block until everything has been written.
// This should only be used on rare occasions where pushing the currently queued data is critical.
func (e *Encoder) Flush() error {
s := &e.state
if len(s.filling) > 0 {
err := e.nextBlock(false)
if err != nil {
return err
}
}
s.wg.Wait()
s.wWg.Wait()
if s.err != nil {
return s.err
}
return s.writeErr
}
// Close will flush the final output and close the stream.
// The function will block until everything has been written.
// The Encoder can still be re-used after calling this.
func (e *Encoder) Close() error {
s := &e.state
if s.encoder == nil {
return nil
}
err := e.nextBlock(true)
if err != nil {
return err
}
s.wg.Wait()
s.wWg.Wait()
if s.err != nil {
return s.err
}
if s.writeErr != nil {
return s.writeErr
}
// Write CRC
if e.o.crc && s.err == nil {
// heap alloc.
var tmp [4]byte
_, s.err = s.w.Write(s.encoder.AppendCRC(tmp[:0]))
s.nWritten += 4
}
// Add padding with content from crypto/rand.Reader
if s.err == nil && e.o.pad > 0 {
add := calcSkippableFrame(s.nWritten, int64(e.o.pad))
frame, err := skippableFrame(s.filling[:0], add, rand.Reader)
if err != nil {
return err
}
_, s.err = s.w.Write(frame)
}
return s.err
}
// EncodeAll will encode all input in src and append it to dst.
// This function can be called concurrently, but each call will only run on a single goroutine.
// If empty input is given, nothing is returned.
// Encoded blocks can be concatenated and the result will be the combined input stream.
// Data compressed with EncodeAll can be decoded with the Decoder,
// using either a stream or DecodeAll.
func (e *Encoder) EncodeAll(src, dst []byte) []byte {
if len(src) == 0 {
return dst
}
e.init.Do(func() {
e.o.setDefault()
e.initialize()
})
enc := <-e.encoders
defer func() {
// Release encoder reference to last block.
enc.Reset()
e.encoders <- enc
}()
enc.Reset()
blk := enc.Block()
single := len(src) > 1<<20
if e.o.single != nil {
single = *e.o.single
}
fh := frameHeader{
ContentSize: uint64(len(src)),
WindowSize: uint32(enc.WindowSize(len(src))),
SingleSegment: single,
Checksum: e.o.crc,
DictID: 0,
}
// If less than 1MB, allocate a buffer up front.
if len(dst) == 0 && cap(dst) == 0 && len(src) < 1<<20 {
dst = make([]byte, 0, len(src))
}
dst, err := fh.appendTo(dst)
if err != nil {
panic(err)
}
for len(src) > 0 {
todo := src
if len(todo) > e.o.blockSize {
todo = todo[:e.o.blockSize]
}
src = src[len(todo):]
if e.o.crc {
_, _ = enc.CRC().Write(todo)
}
blk.reset(nil)
blk.pushOffsets()
enc.Encode(blk, todo)
if len(src) == 0 {
blk.last = true
}
err := blk.encode()
switch err {
case errIncompressible:
if debug {
println("Storing incompressible block as raw")
}
blk.encodeRaw(todo)
blk.popOffsets()
case nil:
default:
panic(err)
}
dst = append(dst, blk.output...)
}
if e.o.crc {
dst = enc.AppendCRC(dst)
}
// Add padding with content from crypto/rand.Reader
if e.o.pad > 0 {
add := calcSkippableFrame(int64(len(dst)), int64(e.o.pad))
dst, err = skippableFrame(dst, add, rand.Reader)
if err != nil {
panic(err)
}
}
return dst
}

184
vendor/github.com/klauspost/compress/zstd/encoder_options.go generated vendored Normal file
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package zstd
import (
"fmt"
"runtime"
"strings"
)
// DOption is an option for creating a encoder.
type EOption func(*encoderOptions) error
// options retains accumulated state of multiple options.
type encoderOptions struct {
concurrent int
crc bool
single *bool
pad int
blockSize int
windowSize int
level EncoderLevel
}
func (o *encoderOptions) setDefault() {
*o = encoderOptions{
// use less ram: true for now, but may change.
concurrent: runtime.GOMAXPROCS(0),
crc: true,
single: nil,
blockSize: 1 << 16,
windowSize: 1 << 22,
level: SpeedDefault,
}
}
// encoder returns an encoder with the selected options.
func (o encoderOptions) encoder() encoder {
switch o.level {
case SpeedDefault:
return &doubleFastEncoder{fastEncoder: fastEncoder{maxMatchOff: int32(o.windowSize)}}
case SpeedFastest:
return &fastEncoder{maxMatchOff: int32(o.windowSize)}
}
panic("unknown compression level")
}
// WithEncoderCRC will add CRC value to output.
// Output will be 4 bytes larger.
func WithEncoderCRC(b bool) EOption {
return func(o *encoderOptions) error { o.crc = b; return nil }
}
// WithEncoderConcurrency will set the concurrency,
// meaning the maximum number of decoders to run concurrently.
// The value supplied must be at least 1.
// By default this will be set to GOMAXPROCS.
func WithEncoderConcurrency(n int) EOption {
return func(o *encoderOptions) error {
if n <= 0 {
return fmt.Errorf("concurrency must be at least 1")
}
o.concurrent = n
return nil
}
}
// WithEncoderPadding will add padding to all output so the size will be a multiple of n.
// This can be used to obfuscate the exact output size or make blocks of a certain size.
// The contents will be a skippable frame, so it will be invisible by the decoder.
// n must be > 0 and <= 1GB, 1<<30 bytes.
// The padded area will be filled with data from crypto/rand.Reader.
// If `EncodeAll` is used with data already in the destination, the total size will be multiple of this.
func WithEncoderPadding(n int) EOption {
return func(o *encoderOptions) error {
if n <= 0 {
return fmt.Errorf("padding must be at least 1")
}
// No need to waste our time.
if n == 1 {
o.pad = 0
}
if n > 1<<30 {
return fmt.Errorf("padding must less than 1GB (1<<30 bytes) ")
}
o.pad = n
return nil
}
}
// EncoderLevel predefines encoder compression levels.
// Only use the constants made available, since the actual mapping
// of these values are very likely to change and your compression could change
// unpredictably when upgrading the library.
type EncoderLevel int
const (
speedNotSet EncoderLevel = iota
// SpeedFastest will choose the fastest reasonable compression.
// This is roughly equivalent to the fastest Zstandard mode.
SpeedFastest
// SpeedDefault is the default "pretty fast" compression option.
// This is roughly equivalent to the default Zstandard mode (level 3).
SpeedDefault
// speedLast should be kept as the last actual compression option.
// The is not for external usage, but is used to keep track of the valid options.
speedLast
// SpeedBetterCompression will (in the future) yield better compression than the default,
// but at approximately 4x the CPU usage of the default.
// For now this is not implemented.
SpeedBetterCompression = SpeedDefault
// SpeedBestCompression will choose the best available compression option.
// For now this is not implemented.
SpeedBestCompression = SpeedDefault
)
// EncoderLevelFromString will convert a string representation of an encoding level back
// to a compression level. The compare is not case sensitive.
// If the string wasn't recognized, (false, SpeedDefault) will be returned.
func EncoderLevelFromString(s string) (bool, EncoderLevel) {
for l := EncoderLevel(speedNotSet + 1); l < speedLast; l++ {
if strings.EqualFold(s, l.String()) {
return true, l
}
}
return false, SpeedDefault
}
// EncoderLevelFromZstd will return an encoder level that closest matches the compression
// ratio of a specific zstd compression level.
// Many input values will provide the same compression level.
func EncoderLevelFromZstd(level int) EncoderLevel {
switch {
case level < 3:
return SpeedFastest
case level >= 3:
return SpeedDefault
}
return SpeedDefault
}
// String provides a string representation of the compression level.
func (e EncoderLevel) String() string {
switch e {
case SpeedFastest:
return "fastest"
case SpeedDefault:
return "default"
default:
return "invalid"
}
}
// WithEncoderLevel specifies a predefined compression level.
func WithEncoderLevel(l EncoderLevel) EOption {
return func(o *encoderOptions) error {
switch {
case l <= speedNotSet || l >= speedLast:
return fmt.Errorf("unknown encoder level")
}
o.level = l
return nil
}
}
// WithSingleSegment will set the "single segment" flag when EncodeAll is used.
// If this flag is set, data must be regenerated within a single continuous memory segment.
// In this case, Window_Descriptor byte is skipped, but Frame_Content_Size is necessarily present.
// As a consequence, the decoder must allocate a memory segment of size equal or larger than size of your content.
// In order to preserve the decoder from unreasonable memory requirements,
// a decoder is allowed to reject a compressed frame which requests a memory size beyond decoder's authorized range.
// For broader compatibility, decoders are recommended to support memory sizes of at least 8 MB.
// This is only a recommendation, each decoder is free to support higher or lower limits, depending on local limitations.
// If this is not specified, block encodes will automatically choose this based on the input size.
// This setting has no effect on streamed encodes.
func WithSingleSegment(b bool) EOption {
return func(o *encoderOptions) error {
o.single = &b
return nil
}
}

