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/*
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* Copyright ( c ) Meta Platforms , Inc . and affiliates .
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* All rights reserved .
*
* This source code is licensed under both the BSD - style license ( found in the
* LICENSE file in the root directory of this source tree ) and the GPLv2 ( found
* in the COPYING file in the root directory of this source tree ) .
* You may select , at your option , one of the above - listed licenses .
*/
# if defined (__cplusplus)
extern " C " {
# endif
# ifndef ZSTD_H_235446
# define ZSTD_H_235446
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/* ====== Dependencies ======*/
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# include <limits.h> /* INT_MAX */
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# include <stddef.h> /* size_t */
/* ===== ZSTDLIB_API : control library symbols visibility ===== */
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# ifndef ZSTDLIB_VISIBLE
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/* Backwards compatibility with old macro name */
# ifdef ZSTDLIB_VISIBILITY
# define ZSTDLIB_VISIBLE ZSTDLIB_VISIBILITY
# elif defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__)
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# define ZSTDLIB_VISIBLE __attribute__ ((visibility ("default")))
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# else
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# define ZSTDLIB_VISIBLE
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# endif
# endif
# ifndef ZSTDLIB_HIDDEN
# if defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__)
# define ZSTDLIB_HIDDEN __attribute__ ((visibility ("hidden")))
# else
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# define ZSTDLIB_HIDDEN
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# endif
# endif
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# if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
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# define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBLE
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# elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
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# define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBLE /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
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# else
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# define ZSTDLIB_API ZSTDLIB_VISIBLE
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# endif
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/* Deprecation warnings :
* Should these warnings be a problem , it is generally possible to disable them ,
* typically with - Wno - deprecated - declarations for gcc or _CRT_SECURE_NO_WARNINGS in Visual .
* Otherwise , it ' s also possible to define ZSTD_DISABLE_DEPRECATE_WARNINGS .
*/
# ifdef ZSTD_DISABLE_DEPRECATE_WARNINGS
# define ZSTD_DEPRECATED(message) /* disable deprecation warnings */
# else
# if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
# define ZSTD_DEPRECATED(message) [[deprecated(message)]]
# elif (defined(GNUC) && (GNUC > 4 || (GNUC == 4 && GNUC_MINOR >= 5))) || defined(__clang__)
# define ZSTD_DEPRECATED(message) __attribute__((deprecated(message)))
# elif defined(__GNUC__) && (__GNUC__ >= 3)
# define ZSTD_DEPRECATED(message) __attribute__((deprecated))
# elif defined(_MSC_VER)
# define ZSTD_DEPRECATED(message) __declspec(deprecated(message))
# else
# pragma message("WARNING: You need to implement ZSTD_DEPRECATED for this compiler")
# define ZSTD_DEPRECATED(message)
# endif
# endif /* ZSTD_DISABLE_DEPRECATE_WARNINGS */
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/*******************************************************************************
Introduction
zstd , short for Zstandard , is a fast lossless compression algorithm , targeting
real - time compression scenarios at zlib - level and better compression ratios .
The zstd compression library provides in - memory compression and decompression
functions .
The library supports regular compression levels from 1 up to ZSTD_maxCLevel ( ) ,
which is currently 22. Levels > = 20 , labeled ` - - ultra ` , should be used with
caution , as they require more memory . The library also offers negative
compression levels , which extend the range of speed vs . ratio preferences .
The lower the level , the faster the speed ( at the cost of compression ) .
Compression can be done in :
- a single step ( described as Simple API )
- a single step , reusing a context ( described as Explicit context )
- unbounded multiple steps ( described as Streaming compression )
The compression ratio achievable on small data can be highly improved using
a dictionary . Dictionary compression can be performed in :
- a single step ( described as Simple dictionary API )
- a single step , reusing a dictionary ( described as Bulk - processing
dictionary API )
Advanced experimental functions can be accessed using
` # define ZSTD_STATIC_LINKING_ONLY ` before including zstd . h .
Advanced experimental APIs should never be used with a dynamically - linked
library . They are not " stable " ; their definitions or signatures may change in
the future . Only static linking is allowed .
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*------ Version ------*/
# define ZSTD_VERSION_MAJOR 1
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# define ZSTD_VERSION_MINOR 5
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# define ZSTD_VERSION_RELEASE 5
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# define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
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/*! ZSTD_versionNumber() :
* Return runtime library version , the value is ( MAJOR * 100 * 100 + MINOR * 100 + RELEASE ) . */
ZSTDLIB_API unsigned ZSTD_versionNumber ( void ) ;
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# define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE
# define ZSTD_QUOTE(str) #str
# define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str)
# define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION)
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/*! ZSTD_versionString() :
* Return runtime library version , like " 1.4.5 " . Requires v1 .3 .0 + . */
ZSTDLIB_API const char * ZSTD_versionString ( void ) ;
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/* *************************************
* Default constant
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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# ifndef ZSTD_CLEVEL_DEFAULT
# define ZSTD_CLEVEL_DEFAULT 3
# endif
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/* *************************************
* Constants
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/* All magic numbers are supposed read/written to/from files/memory using little-endian convention */
# define ZSTD_MAGICNUMBER 0xFD2FB528 /* valid since v0.8.0 */
# define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* valid since v0.7.0 */
# define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50 /* all 16 values, from 0x184D2A50 to 0x184D2A5F, signal the beginning of a skippable frame */
# define ZSTD_MAGIC_SKIPPABLE_MASK 0xFFFFFFF0
# define ZSTD_BLOCKSIZELOG_MAX 17
# define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX)
/***************************************
* Simple API
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_compress() :
* Compresses ` src ` content as a single zstd compressed frame into already allocated ` dst ` .
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* NOTE : Providing ` dstCapacity > = ZSTD_compressBound ( srcSize ) ` guarantees that zstd will have
* enough space to successfully compress the data .
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* @ return : compressed size written into ` dst ` ( < = ` dstCapacity ) ,
* or an error code if it fails ( which can be tested using ZSTD_isError ( ) ) . */
ZSTDLIB_API size_t ZSTD_compress ( void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
int compressionLevel ) ;
/*! ZSTD_decompress() :
* ` compressedSize ` : must be the _exact_ size of some number of compressed and / or skippable frames .
* ` dstCapacity ` is an upper bound of originalSize to regenerate .
* If user cannot imply a maximum upper bound , it ' s better to use streaming mode to decompress data .
* @ return : the number of bytes decompressed into ` dst ` ( < = ` dstCapacity ` ) ,
* or an errorCode if it fails ( which can be tested using ZSTD_isError ( ) ) . */
ZSTDLIB_API size_t ZSTD_decompress ( void * dst , size_t dstCapacity ,
const void * src , size_t compressedSize ) ;
/*! ZSTD_getFrameContentSize() : requires v1.3.0+
* ` src ` should point to the start of a ZSTD encoded frame .
* ` srcSize ` must be at least as large as the frame header .
* hint : any size > = ` ZSTD_frameHeaderSize_max ` is large enough .
* @ return : - decompressed size of ` src ` frame content , if known
* - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
* - ZSTD_CONTENTSIZE_ERROR if an error occurred ( e . g . invalid magic number , srcSize too small )
* note 1 : a 0 return value means the frame is valid but " empty " .
* note 2 : decompressed size is an optional field , it may not be present , typically in streaming mode .
* When ` return = = ZSTD_CONTENTSIZE_UNKNOWN ` , data to decompress could be any size .
* In which case , it ' s necessary to use streaming mode to decompress data .
* Optionally , application can rely on some implicit limit ,
* as ZSTD_decompress ( ) only needs an upper bound of decompressed size .
* ( For example , data could be necessarily cut into blocks < = 16 KB ) .
* note 3 : decompressed size is always present when compression is completed using single - pass functions ,
* such as ZSTD_compress ( ) , ZSTD_compressCCtx ( ) ZSTD_compress_usingDict ( ) or ZSTD_compress_usingCDict ( ) .
* note 4 : decompressed size can be very large ( 64 - bits value ) ,
* potentially larger than what local system can handle as a single memory segment .
* In which case , it ' s necessary to use streaming mode to decompress data .
* note 5 : If source is untrusted , decompressed size could be wrong or intentionally modified .
* Always ensure return value fits within application ' s authorized limits .
* Each application can set its own limits .
* note 6 : This function replaces ZSTD_getDecompressedSize ( ) */
# define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
# define ZSTD_CONTENTSIZE_ERROR (0ULL - 2)
ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize ( const void * src , size_t srcSize ) ;
/*! ZSTD_getDecompressedSize() :
* NOTE : This function is now obsolete , in favor of ZSTD_getFrameContentSize ( ) .
* Both functions work the same way , but ZSTD_getDecompressedSize ( ) blends
* " empty " , " unknown " and " error " results to the same return value ( 0 ) ,
* while ZSTD_getFrameContentSize ( ) gives them separate return values .
* @ return : decompressed size of ` src ` frame content _if known and not empty_ , 0 otherwise . */
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ZSTD_DEPRECATED ( " Replaced by ZSTD_getFrameContentSize " )
ZSTDLIB_API
unsigned long long ZSTD_getDecompressedSize ( const void * src , size_t srcSize ) ;
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/*! ZSTD_findFrameCompressedSize() : Requires v1.4.0+
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* ` src ` should point to the start of a ZSTD frame or skippable frame .
* ` srcSize ` must be > = first frame size
* @ return : the compressed size of the first frame starting at ` src ` ,
* suitable to pass as ` srcSize ` to ` ZSTD_decompress ` or similar ,
* or an error code if input is invalid */
ZSTDLIB_API size_t ZSTD_findFrameCompressedSize ( const void * src , size_t srcSize ) ;
/*====== Helper functions ======*/
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/* ZSTD_compressBound() :
* maximum compressed size in worst case single - pass scenario .
* When invoking ` ZSTD_compress ( ) ` or any other one - pass compression function ,
* it ' s recommended to provide @ dstCapacity > = ZSTD_compressBound ( srcSize )
* as it eliminates one potential failure scenario ,
* aka not enough room in dst buffer to write the compressed frame .
* Note : ZSTD_compressBound ( ) itself can fail , if @ srcSize > ZSTD_MAX_INPUT_SIZE .
* In which case , ZSTD_compressBound ( ) will return an error code
* which can be tested using ZSTD_isError ( ) .
*
* ZSTD_COMPRESSBOUND ( ) :
* same as ZSTD_compressBound ( ) , but as a macro .
* It can be used to produce constants , which can be useful for static allocation ,
* for example to size a static array on stack .
* Will produce constant value 0 if srcSize too large .
*/
# define ZSTD_MAX_INPUT_SIZE ((sizeof(size_t)==8) ? 0xFF00FF00FF00FF00LLU : 0xFF00FF00U)
# define ZSTD_COMPRESSBOUND(srcSize) (((size_t)(srcSize) >= ZSTD_MAX_INPUT_SIZE) ? 0 : (srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */
ZSTDLIB_API size_t ZSTD_compressBound ( size_t srcSize ) ; /*!< maximum compressed size in worst case single-pass scenario */
/* ZSTD_isError() :
* Most ZSTD_ * functions returning a size_t value can be tested for error ,
* using ZSTD_isError ( ) .
* @ return 1 if error , 0 otherwise
*/
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ZSTDLIB_API unsigned ZSTD_isError ( size_t code ) ; /*!< tells if a `size_t` function result is an error code */
ZSTDLIB_API const char * ZSTD_getErrorName ( size_t code ) ; /*!< provides readable string from an error code */
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ZSTDLIB_API int ZSTD_minCLevel ( void ) ; /*!< minimum negative compression level allowed, requires v1.4.0+ */
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ZSTDLIB_API int ZSTD_maxCLevel ( void ) ; /*!< maximum compression level available */
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ZSTDLIB_API int ZSTD_defaultCLevel ( void ) ; /*!< default compression level, specified by ZSTD_CLEVEL_DEFAULT, requires v1.5.0+ */
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/***************************************
* Explicit context
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*= Compression context
* When compressing many times ,
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* it is recommended to allocate a context just once ,
* and re - use it for each successive compression operation .
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* This will make workload friendlier for system ' s memory .
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* Note : re - using context is just a speed / resource optimization .
* It doesn ' t change the compression ratio , which remains identical .
* Note 2 : In multi - threaded environments ,
* use one different context per thread for parallel execution .
*/
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typedef struct ZSTD_CCtx_s ZSTD_CCtx ;
ZSTDLIB_API ZSTD_CCtx * ZSTD_createCCtx ( void ) ;
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ZSTDLIB_API size_t ZSTD_freeCCtx ( ZSTD_CCtx * cctx ) ; /* accept NULL pointer */
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/*! ZSTD_compressCCtx() :
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* Same as ZSTD_compress ( ) , using an explicit ZSTD_CCtx .
* Important : in order to behave similarly to ` ZSTD_compress ( ) ` ,
* this function compresses at requested compression level ,
* __ignoring any other parameter__ .
* If any advanced parameter was set using the advanced API ,
* they will all be reset . Only ` compressionLevel ` remains .
*/
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ZSTDLIB_API size_t ZSTD_compressCCtx ( ZSTD_CCtx * cctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
int compressionLevel ) ;
/*= Decompression context
* When decompressing many times ,
* it is recommended to allocate a context only once ,
* and re - use it for each successive compression operation .
* This will make workload friendlier for system ' s memory .
* Use one context per thread for parallel execution . */
typedef struct ZSTD_DCtx_s ZSTD_DCtx ;
ZSTDLIB_API ZSTD_DCtx * ZSTD_createDCtx ( void ) ;
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ZSTDLIB_API size_t ZSTD_freeDCtx ( ZSTD_DCtx * dctx ) ; /* accept NULL pointer */
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/*! ZSTD_decompressDCtx() :
* Same as ZSTD_decompress ( ) ,
* requires an allocated ZSTD_DCtx .
* Compatible with sticky parameters .
*/
ZSTDLIB_API size_t ZSTD_decompressDCtx ( ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ) ;
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/*********************************************
* Advanced compression API ( Requires v1 .4 .0 + )
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/* API design :
* Parameters are pushed one by one into an existing context ,
* using ZSTD_CCtx_set * ( ) functions .
* Pushed parameters are sticky : they are valid for next compressed frame , and any subsequent frame .
* " sticky " parameters are applicable to ` ZSTD_compress2 ( ) ` and ` ZSTD_compressStream * ( ) ` !
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* __They do not apply to " simple " one - shot variants such as ZSTD_compressCCtx ( ) __ .
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*
* It ' s possible to reset all parameters to " default " using ZSTD_CCtx_reset ( ) .
*
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* This API supersedes all other " advanced " API entry points in the experimental section .
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* In the future , we expect to remove from experimental API entry points which are redundant with this API .
*/
/* Compression strategies, listed from fastest to strongest */
typedef enum { ZSTD_fast = 1 ,
ZSTD_dfast = 2 ,
ZSTD_greedy = 3 ,
ZSTD_lazy = 4 ,
ZSTD_lazy2 = 5 ,
ZSTD_btlazy2 = 6 ,
ZSTD_btopt = 7 ,
ZSTD_btultra = 8 ,
ZSTD_btultra2 = 9
/* note : new strategies _might_ be added in the future.
Only the order ( from fast to strong ) is guaranteed */
} ZSTD_strategy ;
typedef enum {
/* compression parameters
* Note : When compressing with a ZSTD_CDict these parameters are superseded
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* by the parameters used to construct the ZSTD_CDict .
* See ZSTD_CCtx_refCDict ( ) for more info ( superseded - by - cdict ) . */
ZSTD_c_compressionLevel = 100 , /* Set compression parameters according to pre-defined cLevel table.
* Note that exact compression parameters are dynamically determined ,
* depending on both compression level and srcSize ( when known ) .
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* Default level is ZSTD_CLEVEL_DEFAULT = = 3.
* Special : value 0 means default , which is controlled by ZSTD_CLEVEL_DEFAULT .
* Note 1 : it ' s possible to pass a negative compression level .
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* Note 2 : setting a level does not automatically set all other compression parameters
* to default . Setting this will however eventually dynamically impact the compression
* parameters which have not been manually set . The manually set
* ones will ' stick ' . */
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/* Advanced compression parameters :
* It ' s possible to pin down compression parameters to some specific values .
* In which case , these values are no longer dynamically selected by the compressor */
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ZSTD_c_windowLog = 101 , /* Maximum allowed back-reference distance, expressed as power of 2.
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* This will set a memory budget for streaming decompression ,
* with larger values requiring more memory
* and typically compressing more .
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* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX .
* Special : value 0 means " use default windowLog " .
* Note : Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT
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* requires explicitly allowing such size at streaming decompression stage . */
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ZSTD_c_hashLog = 102 , /* Size of the initial probe table, as a power of 2.
* Resulting memory usage is ( 1 < < ( hashLog + 2 ) ) .
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX .
* Larger tables improve compression ratio of strategies < = dFast ,
* and improve speed of strategies > dFast .
* Special : value 0 means " use default hashLog " . */
ZSTD_c_chainLog = 103 , /* Size of the multi-probe search table, as a power of 2.
* Resulting memory usage is ( 1 < < ( chainLog + 2 ) ) .
* Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX .
* Larger tables result in better and slower compression .
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* This parameter is useless for " fast " strategy .
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* It ' s still useful when using " dfast " strategy ,
* in which case it defines a secondary probe table .
* Special : value 0 means " use default chainLog " . */
ZSTD_c_searchLog = 104 , /* Number of search attempts, as a power of 2.
* More attempts result in better and slower compression .
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* This parameter is useless for " fast " and " dFast " strategies .
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* Special : value 0 means " use default searchLog " . */
ZSTD_c_minMatch = 105 , /* Minimum size of searched matches.
* Note that Zstandard can still find matches of smaller size ,
* it just tweaks its search algorithm to look for this size and larger .
* Larger values increase compression and decompression speed , but decrease ratio .
* Must be clamped between ZSTD_MINMATCH_MIN and ZSTD_MINMATCH_MAX .
* Note that currently , for all strategies < btopt , effective minimum is 4.
* , for all strategies > fast , effective maximum is 6.
* Special : value 0 means " use default minMatchLength " . */
ZSTD_c_targetLength = 106 , /* Impact of this field depends on strategy.
* For strategies btopt , btultra & btultra2 :
* Length of Match considered " good enough " to stop search .
* Larger values make compression stronger , and slower .
* For strategy fast :
* Distance between match sampling .
* Larger values make compression faster , and weaker .
* Special : value 0 means " use default targetLength " . */
ZSTD_c_strategy = 107 , /* See ZSTD_strategy enum definition.
* The higher the value of selected strategy , the more complex it is ,
* resulting in stronger and slower compression .
* Special : value 0 means " use default strategy " . */
/* LDM mode parameters */
ZSTD_c_enableLongDistanceMatching = 160 , /* Enable long distance matching.
* This parameter is designed to improve compression ratio
* for large inputs , by finding large matches at long distance .
* It increases memory usage and window size .
* Note : enabling this parameter increases default ZSTD_c_windowLog to 128 MB
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* except when expressly set to a different value .
* Note : will be enabled by default if ZSTD_c_windowLog > = 128 MB and
* compression strategy > = ZSTD_btopt ( = = compression level 16 + ) */
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ZSTD_c_ldmHashLog = 161 , /* Size of the table for long distance matching, as a power of 2.
* Larger values increase memory usage and compression ratio ,
* but decrease compression speed .
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
* default : windowlog - 7.
* Special : value 0 means " automatically determine hashlog " . */
ZSTD_c_ldmMinMatch = 162 , /* Minimum match size for long distance matcher.
* Larger / too small values usually decrease compression ratio .
* Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX .
* Special : value 0 means " use default value " ( default : 64 ) . */
ZSTD_c_ldmBucketSizeLog = 163 , /* Log size of each bucket in the LDM hash table for collision resolution.
