lib/encoding: explicitly set slice length passed to binary.BigEndian.Uint*

This allows Go complier to generate more optimal code without bound checks
This commit is contained in:
Aliaksandr Valialkin 2022-04-12 12:55:18 +03:00
parent a91c2a4377
commit c6eb404c69
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GPG key ID: A72BEC6CD3D0DED1

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@ -14,7 +14,7 @@ func MarshalUint16(dst []byte, u uint16) []byte {
// UnmarshalUint16 returns unmarshaled uint32 from src. // UnmarshalUint16 returns unmarshaled uint32 from src.
func UnmarshalUint16(src []byte) uint16 { func UnmarshalUint16(src []byte) uint16 {
// This is faster than the manual conversion. // This is faster than the manual conversion.
return binary.BigEndian.Uint16(src) return binary.BigEndian.Uint16(src[:2])
} }
// MarshalUint32 appends marshaled v to dst and returns the result. // MarshalUint32 appends marshaled v to dst and returns the result.
@ -25,7 +25,7 @@ func MarshalUint32(dst []byte, u uint32) []byte {
// UnmarshalUint32 returns unmarshaled uint32 from src. // UnmarshalUint32 returns unmarshaled uint32 from src.
func UnmarshalUint32(src []byte) uint32 { func UnmarshalUint32(src []byte) uint32 {
// This is faster than the manual conversion. // This is faster than the manual conversion.
return binary.BigEndian.Uint32(src) return binary.BigEndian.Uint32(src[:4])
} }
// MarshalUint64 appends marshaled v to dst and returns the result. // MarshalUint64 appends marshaled v to dst and returns the result.
@ -36,7 +36,7 @@ func MarshalUint64(dst []byte, u uint64) []byte {
// UnmarshalUint64 returns unmarshaled uint64 from src. // UnmarshalUint64 returns unmarshaled uint64 from src.
func UnmarshalUint64(src []byte) uint64 { func UnmarshalUint64(src []byte) uint64 {
// This is faster than the manual conversion. // This is faster than the manual conversion.
return binary.BigEndian.Uint64(src) return binary.BigEndian.Uint64(src[:8])
} }
// MarshalInt16 appends marshaled v to dst and returns the result. // MarshalInt16 appends marshaled v to dst and returns the result.
@ -50,7 +50,7 @@ func MarshalInt16(dst []byte, v int16) []byte {
// UnmarshalInt16 returns unmarshaled int16 from src. // UnmarshalInt16 returns unmarshaled int16 from src.
func UnmarshalInt16(src []byte) int16 { func UnmarshalInt16(src []byte) int16 {
// This is faster than the manual conversion. // This is faster than the manual conversion.
u := binary.BigEndian.Uint16(src) u := binary.BigEndian.Uint16(src[:2])
v := int16(u>>1) ^ (int16(u<<15) >> 15) // zig-zag decoding without branching. v := int16(u>>1) ^ (int16(u<<15) >> 15) // zig-zag decoding without branching.
return v return v
} }
@ -66,7 +66,7 @@ func MarshalInt64(dst []byte, v int64) []byte {
// UnmarshalInt64 returns unmarshaled int64 from src. // UnmarshalInt64 returns unmarshaled int64 from src.
func UnmarshalInt64(src []byte) int64 { func UnmarshalInt64(src []byte) int64 {
// This is faster than the manual conversion. // This is faster than the manual conversion.
u := binary.BigEndian.Uint64(src) u := binary.BigEndian.Uint64(src[:8])
v := int64(u>>1) ^ (int64(u<<63) >> 63) // zig-zag decoding without branching. v := int64(u>>1) ^ (int64(u<<63) >> 63) // zig-zag decoding without branching.
return v return v
} }