477
vendor/github.com/klauspost/compress/zstd/framedec.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"bytes"
"encoding/hex"
"errors"
"hash"
"io"
"sync"
"github.com/klauspost/compress/zstd/internal/xxhash"
)
type frameDec struct {
o decoderOptions
crc hash.Hash64
frameDone sync.WaitGroup
offset int64
WindowSize uint64
DictionaryID uint32
FrameContentSize uint64
HasCheckSum bool
SingleSegment bool
// maxWindowSize is the maximum windows size to support.
// should never be bigger than max-int.
maxWindowSize uint64
// In order queue of blocks being decoded.
decoding chan *blockDec
// Frame history passed between blocks
history history
rawInput byteBuffer
// asyncRunning indicates whether the async routine processes input on 'decoding'.
asyncRunning bool
asyncRunningMu sync.Mutex
}
const (
// The minimum Window_Size is 1 KB.
minWindowSize = 1 << 10
)
var (
frameMagic = []byte{0x28, 0xb5, 0x2f, 0xfd}
skippableFrameMagic = []byte{0x2a, 0x4d, 0x18}
)
func newFrameDec(o decoderOptions) *frameDec {
d := frameDec{
o: o,
maxWindowSize: 1 << 30,
}
return &d
}
// reset will read the frame header and prepare for block decoding.
// If nothing can be read from the input, io.EOF will be returned.
// Any other error indicated that the stream contained data, but
// there was a problem.
func (d *frameDec) reset(br byteBuffer) error {
d.HasCheckSum = false
d.WindowSize = 0
var b []byte
for {
b = br.readSmall(4)
if b == nil {
return io.EOF
}
if !bytes.Equal(b[1:4], skippableFrameMagic) || b[0]&0xf0 != 0x50 {
if debug {
println("Not skippable", hex.EncodeToString(b), hex.EncodeToString(skippableFrameMagic))
}
// Break if not skippable frame.
break
}
// Read size to skip
b = br.readSmall(4)
if b == nil {
println("Reading Frame Size EOF")
return io.ErrUnexpectedEOF
}
n := uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
println("Skipping frame with", n, "bytes.")
err := br.skipN(int(n))
if err != nil {
if debug {
println("Reading discarded frame", err)
}
return err
}
}
if !bytes.Equal(b, frameMagic) {
println("Got magic numbers: ", b, "want:", frameMagic)
return ErrMagicMismatch
}
// Read Frame_Header_Descriptor
fhd, err := br.readByte()
if err != nil {
println("Reading Frame_Header_Descriptor", err)
return err
}
d.SingleSegment = fhd&(1<<5) != 0
if fhd&(1<<3) != 0 {
return errors.New("Reserved bit set on frame header")
}
// Read Window_Descriptor
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#window_descriptor
d.WindowSize = 0
if !d.SingleSegment {
wd, err := br.readByte()
if err != nil {
println("Reading Window_Descriptor", err)
return err
}
printf("raw: %x, mantissa: %d, exponent: %d\n", wd, wd&7, wd>>3)
windowLog := 10 + (wd >> 3)
windowBase := uint64(1) << windowLog
windowAdd := (windowBase / 8) * uint64(wd&0x7)
d.WindowSize = windowBase + windowAdd
}
// Read Dictionary_ID
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#dictionary_id
d.DictionaryID = 0
if size := fhd & 3; size != 0 {
if size == 3 {
size = 4
}
b = br.readSmall(int(size))
if b == nil {
if debug {
println("Reading Dictionary_ID", io.ErrUnexpectedEOF)
}
return io.ErrUnexpectedEOF
}
switch size {
case 1:
d.DictionaryID = uint32(b[0])
case 2:
d.DictionaryID = uint32(b[0]) | (uint32(b[1]) << 8)
case 4:
d.DictionaryID = uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
}
if debug {
println("Dict size", size, "ID:", d.DictionaryID)
}
if d.DictionaryID != 0 {
return ErrUnknownDictionary
}
}
// Read Frame_Content_Size
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#frame_content_size
var fcsSize int
v := fhd >> 6
switch v {
case 0:
if d.SingleSegment {
fcsSize = 1
}
default:
fcsSize = 1 << v
}
d.FrameContentSize = 0
if fcsSize > 0 {
b := br.readSmall(fcsSize)
if b == nil {
println("Reading Frame content", io.ErrUnexpectedEOF)
return io.ErrUnexpectedEOF
}
switch fcsSize {
case 1:
d.FrameContentSize = uint64(b[0])
case 2:
// When FCS_Field_Size is 2, the offset of 256 is added.
d.FrameContentSize = uint64(b[0]) | (uint64(b[1]) << 8) + 256
case 4:
d.FrameContentSize = uint64(b[0]) | (uint64(b[1]) << 8) | (uint64(b[2]) << 16) | (uint64(b[3] << 24))
case 8:
d1 := uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
d2 := uint32(b[4]) | (uint32(b[5]) << 8) | (uint32(b[6]) << 16) | (uint32(b[7]) << 24)
d.FrameContentSize = uint64(d1) | (uint64(d2) << 32)
}
if debug {
println("field size bits:", v, "fcsSize:", fcsSize, "FrameContentSize:", d.FrameContentSize, hex.EncodeToString(b[:fcsSize]))
}
}
// Move this to shared.
d.HasCheckSum = fhd&(1<<2) != 0
if d.HasCheckSum {
if d.crc == nil {
d.crc = xxhash.New()
}
d.crc.Reset()
}
if d.WindowSize == 0 && d.SingleSegment {
// We may not need window in this case.
d.WindowSize = d.FrameContentSize
if d.WindowSize < minWindowSize {
d.WindowSize = minWindowSize
}
}
if d.WindowSize > d.maxWindowSize {
printf("window size %d > max %d\n", d.WindowSize, d.maxWindowSize)
return ErrWindowSizeExceeded
}
// The minimum Window_Size is 1 KB.
if d.WindowSize < minWindowSize {
println("got window size: ", d.WindowSize)
return ErrWindowSizeTooSmall
}
d.history.windowSize = int(d.WindowSize)
d.history.maxSize = d.history.windowSize + maxBlockSize
// history contains input - maybe we do something
d.rawInput = br
return nil
}
// next will start decoding the next block from stream.
func (d *frameDec) next(block *blockDec) error {
if debug {
printf("decoding new block %p:%p", block, block.data)
}
err := block.reset(d.rawInput, d.WindowSize)
if err != nil {
println("block error:", err)
// Signal the frame decoder we have a problem.
d.sendErr(block, err)
return err
}
block.input <- struct{}{}
if debug {
println("next block:", block)
}
d.asyncRunningMu.Lock()
defer d.asyncRunningMu.Unlock()
if !d.asyncRunning {
return nil
}
if block.Last {
// We indicate the frame is done by sending io.EOF
d.decoding <- block
return io.EOF
}
d.decoding <- block
return nil
}
// sendEOF will queue an error block on the frame.
// This will cause the frame decoder to return when it encounters the block.
// Returns true if the decoder was added.
func (d *frameDec) sendErr(block *blockDec, err error) bool {
d.asyncRunningMu.Lock()
defer d.asyncRunningMu.Unlock()
if !d.asyncRunning {
return false
}
println("sending error", err.Error())
block.sendErr(err)
d.decoding <- block
return true
}
// checkCRC will check the checksum if the frame has one.
// Will return ErrCRCMismatch if crc check failed, otherwise nil.
func (d *frameDec) checkCRC() error {
if !d.HasCheckSum {
return nil
}
var tmp [4]byte
got := d.crc.Sum64()
// Flip to match file order.
tmp[0] = byte(got >> 0)
tmp[1] = byte(got >> 8)
tmp[2] = byte(got >> 16)
tmp[3] = byte(got >> 24)
// We can overwrite upper tmp now
want := d.rawInput.readSmall(4)
if want == nil {
println("CRC missing?")
return io.ErrUnexpectedEOF
}
if !bytes.Equal(tmp[:], want) {
if debug {
println("CRC Check Failed:", tmp[:], "!=", want)
}
return ErrCRCMismatch
}
println("CRC ok")
return nil
}
func (d *frameDec) initAsync() {
if !d.o.lowMem && !d.SingleSegment {
// set max extra size history to 20MB.
d.history.maxSize = d.history.windowSize + maxBlockSize*10
}
// re-alloc if more than one extra block size.
if d.o.lowMem && cap(d.history.b) > d.history.maxSize+maxBlockSize {
d.history.b = make([]byte, 0, d.history.maxSize)
}
if cap(d.history.b) < d.history.maxSize {
d.history.b = make([]byte, 0, d.history.maxSize)
}
if cap(d.decoding) < d.o.concurrent {
d.decoding = make(chan *blockDec, d.o.concurrent)
}
if debug {
h := d.history
printf("history init. len: %d, cap: %d", len(h.b), cap(h.b))
}
d.asyncRunningMu.Lock()
d.asyncRunning = true
d.asyncRunningMu.Unlock()
}
// startDecoder will start decoding blocks and write them to the writer.
// The decoder will stop as soon as an error occurs or at end of frame.
// When the frame has finished decoding the *bufio.Reader
// containing the remaining input will be sent on frameDec.frameDone.
func (d *frameDec) startDecoder(output chan decodeOutput) {
// TODO: Init to dictionary
d.history.reset()
written := int64(0)
defer func() {
d.asyncRunningMu.Lock()
d.asyncRunning = false
d.asyncRunningMu.Unlock()
// Drain the currently decoding.
d.history.error = true
flushdone:
for {
select {
case b := <-d.decoding:
b.history <- &d.history
output <- <-b.result
default:
break flushdone
}
}
println("frame decoder done, signalling done")
d.frameDone.Done()
}()
// Get decoder for first block.
block := <-d.decoding
block.history <- &d.history
for {
var next *blockDec
// Get result
r := <-block.result
if r.err != nil {
println("Result contained error", r.err)
output <- r
return
}
if debug {
println("got result, from ", d.offset, "to", d.offset+int64(len(r.b)))
d.offset += int64(len(r.b))
}
if !block.Last {
// Send history to next block
select {
case next = <-d.decoding:
if debug {
println("Sending ", len(d.history.b), "bytes as history")
}
next.history <- &d.history
default:
// Wait until we have sent the block, so
// other decoders can potentially get the decoder.
next = nil
}
}
// Add checksum, async to decoding.
if d.HasCheckSum {
n, err := d.crc.Write(r.b)
if err != nil {
r.err = err
if n != len(r.b) {
r.err = io.ErrShortWrite
}
output <- r
return
}
}
written += int64(len(r.b))
if d.SingleSegment && uint64(written) > d.FrameContentSize {
r.err = ErrFrameSizeExceeded
output <- r
return
}
if block.Last {
r.err = d.checkCRC()
output <- r
return
}
output <- r
if next == nil {
// There was no decoder available, we wait for one now that we have sent to the writer.
if debug {
println("Sending ", len(d.history.b), " bytes as history")
}
next = <-d.decoding
next.history <- &d.history
}
block = next
}
}
// runDecoder will create a sync decoder that will decode a block of data.
func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
// TODO: Init to dictionary
d.history.reset()
saved := d.history.b
// We use the history for output to avoid copying it.
d.history.b = dst
// Store input length, so we only check new data.
crcStart := len(dst)
var err error
for {
err = dec.reset(d.rawInput, d.WindowSize)
if err != nil {
break
}
if debug {
println("next block:", dec)
}
err = dec.decodeBuf(&d.history)
if err != nil || dec.Last {
break
}
if uint64(len(d.history.b)) > d.o.maxDecodedSize {
err = ErrDecoderSizeExceeded
break
}
if d.SingleSegment && uint64(len(d.history.b)) > d.o.maxDecodedSize {
err = ErrFrameSizeExceeded
break
}
}
dst = d.history.b
if err == nil {
if d.HasCheckSum {
var n int
n, err = d.crc.Write(dst[crcStart:])
if err == nil {
if n != len(dst)-crcStart {
err = io.ErrShortWrite
}
}
err = d.checkCRC()
}
}
d.history.b = saved
return dst, err
}

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vendor/github.com/klauspost/compress/zstd/frameenc.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"io"
"math"
"math/bits"
)
type frameHeader struct {
ContentSize uint64
WindowSize uint32
SingleSegment bool
Checksum bool
DictID uint32 // Not stored.
}
const maxHeaderSize = 14
func (f frameHeader) appendTo(dst []byte) ([]byte, error) {
dst = append(dst, frameMagic...)
var fhd uint8
if f.Checksum {
fhd |= 1 << 2
}
if f.SingleSegment {
fhd |= 1 << 5
}
var fcs uint8
if f.ContentSize >= 256 {
fcs++
}
if f.ContentSize >= 65536+256 {
fcs++
}
if f.ContentSize >= 0xffffffff {
fcs++
}
fhd |= fcs << 6
dst = append(dst, fhd)
if !f.SingleSegment {
const winLogMin = 10
windowLog := (bits.Len32(f.WindowSize-1) - winLogMin) << 3
dst = append(dst, uint8(windowLog))
}
if f.SingleSegment && f.ContentSize == 0 {
return nil, errors.New("single segment, but no size set")
}
switch fcs {
case 0:
if f.SingleSegment {
dst = append(dst, uint8(f.ContentSize))
}
// Unless SingleSegment is set, framessizes < 256 are nto stored.
case 1:
f.ContentSize -= 256
dst = append(dst, uint8(f.ContentSize), uint8(f.ContentSize>>8))
case 2:
dst = append(dst, uint8(f.ContentSize), uint8(f.ContentSize>>8), uint8(f.ContentSize>>16), uint8(f.ContentSize>>24))
case 3:
dst = append(dst, uint8(f.ContentSize), uint8(f.ContentSize>>8), uint8(f.ContentSize>>16), uint8(f.ContentSize>>24),
uint8(f.ContentSize>>32), uint8(f.ContentSize>>40), uint8(f.ContentSize>>48), uint8(f.ContentSize>>56))
default:
panic("invalid fcs")
}
return dst, nil
}
const skippableFrameHeader = 4 + 4
// calcSkippableFrame will return a total size to be added for written
// to be divisible by multiple.
// The value will always be > skippableFrameHeader.
// The function will panic if written < 0 or wantMultiple <= 0.
func calcSkippableFrame(written, wantMultiple int64) int {
if wantMultiple <= 0 {
panic("wantMultiple <= 0")
}
if written < 0 {
panic("written < 0")
}
leftOver := written % wantMultiple
if leftOver == 0 {
return 0
}
toAdd := wantMultiple - leftOver
for toAdd < skippableFrameHeader {
toAdd += wantMultiple
}
return int(toAdd)
}
// skippableFrame will add a skippable frame with a total size of bytes.
// total should be >= skippableFrameHeader and < math.MaxUint32.
func skippableFrame(dst []byte, total int, r io.Reader) ([]byte, error) {
if total == 0 {
return dst, nil
}
if total < skippableFrameHeader {
return dst, fmt.Errorf("requested skippable frame (%d) < 8", total)
}
if int64(total) > math.MaxUint32 {
return dst, fmt.Errorf("requested skippable frame (%d) > max uint32", total)
}
dst = append(dst, 0x50, 0x2a, 0x4d, 0x18)
f := uint32(total - skippableFrameHeader)
dst = append(dst, uint8(f), uint8(f>>8), uint8(f>>16), uint8(f>>24))
start := len(dst)
dst = append(dst, make([]byte, f)...)
_, err := io.ReadFull(r, dst[start:])
return dst, err
}