* Larger values improve collision resolution but decrease compression speed .
* The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX .
* Special : value 0 means " use default value " ( default : 3 ) . */
ZSTD_c_ldmHashRateLog = 164 , /* Frequency of inserting/looking up entries into the LDM hash table.
* Must be clamped between 0 and ( ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN ) .
* Default is MAX ( 0 , ( windowLog - ldmHashLog ) ) , optimizing hash table usage .
* Larger values improve compression speed .
* Deviating far from default value will likely result in a compression ratio decrease .
* Special : value 0 means " automatically determine hashRateLog " . */
/* frame parameters */
ZSTD_c_contentSizeFlag = 200 , /* Content size will be written into frame header _whenever known_ (default:1)
* Content size must be known at the beginning of compression .
* This is automatically the case when using ZSTD_compress2 ( ) ,
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* For streaming scenarios , content size must be provided with ZSTD_CCtx_setPledgedSrcSize ( ) */
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ZSTD_c_checksumFlag = 201 , /* A 32-bits checksum of content is written at end of frame (default:0) */
ZSTD_c_dictIDFlag = 202 , /* When applicable, dictionary's ID is written into frame header (default:1) */
/* multi-threading parameters */
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/* These parameters are only active if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD).
* Otherwise , trying to set any other value than default ( 0 ) will be a no - op and return an error .
* In a situation where it ' s unknown if the linked library supports multi - threading or not ,
* setting ZSTD_c_nbWorkers to any value > = 1 and consulting the return value provides a quick way to check this property .
*/
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ZSTD_c_nbWorkers = 400 , /* Select how many threads will be spawned to compress in parallel.
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* When nbWorkers > = 1 , triggers asynchronous mode when invoking ZSTD_compressStream * ( ) :
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* ZSTD_compressStream * ( ) consumes input and flush output if possible , but immediately gives back control to caller ,
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* while compression is performed in parallel , within worker thread ( s ) .
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* ( note : a strong exception to this rule is when first invocation of ZSTD_compressStream2 ( ) sets ZSTD_e_end :
* in which case , ZSTD_compressStream2 ( ) delegates to ZSTD_compress2 ( ) , which is always a blocking call ) .
* More workers improve speed , but also increase memory usage .
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* Default value is ` 0 ` , aka " single-threaded mode " : no worker is spawned ,
* compression is performed inside Caller ' s thread , and all invocations are blocking */
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ZSTD_c_jobSize = 401 , /* Size of a compression job. This value is enforced only when nbWorkers >= 1.
* Each compression job is completed in parallel , so this value can indirectly impact the nb of active threads .
* 0 means default , which is dynamically determined based on compression parameters .
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* Job size must be a minimum of overlap size , or ZSTDMT_JOBSIZE_MIN ( = 512 KB ) , whichever is largest .
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* The minimum size is automatically and transparently enforced . */
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ZSTD_c_overlapLog = 402 , /* Control the overlap size, as a fraction of window size.
* The overlap size is an amount of data reloaded from previous job at the beginning of a new job .
* It helps preserve compression ratio , while each job is compressed in parallel .
* This value is enforced only when nbWorkers > = 1.
* Larger values increase compression ratio , but decrease speed .
* Possible values range from 0 to 9 :
* - 0 means " default " : value will be determined by the library , depending on strategy
* - 1 means " no overlap "
* - 9 means " full overlap " , using a full window size .
* Each intermediate rank increases / decreases load size by a factor 2 :
* 9 : full window ; 8 : w / 2 ; 7 : w / 4 ; 6 : w / 8 ; 5 : w / 16 ; 4 : w / 32 ; 3 : w / 64 ; 2 : w / 128 ; 1 : no overlap ; 0 : default
* default value varies between 6 and 9 , depending on strategy */
/* note : additional experimental parameters are also available
* within the experimental section of the API .
* At the time of this writing , they include :
* ZSTD_c_rsyncable
* ZSTD_c_format
* ZSTD_c_forceMaxWindow
* ZSTD_c_forceAttachDict
* ZSTD_c_literalCompressionMode
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* ZSTD_c_targetCBlockSize
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* ZSTD_c_srcSizeHint
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* ZSTD_c_enableDedicatedDictSearch
* ZSTD_c_stableInBuffer
* ZSTD_c_stableOutBuffer
* ZSTD_c_blockDelimiters
* ZSTD_c_validateSequences
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* ZSTD_c_useBlockSplitter
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* ZSTD_c_useRowMatchFinder
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* ZSTD_c_prefetchCDictTables
* ZSTD_c_enableSeqProducerFallback
* ZSTD_c_maxBlockSize
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* Because they are not stable , it ' s necessary to define ZSTD_STATIC_LINKING_ONLY to access them .
* note : never ever use experimentalParam ? names directly ;
* also , the enums values themselves are unstable and can still change .
*/
ZSTD_c_experimentalParam1 = 500 ,
ZSTD_c_experimentalParam2 = 10 ,
ZSTD_c_experimentalParam3 = 1000 ,
ZSTD_c_experimentalParam4 = 1001 ,
ZSTD_c_experimentalParam5 = 1002 ,
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ZSTD_c_experimentalParam6 = 1003 ,
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ZSTD_c_experimentalParam7 = 1004 ,
ZSTD_c_experimentalParam8 = 1005 ,
ZSTD_c_experimentalParam9 = 1006 ,
ZSTD_c_experimentalParam10 = 1007 ,
ZSTD_c_experimentalParam11 = 1008 ,
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ZSTD_c_experimentalParam12 = 1009 ,
ZSTD_c_experimentalParam13 = 1010 ,
ZSTD_c_experimentalParam14 = 1011 ,
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ZSTD_c_experimentalParam15 = 1012 ,
ZSTD_c_experimentalParam16 = 1013 ,
ZSTD_c_experimentalParam17 = 1014 ,
ZSTD_c_experimentalParam18 = 1015 ,
ZSTD_c_experimentalParam19 = 1016
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} ZSTD_cParameter ;
typedef struct {
size_t error ;
int lowerBound ;
int upperBound ;
} ZSTD_bounds ;
/*! ZSTD_cParam_getBounds() :
* All parameters must belong to an interval with lower and upper bounds ,
* otherwise they will either trigger an error or be automatically clamped .
* @ return : a structure , ZSTD_bounds , which contains
* - an error status field , which must be tested using ZSTD_isError ( )
* - lower and upper bounds , both inclusive
*/
ZSTDLIB_API ZSTD_bounds ZSTD_cParam_getBounds ( ZSTD_cParameter cParam ) ;
/*! ZSTD_CCtx_setParameter() :
* Set one compression parameter , selected by enum ZSTD_cParameter .
* All parameters have valid bounds . Bounds can be queried using ZSTD_cParam_getBounds ( ) .
* Providing a value beyond bound will either clamp it , or trigger an error ( depending on parameter ) .
* Setting a parameter is generally only possible during frame initialization ( before starting compression ) .
* Exception : when using multi - threading mode ( nbWorkers > = 1 ) ,
* the following parameters can be updated _during_ compression ( within same frame ) :
* = > compressionLevel , hashLog , chainLog , searchLog , minMatch , targetLength and strategy .
* new parameters will be active for next job only ( after a flush ( ) ) .
* @ return : an error code ( which can be tested using ZSTD_isError ( ) ) .
*/
ZSTDLIB_API size_t ZSTD_CCtx_setParameter ( ZSTD_CCtx * cctx , ZSTD_cParameter param , int value ) ;
/*! ZSTD_CCtx_setPledgedSrcSize() :
* Total input data size to be compressed as a single frame .
* Value will be written in frame header , unless if explicitly forbidden using ZSTD_c_contentSizeFlag .
* This value will also be controlled at end of frame , and trigger an error if not respected .
* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Note 1 : pledgedSrcSize = = 0 actually means zero , aka an empty frame .
* In order to mean " unknown content size " , pass constant ZSTD_CONTENTSIZE_UNKNOWN .
* ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame .
* Note 2 : pledgedSrcSize is only valid once , for the next frame .
* It ' s discarded at the end of the frame , and replaced by ZSTD_CONTENTSIZE_UNKNOWN .
* Note 3 : Whenever all input data is provided and consumed in a single round ,
* for example with ZSTD_compress2 ( ) ,
* or invoking immediately ZSTD_compressStream2 ( , , , ZSTD_e_end ) ,
* this value is automatically overridden by srcSize instead .
*/
ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize ( ZSTD_CCtx * cctx , unsigned long long pledgedSrcSize ) ;
typedef enum {
ZSTD_reset_session_only = 1 ,
ZSTD_reset_parameters = 2 ,
ZSTD_reset_session_and_parameters = 3
} ZSTD_ResetDirective ;
/*! ZSTD_CCtx_reset() :
* There are 2 different things that can be reset , independently or jointly :
* - The session : will stop compressing current frame , and make CCtx ready to start a new one .
* Useful after an error , or to interrupt any ongoing compression .
* Any internal data not yet flushed is cancelled .
* Compression parameters and dictionary remain unchanged .
* They will be used to compress next frame .
* Resetting session never fails .
* - The parameters : changes all parameters back to " default " .
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* This also removes any reference to any dictionary or external sequence producer .
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* Parameters can only be changed between 2 sessions ( i . e . no compression is currently ongoing )
* otherwise the reset fails , and function returns an error value ( which can be tested using ZSTD_isError ( ) )
* - Both : similar to resetting the session , followed by resetting parameters .
*/
ZSTDLIB_API size_t ZSTD_CCtx_reset ( ZSTD_CCtx * cctx , ZSTD_ResetDirective reset ) ;
/*! ZSTD_compress2() :
* Behave the same as ZSTD_compressCCtx ( ) , but compression parameters are set using the advanced API .
* ZSTD_compress2 ( ) always starts a new frame .
* Should cctx hold data from a previously unfinished frame , everything about it is forgotten .
* - Compression parameters are pushed into CCtx before starting compression , using ZSTD_CCtx_set * ( )
* - The function is always blocking , returns when compression is completed .
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* NOTE : Providing ` dstCapacity > = ZSTD_compressBound ( srcSize ) ` guarantees that zstd will have
* enough space to successfully compress the data , though it is possible it fails for other reasons .
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* @ return : compressed size written into ` dst ` ( < = ` dstCapacity ) ,
* or an error code if it fails ( which can be tested using ZSTD_isError ( ) ) .
*/
ZSTDLIB_API size_t ZSTD_compress2 ( ZSTD_CCtx * cctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ) ;
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/***********************************************
* Advanced decompression API ( Requires v1 .4 .0 + )
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/* The advanced API pushes parameters one by one into an existing DCtx context.
* Parameters are sticky , and remain valid for all following frames
* using the same DCtx context .
* It ' s possible to reset parameters to default values using ZSTD_DCtx_reset ( ) .
* Note : This API is compatible with existing ZSTD_decompressDCtx ( ) and ZSTD_decompressStream ( ) .
* Therefore , no new decompression function is necessary .
*/
typedef enum {
ZSTD_d_windowLogMax = 100 , /* Select a size limit (in power of 2) beyond which
* the streaming API will refuse to allocate memory buffer
* in order to protect the host from unreasonable memory requirements .
* This parameter is only useful in streaming mode , since no internal buffer is allocated in single - pass mode .
* By default , a decompression context accepts window sizes < = ( 1 < < ZSTD_WINDOWLOG_LIMIT_DEFAULT ) .
* Special : value 0 means " use default maximum windowLog " . */
/* note : additional experimental parameters are also available
* within the experimental section of the API .
* At the time of this writing , they include :
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* ZSTD_d_format
* ZSTD_d_stableOutBuffer
* ZSTD_d_forceIgnoreChecksum
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* ZSTD_d_refMultipleDDicts
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* ZSTD_d_disableHuffmanAssembly
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* Because they are not stable , it ' s necessary to define ZSTD_STATIC_LINKING_ONLY to access them .
* note : never ever use experimentalParam ? names directly
*/
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ZSTD_d_experimentalParam1 = 1000 ,
ZSTD_d_experimentalParam2 = 1001 ,
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ZSTD_d_experimentalParam3 = 1002 ,
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ZSTD_d_experimentalParam4 = 1003 ,
ZSTD_d_experimentalParam5 = 1004
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} ZSTD_dParameter ;
/*! ZSTD_dParam_getBounds() :
* All parameters must belong to an interval with lower and upper bounds ,
* otherwise they will either trigger an error or be automatically clamped .
* @ return : a structure , ZSTD_bounds , which contains
* - an error status field , which must be tested using ZSTD_isError ( )
* - both lower and upper bounds , inclusive
*/
ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds ( ZSTD_dParameter dParam ) ;
/*! ZSTD_DCtx_setParameter() :
* Set one compression parameter , selected by enum ZSTD_dParameter .
* All parameters have valid bounds . Bounds can be queried using ZSTD_dParam_getBounds ( ) .
* Providing a value beyond bound will either clamp it , or trigger an error ( depending on parameter ) .
* Setting a parameter is only possible during frame initialization ( before starting decompression ) .
* @ return : 0 , or an error code ( which can be tested using ZSTD_isError ( ) ) .
*/
ZSTDLIB_API size_t ZSTD_DCtx_setParameter ( ZSTD_DCtx * dctx , ZSTD_dParameter param , int value ) ;
/*! ZSTD_DCtx_reset() :
* Return a DCtx to clean state .
* Session and parameters can be reset jointly or separately .
* Parameters can only be reset when no active frame is being decompressed .
* @ return : 0 , or an error code , which can be tested with ZSTD_isError ( )
*/
ZSTDLIB_API size_t ZSTD_DCtx_reset ( ZSTD_DCtx * dctx , ZSTD_ResetDirective reset ) ;
/****************************
* Streaming
* * * * * * * * * * * * * * * * * * * * * * * * * * * */
typedef struct ZSTD_inBuffer_s {
const void * src ; /**< start of input buffer */
size_t size ; /**< size of input buffer */
size_t pos ; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */
} ZSTD_inBuffer ;
typedef struct ZSTD_outBuffer_s {
void * dst ; /**< start of output buffer */
size_t size ; /**< size of output buffer */
size_t pos ; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */
} ZSTD_outBuffer ;
/*-***********************************************************************
* Streaming compression - HowTo
*
* A ZSTD_CStream object is required to track streaming operation .
* Use ZSTD_createCStream ( ) and ZSTD_freeCStream ( ) to create / release resources .
* ZSTD_CStream objects can be reused multiple times on consecutive compression operations .
* It is recommended to re - use ZSTD_CStream since it will play nicer with system ' s memory , by re - using already allocated memory .
*
* For parallel execution , use one separate ZSTD_CStream per thread .
*
* note : since v1 .3 .0 , ZSTD_CStream and ZSTD_CCtx are the same thing .
*
* Parameters are sticky : when starting a new compression on the same context ,
* it will re - use the same sticky parameters as previous compression session .
* When in doubt , it ' s recommended to fully initialize the context before usage .
* Use ZSTD_CCtx_reset ( ) to reset the context and ZSTD_CCtx_setParameter ( ) ,
* ZSTD_CCtx_setPledgedSrcSize ( ) , or ZSTD_CCtx_loadDictionary ( ) and friends to
* set more specific parameters , the pledged source size , or load a dictionary .
*
* Use ZSTD_compressStream2 ( ) with ZSTD_e_continue as many times as necessary to
* consume input stream . The function will automatically update both ` pos `
* fields within ` input ` and ` output ` .
* Note that the function may not consume the entire input , for example , because
* the output buffer is already full , in which case ` input . pos < input . size ` .
* The caller must check if input has been entirely consumed .
* If not , the caller must make some room to receive more compressed data ,
* and then present again remaining input data .
* note : ZSTD_e_continue is guaranteed to make some forward progress when called ,
* but doesn ' t guarantee maximal forward progress . This is especially relevant
* when compressing with multiple threads . The call won ' t block if it can
* consume some input , but if it can ' t it will wait for some , but not all ,
* output to be flushed .
* @ return : provides a minimum amount of data remaining to be flushed from internal buffers
* or an error code , which can be tested using ZSTD_isError ( ) .
*
* At any moment , it ' s possible to flush whatever data might remain stuck within internal buffer ,
* using ZSTD_compressStream2 ( ) with ZSTD_e_flush . ` output - > pos ` will be updated .
* Note that , if ` output - > size ` is too small , a single invocation with ZSTD_e_flush might not be enough ( return code > 0 ) .
* In which case , make some room to receive more compressed data , and call again ZSTD_compressStream2 ( ) with ZSTD_e_flush .
* You must continue calling ZSTD_compressStream2 ( ) with ZSTD_e_flush until it returns 0 , at which point you can change the
* operation .
* note : ZSTD_e_flush will flush as much output as possible , meaning when compressing with multiple threads , it will
* block until the flush is complete or the output buffer is full .
* @ return : 0 if internal buffers are entirely flushed ,
* > 0 if some data still present within internal buffer ( the value is minimal estimation of remaining size ) ,
* or an error code , which can be tested using ZSTD_isError ( ) .
*
* Calling ZSTD_compressStream2 ( ) with ZSTD_e_end instructs to finish a frame .
* It will perform a flush and write frame epilogue .
* The epilogue is required for decoders to consider a frame completed .
* flush operation is the same , and follows same rules as calling ZSTD_compressStream2 ( ) with ZSTD_e_flush .
* You must continue calling ZSTD_compressStream2 ( ) with ZSTD_e_end until it returns 0 , at which point you are free to
* start a new frame .
* note : ZSTD_e_end will flush as much output as possible , meaning when compressing with multiple threads , it will
* block until the flush is complete or the output buffer is full .
* @ return : 0 if frame fully completed and fully flushed ,
* > 0 if some data still present within internal buffer ( the value is minimal estimation of remaining size ) ,
* or an error code , which can be tested using ZSTD_isError ( ) .
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
typedef ZSTD_CCtx ZSTD_CStream ; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */
/* Continue to distinguish them for compatibility with older versions <= v1.2.0 */
/*===== ZSTD_CStream management functions =====*/
ZSTDLIB_API ZSTD_CStream * ZSTD_createCStream ( void ) ;
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ZSTDLIB_API size_t ZSTD_freeCStream ( ZSTD_CStream * zcs ) ; /* accept NULL pointer */
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/*===== Streaming compression functions =====*/
typedef enum {
ZSTD_e_continue = 0 , /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */
ZSTD_e_flush = 1 , /* flush any data provided so far,
* it creates ( at least ) one new block , that can be decoded immediately on reception ;
* frame will continue : any future data can still reference previously compressed data , improving compression .
* note : multithreaded compression will block to flush as much output as possible . */
ZSTD_e_end = 2 /* flush any remaining data _and_ close current frame.
* note that frame is only closed after compressed data is fully flushed ( return value = = 0 ) .
* After that point , any additional data starts a new frame .
* note : each frame is independent ( does not reference any content from previous frame ) .
: note : multithreaded compression will block to flush as much output as possible . */
} ZSTD_EndDirective ;
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/*! ZSTD_compressStream2() : Requires v1.4.0+
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* Behaves about the same as ZSTD_compressStream , with additional control on end directive .
* - Compression parameters are pushed into CCtx before starting compression , using ZSTD_CCtx_set * ( )
* - Compression parameters cannot be changed once compression is started ( save a list of exceptions in multi - threading mode )
* - output - > pos must be < = dstCapacity , input - > pos must be < = srcSize
* - output - > pos and input - > pos will be updated . They are guaranteed to remain below their respective limit .
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* - endOp must be a valid directive
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* - When nbWorkers = = 0 ( default ) , function is blocking : it completes its job before returning to caller .