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vendor/github.com/klauspost/compress/zstd/fse_decoder.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
)
const (
tablelogAbsoluteMax = 9
)
const (
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
maxMemoryUsage = 11
maxTableLog = maxMemoryUsage - 2
maxTablesize = 1 << maxTableLog
maxTableMask = (1 << maxTableLog) - 1
minTablelog = 5
maxSymbolValue = 255
)
// fseDecoder provides temporary storage for compression and decompression.
type fseDecoder struct {
dt [maxTablesize]decSymbol // Decompression table.
symbolLen uint16 // Length of active part of the symbol table.
actualTableLog uint8 // Selected tablelog.
maxBits uint8 // Maximum number of additional bits
// used for table creation to avoid allocations.
stateTable [256]uint16
norm [maxSymbolValue + 1]int16
preDefined bool
}
// tableStep returns the next table index.
func tableStep(tableSize uint32) uint32 {
return (tableSize >> 1) + (tableSize >> 3) + 3
}
// readNCount will read the symbol distribution so decoding tables can be constructed.
func (s *fseDecoder) readNCount(b *byteReader, maxSymbol uint16) error {
var (
charnum uint16
previous0 bool
)
if b.remain() < 4 {
return errors.New("input too small")
}
bitStream := b.Uint32()
nbBits := uint((bitStream & 0xF) + minTablelog) // extract tableLog
if nbBits > tablelogAbsoluteMax {
println("Invalid tablelog:", nbBits)
return errors.New("tableLog too large")
}
bitStream >>= 4
bitCount := uint(4)
s.actualTableLog = uint8(nbBits)
remaining := int32((1 << nbBits) + 1)
threshold := int32(1 << nbBits)
gotTotal := int32(0)
nbBits++
for remaining > 1 && charnum <= maxSymbol {
if previous0 {
//println("prev0")
n0 := charnum
for (bitStream & 0xFFFF) == 0xFFFF {
//println("24 x 0")
n0 += 24
if r := b.remain(); r > 5 {
b.advance(2)
bitStream = b.Uint32() >> bitCount
} else {
// end of bit stream
bitStream >>= 16
bitCount += 16
}
}
//printf("bitstream: %d, 0b%b", bitStream&3, bitStream)
for (bitStream & 3) == 3 {
n0 += 3
bitStream >>= 2
bitCount += 2
}
n0 += uint16(bitStream & 3)
bitCount += 2
if n0 > maxSymbolValue {
return errors.New("maxSymbolValue too small")
}
//println("inserting ", n0-charnum, "zeroes from idx", charnum, "ending before", n0)
for charnum < n0 {
s.norm[uint8(charnum)] = 0
charnum++
}
if r := b.remain(); r >= 7 || r+int(bitCount>>3) >= 4 {
b.advance(bitCount >> 3)
bitCount &= 7
bitStream = b.Uint32() >> bitCount
} else {
bitStream >>= 2
}
}
max := (2*threshold - 1) - remaining
var count int32
if int32(bitStream)&(threshold-1) < max {
count = int32(bitStream) & (threshold - 1)
if debug && nbBits < 1 {
panic("nbBits underflow")
}
bitCount += nbBits - 1
} else {
count = int32(bitStream) & (2*threshold - 1)
if count >= threshold {
count -= max
}
bitCount += nbBits
}
// extra accuracy
count--
if count < 0 {
// -1 means +1
remaining += count
gotTotal -= count
} else {
remaining -= count
gotTotal += count
}
s.norm[charnum&0xff] = int16(count)
charnum++
previous0 = count == 0
for remaining < threshold {
nbBits--
threshold >>= 1
}
//println("b.off:", b.off, "len:", len(b.b), "bc:", bitCount, "remain:", b.remain())
if r := b.remain(); r >= 7 || r+int(bitCount>>3) >= 4 {
b.advance(bitCount >> 3)
bitCount &= 7
} else {
bitCount -= (uint)(8 * (len(b.b) - 4 - b.off))
b.off = len(b.b) - 4
//println("b.off:", b.off, "len:", len(b.b), "bc:", bitCount, "iend", iend)
}
bitStream = b.Uint32() >> (bitCount & 31)
//printf("bitstream is now: 0b%b", bitStream)
}
s.symbolLen = charnum
if s.symbolLen <= 1 {
return fmt.Errorf("symbolLen (%d) too small", s.symbolLen)
}
if s.symbolLen > maxSymbolValue+1 {
return fmt.Errorf("symbolLen (%d) too big", s.symbolLen)
}
if remaining != 1 {
return fmt.Errorf("corruption detected (remaining %d != 1)", remaining)
}
if bitCount > 32 {
return fmt.Errorf("corruption detected (bitCount %d > 32)", bitCount)
}
if gotTotal != 1<<s.actualTableLog {
return fmt.Errorf("corruption detected (total %d != %d)", gotTotal, 1<<s.actualTableLog)
}
b.advance((bitCount + 7) >> 3)
// println(s.norm[:s.symbolLen], s.symbolLen)
return s.buildDtable()
}
// decSymbol contains information about a state entry,
// Including the state offset base, the output symbol and
// the number of bits to read for the low part of the destination state.
type decSymbol struct {
newState uint16
addBits uint8 // Used for symbols until transformed.
nbBits uint8
baseline uint32
}
// decSymbolValue returns the transformed decSymbol for the given symbol.
func decSymbolValue(symb uint8, t []baseOffset) (decSymbol, error) {
if int(symb) >= len(t) {
return decSymbol{}, fmt.Errorf("rle symbol %d >= max %d", symb, len(t))
}
lu := t[symb]
return decSymbol{
addBits: lu.addBits,
baseline: lu.baseLine,
}, nil
}
// setRLE will set the decoder til RLE mode.
func (s *fseDecoder) setRLE(symbol decSymbol) {
s.actualTableLog = 0
s.maxBits = symbol.addBits
s.dt[0] = symbol
}
// buildDtable will build the decoding table.
func (s *fseDecoder) buildDtable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
symbolNext := s.stateTable[:256]
// Init, lay down lowprob symbols
{
for i, v := range s.norm[:s.symbolLen] {
if v == -1 {
s.dt[highThreshold].addBits = uint8(i)
highThreshold--
symbolNext[i] = 1
} else {
symbolNext[i] = uint16(v)
}
}
}
// Spread symbols
{
tableMask := tableSize - 1
step := tableStep(tableSize)
position := uint32(0)
for ss, v := range s.norm[:s.symbolLen] {
for i := 0; i < int(v); i++ {
s.dt[position].addBits = uint8(ss)
position = (position + step) & tableMask
for position > highThreshold {
// lowprob area
position = (position + step) & tableMask
}
}
}
if position != 0 {
// position must reach all cells once, otherwise normalizedCounter is incorrect
return errors.New("corrupted input (position != 0)")
}
}
// Build Decoding table
{
tableSize := uint16(1 << s.actualTableLog)
for u, v := range s.dt[:tableSize] {
symbol := v.addBits
nextState := symbolNext[symbol]
symbolNext[symbol] = nextState + 1
nBits := s.actualTableLog - byte(highBits(uint32(nextState)))
s.dt[u&maxTableMask].nbBits = nBits
newState := (nextState << nBits) - tableSize
if newState > tableSize {
return fmt.Errorf("newState (%d) outside table size (%d)", newState, tableSize)
}
if newState == uint16(u) && nBits == 0 {
// Seems weird that this is possible with nbits > 0.
return fmt.Errorf("newState (%d) == oldState (%d) and no bits", newState, u)
}
s.dt[u&maxTableMask].newState = newState
}
}
return nil
}
// transform will transform the decoder table into a table usable for
// decoding without having to apply the transformation while decoding.
// The state will contain the base value and the number of bits to read.
func (s *fseDecoder) transform(t []baseOffset) error {
tableSize := uint16(1 << s.actualTableLog)
s.maxBits = 0
for i, v := range s.dt[:tableSize] {
if int(v.addBits) >= len(t) {
return fmt.Errorf("invalid decoding table entry %d, symbol %d >= max (%d)", i, v.addBits, len(t))
}
lu := t[v.addBits]
if lu.addBits > s.maxBits {
s.maxBits = lu.addBits
}
s.dt[i&maxTableMask] = decSymbol{
newState: v.newState,
nbBits: v.nbBits,
addBits: lu.addBits,
baseline: lu.baseLine,
}
}
return nil
}
type fseState struct {
// TODO: Check if *[1 << maxTablelog]decSymbol is faster.
dt []decSymbol
state decSymbol
}
// Initialize and decodeAsync first state and symbol.
func (s *fseState) init(br *bitReader, tableLog uint8, dt []decSymbol) {
s.dt = dt
br.fill()
s.state = dt[br.getBits(tableLog)]
}
// next returns the current symbol and sets the next state.
// At least tablelog bits must be available in the bit reader.
func (s *fseState) next(br *bitReader) {
lowBits := uint16(br.getBits(s.state.nbBits))
s.state = s.dt[s.state.newState+lowBits]
}
// finished returns true if all bits have been read from the bitstream
// and the next state would require reading bits from the input.
func (s *fseState) finished(br *bitReader) bool {
return br.finished() && s.state.nbBits > 0
}
// final returns the current state symbol without decoding the next.
func (s *fseState) final() (int, uint8) {
return int(s.state.baseline), s.state.addBits
}
// nextFast returns the next symbol and sets the next state.
// This can only be used if no symbols are 0 bits.
// At least tablelog bits must be available in the bit reader.
func (s *fseState) nextFast(br *bitReader) (uint32, uint8) {
lowBits := uint16(br.getBitsFast(s.state.nbBits))
s.state = s.dt[s.state.newState+lowBits]
return s.state.baseline, s.state.addBits
}

717
vendor/github.com/klauspost/compress/zstd/fse_encoder.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"math"
)
const (
// For encoding we only support up to
maxEncTableLog = 8
maxEncTablesize = 1 << maxTableLog
maxEncTableMask = (1 << maxTableLog) - 1
minEncTablelog = 5
maxEncSymbolValue = maxMatchLengthSymbol
)
// Scratch provides temporary storage for compression and decompression.
type fseEncoder struct {
symbolLen uint16 // Length of active part of the symbol table.
actualTableLog uint8 // Selected tablelog.
ct cTable // Compression tables.
maxCount int // count of the most probable symbol
zeroBits bool // no bits has prob > 50%.
clearCount bool // clear count
useRLE bool // This encoder is for RLE
preDefined bool // This encoder is predefined.
reUsed bool // Set to know when the encoder has been reused.
rleVal uint8 // RLE Symbol
maxBits uint8 // Maximum output bits after transform.
// TODO: Technically zstd should be fine with 64 bytes.
count [256]uint32
norm [256]int16
}
// cTable contains tables used for compression.
type cTable struct {
tableSymbol []byte
stateTable []uint16
symbolTT []symbolTransform
}
// symbolTransform contains the state transform for a symbol.
type symbolTransform struct {
deltaNbBits uint32
deltaFindState int16
outBits uint8
}
// String prints values as a human readable string.
func (s symbolTransform) String() string {
return fmt.Sprintf("{deltabits: %08x, findstate:%d outbits:%d}", s.deltaNbBits, s.deltaFindState, s.outBits)
}
// Histogram allows to populate the histogram and skip that step in the compression,
// It otherwise allows to inspect the histogram when compression is done.
// To indicate that you have populated the histogram call HistogramFinished
// with the value of the highest populated symbol, as well as the number of entries
// in the most populated entry. These are accepted at face value.
// The returned slice will always be length 256.
func (s *fseEncoder) Histogram() []uint32 {
return s.count[:]
}
// HistogramFinished can be called to indicate that the histogram has been populated.
// maxSymbol is the index of the highest set symbol of the next data segment.
// maxCount is the number of entries in the most populated entry.
// These are accepted at face value.
func (s *fseEncoder) HistogramFinished(maxSymbol uint8, maxCount int) {
s.maxCount = maxCount
s.symbolLen = uint16(maxSymbol) + 1
s.clearCount = maxCount != 0
}
// prepare will prepare and allocate scratch tables used for both compression and decompression.
func (s *fseEncoder) prepare() (*fseEncoder, error) {
if s == nil {
s = &fseEncoder{}
}
s.useRLE = false
if s.clearCount && s.maxCount == 0 {
for i := range s.count {
s.count[i] = 0
}
s.clearCount = false
}
return s, nil
}
// allocCtable will allocate tables needed for compression.
// If existing tables a re big enough, they are simply re-used.
func (s *fseEncoder) allocCtable() {
tableSize := 1 << s.actualTableLog
// get tableSymbol that is big enough.
if cap(s.ct.tableSymbol) < int(tableSize) {
s.ct.tableSymbol = make([]byte, tableSize)
}
s.ct.tableSymbol = s.ct.tableSymbol[:tableSize]
ctSize := tableSize
if cap(s.ct.stateTable) < ctSize {
s.ct.stateTable = make([]uint16, ctSize)
}
s.ct.stateTable = s.ct.stateTable[:ctSize]
if cap(s.ct.symbolTT) < 256 {
s.ct.symbolTT = make([]symbolTransform, 256)
}
s.ct.symbolTT = s.ct.symbolTT[:256]
}
// buildCTable will populate the compression table so it is ready to be used.
func (s *fseEncoder) buildCTable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
var cumul [256]int16
s.allocCtable()
tableSymbol := s.ct.tableSymbol[:tableSize]
// symbol start positions
{
cumul[0] = 0
for ui, v := range s.norm[:s.symbolLen-1] {
u := byte(ui) // one less than reference
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = u
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
}
// Encode last symbol separately to avoid overflowing u
u := int(s.symbolLen - 1)
v := s.norm[s.symbolLen-1]
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = byte(u)
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
if uint32(cumul[s.symbolLen]) != tableSize {
return fmt.Errorf("internal error: expected cumul[s.symbolLen] (%d) == tableSize (%d)", cumul[s.symbolLen], tableSize)
}
cumul[s.symbolLen] = int16(tableSize) + 1
}
// Spread symbols
s.zeroBits = false
{
step := tableStep(tableSize)
tableMask := tableSize - 1
var position uint32
// if any symbol > largeLimit, we may have 0 bits output.
largeLimit := int16(1 << (s.actualTableLog - 1))
for ui, v := range s.norm[:s.symbolLen] {
symbol := byte(ui)
if v > largeLimit {
s.zeroBits = true
}
for nbOccurrences := int16(0); nbOccurrences < v; nbOccurrences++ {
tableSymbol[position] = symbol
position = (position + step) & tableMask
for position > highThreshold {
position = (position + step) & tableMask
} /* Low proba area */
}
}
// Check if we have gone through all positions
if position != 0 {
return errors.New("position!=0")
}
}
// Build table
table := s.ct.stateTable
{
tsi := int(tableSize)
for u, v := range tableSymbol {
// TableU16 : sorted by symbol order; gives next state value
table[cumul[v]] = uint16(tsi + u)
cumul[v]++
}
}
// Build Symbol Transformation Table
{
total := int16(0)
symbolTT := s.ct.symbolTT[:s.symbolLen]
tableLog := s.actualTableLog
tl := (uint32(tableLog) << 16) - (1 << tableLog)
for i, v := range s.norm[:s.symbolLen] {
switch v {
case 0:
case -1, 1:
symbolTT[i].deltaNbBits = tl
symbolTT[i].deltaFindState = int16(total - 1)
total++
default:
maxBitsOut := uint32(tableLog) - highBit(uint32(v-1))
minStatePlus := uint32(v) << maxBitsOut
symbolTT[i].deltaNbBits = (maxBitsOut << 16) - minStatePlus
symbolTT[i].deltaFindState = int16(total - v)
total += v
}
}
if total != int16(tableSize) {
return fmt.Errorf("total mismatch %d (got) != %d (want)", total, tableSize)
}
}
return nil
}
var rtbTable = [...]uint32{0, 473195, 504333, 520860, 550000, 700000, 750000, 830000}
func (s *fseEncoder) setRLE(val byte) {
s.allocCtable()
s.actualTableLog = 0
s.ct.stateTable = s.ct.stateTable[:1]
s.ct.symbolTT[val] = symbolTransform{
deltaFindState: 0,
deltaNbBits: 0,
}
if debug {
println("setRLE: val", val, "symbolTT", s.ct.symbolTT[val])
}
s.rleVal = val
s.useRLE = true
}
// setBits will set output bits for the transform.
// if nil is provided, the number of bits is equal to the index.
func (s *fseEncoder) setBits(transform []byte) {
if s.reUsed || s.preDefined {
return
}
if s.useRLE {
if transform == nil {
s.ct.symbolTT[s.rleVal].outBits = s.rleVal
s.maxBits = s.rleVal
return
}
s.maxBits = transform[s.rleVal]
s.ct.symbolTT[s.rleVal].outBits = s.maxBits
return
}
if transform == nil {
for i := range s.ct.symbolTT[:s.symbolLen] {
s.ct.symbolTT[i].outBits = uint8(i)
}
s.maxBits = uint8(s.symbolLen - 1)
return
}
s.maxBits = 0
for i, v := range transform[:s.symbolLen] {
s.ct.symbolTT[i].outBits = v
if v > s.maxBits {
// We could assume bits always going up, but we play safe.
s.maxBits = v
}
}
}
// normalizeCount will normalize the count of the symbols so
// the total is equal to the table size.
// If successful, compression tables will also be made ready.
func (s *fseEncoder) normalizeCount(length int) error {
if s.reUsed {
return nil
}
s.optimalTableLog(length)
var (
tableLog = s.actualTableLog
scale = 62 - uint64(tableLog)
step = (1 << 62) / uint64(length)
vStep = uint64(1) << (scale - 20)
stillToDistribute = int16(1 << tableLog)
largest int
largestP int16
lowThreshold = (uint32)(length >> tableLog)
)
if s.maxCount == length {
s.useRLE = true
return nil
}
s.useRLE = false
for i, cnt := range s.count[:s.symbolLen] {
// already handled
// if (count[s] == s.length) return 0; /* rle special case */
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
stillToDistribute--
} else {
proba := (int16)((uint64(cnt) * step) >> scale)
if proba < 8 {
restToBeat := vStep * uint64(rtbTable[proba])
v := uint64(cnt)*step - (uint64(proba) << scale)
if v > restToBeat {
proba++
}
}
if proba > largestP {
largestP = proba
largest = i
}
s.norm[i] = proba
stillToDistribute -= proba
}
}
if -stillToDistribute >= (s.norm[largest] >> 1) {
// corner case, need another normalization method
err := s.normalizeCount2(length)
if err != nil {
return err
}
if debug {
err = s.validateNorm()
if err != nil {
return err
}
}
return s.buildCTable()
}
s.norm[largest] += stillToDistribute
if debug {
err := s.validateNorm()
if err != nil {
return err
}
}
return s.buildCTable()
}
// Secondary normalization method.
// To be used when primary method fails.
func (s *fseEncoder) normalizeCount2(length int) error {
const notYetAssigned = -2
var (
distributed uint32
total = uint32(length)
tableLog = s.actualTableLog
lowThreshold = uint32(total >> tableLog)
lowOne = uint32((total * 3) >> (tableLog + 1))
)
for i, cnt := range s.count[:s.symbolLen] {
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
distributed++
total -= cnt
continue
}
if cnt <= lowOne {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
s.norm[i] = notYetAssigned
}
toDistribute := (1 << tableLog) - distributed
if (total / toDistribute) > lowOne {
// risk of rounding to zero
lowOne = uint32((total * 3) / (toDistribute * 2))
for i, cnt := range s.count[:s.symbolLen] {
if (s.norm[i] == notYetAssigned) && (cnt <= lowOne) {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
}
toDistribute = (1 << tableLog) - distributed
}
if distributed == uint32(s.symbolLen)+1 {
// all values are pretty poor;
// probably incompressible data (should have already been detected);
// find max, then give all remaining points to max
var maxV int
var maxC uint32
for i, cnt := range s.count[:s.symbolLen] {
if cnt > maxC {
maxV = i
maxC = cnt
}
}
s.norm[maxV] += int16(toDistribute)
return nil
}
if total == 0 {
// all of the symbols were low enough for the lowOne or lowThreshold
for i := uint32(0); toDistribute > 0; i = (i + 1) % (uint32(s.symbolLen)) {
if s.norm[i] > 0 {
toDistribute--
s.norm[i]++
}
}
return nil
}
var (
vStepLog = 62 - uint64(tableLog)
mid = uint64((1 << (vStepLog - 1)) - 1)
rStep = (((1 << vStepLog) * uint64(toDistribute)) + mid) / uint64(total) // scale on remaining
tmpTotal = mid
)
for i, cnt := range s.count[:s.symbolLen] {
if s.norm[i] == notYetAssigned {
var (
end = tmpTotal + uint64(cnt)*rStep
sStart = uint32(tmpTotal >> vStepLog)
sEnd = uint32(end >> vStepLog)
weight = sEnd - sStart
)
if weight < 1 {
return errors.New("weight < 1")
}
s.norm[i] = int16(weight)
tmpTotal = end
}
}
return nil
}
// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
func (s *fseEncoder) optimalTableLog(length int) {
tableLog := uint8(maxEncTableLog)
minBitsSrc := highBit(uint32(length)) + 1
minBitsSymbols := highBit(uint32(s.symbolLen-1)) + 2
minBits := uint8(minBitsSymbols)
if minBitsSrc < minBitsSymbols {
minBits = uint8(minBitsSrc)
}
maxBitsSrc := uint8(highBit(uint32(length-1))) - 2
if maxBitsSrc < tableLog {
// Accuracy can be reduced
tableLog = maxBitsSrc
}
if minBits > tableLog {
tableLog = minBits
}
// Need a minimum to safely represent all symbol values
if tableLog < minEncTablelog {
tableLog = minEncTablelog
}
if tableLog > maxEncTableLog {
tableLog = maxEncTableLog
}
s.actualTableLog = tableLog
}
// validateNorm validates the normalized histogram table.
func (s *fseEncoder) validateNorm() (err error) {
var total int
for _, v := range s.norm[:s.symbolLen] {
if v >= 0 {
total += int(v)
} else {
total -= int(v)
}
}
defer func() {
if err == nil {
return
}
fmt.Printf("selected TableLog: %d, Symbol length: %d\n", s.actualTableLog, s.symbolLen)
for i, v := range s.norm[:s.symbolLen] {
fmt.Printf("%3d: %5d -> %4d \n", i, s.count[i], v)
}
}()
if total != (1 << s.actualTableLog) {
return fmt.Errorf("warning: Total == %d != %d", total, 1<<s.actualTableLog)
}
for i, v := range s.count[s.symbolLen:] {
if v != 0 {
return fmt.Errorf("warning: Found symbol out of range, %d after cut", i)
}
}
return nil
}
// writeCount will write the normalized histogram count to header.
// This is read back by readNCount.
func (s *fseEncoder) writeCount(out []byte) ([]byte, error) {
var (
tableLog = s.actualTableLog
tableSize = 1 << tableLog
previous0 bool
charnum uint16
maxHeaderSize = ((int(s.symbolLen) * int(tableLog)) >> 3) + 3
// Write Table Size
bitStream = uint32(tableLog - minEncTablelog)
bitCount = uint(4)
remaining = int16(tableSize + 1) /* +1 for extra accuracy */
threshold = int16(tableSize)
nbBits = uint(tableLog + 1)
)
if s.useRLE {
return append(out, s.rleVal), nil
}
if s.preDefined || s.reUsed {
// Never write predefined.
return out, nil
}
outP := len(out)
out = out[:outP+maxHeaderSize]
// stops at 1
for remaining > 1 {
if previous0 {
start := charnum
for s.norm[charnum] == 0 {
charnum++
}
for charnum >= start+24 {
start += 24
bitStream += uint32(0xFFFF) << bitCount
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
}
for charnum >= start+3 {
start += 3
bitStream += 3 << bitCount
bitCount += 2
}
bitStream += uint32(charnum-start) << bitCount
bitCount += 2
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
count := s.norm[charnum]
charnum++
max := (2*threshold - 1) - remaining
if count < 0 {
remaining += count
} else {
remaining -= count
}
count++ // +1 for extra accuracy
if count >= threshold {
count += max // [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[
}
bitStream += uint32(count) << bitCount
bitCount += nbBits
if count < max {
bitCount--
}
previous0 = count == 1
if remaining < 1 {
return nil, errors.New("internal error: remaining < 1")
}
for remaining < threshold {
nbBits--
threshold >>= 1
}
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += int((bitCount + 7) / 8)
if uint16(charnum) > s.symbolLen {
return nil, errors.New("internal error: charnum > s.symbolLen")
}
return out[:outP], nil
}
// Approximate symbol cost, as fractional value, using fixed-point format (accuracyLog fractional bits)
// note 1 : assume symbolValue is valid (<= maxSymbolValue)
// note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits *
func (s *fseEncoder) bitCost(symbolValue uint8, accuracyLog uint32) uint32 {
minNbBits := s.ct.symbolTT[symbolValue].deltaNbBits >> 16
threshold := (minNbBits + 1) << 16
if debug {
if !(s.actualTableLog < 16) {
panic("!s.actualTableLog < 16")
}
// ensure enough room for renormalization double shift
if !(uint8(accuracyLog) < 31-s.actualTableLog) {
panic("!uint8(accuracyLog) < 31-s.actualTableLog")
}
}
tableSize := uint32(1) << s.actualTableLog
deltaFromThreshold := threshold - (s.ct.symbolTT[symbolValue].deltaNbBits + tableSize)
// linear interpolation (very approximate)
normalizedDeltaFromThreshold := (deltaFromThreshold << accuracyLog) >> s.actualTableLog
bitMultiplier := uint32(1) << accuracyLog
if debug {
if s.ct.symbolTT[symbolValue].deltaNbBits+tableSize > threshold {
panic("s.ct.symbolTT[symbolValue].deltaNbBits+tableSize > threshold")
}
if normalizedDeltaFromThreshold > bitMultiplier {
panic("normalizedDeltaFromThreshold > bitMultiplier")
}
}
return (minNbBits+1)*bitMultiplier - normalizedDeltaFromThreshold
}
// Returns the cost in bits of encoding the distribution in count using ctable.
// Histogram should only be up to the last non-zero symbol.
// Returns an -1 if ctable cannot represent all the symbols in count.
func (s *fseEncoder) approxSize(hist []uint32) uint32 {
if int(s.symbolLen) < len(hist) {
// More symbols than we have.
return math.MaxUint32
}
if s.useRLE {
// We will never reuse RLE encoders.
return math.MaxUint32
}
const kAccuracyLog = 8
badCost := (uint32(s.actualTableLog) + 1) << kAccuracyLog
var cost uint32
for i, v := range hist {
if v == 0 {
continue
}
if s.norm[i] == 0 {
return math.MaxUint32
}
bitCost := s.bitCost(uint8(i), kAccuracyLog)
if bitCost > badCost {
return math.MaxUint32
}
cost += v * bitCost
}
return cost >> kAccuracyLog
}
// maxHeaderSize returns the maximum header size in bits.
// This is not exact size, but we want a penalty for new tables anyway.
func (s *fseEncoder) maxHeaderSize() uint32 {
if s.preDefined {
return 0
}
if s.useRLE {
return 8
}
return (((uint32(s.symbolLen) * uint32(s.actualTableLog)) >> 3) + 3) * 8
}
// cState contains the compression state of a stream.
type cState struct {
bw *bitWriter
stateTable []uint16
state uint16
}
// init will initialize the compression state to the first symbol of the stream.
func (c *cState) init(bw *bitWriter, ct *cTable, first symbolTransform) {
c.bw = bw
c.stateTable = ct.stateTable
if len(c.stateTable) == 1 {
// RLE
c.stateTable[0] = uint16(0)
c.state = 0
return
}
nbBitsOut := (first.deltaNbBits + (1 << 15)) >> 16
im := int32((nbBitsOut << 16) - first.deltaNbBits)
lu := (im >> nbBitsOut) + int32(first.deltaFindState)
c.state = c.stateTable[lu]
return
}
// encode the output symbol provided and write it to the bitstream.
func (c *cState) encode(symbolTT symbolTransform) {
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
dstState := int32(c.state>>(nbBitsOut&15)) + int32(symbolTT.deltaFindState)
c.bw.addBits16NC(c.state, uint8(nbBitsOut))
c.state = c.stateTable[dstState]
}
// flush will write the tablelog to the output and flush the remaining full bytes.
func (c *cState) flush(tableLog uint8) {
c.bw.flush32()
c.bw.addBits16NC(c.state, tableLog)
}