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* - When nbWorkers > = 1 , function is non - blocking : it copies a portion of input , distributes jobs to internal worker threads , flush to output whatever is available ,
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* and then immediately returns , just indicating that there is some data remaining to be flushed .
* The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1 + byte .
* - Exception : if the first call requests a ZSTD_e_end directive and provides enough dstCapacity , the function delegates to ZSTD_compress2 ( ) which is always blocking .
* - @ return provides a minimum amount of data remaining to be flushed from internal buffers
* or an error code , which can be tested using ZSTD_isError ( ) .
* if @ return ! = 0 , flush is not fully completed , there is still some data left within internal buffers .
* This is useful for ZSTD_e_flush , since in this case more flushes are necessary to empty all buffers .
* For ZSTD_e_end , @ return = = 0 when internal buffers are fully flushed and frame is completed .
* - after a ZSTD_e_end directive , if internal buffer is not fully flushed ( @ return ! = 0 ) ,
* only ZSTD_e_end or ZSTD_e_flush operations are allowed .
* Before starting a new compression job , or changing compression parameters ,
* it is required to fully flush internal buffers .
*/
ZSTDLIB_API size_t ZSTD_compressStream2 ( ZSTD_CCtx * cctx ,
ZSTD_outBuffer * output ,
ZSTD_inBuffer * input ,
ZSTD_EndDirective endOp ) ;
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/* These buffer sizes are softly recommended.
* They are not required : ZSTD_compressStream * ( ) happily accepts any buffer size , for both input and output .
* Respecting the recommended size just makes it a bit easier for ZSTD_compressStream * ( ) ,
* reducing the amount of memory shuffling and buffering , resulting in minor performance savings .
*
* However , note that these recommendations are from the perspective of a C caller program .
* If the streaming interface is invoked from some other language ,
* especially managed ones such as Java or Go , through a foreign function interface such as jni or cgo ,
* a major performance rule is to reduce crossing such interface to an absolute minimum .
* It ' s not rare that performance ends being spent more into the interface , rather than compression itself .
* In which cases , prefer using large buffers , as large as practical ,
* for both input and output , to reduce the nb of roundtrips .
*/
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ZSTDLIB_API size_t ZSTD_CStreamInSize ( void ) ; /**< recommended size for input buffer */
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ZSTDLIB_API size_t ZSTD_CStreamOutSize ( void ) ; /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */
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/* *****************************************************************************
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* This following is a legacy streaming API , available since v1 .0 + .
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* It can be replaced by ZSTD_CCtx_reset ( ) and ZSTD_compressStream2 ( ) .
* It is redundant , but remains fully supported .
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/*!
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* Equivalent to :
*
* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
* ZSTD_CCtx_refCDict ( zcs , NULL ) ; // clear the dictionary (if any)
* ZSTD_CCtx_setParameter ( zcs , ZSTD_c_compressionLevel , compressionLevel ) ;
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*
* Note that ZSTD_initCStream ( ) clears any previously set dictionary . Use the new API
* to compress with a dictionary .
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*/
ZSTDLIB_API size_t ZSTD_initCStream ( ZSTD_CStream * zcs , int compressionLevel ) ;
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/*!
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* Alternative for ZSTD_compressStream2 ( zcs , output , input , ZSTD_e_continue ) .
* NOTE : The return value is different . ZSTD_compressStream ( ) returns a hint for
* the next read size ( if non - zero and not an error ) . ZSTD_compressStream2 ( )
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* returns the minimum nb of bytes left to flush ( if non - zero and not an error ) .
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*/
ZSTDLIB_API size_t ZSTD_compressStream ( ZSTD_CStream * zcs , ZSTD_outBuffer * output , ZSTD_inBuffer * input ) ;
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/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */
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ZSTDLIB_API size_t ZSTD_flushStream ( ZSTD_CStream * zcs , ZSTD_outBuffer * output ) ;
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/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */
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ZSTDLIB_API size_t ZSTD_endStream ( ZSTD_CStream * zcs , ZSTD_outBuffer * output ) ;
/*-***************************************************************************
* Streaming decompression - HowTo
*
* A ZSTD_DStream object is required to track streaming operations .
* Use ZSTD_createDStream ( ) and ZSTD_freeDStream ( ) to create / release resources .
* ZSTD_DStream objects can be re - used multiple times .
*
* Use ZSTD_initDStream ( ) to start a new decompression operation .
* @ return : recommended first input size
* Alternatively , use advanced API to set specific properties .
*
* Use ZSTD_decompressStream ( ) repetitively to consume your input .
* The function will update both ` pos ` fields .
* If ` input . pos < input . size ` , some input has not been consumed .
* It ' s up to the caller to present again remaining data .
* The function tries to flush all data decoded immediately , respecting output buffer size .
* If ` output . pos < output . size ` , decoder has flushed everything it could .
* But if ` output . pos = = output . size ` , there might be some data left within internal buffers . ,
* In which case , call ZSTD_decompressStream ( ) again to flush whatever remains in the buffer .
* Note : with no additional input provided , amount of data flushed is necessarily < = ZSTD_BLOCKSIZE_MAX .
* @ return : 0 when a frame is completely decoded and fully flushed ,
* or an error code , which can be tested using ZSTD_isError ( ) ,
* or any other value > 0 , which means there is still some decoding or flushing to do to complete current frame :
* the return value is a suggested next input size ( just a hint for better latency )
* that will never request more than the remaining frame size .
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
typedef ZSTD_DCtx ZSTD_DStream ; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */
/* For compatibility with versions <= v1.2.0, prefer differentiating them. */
/*===== ZSTD_DStream management functions =====*/
ZSTDLIB_API ZSTD_DStream * ZSTD_createDStream ( void ) ;
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ZSTDLIB_API size_t ZSTD_freeDStream ( ZSTD_DStream * zds ) ; /* accept NULL pointer */
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/*===== Streaming decompression functions =====*/
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/*! ZSTD_initDStream() :
* Initialize / reset DStream state for new decompression operation .
* Call before new decompression operation using same DStream .
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*
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* Note : This function is redundant with the advanced API and equivalent to :
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* ZSTD_DCtx_reset ( zds , ZSTD_reset_session_only ) ;
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* ZSTD_DCtx_refDDict ( zds , NULL ) ;
*/
ZSTDLIB_API size_t ZSTD_initDStream ( ZSTD_DStream * zds ) ;
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/*! ZSTD_decompressStream() :
* Streaming decompression function .
* Call repetitively to consume full input updating it as necessary .
* Function will update both input and output ` pos ` fields exposing current state via these fields :
* - ` input . pos < input . size ` , some input remaining and caller should provide remaining input
* on the next call .
* - ` output . pos < output . size ` , decoder finished and flushed all remaining buffers .
* - ` output . pos = = output . size ` , potentially uncflushed data present in the internal buffers ,
* call ZSTD_decompressStream ( ) again to flush remaining data to output .
* Note : with no additional input , amount of data flushed < = ZSTD_BLOCKSIZE_MAX .
*
* @ return : 0 when a frame is completely decoded and fully flushed ,
* or an error code , which can be tested using ZSTD_isError ( ) ,
* or any other value > 0 , which means there is some decoding or flushing to do to complete current frame .
*/
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ZSTDLIB_API size_t ZSTD_decompressStream ( ZSTD_DStream * zds , ZSTD_outBuffer * output , ZSTD_inBuffer * input ) ;
ZSTDLIB_API size_t ZSTD_DStreamInSize ( void ) ; /*!< recommended size for input buffer */
ZSTDLIB_API size_t ZSTD_DStreamOutSize ( void ) ; /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */
/**************************
* Simple dictionary API
* * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_compress_usingDict() :
* Compression at an explicit compression level using a Dictionary .
* A dictionary can be any arbitrary data segment ( also called a prefix ) ,
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* or a buffer with specified information ( see zdict . h ) .
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* Note : This function loads the dictionary , resulting in significant startup delay .
* It ' s intended for a dictionary used only once .
* Note 2 : When ` dict = = NULL | | dictSize < 8 ` no dictionary is used . */
ZSTDLIB_API size_t ZSTD_compress_usingDict ( ZSTD_CCtx * ctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const void * dict , size_t dictSize ,
int compressionLevel ) ;
/*! ZSTD_decompress_usingDict() :
* Decompression using a known Dictionary .
* Dictionary must be identical to the one used during compression .
* Note : This function loads the dictionary , resulting in significant startup delay .
* It ' s intended for a dictionary used only once .
* Note : When ` dict = = NULL | | dictSize < 8 ` no dictionary is used . */
ZSTDLIB_API size_t ZSTD_decompress_usingDict ( ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const void * dict , size_t dictSize ) ;
/***********************************
* Bulk processing dictionary API
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
typedef struct ZSTD_CDict_s ZSTD_CDict ;
/*! ZSTD_createCDict() :
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* When compressing multiple messages or blocks using the same dictionary ,
* it ' s recommended to digest the dictionary only once , since it ' s a costly operation .
* ZSTD_createCDict ( ) will create a state from digesting a dictionary .
* The resulting state can be used for future compression operations with very limited startup cost .
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* ZSTD_CDict can be created once and shared by multiple threads concurrently , since its usage is read - only .
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* @ dictBuffer can be released after ZSTD_CDict creation , because its content is copied within CDict .
* Note 1 : Consider experimental function ` ZSTD_createCDict_byReference ( ) ` if you prefer to not duplicate @ dictBuffer content .
* Note 2 : A ZSTD_CDict can be created from an empty @ dictBuffer ,
* in which case the only thing that it transports is the @ compressionLevel .
* This can be useful in a pipeline featuring ZSTD_compress_usingCDict ( ) exclusively ,
* expecting a ZSTD_CDict parameter with any data , including those without a known dictionary . */
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ZSTDLIB_API ZSTD_CDict * ZSTD_createCDict ( const void * dictBuffer , size_t dictSize ,
int compressionLevel ) ;
/*! ZSTD_freeCDict() :
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* Function frees memory allocated by ZSTD_createCDict ( ) .
* If a NULL pointer is passed , no operation is performed . */
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ZSTDLIB_API size_t ZSTD_freeCDict ( ZSTD_CDict * CDict ) ;
/*! ZSTD_compress_usingCDict() :
* Compression using a digested Dictionary .
* Recommended when same dictionary is used multiple times .
* Note : compression level is _decided at dictionary creation time_ ,
* and frame parameters are hardcoded ( dictID = yes , contentSize = yes , checksum = no ) */
ZSTDLIB_API size_t ZSTD_compress_usingCDict ( ZSTD_CCtx * cctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const ZSTD_CDict * cdict ) ;
typedef struct ZSTD_DDict_s ZSTD_DDict ;
/*! ZSTD_createDDict() :
* Create a digested dictionary , ready to start decompression operation without startup delay .
* dictBuffer can be released after DDict creation , as its content is copied inside DDict . */
ZSTDLIB_API ZSTD_DDict * ZSTD_createDDict ( const void * dictBuffer , size_t dictSize ) ;
/*! ZSTD_freeDDict() :
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* Function frees memory allocated with ZSTD_createDDict ( )
* If a NULL pointer is passed , no operation is performed . */
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ZSTDLIB_API size_t ZSTD_freeDDict ( ZSTD_DDict * ddict ) ;
/*! ZSTD_decompress_usingDDict() :
* Decompression using a digested Dictionary .
* Recommended when same dictionary is used multiple times . */
ZSTDLIB_API size_t ZSTD_decompress_usingDDict ( ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const ZSTD_DDict * ddict ) ;
/********************************
* Dictionary helper functions
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/*! ZSTD_getDictID_fromDict() : Requires v1.4.0+
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* Provides the dictID stored within dictionary .
* if @ return = = 0 , the dictionary is not conformant with Zstandard specification .
* It can still be loaded , but as a content - only dictionary . */
ZSTDLIB_API unsigned ZSTD_getDictID_fromDict ( const void * dict , size_t dictSize ) ;
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/*! ZSTD_getDictID_fromCDict() : Requires v1.5.0+
* Provides the dictID of the dictionary loaded into ` cdict ` .
* If @ return = = 0 , the dictionary is not conformant to Zstandard specification , or empty .
* Non - conformant dictionaries can still be loaded , but as content - only dictionaries . */
ZSTDLIB_API unsigned ZSTD_getDictID_fromCDict ( const ZSTD_CDict * cdict ) ;
/*! ZSTD_getDictID_fromDDict() : Requires v1.4.0+
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* Provides the dictID of the dictionary loaded into ` ddict ` .
* If @ return = = 0 , the dictionary is not conformant to Zstandard specification , or empty .
* Non - conformant dictionaries can still be loaded , but as content - only dictionaries . */
ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict ( const ZSTD_DDict * ddict ) ;
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/*! ZSTD_getDictID_fromFrame() : Requires v1.4.0+
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* Provides the dictID required to decompressed the frame stored within ` src ` .
* If @ return = = 0 , the dictID could not be decoded .
* This could for one of the following reasons :
* - The frame does not require a dictionary to be decoded ( most common case ) .
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* - The frame was built with dictID intentionally removed . Whatever dictionary is necessary is a hidden piece of information .
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* Note : this use case also happens when using a non - conformant dictionary .
* - ` srcSize ` is too small , and as a result , the frame header could not be decoded ( only possible if ` srcSize < ZSTD_FRAMEHEADERSIZE_MAX ` ) .
* - This is not a Zstandard frame .
* When identifying the exact failure cause , it ' s possible to use ZSTD_getFrameHeader ( ) , which will provide a more precise error code . */
ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame ( const void * src , size_t srcSize ) ;
/*******************************************************************************
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* Advanced dictionary and prefix API ( Requires v1 .4 .0 + )
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*
* This API allows dictionaries to be used with ZSTD_compress2 ( ) ,
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* ZSTD_compressStream2 ( ) , and ZSTD_decompressDCtx ( ) .
* Dictionaries are sticky , they remain valid when same context is re - used ,
* they only reset when the context is reset
* with ZSTD_reset_parameters or ZSTD_reset_session_and_parameters .
* In contrast , Prefixes are single - use .
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/*! ZSTD_CCtx_loadDictionary() : Requires v1.4.0+
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* Create an internal CDict from ` dict ` buffer .
* Decompression will have to use same dictionary .
* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Special : Loading a NULL ( or 0 - size ) dictionary invalidates previous dictionary ,
* meaning " return to no-dictionary mode " .
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* Note 1 : Dictionary is sticky , it will be used for all future compressed frames ,
* until parameters are reset , a new dictionary is loaded , or the dictionary
* is explicitly invalidated by loading a NULL dictionary .
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* Note 2 : Loading a dictionary involves building tables .
* It ' s also a CPU consuming operation , with non - negligible impact on latency .
* Tables are dependent on compression parameters , and for this reason ,
* compression parameters can no longer be changed after loading a dictionary .
* Note 3 : ` dict ` content will be copied internally .
* Use experimental ZSTD_CCtx_loadDictionary_byReference ( ) to reference content instead .
* In such a case , dictionary buffer must outlive its users .
* Note 4 : Use ZSTD_CCtx_loadDictionary_advanced ( )
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* to precisely select how dictionary content must be interpreted .
* Note 5 : This method does not benefit from LDM ( long distance mode ) .
* If you want to employ LDM on some large dictionary content ,
* prefer employing ZSTD_CCtx_refPrefix ( ) described below .
*/
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ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary ( ZSTD_CCtx * cctx , const void * dict , size_t dictSize ) ;
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/*! ZSTD_CCtx_refCDict() : Requires v1.4.0+
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* Reference a prepared dictionary , to be used for all future compressed frames .
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* Note that compression parameters are enforced from within CDict ,
* and supersede any compression parameter previously set within CCtx .
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* The parameters ignored are labelled as " superseded-by-cdict " in the ZSTD_cParameter enum docs .
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* The ignored parameters will be used again if the CCtx is returned to no - dictionary mode .
* The dictionary will remain valid for future compressed frames using same CCtx .
* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Special : Referencing a NULL CDict means " return to no-dictionary mode " .
* Note 1 : Currently , only one dictionary can be managed .
* Referencing a new dictionary effectively " discards " any previous one .
* Note 2 : CDict is just referenced , its lifetime must outlive its usage within CCtx . */
ZSTDLIB_API size_t ZSTD_CCtx_refCDict ( ZSTD_CCtx * cctx , const ZSTD_CDict * cdict ) ;
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/*! ZSTD_CCtx_refPrefix() : Requires v1.4.0+
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* Reference a prefix ( single - usage dictionary ) for next compressed frame .
* A prefix is * * only used once * * . Tables are discarded at end of frame ( ZSTD_e_end ) .
* Decompression will need same prefix to properly regenerate data .
* Compressing with a prefix is similar in outcome as performing a diff and compressing it ,
* but performs much faster , especially during decompression ( compression speed is tunable with compression level ) .
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* This method is compatible with LDM ( long distance mode ) .
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* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Special : Adding any prefix ( including NULL ) invalidates any previous prefix or dictionary
* Note 1 : Prefix buffer is referenced . It * * must * * outlive compression .
* Its content must remain unmodified during compression .
* Note 2 : If the intention is to diff some large src data blob with some prior version of itself ,
* ensure that the window size is large enough to contain the entire source .
* See ZSTD_c_windowLog .
* Note 3 : Referencing a prefix involves building tables , which are dependent on compression parameters .
* It ' s a CPU consuming operation , with non - negligible impact on latency .
* If there is a need to use the same prefix multiple times , consider loadDictionary instead .
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* Note 4 : By default , the prefix is interpreted as raw content ( ZSTD_dct_rawContent ) .
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* Use experimental ZSTD_CCtx_refPrefix_advanced ( ) to alter dictionary interpretation . */
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix ( ZSTD_CCtx * cctx ,
const void * prefix , size_t prefixSize ) ;
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/*! ZSTD_DCtx_loadDictionary() : Requires v1.4.0+
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* Create an internal DDict from dict buffer , to be used to decompress all future frames .
* The dictionary remains valid for all future frames , until explicitly invalidated , or
* a new dictionary is loaded .
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* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Special : Adding a NULL ( or 0 - size ) dictionary invalidates any previous dictionary ,
* meaning " return to no-dictionary mode " .
* Note 1 : Loading a dictionary involves building tables ,
* which has a non - negligible impact on CPU usage and latency .
* It ' s recommended to " load once, use many times " , to amortize the cost
* Note 2 : ` dict ` content will be copied internally , so ` dict ` can be released after loading .
* Use ZSTD_DCtx_loadDictionary_byReference ( ) to reference dictionary content instead .
* Note 3 : Use ZSTD_DCtx_loadDictionary_advanced ( ) to take control of
* how dictionary content is loaded and interpreted .
*/
ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary ( ZSTD_DCtx * dctx , const void * dict , size_t dictSize ) ;
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/*! ZSTD_DCtx_refDDict() : Requires v1.4.0+
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* Reference a prepared dictionary , to be used to decompress next frames .
* The dictionary remains active for decompression of future frames using same DCtx .
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*
* If called with ZSTD_d_refMultipleDDicts enabled , repeated calls of this function
* will store the DDict references in a table , and the DDict used for decompression
* will be determined at decompression time , as per the dict ID in the frame .
* The memory for the table is allocated on the first call to refDDict , and can be
* freed with ZSTD_freeDCtx ( ) .
*
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* If called with ZSTD_d_refMultipleDDicts disabled ( the default ) , only one dictionary
* will be managed , and referencing a dictionary effectively " discards " any previous one .
*
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* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Special : referencing a NULL DDict means " return to no-dictionary mode " .
* Note 2 : DDict is just referenced , its lifetime must outlive its usage from DCtx .
*/
ZSTDLIB_API size_t ZSTD_DCtx_refDDict ( ZSTD_DCtx * dctx , const ZSTD_DDict * ddict ) ;
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/*! ZSTD_DCtx_refPrefix() : Requires v1.4.0+
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* Reference a prefix ( single - usage dictionary ) to decompress next frame .