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vendor/github.com/klauspost/compress/zstd/fse_predefined.go generated vendored Normal file
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@ -0,0 +1,153 @@
// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"fmt"
"math"
)
var (
// fsePredef are the predefined fse tables as defined here:
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#default-distributions
// These values are already transformed.
fsePredef [3]fseDecoder
// fsePredefEnc are the predefined encoder based on fse tables as defined here:
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#default-distributions
// These values are already transformed.
fsePredefEnc [3]fseEncoder
// symbolTableX contain the transformations needed for each type as defined in
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#the-codes-for-literals-lengths-match-lengths-and-offsets
symbolTableX [3][]baseOffset
// maxTableSymbol is the biggest supported symbol for each table type
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#the-codes-for-literals-lengths-match-lengths-and-offsets
maxTableSymbol = [3]uint8{tableLiteralLengths: maxLiteralLengthSymbol, tableOffsets: maxOffsetLengthSymbol, tableMatchLengths: maxMatchLengthSymbol}
// bitTables is the bits table for each table.
bitTables = [3][]byte{tableLiteralLengths: llBitsTable[:], tableOffsets: nil, tableMatchLengths: mlBitsTable[:]}
)
type tableIndex uint8
const (
// indexes for fsePredef and symbolTableX
tableLiteralLengths tableIndex = 0
tableOffsets tableIndex = 1
tableMatchLengths tableIndex = 2
maxLiteralLengthSymbol = 35
maxOffsetLengthSymbol = 30
maxMatchLengthSymbol = 52
)
// baseOffset is used for calculating transformations.
type baseOffset struct {
baseLine uint32
addBits uint8
}
// fillBase will precalculate base offsets with the given bit distributions.
func fillBase(dst []baseOffset, base uint32, bits ...uint8) {
if len(bits) != len(dst) {
panic(fmt.Sprintf("len(dst) (%d) != len(bits) (%d)", len(dst), len(bits)))
}
for i, bit := range bits {
if base > math.MaxInt32 {
panic(fmt.Sprintf("invalid decoding table, base overflows int32"))
}
dst[i] = baseOffset{
baseLine: base,
addBits: bit,
}
base += 1 << bit
}
}
func init() {
// Literals length codes
tmp := make([]baseOffset, 36)
for i := range tmp[:16] {
tmp[i] = baseOffset{
baseLine: uint32(i),
addBits: 0,
}
}
fillBase(tmp[16:], 16, 1, 1, 1, 1, 2, 2, 3, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
symbolTableX[tableLiteralLengths] = tmp
// Match length codes
tmp = make([]baseOffset, 53)
for i := range tmp[:32] {
tmp[i] = baseOffset{
// The transformation adds the 3 length.
baseLine: uint32(i) + 3,
addBits: 0,
}
}
fillBase(tmp[32:], 35, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
symbolTableX[tableMatchLengths] = tmp
// Offset codes
tmp = make([]baseOffset, maxOffsetBits+1)
tmp[1] = baseOffset{
baseLine: 1,
addBits: 1,
}
fillBase(tmp[2:], 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
symbolTableX[tableOffsets] = tmp
// Fill predefined tables and transform them.
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#default-distributions
for i := range fsePredef[:] {
f := &fsePredef[i]
switch tableIndex(i) {
case tableLiteralLengths:
// https://github.com/facebook/zstd/blob/ededcfca57366461021c922720878c81a5854a0a/lib/decompress/zstd_decompress_block.c#L243
f.actualTableLog = 6
copy(f.norm[:], []int16{4, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 1, 1, 1, 1, 1,
-1, -1, -1, -1})
f.symbolLen = 36
case tableOffsets:
// https://github.com/facebook/zstd/blob/ededcfca57366461021c922720878c81a5854a0a/lib/decompress/zstd_decompress_block.c#L281
f.actualTableLog = 5
copy(f.norm[:], []int16{
1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1})
f.symbolLen = 29
case tableMatchLengths:
//https://github.com/facebook/zstd/blob/ededcfca57366461021c922720878c81a5854a0a/lib/decompress/zstd_decompress_block.c#L304
f.actualTableLog = 6
copy(f.norm[:], []int16{
1, 4, 3, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1,
-1, -1, -1, -1, -1})
f.symbolLen = 53
}
if err := f.buildDtable(); err != nil {
panic(fmt.Errorf("building table %v: %v", tableIndex(i), err))
}
if err := f.transform(symbolTableX[i]); err != nil {
panic(fmt.Errorf("building table %v: %v", tableIndex(i), err))
}
f.preDefined = true
// Create encoder as well
enc := &fsePredefEnc[i]
copy(enc.norm[:], f.norm[:])
enc.symbolLen = f.symbolLen
enc.actualTableLog = f.actualTableLog
if err := enc.buildCTable(); err != nil {
panic(fmt.Errorf("building encoding table %v: %v", tableIndex(i), err))
}
enc.setBits(bitTables[i])
enc.preDefined = true
}
}

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vendor/github.com/klauspost/compress/zstd/hash.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
const (
prime3bytes = 506832829
prime4bytes = 2654435761
prime5bytes = 889523592379
prime6bytes = 227718039650203
prime7bytes = 58295818150454627
prime8bytes = 0xcf1bbcdcb7a56463
)
// hashLen returns a hash of the lowest l bytes of u for a size size of h bytes.
// l must be >=4 and <=8. Any other value will return hash for 4 bytes.
// h should always be <32.
// Preferably h and l should be a constant.
// FIXME: This does NOT get resolved, if 'mls' is constant,
// so this cannot be used.
func hashLen(u uint64, hashLog, mls uint8) uint32 {
switch mls {
case 5:
return hash5(u, hashLog)
case 6:
return hash6(u, hashLog)
case 7:
return hash7(u, hashLog)
case 8:
return hash8(u, hashLog)
default:
return hash4x64(u, hashLog)
}
}
// hash3 returns the hash of the lower 3 bytes of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <32.
func hash3(u uint32, h uint8) uint32 {
return ((u << (32 - 24)) * prime3bytes) >> ((32 - h) & 31)
}
// hash4 returns the hash of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <32.
func hash4(u uint32, h uint8) uint32 {
return (u * prime4bytes) >> ((32 - h) & 31)
}
// hash4x64 returns the hash of the lowest 4 bytes of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <32.
func hash4x64(u uint64, h uint8) uint32 {
return (uint32(u) * prime4bytes) >> ((32 - h) & 31)
}
// hash5 returns the hash of the lowest 5 bytes of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <64.
func hash5(u uint64, h uint8) uint32 {
return uint32(((u << (64 - 40)) * prime5bytes) >> ((64 - h) & 63))
}
// hash6 returns the hash of the lowest 6 bytes of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <64.
func hash6(u uint64, h uint8) uint32 {
return uint32(((u << (64 - 48)) * prime6bytes) >> ((64 - h) & 63))
}
// hash6 returns the hash of the lowest 7 bytes of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <64.
func hash7(u uint64, h uint8) uint32 {
return uint32(((u << (64 - 56)) * prime7bytes) >> ((64 - h) & 63))
}
// hash8 returns the hash of u to fit in a hash table with h bits.
// Preferably h should be a constant and should always be <64.
func hash8(u uint64, h uint8) uint32 {
return uint32((u * prime8bytes) >> ((64 - h) & 63))
}

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vendor/github.com/klauspost/compress/zstd/history.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"github.com/klauspost/compress/huff0"
)
// history contains the information transferred between blocks.
type history struct {
b []byte
huffTree *huff0.Scratch
recentOffsets [3]int
decoders sequenceDecs
windowSize int
maxSize int
error bool
}
// reset will reset the history to initial state of a frame.
// The history must already have been initialized to the desired size.
func (h *history) reset() {
h.b = h.b[:0]
h.error = false
h.recentOffsets = [3]int{1, 4, 8}
if f := h.decoders.litLengths.fse; f != nil && !f.preDefined {
fseDecoderPool.Put(f)
}
if f := h.decoders.offsets.fse; f != nil && !f.preDefined {
fseDecoderPool.Put(f)
}
if f := h.decoders.matchLengths.fse; f != nil && !f.preDefined {
fseDecoderPool.Put(f)
}
h.decoders = sequenceDecs{}
if h.huffTree != nil {
huffDecoderPool.Put(h.huffTree)
}
h.huffTree = nil
//printf("history created: %+v (l: %d, c: %d)", *h, len(h.b), cap(h.b))
}
// append bytes to history.
// This function will make sure there is space for it,
// if the buffer has been allocated with enough extra space.
func (h *history) append(b []byte) {
if len(b) >= h.windowSize {
// Discard all history by simply overwriting
h.b = h.b[:h.windowSize]
copy(h.b, b[len(b)-h.windowSize:])
return
}
// If there is space, append it.
if len(b) < cap(h.b)-len(h.b) {
h.b = append(h.b, b...)
return
}
// Move data down so we only have window size left.
// We know we have less than window size in b at this point.
discard := len(b) + len(h.b) - h.windowSize
copy(h.b, h.b[discard:])
h.b = h.b[:h.windowSize]
copy(h.b[h.windowSize-len(b):], b)
}
// append bytes to history without ever discarding anything.
func (h *history) appendKeep(b []byte) {
h.b = append(h.b, b...)
}

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vendor/github.com/klauspost/compress/zstd/internal/xxhash/LICENSE.txt generated vendored Normal file
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Copyright (c) 2016 Caleb Spare
MIT License
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

58
vendor/github.com/klauspost/compress/zstd/internal/xxhash/README.md generated vendored Normal file
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# xxhash
VENDORED: Go to [github.com/cespare/xxhash](https://github.com/cespare/xxhash) for original package.
[![GoDoc](https://godoc.org/github.com/cespare/xxhash?status.svg)](https://godoc.org/github.com/cespare/xxhash)
[![Build Status](https://travis-ci.org/cespare/xxhash.svg?branch=master)](https://travis-ci.org/cespare/xxhash)
xxhash is a Go implementation of the 64-bit
[xxHash](http://cyan4973.github.io/xxHash/) algorithm, XXH64. This is a
high-quality hashing algorithm that is much faster than anything in the Go
standard library.
This package provides a straightforward API:
```
func Sum64(b []byte) uint64
func Sum64String(s string) uint64
type Digest struct{ ... }
func New() *Digest
```
The `Digest` type implements hash.Hash64. Its key methods are:
```
func (*Digest) Write([]byte) (int, error)
func (*Digest) WriteString(string) (int, error)
func (*Digest) Sum64() uint64
```
This implementation provides a fast pure-Go implementation and an even faster
assembly implementation for amd64.
## Benchmarks
Here are some quick benchmarks comparing the pure-Go and assembly
implementations of Sum64.
| input size | purego | asm |
| --- | --- | --- |
| 5 B | 979.66 MB/s | 1291.17 MB/s |
| 100 B | 7475.26 MB/s | 7973.40 MB/s |
| 4 KB | 17573.46 MB/s | 17602.65 MB/s |
| 10 MB | 17131.46 MB/s | 17142.16 MB/s |
These numbers were generated on Ubuntu 18.04 with an Intel i7-8700K CPU using
the following commands under Go 1.11.2:
```
$ go test -tags purego -benchtime 10s -bench '/xxhash,direct,bytes'
$ go test -benchtime 10s -bench '/xxhash,direct,bytes'
```
## Projects using this package
- [InfluxDB](https://github.com/influxdata/influxdb)
- [Prometheus](https://github.com/prometheus/prometheus)
- [FreeCache](https://github.com/coocood/freecache)

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vendor/github.com/klauspost/compress/zstd/internal/xxhash/xxhash.go generated vendored Normal file
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// Package xxhash implements the 64-bit variant of xxHash (XXH64) as described
// at http://cyan4973.github.io/xxHash/.
// THIS IS VENDORED: Go to github.com/cespare/xxhash for original package.
package xxhash
import (
"encoding/binary"
"errors"
"math/bits"
)
const (
prime1 uint64 = 11400714785074694791
prime2 uint64 = 14029467366897019727
prime3 uint64 = 1609587929392839161
prime4 uint64 = 9650029242287828579
prime5 uint64 = 2870177450012600261
)
// NOTE(caleb): I'm using both consts and vars of the primes. Using consts where
// possible in the Go code is worth a small (but measurable) performance boost
// by avoiding some MOVQs. Vars are needed for the asm and also are useful for
// convenience in the Go code in a few places where we need to intentionally
// avoid constant arithmetic (e.g., v1 := prime1 + prime2 fails because the
// result overflows a uint64).
var (
prime1v = prime1
prime2v = prime2
prime3v = prime3
prime4v = prime4
prime5v = prime5
)
// Digest implements hash.Hash64.
type Digest struct {
v1 uint64
v2 uint64
v3 uint64
v4 uint64
total uint64
mem [32]byte
n int // how much of mem is used
}
// New creates a new Digest that computes the 64-bit xxHash algorithm.
func New() *Digest {
var d Digest
d.Reset()
return &d
}
// Reset clears the Digest's state so that it can be reused.
func (d *Digest) Reset() {
d.v1 = prime1v + prime2
d.v2 = prime2
d.v3 = 0
d.v4 = -prime1v
d.total = 0
d.n = 0
}
// Size always returns 8 bytes.
func (d *Digest) Size() int { return 8 }
// BlockSize always returns 32 bytes.
func (d *Digest) BlockSize() int { return 32 }
// Write adds more data to d. It always returns len(b), nil.
func (d *Digest) Write(b []byte) (n int, err error) {
n = len(b)
d.total += uint64(n)
if d.n+n < 32 {
// This new data doesn't even fill the current block.
copy(d.mem[d.n:], b)
d.n += n
return
}
if d.n > 0 {
// Finish off the partial block.
copy(d.mem[d.n:], b)
d.v1 = round(d.v1, u64(d.mem[0:8]))
d.v2 = round(d.v2, u64(d.mem[8:16]))
d.v3 = round(d.v3, u64(d.mem[16:24]))
d.v4 = round(d.v4, u64(d.mem[24:32]))
b = b[32-d.n:]
d.n = 0
}
if len(b) >= 32 {
// One or more full blocks left.
nw := writeBlocks(d, b)
b = b[nw:]
}
// Store any remaining partial block.
copy(d.mem[:], b)
d.n = len(b)
return
}
// Sum appends the current hash to b and returns the resulting slice.
func (d *Digest) Sum(b []byte) []byte {
s := d.Sum64()
return append(
b,
byte(s>>56),
byte(s>>48),
byte(s>>40),
byte(s>>32),
byte(s>>24),
byte(s>>16),
byte(s>>8),
byte(s),
)
}
// Sum64 returns the current hash.
func (d *Digest) Sum64() uint64 {
var h uint64
if d.total >= 32 {
v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
h = mergeRound(h, v1)
h = mergeRound(h, v2)
h = mergeRound(h, v3)
h = mergeRound(h, v4)
} else {
h = d.v3 + prime5
}
h += d.total
i, end := 0, d.n
for ; i+8 <= end; i += 8 {
k1 := round(0, u64(d.mem[i:i+8]))
h ^= k1
h = rol27(h)*prime1 + prime4
}
if i+4 <= end {
h ^= uint64(u32(d.mem[i:i+4])) * prime1
h = rol23(h)*prime2 + prime3
i += 4
}
for i < end {
h ^= uint64(d.mem[i]) * prime5
h = rol11(h) * prime1
i++
}
h ^= h >> 33
h *= prime2
h ^= h >> 29
h *= prime3
h ^= h >> 32
return h
}
const (
magic = "xxh\x06"
marshaledSize = len(magic) + 8*5 + 32
)
// MarshalBinary implements the encoding.BinaryMarshaler interface.
func (d *Digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, marshaledSize)
b = append(b, magic...)
b = appendUint64(b, d.v1)
b = appendUint64(b, d.v2)
b = appendUint64(b, d.v3)
b = appendUint64(b, d.v4)
b = appendUint64(b, d.total)
b = append(b, d.mem[:d.n]...)
b = b[:len(b)+len(d.mem)-d.n]
return b, nil
}
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
func (d *Digest) UnmarshalBinary(b []byte) error {
if len(b) < len(magic) || string(b[:len(magic)]) != magic {
return errors.New("xxhash: invalid hash state identifier")
}
if len(b) != marshaledSize {
return errors.New("xxhash: invalid hash state size")
}
b = b[len(magic):]
b, d.v1 = consumeUint64(b)
b, d.v2 = consumeUint64(b)
b, d.v3 = consumeUint64(b)
b, d.v4 = consumeUint64(b)
b, d.total = consumeUint64(b)
copy(d.mem[:], b)
b = b[len(d.mem):]
d.n = int(d.total % uint64(len(d.mem)))
return nil
}
func appendUint64(b []byte, x uint64) []byte {
var a [8]byte
binary.LittleEndian.PutUint64(a[:], x)
return append(b, a[:]...)
}
func consumeUint64(b []byte) ([]byte, uint64) {
x := u64(b)
return b[8:], x
}
func u64(b []byte) uint64 { return binary.LittleEndian.Uint64(b) }
func u32(b []byte) uint32 { return binary.LittleEndian.Uint32(b) }
func round(acc, input uint64) uint64 {
acc += input * prime2
acc = rol31(acc)
acc *= prime1
return acc
}
func mergeRound(acc, val uint64) uint64 {
val = round(0, val)
acc ^= val
acc = acc*prime1 + prime4
return acc
}
func rol1(x uint64) uint64 { return bits.RotateLeft64(x, 1) }
func rol7(x uint64) uint64 { return bits.RotateLeft64(x, 7) }
func rol11(x uint64) uint64 { return bits.RotateLeft64(x, 11) }
func rol12(x uint64) uint64 { return bits.RotateLeft64(x, 12) }
func rol18(x uint64) uint64 { return bits.RotateLeft64(x, 18) }
func rol23(x uint64) uint64 { return bits.RotateLeft64(x, 23) }
func rol27(x uint64) uint64 { return bits.RotateLeft64(x, 27) }
func rol31(x uint64) uint64 { return bits.RotateLeft64(x, 31) }

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vendor/github.com/klauspost/compress/zstd/internal/xxhash/xxhash_amd64.go generated vendored Normal file
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// +build !appengine
// +build gc
// +build !purego
package xxhash
// Sum64 computes the 64-bit xxHash digest of b.
//
//go:noescape
func Sum64(b []byte) uint64
//go:noescape
func writeBlocks(*Digest, []byte) int

215
vendor/github.com/klauspost/compress/zstd/internal/xxhash/xxhash_amd64.s generated vendored Normal file
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// +build !appengine
// +build gc
// +build !purego
#include "textflag.h"
// Register allocation:
// AX h
// CX pointer to advance through b
// DX n
// BX loop end
// R8 v1, k1
// R9 v2
// R10 v3
// R11 v4
// R12 tmp
// R13 prime1v
// R14 prime2v
// R15 prime4v
// round reads from and advances the buffer pointer in CX.
// It assumes that R13 has prime1v and R14 has prime2v.
#define round(r) \
MOVQ (CX), R12 \
ADDQ $8, CX \
IMULQ R14, R12 \
ADDQ R12, r \
ROLQ $31, r \
IMULQ R13, r
// mergeRound applies a merge round on the two registers acc and val.
// It assumes that R13 has prime1v, R14 has prime2v, and R15 has prime4v.
#define mergeRound(acc, val) \
IMULQ R14, val \
ROLQ $31, val \
IMULQ R13, val \
XORQ val, acc \
IMULQ R13, acc \
ADDQ R15, acc
// func Sum64(b []byte) uint64
TEXT ·Sum64(SB), NOSPLIT, $0-32
// Load fixed primes.
MOVQ ·prime1v(SB), R13
MOVQ ·prime2v(SB), R14
MOVQ ·prime4v(SB), R15
// Load slice.
MOVQ b_base+0(FP), CX
MOVQ b_len+8(FP), DX
LEAQ (CX)(DX*1), BX
// The first loop limit will be len(b)-32.
SUBQ $32, BX
// Check whether we have at least one block.
CMPQ DX, $32
JLT noBlocks
// Set up initial state (v1, v2, v3, v4).
MOVQ R13, R8
ADDQ R14, R8
MOVQ R14, R9
XORQ R10, R10
XORQ R11, R11
SUBQ R13, R11
// Loop until CX > BX.
blockLoop:
round(R8)
round(R9)
round(R10)
round(R11)
CMPQ CX, BX
JLE blockLoop
MOVQ R8, AX
ROLQ $1, AX
MOVQ R9, R12
ROLQ $7, R12
ADDQ R12, AX
MOVQ R10, R12
ROLQ $12, R12
ADDQ R12, AX
MOVQ R11, R12
ROLQ $18, R12
ADDQ R12, AX
mergeRound(AX, R8)
mergeRound(AX, R9)
mergeRound(AX, R10)
mergeRound(AX, R11)
JMP afterBlocks
noBlocks:
MOVQ ·prime5v(SB), AX
afterBlocks:
ADDQ DX, AX
// Right now BX has len(b)-32, and we want to loop until CX > len(b)-8.
ADDQ $24, BX
CMPQ CX, BX
JG fourByte
wordLoop:
// Calculate k1.
MOVQ (CX), R8
ADDQ $8, CX
IMULQ R14, R8
ROLQ $31, R8
IMULQ R13, R8
XORQ R8, AX
ROLQ $27, AX
IMULQ R13, AX
ADDQ R15, AX
CMPQ CX, BX
JLE wordLoop
fourByte:
ADDQ $4, BX
CMPQ CX, BX
JG singles
MOVL (CX), R8
ADDQ $4, CX
IMULQ R13, R8
XORQ R8, AX
ROLQ $23, AX
IMULQ R14, AX
ADDQ ·prime3v(SB), AX
singles:
ADDQ $4, BX
CMPQ CX, BX
JGE finalize
singlesLoop:
MOVBQZX (CX), R12
ADDQ $1, CX
IMULQ ·prime5v(SB), R12
XORQ R12, AX
ROLQ $11, AX
IMULQ R13, AX
CMPQ CX, BX
JL singlesLoop
finalize:
MOVQ AX, R12
SHRQ $33, R12
XORQ R12, AX
IMULQ R14, AX
MOVQ AX, R12
SHRQ $29, R12
XORQ R12, AX
IMULQ ·prime3v(SB), AX
MOVQ AX, R12
SHRQ $32, R12
XORQ R12, AX
MOVQ AX, ret+24(FP)
RET
// writeBlocks uses the same registers as above except that it uses AX to store
// the d pointer.
// func writeBlocks(d *Digest, b []byte) int
TEXT ·writeBlocks(SB), NOSPLIT, $0-40
// Load fixed primes needed for round.
MOVQ ·prime1v(SB), R13
MOVQ ·prime2v(SB), R14
// Load slice.
MOVQ b_base+8(FP), CX
MOVQ b_len+16(FP), DX
LEAQ (CX)(DX*1), BX
SUBQ $32, BX
// Load vN from d.
MOVQ d+0(FP), AX
MOVQ 0(AX), R8 // v1
MOVQ 8(AX), R9 // v2
MOVQ 16(AX), R10 // v3
MOVQ 24(AX), R11 // v4
// We don't need to check the loop condition here; this function is
// always called with at least one block of data to process.
blockLoop:
round(R8)
round(R9)
round(R10)
round(R11)
CMPQ CX, BX
JLE blockLoop
// Copy vN back to d.
MOVQ R8, 0(AX)
MOVQ R9, 8(AX)
MOVQ R10, 16(AX)
MOVQ R11, 24(AX)
// The number of bytes written is CX minus the old base pointer.
SUBQ b_base+8(FP), CX
MOVQ CX, ret+32(FP)
RET

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vendor/github.com/klauspost/compress/zstd/internal/xxhash/xxhash_other.go generated vendored Normal file
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// +build !amd64 appengine !gc purego
package xxhash
// Sum64 computes the 64-bit xxHash digest of b.
func Sum64(b []byte) uint64 {
// A simpler version would be
// d := New()
// d.Write(b)
// return d.Sum64()
// but this is faster, particularly for small inputs.
n := len(b)
var h uint64
if n >= 32 {
v1 := prime1v + prime2
v2 := prime2
v3 := uint64(0)
v4 := -prime1v
for len(b) >= 32 {
v1 = round(v1, u64(b[0:8:len(b)]))
v2 = round(v2, u64(b[8:16:len(b)]))
v3 = round(v3, u64(b[16:24:len(b)]))
v4 = round(v4, u64(b[24:32:len(b)]))
b = b[32:len(b):len(b)]
}
h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
h = mergeRound(h, v1)
h = mergeRound(h, v2)
h = mergeRound(h, v3)
h = mergeRound(h, v4)
} else {
h = prime5
}
h += uint64(n)
i, end := 0, len(b)
for ; i+8 <= end; i += 8 {
k1 := round(0, u64(b[i:i+8:len(b)]))
h ^= k1
h = rol27(h)*prime1 + prime4
}
if i+4 <= end {
h ^= uint64(u32(b[i:i+4:len(b)])) * prime1
h = rol23(h)*prime2 + prime3
i += 4
}
for ; i < end; i++ {
h ^= uint64(b[i]) * prime5
h = rol11(h) * prime1
}
h ^= h >> 33
h *= prime2
h ^= h >> 29
h *= prime3
h ^= h >> 32
return h
}
func writeBlocks(d *Digest, b []byte) int {
v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
n := len(b)
for len(b) >= 32 {
v1 = round(v1, u64(b[0:8:len(b)]))
v2 = round(v2, u64(b[8:16:len(b)]))
v3 = round(v3, u64(b[16:24:len(b)]))
v4 = round(v4, u64(b[24:32:len(b)]))
b = b[32:len(b):len(b)]
}
d.v1, d.v2, d.v3, d.v4 = v1, v2, v3, v4
return n - len(b)
}

11
vendor/github.com/klauspost/compress/zstd/internal/xxhash/xxhash_safe.go generated vendored Normal file
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package xxhash
// Sum64String computes the 64-bit xxHash digest of s.
func Sum64String(s string) uint64 {
return Sum64([]byte(s))
}
// WriteString adds more data to d. It always returns len(s), nil.
func (d *Digest) WriteString(s string) (n int, err error) {
return d.Write([]byte(s))
}