* This is the reverse operation of ZSTD_CCtx_refPrefix ( ) ,
* and must use the same prefix as the one used during compression .
* Prefix is * * only used once * * . Reference is discarded at end of frame .
* End of frame is reached when ZSTD_decompressStream ( ) returns 0.
* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
* Note 1 : Adding any prefix ( including NULL ) invalidates any previously set prefix or dictionary
* Note 2 : Prefix buffer is referenced . It * * must * * outlive decompression .
* Prefix buffer must remain unmodified up to the end of frame ,
* reached when ZSTD_decompressStream ( ) returns 0.
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* Note 3 : By default , the prefix is treated as raw content ( ZSTD_dct_rawContent ) .
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* Use ZSTD_CCtx_refPrefix_advanced ( ) to alter dictMode ( Experimental section )
* Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost .
* A full dictionary is more costly , as it requires building tables .
*/
ZSTDLIB_API size_t ZSTD_DCtx_refPrefix ( ZSTD_DCtx * dctx ,
const void * prefix , size_t prefixSize ) ;
/* === Memory management === */
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/*! ZSTD_sizeof_*() : Requires v1.4.0+
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* These functions give the _current_ memory usage of selected object .
* Note that object memory usage can evolve ( increase or decrease ) over time . */
ZSTDLIB_API size_t ZSTD_sizeof_CCtx ( const ZSTD_CCtx * cctx ) ;
ZSTDLIB_API size_t ZSTD_sizeof_DCtx ( const ZSTD_DCtx * dctx ) ;
ZSTDLIB_API size_t ZSTD_sizeof_CStream ( const ZSTD_CStream * zcs ) ;
ZSTDLIB_API size_t ZSTD_sizeof_DStream ( const ZSTD_DStream * zds ) ;
ZSTDLIB_API size_t ZSTD_sizeof_CDict ( const ZSTD_CDict * cdict ) ;
ZSTDLIB_API size_t ZSTD_sizeof_DDict ( const ZSTD_DDict * ddict ) ;
# endif /* ZSTD_H_235446 */
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/* **************************************************************************************
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* ADVANCED AND EXPERIMENTAL FUNCTIONS
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* The definitions in the following section are considered experimental .
* They are provided for advanced scenarios .
* They should never be used with a dynamic library , as prototypes may change in the future .
* Use them only in association with static linking .
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
# if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
# define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
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/* This can be overridden externally to hide static symbols. */
# ifndef ZSTDLIB_STATIC_API
# if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
# define ZSTDLIB_STATIC_API __declspec(dllexport) ZSTDLIB_VISIBLE
# elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
# define ZSTDLIB_STATIC_API __declspec(dllimport) ZSTDLIB_VISIBLE
# else
# define ZSTDLIB_STATIC_API ZSTDLIB_VISIBLE
# endif
# endif
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/****************************************************************************************
* experimental API ( static linking only )
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* The following symbols and constants
* are not planned to join " stable API " status in the near future .
* They can still change in future versions .
* Some of them are planned to remain in the static_only section indefinitely .
* Some of them might be removed in the future ( especially when redundant with existing stable functions )
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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# define ZSTD_FRAMEHEADERSIZE_PREFIX(format) ((format) == ZSTD_f_zstd1 ? 5 : 1) /* minimum input size required to query frame header size */
# define ZSTD_FRAMEHEADERSIZE_MIN(format) ((format) == ZSTD_f_zstd1 ? 6 : 2)
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# define ZSTD_FRAMEHEADERSIZE_MAX 18 /* can be useful for static allocation */
# define ZSTD_SKIPPABLEHEADERSIZE 8
/* compression parameter bounds */
# define ZSTD_WINDOWLOG_MAX_32 30
# define ZSTD_WINDOWLOG_MAX_64 31
# define ZSTD_WINDOWLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
# define ZSTD_WINDOWLOG_MIN 10
# define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30)
# define ZSTD_HASHLOG_MIN 6
# define ZSTD_CHAINLOG_MAX_32 29
# define ZSTD_CHAINLOG_MAX_64 30
# define ZSTD_CHAINLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64))
# define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
# define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
# define ZSTD_SEARCHLOG_MIN 1
# define ZSTD_MINMATCH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */
# define ZSTD_MINMATCH_MIN 3 /* only for ZSTD_btopt+, faster strategies are limited to 4 */
# define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX
# define ZSTD_TARGETLENGTH_MIN 0 /* note : comparing this constant to an unsigned results in a tautological test */
# define ZSTD_STRATEGY_MIN ZSTD_fast
# define ZSTD_STRATEGY_MAX ZSTD_btultra2
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# define ZSTD_BLOCKSIZE_MAX_MIN (1 << 10) /* The minimum valid max blocksize. Maximum blocksizes smaller than this make compressBound() inaccurate. */
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# define ZSTD_OVERLAPLOG_MIN 0
# define ZSTD_OVERLAPLOG_MAX 9
# define ZSTD_WINDOWLOG_LIMIT_DEFAULT 27 / * by default, the streaming decoder will refuse any frame
* requiring larger than ( 1 < < ZSTD_WINDOWLOG_LIMIT_DEFAULT ) window size ,
* to preserve host ' s memory from unreasonable requirements .
* This limit can be overridden using ZSTD_DCtx_setParameter ( , ZSTD_d_windowLogMax , ) .
* The limit does not apply for one - pass decoders ( such as ZSTD_decompress ( ) ) , since no additional memory is allocated */
/* LDM parameter bounds */
# define ZSTD_LDM_HASHLOG_MIN ZSTD_HASHLOG_MIN
# define ZSTD_LDM_HASHLOG_MAX ZSTD_HASHLOG_MAX
# define ZSTD_LDM_MINMATCH_MIN 4
# define ZSTD_LDM_MINMATCH_MAX 4096
# define ZSTD_LDM_BUCKETSIZELOG_MIN 1
# define ZSTD_LDM_BUCKETSIZELOG_MAX 8
# define ZSTD_LDM_HASHRATELOG_MIN 0
# define ZSTD_LDM_HASHRATELOG_MAX (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN)
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/* Advanced parameter bounds */
# define ZSTD_TARGETCBLOCKSIZE_MIN 64
# define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX
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# define ZSTD_SRCSIZEHINT_MIN 0
# define ZSTD_SRCSIZEHINT_MAX INT_MAX
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/* --- Advanced types --- */
typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params ;
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typedef struct {
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unsigned int offset ; /* The offset of the match. (NOT the same as the offset code)
* If offset = = 0 and matchLength = = 0 , this sequence represents the last
* literals in the block of litLength size .
*/
unsigned int litLength ; /* Literal length of the sequence. */
unsigned int matchLength ; /* Match length of the sequence. */
/* Note: Users of this API may provide a sequence with matchLength == litLength == offset == 0.
* In this case , we will treat the sequence as a marker for a block boundary .
*/
unsigned int rep ; /* Represents which repeat offset is represented by the field 'offset'.
* Ranges from [ 0 , 3 ] .
*
* Repeat offsets are essentially previous offsets from previous sequences sorted in
* recency order . For more detail , see doc / zstd_compression_format . md
*
* If rep = = 0 , then ' offset ' does not contain a repeat offset .
* If rep > 0 :
* If litLength ! = 0 :
* rep = = 1 - - > offset = = repeat_offset_1
* rep = = 2 - - > offset = = repeat_offset_2
* rep = = 3 - - > offset = = repeat_offset_3
* If litLength = = 0 :
* rep = = 1 - - > offset = = repeat_offset_2
* rep = = 2 - - > offset = = repeat_offset_3
* rep = = 3 - - > offset = = repeat_offset_1 - 1
*
* Note : This field is optional . ZSTD_generateSequences ( ) will calculate the value of
* ' rep ' , but repeat offsets do not necessarily need to be calculated from an external
* sequence provider ' s perspective . For example , ZSTD_compressSequences ( ) does not
* use this ' rep ' field at all ( as of now ) .
*/
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} ZSTD_Sequence ;
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typedef struct {
unsigned windowLog ; /**< largest match distance : larger == more compression, more memory needed during decompression */
unsigned chainLog ; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */
unsigned hashLog ; /**< dispatch table : larger == faster, more memory */
unsigned searchLog ; /**< nb of searches : larger == more compression, slower */
unsigned minMatch ; /**< match length searched : larger == faster decompression, sometimes less compression */
unsigned targetLength ; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */
ZSTD_strategy strategy ; /**< see ZSTD_strategy definition above */
} ZSTD_compressionParameters ;
typedef struct {
int contentSizeFlag ; /**< 1: content size will be in frame header (when known) */
int checksumFlag ; /**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */
int noDictIDFlag ; /**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */
} ZSTD_frameParameters ;
typedef struct {
ZSTD_compressionParameters cParams ;
ZSTD_frameParameters fParams ;
} ZSTD_parameters ;
typedef enum {
ZSTD_dct_auto = 0 , /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */
ZSTD_dct_rawContent = 1 , /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */
ZSTD_dct_fullDict = 2 /* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */
} ZSTD_dictContentType_e ;
typedef enum {
ZSTD_dlm_byCopy = 0 , /**< Copy dictionary content internally */
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ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */
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} ZSTD_dictLoadMethod_e ;
typedef enum {
ZSTD_f_zstd1 = 0 , /* zstd frame format, specified in zstd_compression_format.md (default) */
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ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number.
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* Useful to save 4 bytes per generated frame .
* Decoder cannot recognise automatically this format , requiring this instruction . */
} ZSTD_format_e ;
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typedef enum {
/* Note: this enum controls ZSTD_d_forceIgnoreChecksum */
ZSTD_d_validateChecksum = 0 ,
ZSTD_d_ignoreChecksum = 1
} ZSTD_forceIgnoreChecksum_e ;
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typedef enum {
/* Note: this enum controls ZSTD_d_refMultipleDDicts */
ZSTD_rmd_refSingleDDict = 0 ,
ZSTD_rmd_refMultipleDDicts = 1
} ZSTD_refMultipleDDicts_e ;
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typedef enum {
/* Note: this enum and the behavior it controls are effectively internal
* implementation details of the compressor . They are expected to continue
* to evolve and should be considered only in the context of extremely
* advanced performance tuning .
*
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* Zstd currently supports the use of a CDict in three ways :
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*
* - The contents of the CDict can be copied into the working context . This
* means that the compression can search both the dictionary and input
* while operating on a single set of internal tables . This makes
* the compression faster per - byte of input . However , the initial copy of
* the CDict ' s tables incurs a fixed cost at the beginning of the
* compression . For small compressions ( < 8 KB ) , that copy can dominate
* the cost of the compression .
*
* - The CDict ' s tables can be used in - place . In this model , compression is
* slower per input byte , because the compressor has to search two sets of
* tables . However , this model incurs no start - up cost ( as long as the
* working context ' s tables can be reused ) . For small inputs , this can be
* faster than copying the CDict ' s tables .
*
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* - The CDict ' s tables are not used at all , and instead we use the working
* context alone to reload the dictionary and use params based on the source
* size . See ZSTD_compress_insertDictionary ( ) and ZSTD_compress_usingDict ( ) .
* This method is effective when the dictionary sizes are very small relative
* to the input size , and the input size is fairly large to begin with .
*
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* Zstd has a simple internal heuristic that selects which strategy to use
* at the beginning of a compression . However , if experimentation shows that
* Zstd is making poor choices , it is possible to override that choice with
* this enum .
*/
ZSTD_dictDefaultAttach = 0 , /* Use the default heuristic. */
ZSTD_dictForceAttach = 1 , /* Never copy the dictionary. */
ZSTD_dictForceCopy = 2 , /* Always copy the dictionary. */
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ZSTD_dictForceLoad = 3 /* Always reload the dictionary */
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} ZSTD_dictAttachPref_e ;
typedef enum {
ZSTD_lcm_auto = 0 , /**< Automatically determine the compression mode based on the compression level.
* Negative compression levels will be uncompressed , and positive compression
* levels will be compressed . */
ZSTD_lcm_huffman = 1 , /**< Always attempt Huffman compression. Uncompressed literals will still be
* emitted if Huffman compression is not profitable . */
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ZSTD_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */
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} ZSTD_literalCompressionMode_e ;
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typedef enum {
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/* Note: This enum controls features which are conditionally beneficial. Zstd typically will make a final
* decision on whether or not to enable the feature ( ZSTD_ps_auto ) , but setting the switch to ZSTD_ps_enable
* or ZSTD_ps_disable allow for a force enable / disable the feature .
*/
ZSTD_ps_auto = 0 , /* Let the library automatically determine whether the feature shall be enabled */
ZSTD_ps_enable = 1 , /* Force-enable the feature */
ZSTD_ps_disable = 2 /* Do not use the feature */
} ZSTD_paramSwitch_e ;
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/***************************************
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* Frame header and size functions
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_findDecompressedSize() :
* ` src ` should point to the start of a series of ZSTD encoded and / or skippable frames
* ` srcSize ` must be the _exact_ size of this series
* ( i . e . there should be a frame boundary at ` src + srcSize ` )
* @ return : - decompressed size of all data in all successive frames
* - if the decompressed size cannot be determined : ZSTD_CONTENTSIZE_UNKNOWN
* - if an error occurred : ZSTD_CONTENTSIZE_ERROR
*
* note 1 : decompressed size is an optional field , that may not be present , especially in streaming mode .
* When ` return = = ZSTD_CONTENTSIZE_UNKNOWN ` , data to decompress could be any size .
* In which case , it ' s necessary to use streaming mode to decompress data .
* note 2 : decompressed size is always present when compression is done with ZSTD_compress ( )
* note 3 : decompressed size can be very large ( 64 - bits value ) ,
* potentially larger than what local system can handle as a single memory segment .
* In which case , it ' s necessary to use streaming mode to decompress data .
* note 4 : If source is untrusted , decompressed size could be wrong or intentionally modified .
* Always ensure result fits within application ' s authorized limits .
* Each application can set its own limits .
* note 5 : ZSTD_findDecompressedSize handles multiple frames , and so it must traverse the input to
* read each contained frame header . This is fast as most of the data is skipped ,
* however it does mean that all frame data must be present and valid . */
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ZSTDLIB_STATIC_API unsigned long long ZSTD_findDecompressedSize ( const void * src , size_t srcSize ) ;
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/*! ZSTD_decompressBound() :
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* ` src ` should point to the start of a series of ZSTD encoded and / or skippable frames
* ` srcSize ` must be the _exact_ size of this series
* ( i . e . there should be a frame boundary at ` src + srcSize ` )
* @ return : - upper - bound for the decompressed size of all data in all successive frames
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* - if an error occurred : ZSTD_CONTENTSIZE_ERROR
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*
* note 1 : an error can occur if ` src ` contains an invalid or incorrectly formatted frame .
* note 2 : the upper - bound is exact when the decompressed size field is available in every ZSTD encoded frame of ` src ` .
* in this case , ` ZSTD_findDecompressedSize ` and ` ZSTD_decompressBound ` return the same value .
* note 3 : when the decompressed size field isn ' t available , the upper - bound for that frame is calculated by :
* upper - bound = # blocks * min ( 128 KB , Window_Size )
*/
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ZSTDLIB_STATIC_API unsigned long long ZSTD_decompressBound ( const void * src , size_t srcSize ) ;
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/*! ZSTD_frameHeaderSize() :
* srcSize must be > = ZSTD_FRAMEHEADERSIZE_PREFIX .
* @ return : size of the Frame Header ,
* or an error code ( if srcSize is too small ) */
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ZSTDLIB_STATIC_API size_t ZSTD_frameHeaderSize ( const void * src , size_t srcSize ) ;
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typedef enum { ZSTD_frame , ZSTD_skippableFrame } ZSTD_frameType_e ;
typedef struct {
unsigned long long frameContentSize ; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */
unsigned long long windowSize ; /* can be very large, up to <= frameContentSize */
unsigned blockSizeMax ;
ZSTD_frameType_e frameType ; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */
unsigned headerSize ;
unsigned dictID ;
unsigned checksumFlag ;
unsigned _reserved1 ;
unsigned _reserved2 ;
} ZSTD_frameHeader ;
/*! ZSTD_getFrameHeader() :
* decode Frame Header , or requires larger ` srcSize ` .
* @ return : 0 , ` zfhPtr ` is correctly filled ,
* > 0 , ` srcSize ` is too small , value is wanted ` srcSize ` amount ,
* or an error code , which can be tested using ZSTD_isError ( ) */
ZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader ( ZSTD_frameHeader * zfhPtr , const void * src , size_t srcSize ) ; /**< doesn't consume input */
/*! ZSTD_getFrameHeader_advanced() :
* same as ZSTD_getFrameHeader ( ) ,
* with added capability to select a format ( like ZSTD_f_zstd1_magicless ) */
ZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader_advanced ( ZSTD_frameHeader * zfhPtr , const void * src , size_t srcSize , ZSTD_format_e format ) ;
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/*! ZSTD_decompressionMargin() :
* Zstd supports in - place decompression , where the input and output buffers overlap .
* In this case , the output buffer must be at least ( Margin + Output_Size ) bytes large ,
* and the input buffer must be at the end of the output buffer .
*
* _______________________ Output Buffer ________________________
* | |
* | ____ Input Buffer ____ |
* | | |
* v v v
* | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - | - - - - - - - - - - |
* ^ ^ ^
* | ___________________ Output_Size ___________________ | _ Margin _ |
*
* NOTE : See also ZSTD_DECOMPRESSION_MARGIN ( ) .
* NOTE : This applies only to single - pass decompression through ZSTD_decompress ( ) or
* ZSTD_decompressDCtx ( ) .
* NOTE : This function supports multi - frame input .
*
* @ param src The compressed frame ( s )
* @ param srcSize The size of the compressed frame ( s )
* @ returns The decompression margin or an error that can be checked with ZSTD_isError ( ) .
*/
ZSTDLIB_STATIC_API size_t ZSTD_decompressionMargin ( const void * src , size_t srcSize ) ;
/*! ZSTD_DECOMPRESS_MARGIN() :
* Similar to ZSTD_decompressionMargin ( ) , but instead of computing the margin from
* the compressed frame , compute it from the original size and the blockSizeLog .
* See ZSTD_decompressionMargin ( ) for details .
*
* WARNING : This macro does not support multi - frame input , the input must be a single
* zstd frame . If you need that support use the function , or implement it yourself .
*
* @ param originalSize The original uncompressed size of the data .
* @ param blockSize The block size = = MIN ( windowSize , ZSTD_BLOCKSIZE_MAX ) .
* Unless you explicitly set the windowLog smaller than
* ZSTD_BLOCKSIZELOG_MAX you can just use ZSTD_BLOCKSIZE_MAX .
*/
# define ZSTD_DECOMPRESSION_MARGIN(originalSize, blockSize) ((size_t)( \
ZSTD_FRAMEHEADERSIZE_MAX /* Frame header */ + \
4 /* checksum */ + \
( ( originalSize ) = = 0 ? 0 : 3 * ( ( ( originalSize ) + ( blockSize ) - 1 ) / blockSize ) ) /* 3 bytes per block */ + \
( blockSize ) /* One block of margin */ \
) )
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typedef enum {
ZSTD_sf_noBlockDelimiters = 0 , /* Representation of ZSTD_Sequence has no block delimiters, sequences only */
ZSTD_sf_explicitBlockDelimiters = 1 /* Representation of ZSTD_Sequence contains explicit block delimiters */
} ZSTD_sequenceFormat_e ;
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/*! ZSTD_sequenceBound() :
* ` srcSize ` : size of the input buffer
* @ return : upper - bound for the number of sequences that can be generated
* from a buffer of srcSize bytes
*
* note : returns number of sequences - to get bytes , multiply by sizeof ( ZSTD_Sequence ) .