409
vendor/github.com/klauspost/compress/zstd/seqdec.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"errors"
"fmt"
"io"
)
type seq struct {
litLen uint32
matchLen uint32
offset uint32
// Codes are stored here for the encoder
// so they only have to be looked up once.
llCode, mlCode, ofCode uint8
}
func (s seq) String() string {
if s.offset <= 3 {
if s.offset == 0 {
return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset: INVALID (0)")
}
return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset:", s.offset, " (repeat)")
}
return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset:", s.offset-3, " (new)")
}
type seqCompMode uint8
const (
compModePredefined seqCompMode = iota
compModeRLE
compModeFSE
compModeRepeat
)
type sequenceDec struct {
// decoder keeps track of the current state and updates it from the bitstream.
fse *fseDecoder
state fseState
repeat bool
}
// init the state of the decoder with input from stream.
func (s *sequenceDec) init(br *bitReader) error {
if s.fse == nil {
return errors.New("sequence decoder not defined")
}
s.state.init(br, s.fse.actualTableLog, s.fse.dt[:1<<s.fse.actualTableLog])
return nil
}
// sequenceDecs contains all 3 sequence decoders and their state.
type sequenceDecs struct {
litLengths sequenceDec
offsets sequenceDec
matchLengths sequenceDec
prevOffset [3]int
hist []byte
literals []byte
out []byte
maxBits uint8
}
// initialize all 3 decoders from the stream input.
func (s *sequenceDecs) initialize(br *bitReader, hist *history, literals, out []byte) error {
if err := s.litLengths.init(br); err != nil {
return errors.New("litLengths:" + err.Error())
}
if err := s.offsets.init(br); err != nil {
return errors.New("offsets:" + err.Error())
}
if err := s.matchLengths.init(br); err != nil {
return errors.New("matchLengths:" + err.Error())
}
s.literals = literals
s.hist = hist.b
s.prevOffset = hist.recentOffsets
s.maxBits = s.litLengths.fse.maxBits + s.offsets.fse.maxBits + s.matchLengths.fse.maxBits
s.out = out
return nil
}
// decode sequences from the stream with the provided history.
func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
startSize := len(s.out)
for i := seqs - 1; i >= 0; i-- {
if br.overread() {
printf("reading sequence %d, exceeded available data\n", seqs-i)
return io.ErrUnexpectedEOF
}
var litLen, matchOff, matchLen int
if br.off > 4+((maxOffsetBits+16+16)>>3) {
litLen, matchOff, matchLen = s.nextFast(br)
br.fillFast()
} else {
litLen, matchOff, matchLen = s.next(br)
br.fill()
}
if debugSequences {
println("Seq", seqs-i-1, "Litlen:", litLen, "matchOff:", matchOff, "(abs) matchLen:", matchLen)
}
if litLen > len(s.literals) {
return fmt.Errorf("unexpected literal count, want %d bytes, but only %d is available", litLen, len(s.literals))
}
size := litLen + matchLen + len(s.out)
if size-startSize > maxBlockSize {
return fmt.Errorf("output (%d) bigger than max block size", size)
}
if size > cap(s.out) {
// Not enough size, will be extremely rarely triggered,
// but could be if destination slice is too small for sync operations.
// We add maxBlockSize to the capacity.
s.out = append(s.out, make([]byte, maxBlockSize)...)
s.out = s.out[:len(s.out)-maxBlockSize]
}
if matchLen > maxMatchLen {
return fmt.Errorf("match len (%d) bigger than max allowed length", matchLen)
}
if matchOff > len(s.out)+len(hist)+litLen {
return fmt.Errorf("match offset (%d) bigger than current history (%d)", matchOff, len(s.out)+len(hist)+litLen)
}
if matchOff == 0 && matchLen > 0 {
return fmt.Errorf("zero matchoff and matchlen > 0")
}
s.out = append(s.out, s.literals[:litLen]...)
s.literals = s.literals[litLen:]
out := s.out
// Copy from history.
// TODO: Blocks without history could be made to ignore this completely.
if v := matchOff - len(s.out); v > 0 {
// v is the start position in history from end.
start := len(s.hist) - v
if matchLen > v {
// Some goes into current block.
// Copy remainder of history
out = append(out, s.hist[start:]...)
matchOff -= v
matchLen -= v
} else {
out = append(out, s.hist[start:start+matchLen]...)
matchLen = 0
}
}
// We must be in current buffer now
if matchLen > 0 {
start := len(s.out) - matchOff
if matchLen <= len(s.out)-start {
// No overlap
out = append(out, s.out[start:start+matchLen]...)
} else {
// Overlapping copy
// Extend destination slice and copy one byte at the time.
out = out[:len(out)+matchLen]
src := out[start : start+matchLen]
// Destination is the space we just added.
dst := out[len(out)-matchLen:]
dst = dst[:len(src)]
for i := range src {
dst[i] = src[i]
}
}
}
s.out = out
if i == 0 {
// This is the last sequence, so we shouldn't update state.
break
}
if true {
// Manually inlined, ~ 5-20% faster
// Update all 3 states at once. Approx 20% faster.
a, b, c := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
nBits := a.nbBits + b.nbBits + c.nbBits
if nBits == 0 {
s.litLengths.state.state = s.litLengths.state.dt[a.newState]
s.matchLengths.state.state = s.matchLengths.state.dt[b.newState]
s.offsets.state.state = s.offsets.state.dt[c.newState]
} else {
bits := br.getBitsFast(nBits)
lowBits := uint16(bits >> ((c.nbBits + b.nbBits) & 31))
s.litLengths.state.state = s.litLengths.state.dt[a.newState+lowBits]
lowBits = uint16(bits >> (c.nbBits & 31))
lowBits &= bitMask[b.nbBits&15]
s.matchLengths.state.state = s.matchLengths.state.dt[b.newState+lowBits]
lowBits = uint16(bits) & bitMask[c.nbBits&15]
s.offsets.state.state = s.offsets.state.dt[c.newState+lowBits]
}
} else {
s.updateAlt(br)
}
}
// Add final literals
s.out = append(s.out, s.literals...)
return nil
}
// update states, at least 27 bits must be available.
func (s *sequenceDecs) update(br *bitReader) {
// Max 8 bits
s.litLengths.state.next(br)
// Max 9 bits
s.matchLengths.state.next(br)
// Max 8 bits
s.offsets.state.next(br)
}
var bitMask [16]uint16
func init() {
for i := range bitMask[:] {
bitMask[i] = uint16((1 << uint(i)) - 1)
}
}
// update states, at least 27 bits must be available.
func (s *sequenceDecs) updateAlt(br *bitReader) {
// Update all 3 states at once. Approx 20% faster.
a, b, c := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
nBits := a.nbBits + b.nbBits + c.nbBits
if nBits == 0 {
s.litLengths.state.state = s.litLengths.state.dt[a.newState]
s.matchLengths.state.state = s.matchLengths.state.dt[b.newState]
s.offsets.state.state = s.offsets.state.dt[c.newState]
return
}
bits := br.getBitsFast(nBits)
lowBits := uint16(bits >> ((c.nbBits + b.nbBits) & 31))
s.litLengths.state.state = s.litLengths.state.dt[a.newState+lowBits]
lowBits = uint16(bits >> (c.nbBits & 31))
lowBits &= bitMask[b.nbBits&15]
s.matchLengths.state.state = s.matchLengths.state.dt[b.newState+lowBits]
lowBits = uint16(bits) & bitMask[c.nbBits&15]
s.offsets.state.state = s.offsets.state.dt[c.newState+lowBits]
}
// nextFast will return new states when there are at least 4 unused bytes left on the stream when done.
func (s *sequenceDecs) nextFast(br *bitReader) (ll, mo, ml int) {
// Final will not read from stream.
ll, llB := s.litLengths.state.final()
ml, mlB := s.matchLengths.state.final()
mo, moB := s.offsets.state.final()
// extra bits are stored in reverse order.
br.fillFast()
if s.maxBits <= 32 {
mo += br.getBits(moB)
ml += br.getBits(mlB)
ll += br.getBits(llB)
} else {
mo += br.getBits(moB)
br.fillFast()
// matchlength+literal length, max 32 bits
ml += br.getBits(mlB)
ll += br.getBits(llB)
}
// mo = s.adjustOffset(mo, ll, moB)
// Inlined for rather big speedup
if moB > 1 {
s.prevOffset[2] = s.prevOffset[1]
s.prevOffset[1] = s.prevOffset[0]
s.prevOffset[0] = mo
return
}
if ll == 0 {
// There is an exception though, when current sequence's literals_length = 0.
// In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
// an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
mo++
}
if mo == 0 {
mo = s.prevOffset[0]
return
}
var temp int
if mo == 3 {
temp = s.prevOffset[0] - 1
} else {
temp = s.prevOffset[mo]
}
if temp == 0 {
// 0 is not valid; input is corrupted; force offset to 1
println("temp was 0")
temp = 1
}
if mo != 1 {
s.prevOffset[2] = s.prevOffset[1]
}
s.prevOffset[1] = s.prevOffset[0]
s.prevOffset[0] = temp
mo = temp
return
}
func (s *sequenceDecs) next(br *bitReader) (ll, mo, ml int) {
// Final will not read from stream.
ll, llB := s.litLengths.state.final()
ml, mlB := s.matchLengths.state.final()
mo, moB := s.offsets.state.final()
// extra bits are stored in reverse order.
br.fill()
if s.maxBits <= 32 {
mo += br.getBits(moB)
ml += br.getBits(mlB)
ll += br.getBits(llB)
} else {
mo += br.getBits(moB)
br.fill()
// matchlength+literal length, max 32 bits
ml += br.getBits(mlB)
ll += br.getBits(llB)
}
mo = s.adjustOffset(mo, ll, moB)
return
}
func (s *sequenceDecs) adjustOffset(offset, litLen int, offsetB uint8) int {
if offsetB > 1 {
s.prevOffset[2] = s.prevOffset[1]
s.prevOffset[1] = s.prevOffset[0]
s.prevOffset[0] = offset
return offset
}
if litLen == 0 {
// There is an exception though, when current sequence's literals_length = 0.
// In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
// an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
offset++
}
if offset == 0 {
return s.prevOffset[0]
}
var temp int
if offset == 3 {
temp = s.prevOffset[0] - 1
} else {
temp = s.prevOffset[offset]
}
if temp == 0 {
// 0 is not valid; input is corrupted; force offset to 1
println("temp was 0")
temp = 1
}
if offset != 1 {
s.prevOffset[2] = s.prevOffset[1]
}
s.prevOffset[1] = s.prevOffset[0]
s.prevOffset[0] = temp
return temp
}
// mergeHistory will merge history.
func (s *sequenceDecs) mergeHistory(hist *sequenceDecs) (*sequenceDecs, error) {
for i := uint(0); i < 3; i++ {
var sNew, sHist *sequenceDec
switch i {
default:
// same as "case 0":
sNew = &s.litLengths
sHist = &hist.litLengths
case 1:
sNew = &s.offsets
sHist = &hist.offsets
case 2:
sNew = &s.matchLengths
sHist = &hist.matchLengths
}
if sNew.repeat {
if sHist.fse == nil {
return nil, fmt.Errorf("sequence stream %d, repeat requested, but no history", i)
}
continue
}
if sNew.fse == nil {
return nil, fmt.Errorf("sequence stream %d, no fse found", i)
}
if sHist.fse != nil && !sHist.fse.preDefined {
fseDecoderPool.Put(sHist.fse)
}
sHist.fse = sNew.fse
}
return hist, nil
}

115
vendor/github.com/klauspost/compress/zstd/seqenc.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import "math/bits"
type seqCoders struct {
llEnc, ofEnc, mlEnc *fseEncoder
llPrev, ofPrev, mlPrev *fseEncoder
}
// swap coders with another (block).
func (s *seqCoders) swap(other *seqCoders) {
*s, *other = *other, *s
}
// setPrev will update the previous encoders to the actually used ones
// and make sure a fresh one is in the main slot.
func (s *seqCoders) setPrev(ll, ml, of *fseEncoder) {
compareSwap := func(used *fseEncoder, current, prev **fseEncoder) {
// We used the new one, more current to history and reuse the previous history
if *current == used {
*prev, *current = *current, *prev
c := *current
p := *prev
c.reUsed = false
p.reUsed = true
return
}
if used == *prev {
return
}
// Ensure we cannot reuse by accident
prevEnc := *prev
prevEnc.symbolLen = 0
return
}
compareSwap(ll, &s.llEnc, &s.llPrev)
compareSwap(ml, &s.mlEnc, &s.mlPrev)
compareSwap(of, &s.ofEnc, &s.ofPrev)
}
func highBit(val uint32) (n uint32) {
return uint32(bits.Len32(val) - 1)
}
var llCodeTable = [64]byte{0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15,
16, 16, 17, 17, 18, 18, 19, 19,
20, 20, 20, 20, 21, 21, 21, 21,
22, 22, 22, 22, 22, 22, 22, 22,
23, 23, 23, 23, 23, 23, 23, 23,
24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24}
// Up to 6 bits
const maxLLCode = 35
// llBitsTable translates from ll code to number of bits.
var llBitsTable = [maxLLCode + 1]byte{
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 2, 2, 3, 3,
4, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16}
// llCode returns the code that represents the literal length requested.
func llCode(litLength uint32) uint8 {
const llDeltaCode = 19
if litLength <= 63 {
// Compiler insists on bounds check (Go 1.12)
return llCodeTable[litLength&63]
}
return uint8(highBit(litLength)) + llDeltaCode
}
var mlCodeTable = [128]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37,
38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39,
40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40,
41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42}
// Up to 6 bits
const maxMLCode = 52
// mlBitsTable translates from ml code to number of bits.
var mlBitsTable = [maxMLCode + 1]byte{
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 2, 2, 3, 3,
4, 4, 5, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16}
// note : mlBase = matchLength - MINMATCH;
// because it's the format it's stored in seqStore->sequences
func mlCode(mlBase uint32) uint8 {
const mlDeltaCode = 36
if mlBase <= 127 {
// Compiler insists on bounds check (Go 1.12)
return mlCodeTable[mlBase&127]
}
return uint8(highBit(mlBase)) + mlDeltaCode
}
func ofCode(offset uint32) uint8 {
// A valid offset will always be > 0.
return uint8(bits.Len32(offset) - 1)
}