*/
ZSTDLIB_STATIC_API size_t ZSTD_sequenceBound ( size_t srcSize ) ;
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/*! ZSTD_generateSequences() :
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* Generate sequences using ZSTD_compress2 ( ) , given a source buffer .
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*
* Each block will end with a dummy sequence
* with offset = = 0 , matchLength = = 0 , and litLength = = length of last literals .
* litLength may be = = 0 , and if so , then the sequence of ( of : 0 ml : 0 ll : 0 )
* simply acts as a block delimiter .
*
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* @ zc can be used to insert custom compression params .
* This function invokes ZSTD_compress2 ( ) .
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*
* The output of this function can be fed into ZSTD_compressSequences ( ) with CCtx
* setting of ZSTD_c_blockDelimiters as ZSTD_sf_explicitBlockDelimiters
* @ return : number of sequences generated
*/
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ZSTDLIB_STATIC_API size_t
ZSTD_generateSequences ( ZSTD_CCtx * zc ,
ZSTD_Sequence * outSeqs , size_t outSeqsSize ,
const void * src , size_t srcSize ) ;
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/*! ZSTD_mergeBlockDelimiters() :
* Given an array of ZSTD_Sequence , remove all sequences that represent block delimiters / last literals
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* by merging them into the literals of the next sequence .
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*
* As such , the final generated result has no explicit representation of block boundaries ,
* and the final last literals segment is not represented in the sequences .
*
* The output of this function can be fed into ZSTD_compressSequences ( ) with CCtx
* setting of ZSTD_c_blockDelimiters as ZSTD_sf_noBlockDelimiters
* @ return : number of sequences left after merging
*/
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ZSTDLIB_STATIC_API size_t ZSTD_mergeBlockDelimiters ( ZSTD_Sequence * sequences , size_t seqsSize ) ;
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/*! ZSTD_compressSequences() :
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* Compress an array of ZSTD_Sequence , associated with @ src buffer , into dst .
* @ src contains the entire input ( not just the literals ) .
* If @ srcSize > sum ( sequence . length ) , the remaining bytes are considered all literals
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* If a dictionary is included , then the cctx should reference the dict . ( see : ZSTD_CCtx_refCDict ( ) , ZSTD_CCtx_loadDictionary ( ) , etc . )
* The entire source is compressed into a single frame .
*
* The compression behavior changes based on cctx params . In particular :
* If ZSTD_c_blockDelimiters = = ZSTD_sf_noBlockDelimiters , the array of ZSTD_Sequence is expected to contain
* no block delimiters ( defined in ZSTD_Sequence ) . Block boundaries are roughly determined based on
* the block size derived from the cctx , and sequences may be split . This is the default setting .
*
* If ZSTD_c_blockDelimiters = = ZSTD_sf_explicitBlockDelimiters , the array of ZSTD_Sequence is expected to contain
* block delimiters ( defined in ZSTD_Sequence ) . Behavior is undefined if no block delimiters are provided .
*
* If ZSTD_c_validateSequences = = 0 , this function will blindly accept the sequences provided . Invalid sequences cause undefined
* behavior . If ZSTD_c_validateSequences = = 1 , then if sequence is invalid ( see doc / zstd_compression_format . md for
* specifics regarding offset / matchlength requirements ) then the function will bail out and return an error .
*
* In addition to the two adjustable experimental params , there are other important cctx params .
* - ZSTD_c_minMatch MUST be set as less than or equal to the smallest match generated by the match finder . It has a minimum value of ZSTD_MINMATCH_MIN .
* - ZSTD_c_compressionLevel accordingly adjusts the strength of the entropy coder , as it would in typical compression .
* - ZSTD_c_windowLog affects offset validation : this function will return an error at higher debug levels if a provided offset
* is larger than what the spec allows for a given window log and dictionary ( if present ) . See : doc / zstd_compression_format . md
*
* Note : Repcodes are , as of now , always re - calculated within this function , so ZSTD_Sequence : : rep is unused .
* Note 2 : Once we integrate ability to ingest repcodes , the explicit block delims mode must respect those repcodes exactly ,
* and cannot emit an RLE block that disagrees with the repcode history
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* @ return : final compressed size , or a ZSTD error code .
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*/
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ZSTDLIB_STATIC_API size_t
ZSTD_compressSequences ( ZSTD_CCtx * cctx , void * dst , size_t dstSize ,
const ZSTD_Sequence * inSeqs , size_t inSeqsSize ,
const void * src , size_t srcSize ) ;
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/*! ZSTD_writeSkippableFrame() :
* Generates a zstd skippable frame containing data given by src , and writes it to dst buffer .
*
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* Skippable frames begin with a 4 - byte magic number . There are 16 possible choices of magic number ,
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* ranging from ZSTD_MAGIC_SKIPPABLE_START to ZSTD_MAGIC_SKIPPABLE_START + 15.
* As such , the parameter magicVariant controls the exact skippable frame magic number variant used , so
* the magic number used will be ZSTD_MAGIC_SKIPPABLE_START + magicVariant .
*
* Returns an error if destination buffer is not large enough , if the source size is not representable
* with a 4 - byte unsigned int , or if the parameter magicVariant is greater than 15 ( and therefore invalid ) .
*
* @ return : number of bytes written or a ZSTD error .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_writeSkippableFrame ( void * dst , size_t dstCapacity ,
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const void * src , size_t srcSize , unsigned magicVariant ) ;
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/*! ZSTD_readSkippableFrame() :
* Retrieves a zstd skippable frame containing data given by src , and writes it to dst buffer .
*
* The parameter magicVariant will receive the magicVariant that was supplied when the frame was written ,
* i . e . magicNumber - ZSTD_MAGIC_SKIPPABLE_START . This can be NULL if the caller is not interested
* in the magicVariant .
*
* Returns an error if destination buffer is not large enough , or if the frame is not skippable .
*
* @ return : number of bytes written or a ZSTD error .
*/
ZSTDLIB_API size_t ZSTD_readSkippableFrame ( void * dst , size_t dstCapacity , unsigned * magicVariant ,
const void * src , size_t srcSize ) ;
/*! ZSTD_isSkippableFrame() :
* Tells if the content of ` buffer ` starts with a valid Frame Identifier for a skippable frame .
*/
ZSTDLIB_API unsigned ZSTD_isSkippableFrame ( const void * buffer , size_t size ) ;
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/***************************************
* Memory management
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_estimate*() :
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* These functions make it possible to estimate memory usage
* of a future { D , C } Ctx , before its creation .
*
* ZSTD_estimateCCtxSize ( ) will provide a memory budget large enough
* for any compression level up to selected one .
* Note : Unlike ZSTD_estimateCStreamSize * ( ) , this estimate
* does not include space for a window buffer .
* Therefore , the estimation is only guaranteed for single - shot compressions , not streaming .
* The estimate will assume the input may be arbitrarily large ,
* which is the worst case .
*
* When srcSize can be bound by a known and rather " small " value ,
* this fact can be used to provide a tighter estimation
* because the CCtx compression context will need less memory .
* This tighter estimation can be provided by more advanced functions
* ZSTD_estimateCCtxSize_usingCParams ( ) , which can be used in tandem with ZSTD_getCParams ( ) ,
* and ZSTD_estimateCCtxSize_usingCCtxParams ( ) , which can be used in tandem with ZSTD_CCtxParams_setParameter ( ) .
* Both can be used to estimate memory using custom compression parameters and arbitrary srcSize limits .
*
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* Note : only single - threaded compression is supported .
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* ZSTD_estimateCCtxSize_usingCCtxParams ( ) will return an error code if ZSTD_c_nbWorkers is > = 1.
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*
* Note 2 : ZSTD_estimateCCtxSize * functions are not compatible with the Block - Level Sequence Producer API at this time .
* Size estimates assume that no external sequence producer is registered .
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*/
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ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize ( int compressionLevel ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCParams ( ZSTD_compressionParameters cParams ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCCtxParams ( const ZSTD_CCtx_params * params ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateDCtxSize ( void ) ;
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/*! ZSTD_estimateCStreamSize() :
* ZSTD_estimateCStreamSize ( ) will provide a budget large enough for any compression level up to selected one .
* It will also consider src size to be arbitrarily " large " , which is worst case .
* If srcSize is known to always be small , ZSTD_estimateCStreamSize_usingCParams ( ) can provide a tighter estimation .
* ZSTD_estimateCStreamSize_usingCParams ( ) can be used in tandem with ZSTD_getCParams ( ) to create cParams from compressionLevel .
* ZSTD_estimateCStreamSize_usingCCtxParams ( ) can be used in tandem with ZSTD_CCtxParams_setParameter ( ) . Only single - threaded compression is supported . This function will return an error code if ZSTD_c_nbWorkers is > = 1.
* Note : CStream size estimation is only correct for single - threaded compression .
* ZSTD_DStream memory budget depends on window Size .
* This information can be passed manually , using ZSTD_estimateDStreamSize ,
* or deducted from a valid frame Header , using ZSTD_estimateDStreamSize_fromFrame ( ) ;
* Note : if streaming is init with function ZSTD_init ? Stream_usingDict ( ) ,
* an internal ? Dict will be created , which additional size is not estimated here .
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* In this case , get total size by adding ZSTD_estimate ? DictSize
* Note 2 : only single - threaded compression is supported .
* ZSTD_estimateCStreamSize_usingCCtxParams ( ) will return an error code if ZSTD_c_nbWorkers is > = 1.
* Note 3 : ZSTD_estimateCStreamSize * functions are not compatible with the Block - Level Sequence Producer API at this time .
* Size estimates assume that no external sequence producer is registered .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize ( int compressionLevel ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCParams ( ZSTD_compressionParameters cParams ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCCtxParams ( const ZSTD_CCtx_params * params ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize ( size_t windowSize ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize_fromFrame ( const void * src , size_t srcSize ) ;
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/*! ZSTD_estimate?DictSize() :
* ZSTD_estimateCDictSize ( ) will bet that src size is relatively " small " , and content is copied , like ZSTD_createCDict ( ) .
* ZSTD_estimateCDictSize_advanced ( ) makes it possible to control compression parameters precisely , like ZSTD_createCDict_advanced ( ) .
* Note : dictionaries created by reference ( ` ZSTD_dlm_byRef ` ) are logically smaller .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize ( size_t dictSize , int compressionLevel ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize_advanced ( size_t dictSize , ZSTD_compressionParameters cParams , ZSTD_dictLoadMethod_e dictLoadMethod ) ;
ZSTDLIB_STATIC_API size_t ZSTD_estimateDDictSize ( size_t dictSize , ZSTD_dictLoadMethod_e dictLoadMethod ) ;
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/*! ZSTD_initStatic*() :
* Initialize an object using a pre - allocated fixed - size buffer .
* workspace : The memory area to emplace the object into .
* Provided pointer * must be 8 - bytes aligned * .
* Buffer must outlive object .
* workspaceSize : Use ZSTD_estimate * Size ( ) to determine
* how large workspace must be to support target scenario .
* @ return : pointer to object ( same address as workspace , just different type ) ,
* or NULL if error ( size too small , incorrect alignment , etc . )
* Note : zstd will never resize nor malloc ( ) when using a static buffer .
* If the object requires more memory than available ,
* zstd will just error out ( typically ZSTD_error_memory_allocation ) .
* Note 2 : there is no corresponding " free " function .
* Since workspace is allocated externally , it must be freed externally too .
* Note 3 : cParams : use ZSTD_getCParams ( ) to convert a compression level
* into its associated cParams .
* Limitation 1 : currently not compatible with internal dictionary creation , triggered by
* ZSTD_CCtx_loadDictionary ( ) , ZSTD_initCStream_usingDict ( ) or ZSTD_initDStream_usingDict ( ) .
* Limitation 2 : static cctx currently not compatible with multi - threading .
* Limitation 3 : static dctx is incompatible with legacy support .
*/
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ZSTDLIB_STATIC_API ZSTD_CCtx * ZSTD_initStaticCCtx ( void * workspace , size_t workspaceSize ) ;
ZSTDLIB_STATIC_API ZSTD_CStream * ZSTD_initStaticCStream ( void * workspace , size_t workspaceSize ) ; /**< same as ZSTD_initStaticCCtx() */
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ZSTDLIB_STATIC_API ZSTD_DCtx * ZSTD_initStaticDCtx ( void * workspace , size_t workspaceSize ) ;
ZSTDLIB_STATIC_API ZSTD_DStream * ZSTD_initStaticDStream ( void * workspace , size_t workspaceSize ) ; /**< same as ZSTD_initStaticDCtx() */
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ZSTDLIB_STATIC_API const ZSTD_CDict * ZSTD_initStaticCDict (
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void * workspace , size_t workspaceSize ,
const void * dict , size_t dictSize ,
ZSTD_dictLoadMethod_e dictLoadMethod ,
ZSTD_dictContentType_e dictContentType ,
ZSTD_compressionParameters cParams ) ;
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ZSTDLIB_STATIC_API const ZSTD_DDict * ZSTD_initStaticDDict (
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void * workspace , size_t workspaceSize ,
const void * dict , size_t dictSize ,
ZSTD_dictLoadMethod_e dictLoadMethod ,
ZSTD_dictContentType_e dictContentType ) ;
/*! Custom memory allocation :
* These prototypes make it possible to pass your own allocation / free functions .
* ZSTD_customMem is provided at creation time , using ZSTD_create * _advanced ( ) variants listed below .
* All allocation / free operations will be completed using these custom variants instead of regular < stdlib . h > ones .
*/
typedef void * ( * ZSTD_allocFunction ) ( void * opaque , size_t size ) ;
typedef void ( * ZSTD_freeFunction ) ( void * opaque , void * address ) ;
typedef struct { ZSTD_allocFunction customAlloc ; ZSTD_freeFunction customFree ; void * opaque ; } ZSTD_customMem ;
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static
# ifdef __GNUC__
__attribute__ ( ( __unused__ ) )
# endif
ZSTD_customMem const ZSTD_defaultCMem = { NULL , NULL , NULL } ; /**< this constant defers to stdlib's functions */
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ZSTDLIB_STATIC_API ZSTD_CCtx * ZSTD_createCCtx_advanced ( ZSTD_customMem customMem ) ;
ZSTDLIB_STATIC_API ZSTD_CStream * ZSTD_createCStream_advanced ( ZSTD_customMem customMem ) ;
ZSTDLIB_STATIC_API ZSTD_DCtx * ZSTD_createDCtx_advanced ( ZSTD_customMem customMem ) ;
ZSTDLIB_STATIC_API ZSTD_DStream * ZSTD_createDStream_advanced ( ZSTD_customMem customMem ) ;
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ZSTDLIB_STATIC_API ZSTD_CDict * ZSTD_createCDict_advanced ( const void * dict , size_t dictSize ,
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ZSTD_dictLoadMethod_e dictLoadMethod ,
ZSTD_dictContentType_e dictContentType ,
ZSTD_compressionParameters cParams ,
ZSTD_customMem customMem ) ;
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/*! Thread pool :
* These prototypes make it possible to share a thread pool among multiple compression contexts .
* This can limit resources for applications with multiple threads where each one uses
* a threaded compression mode ( via ZSTD_c_nbWorkers parameter ) .
* ZSTD_createThreadPool creates a new thread pool with a given number of threads .
* Note that the lifetime of such pool must exist while being used .
* ZSTD_CCtx_refThreadPool assigns a thread pool to a context ( use NULL argument value
* to use an internal thread pool ) .
* ZSTD_freeThreadPool frees a thread pool , accepts NULL pointer .
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*/
typedef struct POOL_ctx_s ZSTD_threadPool ;
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ZSTDLIB_STATIC_API ZSTD_threadPool * ZSTD_createThreadPool ( size_t numThreads ) ;
ZSTDLIB_STATIC_API void ZSTD_freeThreadPool ( ZSTD_threadPool * pool ) ; /* accept NULL pointer */
ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refThreadPool ( ZSTD_CCtx * cctx , ZSTD_threadPool * pool ) ;
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/*
* This API is temporary and is expected to change or disappear in the future !
*/
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ZSTDLIB_STATIC_API ZSTD_CDict * ZSTD_createCDict_advanced2 (
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const void * dict , size_t dictSize ,
ZSTD_dictLoadMethod_e dictLoadMethod ,
ZSTD_dictContentType_e dictContentType ,
const ZSTD_CCtx_params * cctxParams ,
ZSTD_customMem customMem ) ;
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ZSTDLIB_STATIC_API ZSTD_DDict * ZSTD_createDDict_advanced (
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const void * dict , size_t dictSize ,
ZSTD_dictLoadMethod_e dictLoadMethod ,
ZSTD_dictContentType_e dictContentType ,
ZSTD_customMem customMem ) ;
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/***************************************
* Advanced compression functions
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_createCDict_byReference() :
* Create a digested dictionary for compression
* Dictionary content is just referenced , not duplicated .
* As a consequence , ` dictBuffer ` * * must * * outlive CDict ,
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* and its content must remain unmodified throughout the lifetime of CDict .
* note : equivalent to ZSTD_createCDict_advanced ( ) , with dictLoadMethod = = ZSTD_dlm_byRef */
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ZSTDLIB_STATIC_API ZSTD_CDict * ZSTD_createCDict_byReference ( const void * dictBuffer , size_t dictSize , int compressionLevel ) ;
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/*! ZSTD_getCParams() :
* @ return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize .
* ` estimatedSrcSize ` value is optional , select 0 if not known */
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ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_getCParams ( int compressionLevel , unsigned long long estimatedSrcSize , size_t dictSize ) ;
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/*! ZSTD_getParams() :
* same as ZSTD_getCParams ( ) , but @ return a full ` ZSTD_parameters ` object instead of sub - component ` ZSTD_compressionParameters ` .
* All fields of ` ZSTD_frameParameters ` are set to default : contentSize = 1 , checksum = 0 , noDictID = 0 */
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ZSTDLIB_STATIC_API ZSTD_parameters ZSTD_getParams ( int compressionLevel , unsigned long long estimatedSrcSize , size_t dictSize ) ;
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/*! ZSTD_checkCParams() :
* Ensure param values remain within authorized range .
* @ return 0 on success , or an error code ( can be checked with ZSTD_isError ( ) ) */
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ZSTDLIB_STATIC_API size_t ZSTD_checkCParams ( ZSTD_compressionParameters params ) ;
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/*! ZSTD_adjustCParams() :
* optimize params for a given ` srcSize ` and ` dictSize ` .
* ` srcSize ` can be unknown , in which case use ZSTD_CONTENTSIZE_UNKNOWN .
* ` dictSize ` must be ` 0 ` when there is no dictionary .
* cPar can be invalid : all parameters will be clamped within valid range in the @ return struct .
* This function never fails ( wide contract ) */
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ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_adjustCParams ( ZSTD_compressionParameters cPar , unsigned long long srcSize , size_t dictSize ) ;
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/*! ZSTD_CCtx_setCParams() :
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* Set all parameters provided within @ p cparams into the working @ p cctx .
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* Note : if modifying parameters during compression ( MT mode only ) ,
* note that changes to the . windowLog parameter will be ignored .
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* @ return 0 on success , or an error code ( can be checked with ZSTD_isError ( ) ) .
* On failure , no parameters are updated .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setCParams ( ZSTD_CCtx * cctx , ZSTD_compressionParameters cparams ) ;
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/*! ZSTD_CCtx_setFParams() :
* Set all parameters provided within @ p fparams into the working @ p cctx .
* @ return 0 on success , or an error code ( can be checked with ZSTD_isError ( ) ) .
*/
ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setFParams ( ZSTD_CCtx * cctx , ZSTD_frameParameters fparams ) ;
/*! ZSTD_CCtx_setParams() :
* Set all parameters provided within @ p params into the working @ p cctx .
* @ return 0 on success , or an error code ( can be checked with ZSTD_isError ( ) ) .
*/
ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParams ( ZSTD_CCtx * cctx , ZSTD_parameters params ) ;
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/*! ZSTD_compress_advanced() :
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* Note : this function is now DEPRECATED .
* It can be replaced by ZSTD_compress2 ( ) , in combination with ZSTD_CCtx_setParameter ( ) and other parameter setters .
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* This prototype will generate compilation warnings . */
ZSTD_DEPRECATED ( " use ZSTD_compress2 " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_compress_advanced ( ZSTD_CCtx * cctx ,
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void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const void * dict , size_t dictSize ,
ZSTD_parameters params ) ;
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/*! ZSTD_compress_usingCDict_advanced() :
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* Note : this function is now DEPRECATED .
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* It can be replaced by ZSTD_compress2 ( ) , in combination with ZSTD_CCtx_loadDictionary ( ) and other parameter setters .
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* This prototype will generate compilation warnings . */
ZSTD_DEPRECATED ( " use ZSTD_compress2 with ZSTD_CCtx_loadDictionary " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_compress_usingCDict_advanced ( ZSTD_CCtx * cctx ,
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void * dst , size_t dstCapacity ,
const void * src , size_t srcSize ,
const ZSTD_CDict * cdict ,
ZSTD_frameParameters fParams ) ;
/*! ZSTD_CCtx_loadDictionary_byReference() :
* Same as ZSTD_CCtx_loadDictionary ( ) , but dictionary content is referenced , instead of being copied into CCtx .
* It saves some memory , but also requires that ` dict ` outlives its usage within ` cctx ` */
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_byReference ( ZSTD_CCtx * cctx , const void * dict , size_t dictSize ) ;
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/*! ZSTD_CCtx_loadDictionary_advanced() :
* Same as ZSTD_CCtx_loadDictionary ( ) , but gives finer control over
* how to load the dictionary ( by copy ? by reference ? )
* and how to interpret it ( automatic ? force raw mode ? full mode only ? ) */
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_advanced ( ZSTD_CCtx * cctx , const void * dict , size_t dictSize , ZSTD_dictLoadMethod_e dictLoadMethod , ZSTD_dictContentType_e dictContentType ) ;
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/*! ZSTD_CCtx_refPrefix_advanced() :
* Same as ZSTD_CCtx_refPrefix ( ) , but gives finer control over
* how to interpret prefix content ( automatic ? force raw mode ( default ) ? full mode only ? ) */
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced ( ZSTD_CCtx * cctx , const void * prefix , size_t prefixSize , ZSTD_dictContentType_e dictContentType ) ;
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/* === experimental parameters === */
/* these parameters can be used with ZSTD_setParameter()
* they are not guaranteed to remain supported in the future */
/* Enables rsyncable mode,
* which makes compressed files more rsync friendly
* by adding periodic synchronization points to the compressed data .
* The target average block size is ZSTD_c_jobSize / 2.
* It ' s possible to modify the job size to increase or decrease
* the granularity of the synchronization point .
* Once the jobSize is smaller than the window size ,
* it will result in compression ratio degradation .
* NOTE 1 : rsyncable mode only works when multithreading is enabled .
* NOTE 2 : rsyncable performs poorly in combination with long range mode ,
* since it will decrease the effectiveness of synchronization points ,
* though mileage may vary .
* NOTE 3 : Rsyncable mode limits maximum compression speed to ~ 400 MB / s .
* If the selected compression level is already running significantly slower ,
* the overall speed won ' t be significantly impacted .
*/
# define ZSTD_c_rsyncable ZSTD_c_experimentalParam1
/* Select a compression format.
* The value must be of type ZSTD_format_e .
* See ZSTD_format_e enum definition for details */
# define ZSTD_c_format ZSTD_c_experimentalParam2
/* Force back-reference distances to remain < windowSize,
* even when referencing into Dictionary content ( default : 0 ) */
# define ZSTD_c_forceMaxWindow ZSTD_c_experimentalParam3
/* Controls whether the contents of a CDict
* are used in place , or copied into the working context .
* Accepts values from the ZSTD_dictAttachPref_e enum .
* See the comments on that enum for an explanation of the feature . */
# define ZSTD_c_forceAttachDict ZSTD_c_experimentalParam4
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/* Controlled with ZSTD_paramSwitch_e enum.
* Default is ZSTD_ps_auto .
* Set to ZSTD_ps_disable to never compress literals .
* Set to ZSTD_ps_enable to always compress literals . ( Note : uncompressed literals
* may still be emitted if huffman is not beneficial to use . )
*
* By default , in ZSTD_ps_auto , the library will decide at runtime whether to use
* literals compression based on the compression parameters - specifically ,
* negative compression levels do not use literal compression .
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*/
# define ZSTD_c_literalCompressionMode ZSTD_c_experimentalParam5
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/* Tries to fit compressed block size to be around targetCBlockSize.
* No target when targetCBlockSize = = 0.
* There is no guarantee on compressed block size ( default : 0 ) */
# define ZSTD_c_targetCBlockSize ZSTD_c_experimentalParam6
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/* User's best guess of source size.
* Hint is not valid when srcSizeHint = = 0.
* There is no guarantee that hint is close to actual source size ,
* but compression ratio may regress significantly if guess considerably underestimates */
# define ZSTD_c_srcSizeHint ZSTD_c_experimentalParam7
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/* Controls whether the new and experimental "dedicated dictionary search
* structure " can be used. This feature is still rough around the edges, be
* prepared for surprising behavior !
*
* How to use it :
*
* When using a CDict , whether to use this feature or not is controlled at
* CDict creation , and it must be set in a CCtxParams set passed into that
* construction ( via ZSTD_createCDict_advanced2 ( ) ) . A compression will then
* use the feature or not based on how the CDict was constructed ; the value of
* this param , set in the CCtx , will have no effect .
*
* However , when a dictionary buffer is passed into a CCtx , such as via
* ZSTD_CCtx_loadDictionary ( ) , this param can be set on the CCtx to control
* whether the CDict that is created internally can use the feature or not .
*
* What it does :
*
* Normally , the internal data structures of the CDict are analogous to what
* would be stored in a CCtx after compressing the contents of a dictionary .
* To an approximation , a compression using a dictionary can then use those
* data structures to simply continue what is effectively a streaming
* compression where the simulated compression of the dictionary left off .
* Which is to say , the search structures in the CDict are normally the same
* format as in the CCtx .
*
* It is possible to do better , since the CDict is not like a CCtx : the search
* structures are written once during CDict creation , and then are only read
* after that , while the search structures in the CCtx are both read and
* written as the compression goes along . This means we can choose a search
* structure for the dictionary that is read - optimized .
*
* This feature enables the use of that different structure .
*
* Note that some of the members of the ZSTD_compressionParameters struct have
* different semantics and constraints in the dedicated search structure . It is
* highly recommended that you simply set a compression level in the CCtxParams
* you pass into the CDict creation call , and avoid messing with the cParams
* directly .
*
* Effects :
*
* This will only have any effect when the selected ZSTD_strategy
* implementation supports this feature . Currently , that ' s limited to
* ZSTD_greedy , ZSTD_lazy , and ZSTD_lazy2 .
*
* Note that this means that the CDict tables can no longer be copied into the
* CCtx , so the dict attachment mode ZSTD_dictForceCopy will no longer be
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* usable . The dictionary can only be attached or reloaded .
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*
* In general , you should expect compression to be faster - - sometimes very much
* so - - and CDict creation to be slightly slower . Eventually , we will probably
* make this mode the default .
*/
# define ZSTD_c_enableDedicatedDictSearch ZSTD_c_experimentalParam8
/* ZSTD_c_stableInBuffer
* Experimental parameter .
* Default is 0 = = disabled . Set to 1 to enable .
*
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* Tells the compressor that input data presented with ZSTD_inBuffer
* will ALWAYS be the same between calls .
* Technically , the @ src pointer must never be changed ,
* and the @ pos field can only be updated by zstd .
* However , it ' s possible to increase the @ size field ,
* allowing scenarios where more data can be appended after compressions starts .
* These conditions are checked by the compressor ,
* and compression will fail if they are not respected .
* Also , data in the ZSTD_inBuffer within the range [ src , src + pos )
* MUST not be modified during compression or it will result in data corruption .
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*
* When this flag is enabled zstd won ' t allocate an input window buffer ,
* because the user guarantees it can reference the ZSTD_inBuffer until
* the frame is complete . But , it will still allocate an output buffer
* large enough to fit a block ( see ZSTD_c_stableOutBuffer ) . This will also
* avoid the memcpy ( ) from the input buffer to the input window buffer .
*
* NOTE : So long as the ZSTD_inBuffer always points to valid memory , using
* this flag is ALWAYS memory safe , and will never access out - of - bounds
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* memory . However , compression WILL fail if conditions are not respected .
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*
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* WARNING : The data in the ZSTD_inBuffer in the range [ src , src + pos ) MUST
* not be modified during compression or it will result in data corruption .
* This is because zstd needs to reference data in the ZSTD_inBuffer to find
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* matches . Normally zstd maintains its own window buffer for this purpose ,
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* but passing this flag tells zstd to rely on user provided buffer instead .
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*/
# define ZSTD_c_stableInBuffer ZSTD_c_experimentalParam9
/* ZSTD_c_stableOutBuffer
* Experimental parameter .
* Default is 0 = = disabled . Set to 1 to enable .
*
* Tells he compressor that the ZSTD_outBuffer will not be resized between
* calls . Specifically : ( out . size - out . pos ) will never grow . This gives the
* compressor the freedom to say : If the compressed data doesn ' t fit in the
* output buffer then return ZSTD_error_dstSizeTooSmall . This allows us to
* always decompress directly into the output buffer , instead of decompressing
* into an internal buffer and copying to the output buffer .
*
* When this flag is enabled zstd won ' t allocate an output buffer , because
* it can write directly to the ZSTD_outBuffer . It will still allocate the
* input window buffer ( see ZSTD_c_stableInBuffer ) .
*
* Zstd will check that ( out . size - out . pos ) never grows and return an error
* if it does . While not strictly necessary , this should prevent surprises .
*/
# define ZSTD_c_stableOutBuffer ZSTD_c_experimentalParam10
/* ZSTD_c_blockDelimiters
* Default is 0 = = ZSTD_sf_noBlockDelimiters .
*
* For use with sequence compression API : ZSTD_compressSequences ( ) .
*
* Designates whether or not the given array of ZSTD_Sequence contains block delimiters
* and last literals , which are defined as sequences with offset = = 0 and matchLength = = 0.
* See the definition of ZSTD_Sequence for more specifics .
*/
# define ZSTD_c_blockDelimiters ZSTD_c_experimentalParam11
/* ZSTD_c_validateSequences
* Default is 0 = = disabled . Set to 1 to enable sequence validation .
*
* For use with sequence compression API : ZSTD_compressSequences ( ) .
* Designates whether or not we validate sequences provided to ZSTD_compressSequences ( )
* during function execution .
*
* Without validation , providing a sequence that does not conform to the zstd spec will cause
* undefined behavior , and may produce a corrupted block .
*
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* With validation enabled , if sequence is invalid ( see doc / zstd_compression_format . md for
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* specifics regarding offset / matchlength requirements ) then the function will bail out and
* return an error .
*
*/
# define ZSTD_c_validateSequences ZSTD_c_experimentalParam12
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/* ZSTD_c_useBlockSplitter
* Controlled with ZSTD_paramSwitch_e enum .
* Default is ZSTD_ps_auto .
* Set to ZSTD_ps_disable to never use block splitter .
* Set to ZSTD_ps_enable to always use block splitter .
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*
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* By default , in ZSTD_ps_auto , the library will decide at runtime whether to use
* block splitting based on the compression parameters .
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*/
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# define ZSTD_c_useBlockSplitter ZSTD_c_experimentalParam13
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/* ZSTD_c_useRowMatchFinder
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* Controlled with ZSTD_paramSwitch_e enum .
* Default is ZSTD_ps_auto .
* Set to ZSTD_ps_disable to never use row - based matchfinder .
* Set to ZSTD_ps_enable to force usage of row - based matchfinder .
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*
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* By default , in ZSTD_ps_auto , the library will decide at runtime whether to use
* the row - based matchfinder based on support for SIMD instructions and the window log .
* Note that this only pertains to compression strategies : greedy , lazy , and lazy2
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*/
# define ZSTD_c_useRowMatchFinder ZSTD_c_experimentalParam14
/* ZSTD_c_deterministicRefPrefix
* Default is 0 = = disabled . Set to 1 to enable .
*
* Zstd produces different results for prefix compression when the prefix is
* directly adjacent to the data about to be compressed vs . when it isn ' t .
* This is because zstd detects that the two buffers are contiguous and it can
* use a more efficient match finding algorithm . However , this produces different
* results than when the two buffers are non - contiguous . This flag forces zstd
* to always load the prefix in non - contiguous mode , even if it happens to be
* adjacent to the data , to guarantee determinism .
*
* If you really care about determinism when using a dictionary or prefix ,
* like when doing delta compression , you should select this option . It comes
* at a speed penalty of about ~ 2.5 % if the dictionary and data happened to be
* contiguous , and is free if they weren ' t contiguous . We don ' t expect that
* intentionally making the dictionary and data contiguous will be worth the
* cost to memcpy ( ) the data .
*/
# define ZSTD_c_deterministicRefPrefix ZSTD_c_experimentalParam15
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/* ZSTD_c_prefetchCDictTables
* Controlled with ZSTD_paramSwitch_e enum . Default is ZSTD_ps_auto .
*
* In some situations , zstd uses CDict tables in - place rather than copying them
* into the working context . ( See docs on ZSTD_dictAttachPref_e above for details ) .
* In such situations , compression speed is seriously impacted when CDict tables are
* " cold " ( outside CPU cache ) . This parameter instructs zstd to prefetch CDict tables
* when they are used in - place .
*
* For sufficiently small inputs , the cost of the prefetch will outweigh the benefit .
* For sufficiently large inputs , zstd will by default memcpy ( ) CDict tables
* into the working context , so there is no need to prefetch . This parameter is
* targeted at a middle range of input sizes , where a prefetch is cheap enough to be
* useful but memcpy ( ) is too expensive . The exact range of input sizes where this
* makes sense is best determined by careful experimentation .
*
* Note : for this parameter , ZSTD_ps_auto is currently equivalent to ZSTD_ps_disable ,
* but in the future zstd may conditionally enable this feature via an auto - detection
* heuristic for cold CDicts .
* Use ZSTD_ps_disable to opt out of prefetching under any circumstances .
*/
# define ZSTD_c_prefetchCDictTables ZSTD_c_experimentalParam16
/* ZSTD_c_enableSeqProducerFallback
* Allowed values are 0 ( disable ) and 1 ( enable ) . The default setting is 0.
*
* Controls whether zstd will fall back to an internal sequence producer if an
* external sequence producer is registered and returns an error code . This fallback
* is block - by - block : the internal sequence producer will only be called for blocks
* where the external sequence producer returns an error code . Fallback parsing will
* follow any other cParam settings , such as compression level , the same as in a
* normal ( fully - internal ) compression operation .
*
* The user is strongly encouraged to read the full Block - Level Sequence Producer API
* documentation ( below ) before setting this parameter . */
# define ZSTD_c_enableSeqProducerFallback ZSTD_c_experimentalParam17
/* ZSTD_c_maxBlockSize
* Allowed values are between 1 KB and ZSTD_BLOCKSIZE_MAX ( 128 KB ) .
* The default is ZSTD_BLOCKSIZE_MAX , and setting to 0 will set to the default .
*
* This parameter can be used to set an upper bound on the blocksize
* that overrides the default ZSTD_BLOCKSIZE_MAX . It cannot be used to set upper
* bounds greater than ZSTD_BLOCKSIZE_MAX or bounds lower than 1 KB ( will make
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* compressBound ( ) inaccurate ) . Only currently meant to be used for testing .
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*
*/
# define ZSTD_c_maxBlockSize ZSTD_c_experimentalParam18
/* ZSTD_c_searchForExternalRepcodes
* This parameter affects how zstd parses external sequences , such as sequences
* provided through the compressSequences ( ) API or from an external block - level
* sequence producer .
*
* If set to ZSTD_ps_enable , the library will check for repeated offsets in
* external sequences , even if those repcodes are not explicitly indicated in
* the " rep " field . Note that this is the only way to exploit repcode matches
* while using compressSequences ( ) or an external sequence producer , since zstd
* currently ignores the " rep " field of external sequences .
*
* If set to ZSTD_ps_disable , the library will not exploit repeated offsets in
* external sequences , regardless of whether the " rep " field has been set . This
* reduces sequence compression overhead by about 25 % while sacrificing some
* compression ratio .
*
* The default value is ZSTD_ps_auto , for which the library will enable / disable
* based on compression level .
*
* Note : for now , this param only has an effect if ZSTD_c_blockDelimiters is
* set to ZSTD_sf_explicitBlockDelimiters . That may change in the future .
*/
# define ZSTD_c_searchForExternalRepcodes ZSTD_c_experimentalParam19
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/*! ZSTD_CCtx_getParameter() :
* Get the requested compression parameter value , selected by enum ZSTD_cParameter ,
* and store it into int * value .
* @ return : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_getParameter ( const ZSTD_CCtx * cctx , ZSTD_cParameter param , int * value ) ;
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/*! ZSTD_CCtx_params :
* Quick howto :
* - ZSTD_createCCtxParams ( ) : Create a ZSTD_CCtx_params structure
* - ZSTD_CCtxParams_setParameter ( ) : Push parameters one by one into
* an existing ZSTD_CCtx_params structure .
* This is similar to
* ZSTD_CCtx_setParameter ( ) .
* - ZSTD_CCtx_setParametersUsingCCtxParams ( ) : Apply parameters to
* an existing CCtx .
* These parameters will be applied to
* all subsequent frames .
* - ZSTD_compressStream2 ( ) : Do compression using the CCtx .
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* - ZSTD_freeCCtxParams ( ) : Free the memory , accept NULL pointer .
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*
* This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams ( )
* for static allocation of CCtx for single - threaded compression .
*/
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ZSTDLIB_STATIC_API ZSTD_CCtx_params * ZSTD_createCCtxParams ( void ) ;
ZSTDLIB_STATIC_API size_t ZSTD_freeCCtxParams ( ZSTD_CCtx_params * params ) ; /* accept NULL pointer */
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/*! ZSTD_CCtxParams_reset() :
* Reset params to default values .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_reset ( ZSTD_CCtx_params * params ) ;
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/*! ZSTD_CCtxParams_init() :
* Initializes the compression parameters of cctxParams according to
* compression level . All other parameters are reset to their default values .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init ( ZSTD_CCtx_params * cctxParams , int compressionLevel ) ;
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/*! ZSTD_CCtxParams_init_advanced() :
* Initializes the compression and frame parameters of cctxParams according to
* params . All other parameters are reset to their default values .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init_advanced ( ZSTD_CCtx_params * cctxParams , ZSTD_parameters params ) ;
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/*! ZSTD_CCtxParams_setParameter() : Requires v1.4.0+
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* Similar to ZSTD_CCtx_setParameter .
* Set one compression parameter , selected by enum ZSTD_cParameter .
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* Parameters must be applied to a ZSTD_CCtx using
* ZSTD_CCtx_setParametersUsingCCtxParams ( ) .
* @ result : a code representing success or failure ( which can be tested with
* ZSTD_isError ( ) ) .
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*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_setParameter ( ZSTD_CCtx_params * params , ZSTD_cParameter param , int value ) ;
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/*! ZSTD_CCtxParams_getParameter() :
* Similar to ZSTD_CCtx_getParameter .