435
vendor/github.com/klauspost/compress/zstd/snappy.go generated vendored Normal file
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// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"encoding/binary"
"errors"
"hash/crc32"
"io"
"github.com/klauspost/compress/huff0"
"github.com/klauspost/compress/snappy"
)
const (
snappyTagLiteral = 0x00
snappyTagCopy1 = 0x01
snappyTagCopy2 = 0x02
snappyTagCopy4 = 0x03
)
const (
snappyChecksumSize = 4
snappyMagicBody = "sNaPpY"
// snappyMaxBlockSize is the maximum size of the input to encodeBlock. It is not
// part of the wire format per se, but some parts of the encoder assume
// that an offset fits into a uint16.
//
// Also, for the framing format (Writer type instead of Encode function),
// https://github.com/google/snappy/blob/master/framing_format.txt says
// that "the uncompressed data in a chunk must be no longer than 65536
// bytes".
snappyMaxBlockSize = 65536
// snappyMaxEncodedLenOfMaxBlockSize equals MaxEncodedLen(snappyMaxBlockSize), but is
// hard coded to be a const instead of a variable, so that obufLen can also
// be a const. Their equivalence is confirmed by
// TestMaxEncodedLenOfMaxBlockSize.
snappyMaxEncodedLenOfMaxBlockSize = 76490
)
const (
chunkTypeCompressedData = 0x00
chunkTypeUncompressedData = 0x01
chunkTypePadding = 0xfe
chunkTypeStreamIdentifier = 0xff
)
var (
// ErrSnappyCorrupt reports that the input is invalid.
ErrSnappyCorrupt = errors.New("snappy: corrupt input")
// ErrSnappyTooLarge reports that the uncompressed length is too large.
ErrSnappyTooLarge = errors.New("snappy: decoded block is too large")
// ErrSnappyUnsupported reports that the input isn't supported.
ErrSnappyUnsupported = errors.New("snappy: unsupported input")
errUnsupportedLiteralLength = errors.New("snappy: unsupported literal length")
)
// SnappyConverter can read SnappyConverter-compressed streams and convert them to zstd.
// Conversion is done by converting the stream directly from Snappy without intermediate
// full decoding.
// Therefore the compression ratio is much less than what can be done by a full decompression
// and compression, and a faulty Snappy stream may lead to a faulty Zstandard stream without
// any errors being generated.
// No CRC value is being generated and not all CRC values of the Snappy stream are checked.
// However, it provides really fast recompression of Snappy streams.
// The converter can be reused to avoid allocations, even after errors.
type SnappyConverter struct {
r io.Reader
err error
buf []byte
block *blockEnc
}
// Convert the Snappy stream supplied in 'in' and write the zStandard stream to 'w'.
// If any error is detected on the Snappy stream it is returned.
// The number of bytes written is returned.
func (r *SnappyConverter) Convert(in io.Reader, w io.Writer) (int64, error) {
r.err = nil
r.r = in
if r.block == nil {
r.block = &blockEnc{}
r.block.init()
}
r.block.initNewEncode()
if len(r.buf) != snappyMaxEncodedLenOfMaxBlockSize+snappyChecksumSize {
r.buf = make([]byte, snappyMaxEncodedLenOfMaxBlockSize+snappyChecksumSize)
}
r.block.litEnc.Reuse = huff0.ReusePolicyNone
var written int64
var readHeader bool
{
var header []byte
var n int
header, r.err = frameHeader{WindowSize: snappyMaxBlockSize}.appendTo(r.buf[:0])
n, r.err = w.Write(header)
if r.err != nil {
return written, r.err
}
written += int64(n)
}
for {
if !r.readFull(r.buf[:4], true) {
// Add empty last block
r.block.reset(nil)
r.block.last = true
err := r.block.encodeLits()
if err != nil {
return written, err
}
n, err := w.Write(r.block.output)
if err != nil {
return written, err
}
written += int64(n)
return written, r.err
}
chunkType := r.buf[0]
if !readHeader {
if chunkType != chunkTypeStreamIdentifier {
println("chunkType != chunkTypeStreamIdentifier", chunkType)
r.err = ErrSnappyCorrupt
return written, r.err
}
readHeader = true
}
chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
if chunkLen > len(r.buf) {
println("chunkLen > len(r.buf)", chunkType)
r.err = ErrSnappyUnsupported
return written, r.err
}
// The chunk types are specified at
// https://github.com/google/snappy/blob/master/framing_format.txt
switch chunkType {
case chunkTypeCompressedData:
// Section 4.2. Compressed data (chunk type 0x00).
if chunkLen < snappyChecksumSize {
println("chunkLen < snappyChecksumSize", chunkLen, snappyChecksumSize)
r.err = ErrSnappyCorrupt
return written, r.err
}
buf := r.buf[:chunkLen]
if !r.readFull(buf, false) {
return written, r.err
}
//checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
buf = buf[snappyChecksumSize:]
n, hdr, err := snappyDecodedLen(buf)
if err != nil {
r.err = err
return written, r.err
}
buf = buf[hdr:]
if n > snappyMaxBlockSize {
println("n > snappyMaxBlockSize", n, snappyMaxBlockSize)
r.err = ErrSnappyCorrupt
return written, r.err
}
r.block.reset(nil)
r.block.pushOffsets()
if err := decodeSnappy(r.block, buf); err != nil {
r.err = err
return written, r.err
}
if r.block.size+r.block.extraLits != n {
printf("invalid size, want %d, got %d\n", n, r.block.size+r.block.extraLits)
r.err = ErrSnappyCorrupt
return written, r.err
}
err = r.block.encode()
switch err {
case errIncompressible:
r.block.popOffsets()
r.block.reset(nil)
r.block.literals, err = snappy.Decode(r.block.literals[:n], r.buf[snappyChecksumSize:chunkLen])
if err != nil {
println("snappy.Decode:", err)
return written, err
}
err = r.block.encodeLits()
if err != nil {
return written, err
}
case nil:
default:
return written, err
}
n, r.err = w.Write(r.block.output)
if r.err != nil {
return written, err
}
written += int64(n)
continue
case chunkTypeUncompressedData:
if debug {
println("Uncompressed, chunklen", chunkLen)
}
// Section 4.3. Uncompressed data (chunk type 0x01).
if chunkLen < snappyChecksumSize {
println("chunkLen < snappyChecksumSize", chunkLen, snappyChecksumSize)
r.err = ErrSnappyCorrupt
return written, r.err
}
r.block.reset(nil)
buf := r.buf[:snappyChecksumSize]
if !r.readFull(buf, false) {
return written, r.err
}
checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
// Read directly into r.decoded instead of via r.buf.
n := chunkLen - snappyChecksumSize
if n > snappyMaxBlockSize {
println("n > snappyMaxBlockSize", n, snappyMaxBlockSize)
r.err = ErrSnappyCorrupt
return written, r.err
}
r.block.literals = r.block.literals[:n]
if !r.readFull(r.block.literals, false) {
return written, r.err
}
if snappyCRC(r.block.literals) != checksum {
println("literals crc mismatch")
r.err = ErrSnappyCorrupt
return written, r.err
}
err := r.block.encodeLits()
if err != nil {
return written, err
}
n, r.err = w.Write(r.block.output)
if r.err != nil {
return written, err
}
written += int64(n)
continue
case chunkTypeStreamIdentifier:
if debug {
println("stream id", chunkLen, len(snappyMagicBody))
}
// Section 4.1. Stream identifier (chunk type 0xff).
if chunkLen != len(snappyMagicBody) {
println("chunkLen != len(snappyMagicBody)", chunkLen, len(snappyMagicBody))
r.err = ErrSnappyCorrupt
return written, r.err
}
if !r.readFull(r.buf[:len(snappyMagicBody)], false) {
return written, r.err
}
for i := 0; i < len(snappyMagicBody); i++ {
if r.buf[i] != snappyMagicBody[i] {
println("r.buf[i] != snappyMagicBody[i]", r.buf[i], snappyMagicBody[i], i)
r.err = ErrSnappyCorrupt
return written, r.err
}
}
continue
}
if chunkType <= 0x7f {
// Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
println("chunkType <= 0x7f")
r.err = ErrSnappyUnsupported
return written, r.err
}
// Section 4.4 Padding (chunk type 0xfe).
// Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
if !r.readFull(r.buf[:chunkLen], false) {
return written, r.err
}
}
}
// decodeSnappy writes the decoding of src to dst. It assumes that the varint-encoded
// length of the decompressed bytes has already been read.
func decodeSnappy(blk *blockEnc, src []byte) error {
//decodeRef(make([]byte, snappyMaxBlockSize), src)
var s, length int
lits := blk.extraLits
var offset uint32
for s < len(src) {
switch src[s] & 0x03 {
case snappyTagLiteral:
x := uint32(src[s] >> 2)
switch {
case x < 60:
s++
case x == 60:
s += 2
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, src)
return ErrSnappyCorrupt
}
x = uint32(src[s-1])
case x == 61:
s += 3
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, src)
return ErrSnappyCorrupt
}
x = uint32(src[s-2]) | uint32(src[s-1])<<8
case x == 62:
s += 4
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, src)
return ErrSnappyCorrupt
}
x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
case x == 63:
s += 5
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, src)
return ErrSnappyCorrupt
}
x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
}
if x > snappyMaxBlockSize {
println("x > snappyMaxBlockSize", x, snappyMaxBlockSize)
return ErrSnappyCorrupt
}
length = int(x) + 1
if length <= 0 {
println("length <= 0 ", length)
return errUnsupportedLiteralLength
}
//if length > snappyMaxBlockSize-d || uint32(length) > len(src)-s {
// return ErrSnappyCorrupt
//}
blk.literals = append(blk.literals, src[s:s+length]...)
//println(length, "litLen")
lits += length
s += length
continue
case snappyTagCopy1:
s += 2
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, len(src))
return ErrSnappyCorrupt
}
length = 4 + int(src[s-2])>>2&0x7
offset = uint32(src[s-2])&0xe0<<3 | uint32(src[s-1])
case snappyTagCopy2:
s += 3
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, len(src))
return ErrSnappyCorrupt
}
length = 1 + int(src[s-3])>>2
offset = uint32(src[s-2]) | uint32(src[s-1])<<8
case snappyTagCopy4:
s += 5
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
println("uint(s) > uint(len(src)", s, len(src))
return ErrSnappyCorrupt
}
length = 1 + int(src[s-5])>>2
offset = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
}
if offset <= 0 || blk.size+lits < int(offset) /*|| length > len(blk)-d */ {
println("offset <= 0 || blk.size+lits < int(offset)", offset, blk.size+lits, int(offset), blk.size, lits)
return ErrSnappyCorrupt
}
// Check if offset is one of the recent offsets.
// Adjusts the output offset accordingly.
// Gives a tiny bit of compression, typically around 1%.
if false {
offset = blk.matchOffset(offset, uint32(lits))
} else {
offset += 3
}
blk.sequences = append(blk.sequences, seq{
litLen: uint32(lits),
offset: offset,
matchLen: uint32(length) - zstdMinMatch,
})
blk.size += length + lits
lits = 0
}
blk.extraLits = lits
return nil
}
func (r *SnappyConverter) readFull(p []byte, allowEOF bool) (ok bool) {
if _, r.err = io.ReadFull(r.r, p); r.err != nil {
if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
r.err = ErrSnappyCorrupt
}
return false
}
return true
}
var crcTable = crc32.MakeTable(crc32.Castagnoli)
// crc implements the checksum specified in section 3 of
// https://github.com/google/snappy/blob/master/framing_format.txt
func snappyCRC(b []byte) uint32 {
c := crc32.Update(0, crcTable, b)
return uint32(c>>15|c<<17) + 0xa282ead8
}
// snappyDecodedLen returns the length of the decoded block and the number of bytes
// that the length header occupied.
func snappyDecodedLen(src []byte) (blockLen, headerLen int, err error) {
v, n := binary.Uvarint(src)
if n <= 0 || v > 0xffffffff {
return 0, 0, ErrSnappyCorrupt
}
const wordSize = 32 << (^uint(0) >> 32 & 1)
if wordSize == 32 && v > 0x7fffffff {
return 0, 0, ErrSnappyTooLarge
}
return int(v), n, nil
}

135
vendor/github.com/klauspost/compress/zstd/zstd.go generated vendored Normal file
View file

@ -0,0 +1,135 @@
// Package zstd provides decompression of zstandard files.
//
// For advanced usage and examples, go to the README: https://github.com/klauspost/compress/tree/master/zstd#zstd
package zstd
import (
"errors"
"log"
"math/bits"
)
const debug = false
const debugSequences = false
// force encoder to use predefined tables.
const forcePreDef = false
// zstdMinMatch is the minimum zstd match length.
const zstdMinMatch = 3
var (
// ErrReservedBlockType is returned when a reserved block type is found.
// Typically this indicates wrong or corrupted input.
ErrReservedBlockType = errors.New("invalid input: reserved block type encountered")
// ErrCompressedSizeTooBig is returned when a block is bigger than allowed.
// Typically this indicates wrong or corrupted input.
ErrCompressedSizeTooBig = errors.New("invalid input: compressed size too big")
// ErrBlockTooSmall is returned when a block is too small to be decoded.
// Typically returned on invalid input.
ErrBlockTooSmall = errors.New("block too small")
// ErrMagicMismatch is returned when a "magic" number isn't what is expected.
// Typically this indicates wrong or corrupted input.
ErrMagicMismatch = errors.New("invalid input: magic number mismatch")
// ErrWindowSizeExceeded is returned when a reference exceeds the valid window size.
// Typically this indicates wrong or corrupted input.
ErrWindowSizeExceeded = errors.New("window size exceeded")
// ErrWindowSizeTooSmall is returned when no window size is specified.
// Typically this indicates wrong or corrupted input.
ErrWindowSizeTooSmall = errors.New("invalid input: window size was too small")
// ErrDecoderSizeExceeded is returned if decompressed size exceeds the configured limit.
ErrDecoderSizeExceeded = errors.New("decompressed size exceeds configured limit")
// ErrUnknownDictionary is returned if the dictionary ID is unknown.
// For the time being dictionaries are not supported.
ErrUnknownDictionary = errors.New("unknown dictionary")
// ErrFrameSizeExceeded is returned if the stated frame size is exceeded.
// This is only returned if SingleSegment is specified on the frame.
ErrFrameSizeExceeded = errors.New("frame size exceeded")
// ErrCRCMismatch is returned if CRC mismatches.
ErrCRCMismatch = errors.New("CRC check failed")
// ErrDecoderClosed will be returned if the Decoder was used after
// Close has been called.
ErrDecoderClosed = errors.New("decoder used after Close")
)
func println(a ...interface{}) {
if debug {
log.Println(a...)
}
}
func printf(format string, a ...interface{}) {
if debug {
log.Printf(format, a...)
}
}
// matchLen returns the maximum length.
// a must be the shortest of the two.
// The function also returns whether all bytes matched.
func matchLen(a, b []byte) int {
b = b[:len(a)]
for i := 0; i < len(a)-7; i += 8 {
if diff := load64(a, i) ^ load64(b, i); diff != 0 {
return i + (bits.TrailingZeros64(diff) >> 3)
}
}
checked := (len(a) >> 3) << 3
a = a[checked:]
b = b[checked:]
// TODO: We could do a 4 check.
for i := range a {
if a[i] != b[i] {
return int(i) + checked
}
}
return len(a) + checked
}
// matchLen returns a match length in src between index s and t
func matchLenIn(src []byte, s, t int32) int32 {
s1 := len(src)
b := src[t:]
a := src[s:s1]
b = b[:len(a)]
// Extend the match to be as long as possible.
for i := range a {
if a[i] != b[i] {
return int32(i)
}
}
return int32(len(a))
}
func load3232(b []byte, i int32) uint32 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:4]
return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
}
func load6432(b []byte, i int32) uint64 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:8]
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}
func load64(b []byte, i int) uint64 {
// Help the compiler eliminate bounds checks on the read so it can be done in a single read.
b = b[i:]
b = b[:8]
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}

6
vendor/modules.txt vendored
View file

@ -6,6 +6,12 @@ github.com/VictoriaMetrics/metrics
github.com/cespare/xxhash/v2
# github.com/golang/snappy v0.0.1
github.com/golang/snappy
# github.com/klauspost/compress v1.7.4
github.com/klauspost/compress/zstd
github.com/klauspost/compress/huff0
github.com/klauspost/compress/snappy
github.com/klauspost/compress/zstd/internal/xxhash
github.com/klauspost/compress/fse
# github.com/valyala/bytebufferpool v1.0.0
github.com/valyala/bytebufferpool
# github.com/valyala/fastjson v1.4.1