* Get the requested value of one compression parameter , selected by enum ZSTD_cParameter .
* @ result : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_getParameter ( const ZSTD_CCtx_params * params , ZSTD_cParameter param , int * value ) ;
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/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
* Apply a set of ZSTD_CCtx_params to the compression context .
* This can be done even after compression is started ,
* if nbWorkers = = 0 , this will have no impact until a new compression is started .
* if nbWorkers > = 1 , new parameters will be picked up at next job ,
* with a few restrictions ( windowLog , pledgedSrcSize , nbWorkers , jobSize , and overlapLog are not updated ) .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParametersUsingCCtxParams (
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ZSTD_CCtx * cctx , const ZSTD_CCtx_params * params ) ;
/*! ZSTD_compressStream2_simpleArgs() :
* Same as ZSTD_compressStream2 ( ) ,
* but using only integral types as arguments .
* This variant might be helpful for binders from dynamic languages
* which have troubles handling structures containing memory pointers .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_compressStream2_simpleArgs (
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ZSTD_CCtx * cctx ,
void * dst , size_t dstCapacity , size_t * dstPos ,
const void * src , size_t srcSize , size_t * srcPos ,
ZSTD_EndDirective endOp ) ;
/***************************************
* Advanced decompression functions
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_isFrame() :
* Tells if the content of ` buffer ` starts with a valid Frame Identifier .
* Note : Frame Identifier is 4 bytes . If ` size < 4 ` , @ return will always be 0.
* Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled .
* Note 3 : Skippable Frame Identifiers are considered valid . */
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ZSTDLIB_STATIC_API unsigned ZSTD_isFrame ( const void * buffer , size_t size ) ;
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/*! ZSTD_createDDict_byReference() :
* Create a digested dictionary , ready to start decompression operation without startup delay .
* Dictionary content is referenced , and therefore stays in dictBuffer .
* It is important that dictBuffer outlives DDict ,
* it must remain read accessible throughout the lifetime of DDict */
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ZSTDLIB_STATIC_API ZSTD_DDict * ZSTD_createDDict_byReference ( const void * dictBuffer , size_t dictSize ) ;
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/*! ZSTD_DCtx_loadDictionary_byReference() :
* Same as ZSTD_DCtx_loadDictionary ( ) ,
* but references ` dict ` content instead of copying it into ` dctx ` .
* This saves memory if ` dict ` remains around . ,
* However , it ' s imperative that ` dict ` remains accessible ( and unmodified ) while being used , so it must outlive decompression . */
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ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_byReference ( ZSTD_DCtx * dctx , const void * dict , size_t dictSize ) ;
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/*! ZSTD_DCtx_loadDictionary_advanced() :
* Same as ZSTD_DCtx_loadDictionary ( ) ,
* but gives direct control over
* how to load the dictionary ( by copy ? by reference ? )
* and how to interpret it ( automatic ? force raw mode ? full mode only ? ) . */
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ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_advanced ( ZSTD_DCtx * dctx , const void * dict , size_t dictSize , ZSTD_dictLoadMethod_e dictLoadMethod , ZSTD_dictContentType_e dictContentType ) ;
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/*! ZSTD_DCtx_refPrefix_advanced() :
* Same as ZSTD_DCtx_refPrefix ( ) , but gives finer control over
* how to interpret prefix content ( automatic ? force raw mode ( default ) ? full mode only ? ) */
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ZSTDLIB_STATIC_API size_t ZSTD_DCtx_refPrefix_advanced ( ZSTD_DCtx * dctx , const void * prefix , size_t prefixSize , ZSTD_dictContentType_e dictContentType ) ;
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/*! ZSTD_DCtx_setMaxWindowSize() :
* Refuses allocating internal buffers for frames requiring a window size larger than provided limit .
* This protects a decoder context from reserving too much memory for itself ( potential attack scenario ) .
* This parameter is only useful in streaming mode , since no internal buffer is allocated in single - pass mode .
* By default , a decompression context accepts all window sizes < = ( 1 < < ZSTD_WINDOWLOG_LIMIT_DEFAULT )
* @ return : 0 , or an error code ( which can be tested using ZSTD_isError ( ) ) .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_DCtx_setMaxWindowSize ( ZSTD_DCtx * dctx , size_t maxWindowSize ) ;
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/*! ZSTD_DCtx_getParameter() :
* Get the requested decompression parameter value , selected by enum ZSTD_dParameter ,
* and store it into int * value .
* @ return : 0 , or an error code ( which can be tested with ZSTD_isError ( ) ) .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_DCtx_getParameter ( ZSTD_DCtx * dctx , ZSTD_dParameter param , int * value ) ;
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/* ZSTD_d_format
* experimental parameter ,
* allowing selection between ZSTD_format_e input compression formats
*/
# define ZSTD_d_format ZSTD_d_experimentalParam1
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/* ZSTD_d_stableOutBuffer
* Experimental parameter .
* Default is 0 = = disabled . Set to 1 to enable .
*
* Tells the decompressor that the ZSTD_outBuffer will ALWAYS be the same
* between calls , except for the modifications that zstd makes to pos ( the
* caller must not modify pos ) . This is checked by the decompressor , and
* decompression will fail if it ever changes . Therefore the ZSTD_outBuffer
* MUST be large enough to fit the entire decompressed frame . This will be
* checked when the frame content size is known . The data in the ZSTD_outBuffer
* in the range [ dst , dst + pos ) MUST not be modified during decompression
* or you will get data corruption .
*
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* When this flag is enabled zstd won ' t allocate an output buffer , because
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* it can write directly to the ZSTD_outBuffer , but it will still allocate
* an input buffer large enough to fit any compressed block . This will also
* avoid the memcpy ( ) from the internal output buffer to the ZSTD_outBuffer .
* If you need to avoid the input buffer allocation use the buffer - less
* streaming API .
*
* NOTE : So long as the ZSTD_outBuffer always points to valid memory , using
* this flag is ALWAYS memory safe , and will never access out - of - bounds
* memory . However , decompression WILL fail if you violate the preconditions .
*
* WARNING : The data in the ZSTD_outBuffer in the range [ dst , dst + pos ) MUST
* not be modified during decompression or you will get data corruption . This
* is because zstd needs to reference data in the ZSTD_outBuffer to regenerate
* matches . Normally zstd maintains its own buffer for this purpose , but passing
* this flag tells zstd to use the user provided buffer .
*/
# define ZSTD_d_stableOutBuffer ZSTD_d_experimentalParam2
/* ZSTD_d_forceIgnoreChecksum
* Experimental parameter .
* Default is 0 = = disabled . Set to 1 to enable
*
* Tells the decompressor to skip checksum validation during decompression , regardless
* of whether checksumming was specified during compression . This offers some
* slight performance benefits , and may be useful for debugging .
* Param has values of type ZSTD_forceIgnoreChecksum_e
*/
# define ZSTD_d_forceIgnoreChecksum ZSTD_d_experimentalParam3
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/* ZSTD_d_refMultipleDDicts
* Experimental parameter .
* Default is 0 = = disabled . Set to 1 to enable
*
* If enabled and dctx is allocated on the heap , then additional memory will be allocated
* to store references to multiple ZSTD_DDict . That is , multiple calls of ZSTD_refDDict ( )
* using a given ZSTD_DCtx , rather than overwriting the previous DDict reference , will instead
* store all references . At decompression time , the appropriate dictID is selected
* from the set of DDicts based on the dictID in the frame .
*
* Usage is simply calling ZSTD_refDDict ( ) on multiple dict buffers .
*
* Param has values of byte ZSTD_refMultipleDDicts_e
*
* WARNING : Enabling this parameter and calling ZSTD_DCtx_refDDict ( ) , will trigger memory
* allocation for the hash table . ZSTD_freeDCtx ( ) also frees this memory .
* Memory is allocated as per ZSTD_DCtx : : customMem .
*
* Although this function allocates memory for the table , the user is still responsible for
* memory management of the underlying ZSTD_DDict * themselves .
*/
# define ZSTD_d_refMultipleDDicts ZSTD_d_experimentalParam4
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/* ZSTD_d_disableHuffmanAssembly
* Set to 1 to disable the Huffman assembly implementation .
* The default value is 0 , which allows zstd to use the Huffman assembly
* implementation if available .
*
* This parameter can be used to disable Huffman assembly at runtime .
* If you want to disable it at compile time you can define the macro
* ZSTD_DISABLE_ASM .
*/
# define ZSTD_d_disableHuffmanAssembly ZSTD_d_experimentalParam5
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/*! ZSTD_DCtx_setFormat() :
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* This function is REDUNDANT . Prefer ZSTD_DCtx_setParameter ( ) .
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* Instruct the decoder context about what kind of data to decode next .
* This instruction is mandatory to decode data without a fully - formed header ,
* such ZSTD_f_zstd1_magicless for example .
* @ return : 0 , or an error code ( which can be tested using ZSTD_isError ( ) ) . */
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ZSTD_DEPRECATED ( " use ZSTD_DCtx_setParameter() instead " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_DCtx_setFormat ( ZSTD_DCtx * dctx , ZSTD_format_e format ) ;
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/*! ZSTD_decompressStream_simpleArgs() :
* Same as ZSTD_decompressStream ( ) ,
* but using only integral types as arguments .
* This can be helpful for binders from dynamic languages
* which have troubles handling structures containing memory pointers .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_decompressStream_simpleArgs (
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ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity , size_t * dstPos ,
const void * src , size_t srcSize , size_t * srcPos ) ;
/********************************************************************
* Advanced streaming functions
* Warning : most of these functions are now redundant with the Advanced API .
* Once Advanced API reaches " stable " status ,
* redundant functions will be deprecated , and then at some point removed .
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*===== Advanced Streaming compression functions =====*/
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/*! ZSTD_initCStream_srcSize() :
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* This function is DEPRECATED , and equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
* ZSTD_CCtx_refCDict ( zcs , NULL ) ; // clear the dictionary (if any)
* ZSTD_CCtx_setParameter ( zcs , ZSTD_c_compressionLevel , compressionLevel ) ;
* ZSTD_CCtx_setPledgedSrcSize ( zcs , pledgedSrcSize ) ;
*
* pledgedSrcSize must be correct . If it is not known at init time , use
* ZSTD_CONTENTSIZE_UNKNOWN . Note that , for compatibility with older programs ,
* " 0 " also disables frame content size field . It may be enabled in the future .
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_initCStream_srcSize ( ZSTD_CStream * zcs ,
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int compressionLevel ,
unsigned long long pledgedSrcSize ) ;
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/*! ZSTD_initCStream_usingDict() :
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* This function is DEPRECATED , and is equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
* ZSTD_CCtx_setParameter ( zcs , ZSTD_c_compressionLevel , compressionLevel ) ;
* ZSTD_CCtx_loadDictionary ( zcs , dict , dictSize ) ;
*
* Creates of an internal CDict ( incompatible with static CCtx ) , except if
* dict = = NULL or dictSize < 8 , in which case no dict is used .
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* Note : dict is loaded with ZSTD_dct_auto ( treated as a full zstd dictionary if
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* it begins with ZSTD_MAGIC_DICTIONARY , else as raw content ) and ZSTD_dlm_byCopy .
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_initCStream_usingDict ( ZSTD_CStream * zcs ,
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const void * dict , size_t dictSize ,
int compressionLevel ) ;
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/*! ZSTD_initCStream_advanced() :
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* This function is DEPRECATED , and is equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
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* ZSTD_CCtx_setParams ( zcs , params ) ;
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* ZSTD_CCtx_setPledgedSrcSize ( zcs , pledgedSrcSize ) ;
* ZSTD_CCtx_loadDictionary ( zcs , dict , dictSize ) ;
*
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* dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy .
* pledgedSrcSize must be correct .
* If srcSize is not known at init time , use value ZSTD_CONTENTSIZE_UNKNOWN .
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_initCStream_advanced ( ZSTD_CStream * zcs ,
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const void * dict , size_t dictSize ,
ZSTD_parameters params ,
unsigned long long pledgedSrcSize ) ;
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/*! ZSTD_initCStream_usingCDict() :
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* This function is DEPRECATED , and equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
* ZSTD_CCtx_refCDict ( zcs , cdict ) ;
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*
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* note : cdict will just be referenced , and must outlive compression session
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_initCStream_usingCDict ( ZSTD_CStream * zcs , const ZSTD_CDict * cdict ) ;
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/*! ZSTD_initCStream_usingCDict_advanced() :
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* This function is DEPRECATED , and is equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
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* ZSTD_CCtx_setFParams ( zcs , fParams ) ;
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* ZSTD_CCtx_setPledgedSrcSize ( zcs , pledgedSrcSize ) ;
* ZSTD_CCtx_refCDict ( zcs , cdict ) ;
*
* same as ZSTD_initCStream_usingCDict ( ) , with control over frame parameters .
* pledgedSrcSize must be correct . If srcSize is not known at init time , use
* value ZSTD_CONTENTSIZE_UNKNOWN .
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_initCStream_usingCDict_advanced ( ZSTD_CStream * zcs ,
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const ZSTD_CDict * cdict ,
ZSTD_frameParameters fParams ,
unsigned long long pledgedSrcSize ) ;
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/*! ZSTD_resetCStream() :
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* This function is DEPRECATED , and is equivalent to :
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* ZSTD_CCtx_reset ( zcs , ZSTD_reset_session_only ) ;
* ZSTD_CCtx_setPledgedSrcSize ( zcs , pledgedSrcSize ) ;
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* Note : ZSTD_resetCStream ( ) interprets pledgedSrcSize = = 0 as ZSTD_CONTENTSIZE_UNKNOWN , but
* ZSTD_CCtx_setPledgedSrcSize ( ) does not do the same , so ZSTD_CONTENTSIZE_UNKNOWN must be
* explicitly specified .
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*
* start a new frame , using same parameters from previous frame .
* This is typically useful to skip dictionary loading stage , since it will re - use it in - place .
* Note that zcs must be init at least once before using ZSTD_resetCStream ( ) .
* If pledgedSrcSize is not known at reset time , use macro ZSTD_CONTENTSIZE_UNKNOWN .
* If pledgedSrcSize > 0 , its value must be correct , as it will be written in header , and controlled at the end .
* For the time being , pledgedSrcSize = = 0 is interpreted as " srcSize unknown " for compatibility with older programs ,
* but it will change to mean " empty " in future version , so use macro ZSTD_CONTENTSIZE_UNKNOWN instead .
* @ return : 0 , or an error code ( which can be tested using ZSTD_isError ( ) )
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* This prototype will generate compilation warnings .
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*/
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ZSTD_DEPRECATED ( " use ZSTD_CCtx_reset, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_resetCStream ( ZSTD_CStream * zcs , unsigned long long pledgedSrcSize ) ;
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typedef struct {
unsigned long long ingested ; /* nb input bytes read and buffered */
unsigned long long consumed ; /* nb input bytes actually compressed */
unsigned long long produced ; /* nb of compressed bytes generated and buffered */
unsigned long long flushed ; /* nb of compressed bytes flushed : not provided; can be tracked from caller side */
unsigned currentJobID ; /* MT only : latest started job nb */
unsigned nbActiveWorkers ; /* MT only : nb of workers actively compressing at probe time */
} ZSTD_frameProgression ;
/* ZSTD_getFrameProgression() :
* tells how much data has been ingested ( read from input )
* consumed ( input actually compressed ) and produced ( output ) for current frame .
* Note : ( ingested - consumed ) is amount of input data buffered internally , not yet compressed .
* Aggregates progression inside active worker threads .
*/
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ZSTDLIB_STATIC_API ZSTD_frameProgression ZSTD_getFrameProgression ( const ZSTD_CCtx * cctx ) ;
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/*! ZSTD_toFlushNow() :
* Tell how many bytes are ready to be flushed immediately .
* Useful for multithreading scenarios ( nbWorkers > = 1 ) .
* Probe the oldest active job , defined as oldest job not yet entirely flushed ,
* and check its output buffer .
* @ return : amount of data stored in oldest job and ready to be flushed immediately .
* if @ return = = 0 , it means either :
* + there is no active job ( could be checked with ZSTD_frameProgression ( ) ) , or
* + oldest job is still actively compressing data ,
* but everything it has produced has also been flushed so far ,
* therefore flush speed is limited by production speed of oldest job
* irrespective of the speed of concurrent ( and newer ) jobs .
*/
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ZSTDLIB_STATIC_API size_t ZSTD_toFlushNow ( ZSTD_CCtx * cctx ) ;
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/*===== Advanced Streaming decompression functions =====*/
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/*!
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* This function is deprecated , and is equivalent to :
*
* ZSTD_DCtx_reset ( zds , ZSTD_reset_session_only ) ;
* ZSTD_DCtx_loadDictionary ( zds , dict , dictSize ) ;
*
* note : no dictionary will be used if dict = = NULL or dictSize < 8
*/
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ZSTD_DEPRECATED ( " use ZSTD_DCtx_reset + ZSTD_DCtx_loadDictionary, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDict ( ZSTD_DStream * zds , const void * dict , size_t dictSize ) ;
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/*!
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* This function is deprecated , and is equivalent to :
*
* ZSTD_DCtx_reset ( zds , ZSTD_reset_session_only ) ;
* ZSTD_DCtx_refDDict ( zds , ddict ) ;
*
* note : ddict is referenced , it must outlive decompression session
*/
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ZSTD_DEPRECATED ( " use ZSTD_DCtx_reset + ZSTD_DCtx_refDDict, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDDict ( ZSTD_DStream * zds , const ZSTD_DDict * ddict ) ;
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/*!
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* This function is deprecated , and is equivalent to :
*
* ZSTD_DCtx_reset ( zds , ZSTD_reset_session_only ) ;
*
* re - use decompression parameters from previous init ; saves dictionary loading
*/
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ZSTD_DEPRECATED ( " use ZSTD_DCtx_reset, see zstd.h for detailed instructions " )
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ZSTDLIB_STATIC_API size_t ZSTD_resetDStream ( ZSTD_DStream * zds ) ;
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/* ********************* BLOCK-LEVEL SEQUENCE PRODUCER API *********************
*
* * * * OVERVIEW * * *
* The Block - Level Sequence Producer API allows users to provide their own custom
* sequence producer which libzstd invokes to process each block . The produced list
* of sequences ( literals and matches ) is then post - processed by libzstd to produce
* valid compressed blocks .
*
* This block - level offload API is a more granular complement of the existing
* frame - level offload API compressSequences ( ) ( introduced in v1 .5 .1 ) . It offers
* an easier migration story for applications already integrated with libzstd : the
* user application continues to invoke the same compression functions
* ZSTD_compress2 ( ) or ZSTD_compressStream2 ( ) as usual , and transparently benefits
* from the specific advantages of the external sequence producer . For example ,
* the sequence producer could be tuned to take advantage of known characteristics
* of the input , to offer better speed / ratio , or could leverage hardware
* acceleration not available within libzstd itself .
*
* See contrib / externalSequenceProducer for an example program employing the
* Block - Level Sequence Producer API .
*
* * * * USAGE * * *
* The user is responsible for implementing a function of type
* ZSTD_sequenceProducer_F . For each block , zstd will pass the following
* arguments to the user - provided function :
*
* - sequenceProducerState : a pointer to a user - managed state for the sequence
* producer .
*
* - outSeqs , outSeqsCapacity : an output buffer for the sequence producer .
* outSeqsCapacity is guaranteed > = ZSTD_sequenceBound ( srcSize ) . The memory
* backing outSeqs is managed by the CCtx .
*
* - src , srcSize : an input buffer for the sequence producer to parse .
* srcSize is guaranteed to be < = ZSTD_BLOCKSIZE_MAX .
*
* - dict , dictSize : a history buffer , which may be empty , which the sequence
* producer may reference as it parses the src buffer . Currently , zstd will
* always pass dictSize = = 0 into external sequence producers , but this will
* change in the future .
*
* - compressionLevel : a signed integer representing the zstd compression level
* set by the user for the current operation . The sequence producer may choose
* to use this information to change its compression strategy and speed / ratio
* tradeoff . Note : the compression level does not reflect zstd parameters set
* through the advanced API .
*
* - windowSize : a size_t representing the maximum allowed offset for external
* sequences . Note that sequence offsets are sometimes allowed to exceed the
* windowSize if a dictionary is present , see doc / zstd_compression_format . md
* for details .
*
* The user - provided function shall return a size_t representing the number of
* sequences written to outSeqs . This return value will be treated as an error
* code if it is greater than outSeqsCapacity . The return value must be non - zero
* if srcSize is non - zero . The ZSTD_SEQUENCE_PRODUCER_ERROR macro is provided
* for convenience , but any value greater than outSeqsCapacity will be treated as
* an error code .
*
* If the user - provided function does not return an error code , the sequences
* written to outSeqs must be a valid parse of the src buffer . Data corruption may
* occur if the parse is not valid . A parse is defined to be valid if the
* following conditions hold :
* - The sum of matchLengths and literalLengths must equal srcSize .
* - All sequences in the parse , except for the final sequence , must have
* matchLength > = ZSTD_MINMATCH_MIN . The final sequence must have
* matchLength > = ZSTD_MINMATCH_MIN or matchLength = = 0.
* - All offsets must respect the windowSize parameter as specified in
* doc / zstd_compression_format . md .
* - If the final sequence has matchLength = = 0 , it must also have offset = = 0.
*
* zstd will only validate these conditions ( and fail compression if they do not
* hold ) if the ZSTD_c_validateSequences cParam is enabled . Note that sequence
* validation has a performance cost .
*
* If the user - provided function returns an error , zstd will either fall back
* to an internal sequence producer or fail the compression operation . The user can
* choose between the two behaviors by setting the ZSTD_c_enableSeqProducerFallback
* cParam . Fallback compression will follow any other cParam settings , such as
* compression level , the same as in a normal compression operation .
*
* The user shall instruct zstd to use a particular ZSTD_sequenceProducer_F
* function by calling
* ZSTD_registerSequenceProducer ( cctx ,
* sequenceProducerState ,
* sequenceProducer )
* This setting will persist until the next parameter reset of the CCtx .
*
* The sequenceProducerState must be initialized by the user before calling
* ZSTD_registerSequenceProducer ( ) . The user is responsible for destroying the
* sequenceProducerState .
*
* * * * LIMITATIONS * * *
* This API is compatible with all zstd compression APIs which respect advanced parameters .
* However , there are three limitations :
*
* First , the ZSTD_c_enableLongDistanceMatching cParam is not currently supported .
* COMPRESSION WILL FAIL if it is enabled and the user tries to compress with a block - level
* external sequence producer .
* - Note that ZSTD_c_enableLongDistanceMatching is auto - enabled by default in some
* cases ( see its documentation for details ) . Users must explicitly set
* ZSTD_c_enableLongDistanceMatching to ZSTD_ps_disable in such cases if an external
* sequence producer is registered .
* - As of this writing , ZSTD_c_enableLongDistanceMatching is disabled by default
* whenever ZSTD_c_windowLog < 128 MB , but that ' s subject to change . Users should
* check the docs on ZSTD_c_enableLongDistanceMatching whenever the Block - Level Sequence
* Producer API is used in conjunction with advanced settings ( like ZSTD_c_windowLog ) .
*
* Second , history buffers are not currently supported . Concretely , zstd will always pass
* dictSize = = 0 to the external sequence producer ( for now ) . This has two implications :
* - Dictionaries are not currently supported . Compression will * not * fail if the user
* references a dictionary , but the dictionary won ' t have any effect .
* - Stream history is not currently supported . All advanced compression APIs , including
* streaming APIs , work with external sequence producers , but each block is treated as
* an independent chunk without history from previous blocks .
*
* Third , multi - threading within a single compression is not currently supported . In other words ,
* COMPRESSION WILL FAIL if ZSTD_c_nbWorkers > 0 and an external sequence producer is registered .
* Multi - threading across compressions is fine : simply create one CCtx per thread .
*
* Long - term , we plan to overcome all three limitations . There is no technical blocker to
* overcoming them . It is purely a question of engineering effort .
*/
# define ZSTD_SEQUENCE_PRODUCER_ERROR ((size_t)(-1))
typedef size_t ZSTD_sequenceProducer_F (
void * sequenceProducerState ,
ZSTD_Sequence * outSeqs , size_t outSeqsCapacity ,
const void * src , size_t srcSize ,
const void * dict , size_t dictSize ,
int compressionLevel ,
size_t windowSize
) ;
/*! ZSTD_registerSequenceProducer() :
* Instruct zstd to use a block - level external sequence producer function .
*
* The sequenceProducerState must be initialized by the caller , and the caller is
* responsible for managing its lifetime . This parameter is sticky across
* compressions . It will remain set until the user explicitly resets compression
* parameters .
*
* Sequence producer registration is considered to be an " advanced parameter " ,
* part of the " advanced API " . This means it will only have an effect on compression
* APIs which respect advanced parameters , such as compress2 ( ) and compressStream2 ( ) .
* Older compression APIs such as compressCCtx ( ) , which predate the introduction of
* " advanced parameters " , will ignore any external sequence producer setting .
*
* The sequence producer can be " cleared " by registering a NULL function pointer . This
* removes all limitations described above in the " LIMITATIONS " section of the API docs .
*
* The user is strongly encouraged to read the full API documentation ( above ) before
* calling this function . */
ZSTDLIB_STATIC_API void
ZSTD_registerSequenceProducer (
ZSTD_CCtx * cctx ,
void * sequenceProducerState ,
ZSTD_sequenceProducer_F * sequenceProducer
) ;
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/*********************************************************************
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* Buffer - less and synchronous inner streaming functions ( DEPRECATED )
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*
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* This API is deprecated , and will be removed in a future version .
* It allows streaming ( de ) compression with user allocated buffers .
* However , it is hard to use , and not as well tested as the rest of
* our API .
*
* Please use the normal streaming API instead : ZSTD_compressStream2 ,
* and ZSTD_decompressStream .
* If there is functionality that you need , but it doesn ' t provide ,
* please open an issue on our GitHub .
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/**
Buffer - less streaming compression ( synchronous mode )
A ZSTD_CCtx object is required to track streaming operations .
Use ZSTD_createCCtx ( ) / ZSTD_freeCCtx ( ) to manage resource .
ZSTD_CCtx object can be re - used multiple times within successive compression operations .
Start by initializing a context .
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Use ZSTD_compressBegin ( ) , or ZSTD_compressBegin_usingDict ( ) for dictionary compression .
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Then , consume your input using ZSTD_compressContinue ( ) .
There are some important considerations to keep in mind when using this advanced function :
- ZSTD_compressContinue ( ) has no internal buffer . It uses externally provided buffers only .
- Interface is synchronous : input is consumed entirely and produces 1 + compressed blocks .
- Caller must ensure there is enough space in ` dst ` to store compressed data under worst case scenario .
Worst case evaluation is provided by ZSTD_compressBound ( ) .
ZSTD_compressContinue ( ) doesn ' t guarantee recover after a failed compression .
- ZSTD_compressContinue ( ) presumes prior input * * * is still accessible and unmodified * * * ( up to maximum distance size , see WindowLog ) .
It remembers all previous contiguous blocks , plus one separated memory segment ( which can itself consists of multiple contiguous blocks )
- ZSTD_compressContinue ( ) detects that prior input has been overwritten when ` src ` buffer overlaps .
In which case , it will " discard " the relevant memory section from its history .
Finish a frame with ZSTD_compressEnd ( ) , which will write the last block ( s ) and optional checksum .
It ' s possible to use srcSize = = 0 , in which case , it will write a final empty block to end the frame .
Without last block mark , frames are considered unfinished ( hence corrupted ) by compliant decoders .
` ZSTD_CCtx ` object can be re - used ( ZSTD_compressBegin ( ) ) to compress again .
*/
/*===== Buffer-less streaming compression functions =====*/
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ZSTD_DEPRECATED ( " The buffer-less API is deprecated in favor of the normal streaming API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressBegin ( ZSTD_CCtx * cctx , int compressionLevel ) ;
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ZSTD_DEPRECATED ( " The buffer-less API is deprecated in favor of the normal streaming API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingDict ( ZSTD_CCtx * cctx , const void * dict , size_t dictSize , int compressionLevel ) ;
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ZSTD_DEPRECATED ( " The buffer-less API is deprecated in favor of the normal streaming API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingCDict ( ZSTD_CCtx * cctx , const ZSTD_CDict * cdict ) ; /**< note: fails if cdict==NULL */
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ZSTD_DEPRECATED ( " This function will likely be removed in a future release. It is misleading and has very limited utility. " )
ZSTDLIB_STATIC_API
size_t ZSTD_copyCCtx ( ZSTD_CCtx * cctx , const ZSTD_CCtx * preparedCCtx , unsigned long long pledgedSrcSize ) ; /**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */
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ZSTD_DEPRECATED ( " The buffer-less API is deprecated in favor of the normal streaming API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressContinue ( ZSTD_CCtx * cctx , void * dst , size_t dstCapacity , const void * src , size_t srcSize ) ;
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ZSTD_DEPRECATED ( " The buffer-less API is deprecated in favor of the normal streaming API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressEnd ( ZSTD_CCtx * cctx , void * dst , size_t dstCapacity , const void * src , size_t srcSize ) ;
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/* The ZSTD_compressBegin_advanced() and ZSTD_compressBegin_usingCDict_advanced() are now DEPRECATED and will generate a compiler warning */
ZSTD_DEPRECATED ( " use advanced API to access custom parameters " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_compressBegin_advanced ( ZSTD_CCtx * cctx , const void * dict , size_t dictSize , ZSTD_parameters params , unsigned long long pledgedSrcSize ) ; /**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */
ZSTD_DEPRECATED ( " use advanced API to access custom parameters " )
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ZSTDLIB_STATIC_API
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size_t ZSTD_compressBegin_usingCDict_advanced ( ZSTD_CCtx * const cctx , const ZSTD_CDict * const cdict , ZSTD_frameParameters const fParams , unsigned long long const pledgedSrcSize ) ; /* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */
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/**
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Buffer - less streaming decompression ( synchronous mode )
A ZSTD_DCtx object is required to track streaming operations .
Use ZSTD_createDCtx ( ) / ZSTD_freeDCtx ( ) to manage it .
A ZSTD_DCtx object can be re - used multiple times .
First typical operation is to retrieve frame parameters , using ZSTD_getFrameHeader ( ) .
Frame header is extracted from the beginning of compressed frame , so providing only the frame ' s beginning is enough .
Data fragment must be large enough to ensure successful decoding .
` ZSTD_frameHeaderSize_max ` bytes is guaranteed to always be large enough .
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result : 0 : successful decoding , the ` ZSTD_frameHeader ` structure is correctly filled .
> 0 : ` srcSize ` is too small , please provide at least result bytes on next attempt .
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errorCode , which can be tested using ZSTD_isError ( ) .
It fills a ZSTD_frameHeader structure with important information to correctly decode the frame ,
such as the dictionary ID , content size , or maximum back - reference distance ( ` windowSize ` ) .
Note that these values could be wrong , either because of data corruption , or because a 3 rd party deliberately spoofs false information .
As a consequence , check that values remain within valid application range .
For example , do not allocate memory blindly , check that ` windowSize ` is within expectation .
Each application can set its own limits , depending on local restrictions .
For extended interoperability , it is recommended to support ` windowSize ` of at least 8 MB .
ZSTD_decompressContinue ( ) needs previous data blocks during decompression , up to ` windowSize ` bytes .
ZSTD_decompressContinue ( ) is very sensitive to contiguity ,
if 2 blocks don ' t follow each other , make sure that either the compressor breaks contiguity at the same place ,
or that previous contiguous segment is large enough to properly handle maximum back - reference distance .
There are multiple ways to guarantee this condition .
The most memory efficient way is to use a round buffer of sufficient size .
Sufficient size is determined by invoking ZSTD_decodingBufferSize_min ( ) ,
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which can return an error code if required value is too large for current system ( in 32 - bits mode ) .
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In a round buffer methodology , ZSTD_decompressContinue ( ) decompresses each block next to previous one ,
up to the moment there is not enough room left in the buffer to guarantee decoding another full block ,
which maximum size is provided in ` ZSTD_frameHeader ` structure , field ` blockSizeMax ` .
At which point , decoding can resume from the beginning of the buffer .
Note that already decoded data stored in the buffer should be flushed before being overwritten .
There are alternatives possible , for example using two or more buffers of size ` windowSize ` each , though they consume more memory .
Finally , if you control the compression process , you can also ignore all buffer size rules ,
as long as the encoder and decoder progress in " lock-step " ,
aka use exactly the same buffer sizes , break contiguity at the same place , etc .
Once buffers are setup , start decompression , with ZSTD_decompressBegin ( ) .
If decompression requires a dictionary , use ZSTD_decompressBegin_usingDict ( ) or ZSTD_decompressBegin_usingDDict ( ) .
Then use ZSTD_nextSrcSizeToDecompress ( ) and ZSTD_decompressContinue ( ) alternatively .
ZSTD_nextSrcSizeToDecompress ( ) tells how many bytes to provide as ' srcSize ' to ZSTD_decompressContinue ( ) .
ZSTD_decompressContinue ( ) requires this _exact_ amount of bytes , or it will fail .
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result of ZSTD_decompressContinue ( ) is the number of bytes regenerated within ' dst ' ( necessarily < = dstCapacity ) .
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It can be zero : it just means ZSTD_decompressContinue ( ) has decoded some metadata item .
It can also be an error code , which can be tested with ZSTD_isError ( ) .
A frame is fully decoded when ZSTD_nextSrcSizeToDecompress ( ) returns zero .
Context can then be reset to start a new decompression .
Note : it ' s possible to know if next input to present is a header or a block , using ZSTD_nextInputType ( ) .
This information is not required to properly decode a frame .
= = Special case : skippable frames = =
Skippable frames allow integration of user - defined data into a flow of concatenated frames .
Skippable frames will be ignored ( skipped ) by decompressor .
The format of skippable frames is as follows :
a ) Skippable frame ID - 4 Bytes , Little endian format , any value from 0x184D2A50 to 0x184D2A5F
b ) Frame Size - 4 Bytes , Little endian format , unsigned 32 - bits
c ) Frame Content - any content ( User Data ) of length equal to Frame Size
For skippable frames ZSTD_getFrameHeader ( ) returns zfhPtr - > frameType = = ZSTD_skippableFrame .
For skippable frames ZSTD_decompressContinue ( ) always returns 0 : it only skips the content .
*/
/*===== Buffer-less streaming decompression functions =====*/
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ZSTDLIB_STATIC_API size_t ZSTD_decodingBufferSize_min ( unsigned long long windowSize , unsigned long long frameContentSize ) ; /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */
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ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin ( ZSTD_DCtx * dctx ) ;
ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin_usingDict ( ZSTD_DCtx * dctx , const void * dict , size_t dictSize ) ;
ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin_usingDDict ( ZSTD_DCtx * dctx , const ZSTD_DDict * ddict ) ;
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ZSTDLIB_STATIC_API size_t ZSTD_nextSrcSizeToDecompress ( ZSTD_DCtx * dctx ) ;
ZSTDLIB_STATIC_API size_t ZSTD_decompressContinue ( ZSTD_DCtx * dctx , void * dst , size_t dstCapacity , const void * src , size_t srcSize ) ;
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/* misc */
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ZSTD_DEPRECATED ( " This function will likely be removed in the next minor release. It is misleading and has very limited utility. " )
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ZSTDLIB_STATIC_API void ZSTD_copyDCtx ( ZSTD_DCtx * dctx , const ZSTD_DCtx * preparedDCtx ) ;
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typedef enum { ZSTDnit_frameHeader , ZSTDnit_blockHeader , ZSTDnit_block , ZSTDnit_lastBlock , ZSTDnit_checksum , ZSTDnit_skippableFrame } ZSTD_nextInputType_e ;
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ZSTDLIB_STATIC_API ZSTD_nextInputType_e ZSTD_nextInputType ( ZSTD_DCtx * dctx ) ;
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/* ========================================= */
/** Block level API (DEPRECATED) */
/* ========================================= */
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/*!
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This API is deprecated in favor of the regular compression API .
You can get the frame header down to 2 bytes by setting :
- ZSTD_c_format = ZSTD_f_zstd1_magicless
- ZSTD_c_contentSizeFlag = 0
- ZSTD_c_checksumFlag = 0
- ZSTD_c_dictIDFlag = 0
This API is not as well tested as our normal API , so we recommend not using it .
We will be removing it in a future version . If the normal API doesn ' t provide
the functionality you need , please open a GitHub issue .
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Block functions produce and decode raw zstd blocks , without frame metadata .
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Frame metadata cost is typically ~ 12 bytes , which can be non - negligible for very small blocks ( < 100 bytes ) .
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But users will have to take in charge needed metadata to regenerate data , such as compressed and content sizes .
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A few rules to respect :
- Compressing and decompressing require a context structure
+ Use ZSTD_createCCtx ( ) and ZSTD_createDCtx ( )
- It is necessary to init context before starting
+ compression : any ZSTD_compressBegin * ( ) variant , including with dictionary
+ decompression : any ZSTD_decompressBegin * ( ) variant , including with dictionary
- Block size is limited , it must be < = ZSTD_getBlockSize ( ) < = ZSTD_BLOCKSIZE_MAX = = 128 KB
+ If input is larger than a block size , it ' s necessary to split input data into multiple blocks
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+ For inputs larger than a single block , consider using regular ZSTD_compress ( ) instead .
Frame metadata is not that costly , and quickly becomes negligible as source size grows larger than a block .
- When a block is considered not compressible enough , ZSTD_compressBlock ( ) result will be 0 ( zero ) !
= = = > In which case , nothing is produced into ` dst ` !
+ User __must__ test for such outcome and deal directly with uncompressed data
+ A block cannot be declared incompressible if ZSTD_compressBlock ( ) return value was ! = 0.
Doing so would mess up with statistics history , leading to potential data corruption .
+ ZSTD_decompressBlock ( ) _doesn ' t accept uncompressed data as input_ ! !
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+ In case of multiple successive blocks , should some of them be uncompressed ,
decoder must be informed of their existence in order to follow proper history .
Use ZSTD_insertBlock ( ) for such a case .
*/
/*===== Raw zstd block functions =====*/
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ZSTD_DEPRECATED ( " The block API is deprecated in favor of the normal compression API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_getBlockSize ( const ZSTD_CCtx * cctx ) ;
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ZSTD_DEPRECATED ( " The block API is deprecated in favor of the normal compression API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_compressBlock ( ZSTD_CCtx * cctx , void * dst , size_t dstCapacity , const void * src , size_t srcSize ) ;
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ZSTD_DEPRECATED ( " The block API is deprecated in favor of the normal compression API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_decompressBlock ( ZSTD_DCtx * dctx , void * dst , size_t dstCapacity , const void * src , size_t srcSize ) ;
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ZSTD_DEPRECATED ( " The block API is deprecated in favor of the normal compression API. See docs. " )
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ZSTDLIB_STATIC_API size_t ZSTD_insertBlock ( ZSTD_DCtx * dctx , const void * blockStart , size_t blockSize ) ; /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */
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# endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
# if defined (__cplusplus)
}
# endif
