Source code
Revision control
Copy as Markdown
Other Tools
/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
* 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
/* ====== Dependencies ======*/
#include <limits.h> /* INT_MAX */
#include <stddef.h> /* size_t */
/* ===== ZSTDLIB_API : control library symbols visibility ===== */
#ifndef ZSTDLIB_VISIBLE
/* Backwards compatibility with old macro name */
# ifdef ZSTDLIB_VISIBILITY
# define ZSTDLIB_VISIBLE ZSTDLIB_VISIBILITY
# elif defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__)
# define ZSTDLIB_VISIBLE __attribute__ ((visibility ("default")))
# else
# define ZSTDLIB_VISIBLE
# endif
#endif
#ifndef ZSTDLIB_HIDDEN
# if defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__)
# define ZSTDLIB_HIDDEN __attribute__ ((visibility ("hidden")))
# else
# define ZSTDLIB_HIDDEN
# endif
#endif
#if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
# define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBLE
#elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
# 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.*/
#else
# define ZSTDLIB_API ZSTDLIB_VISIBLE
#endif
/* 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 */
/*******************************************************************************
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
#define ZSTD_VERSION_MINOR 5
#define ZSTD_VERSION_RELEASE 6
#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
/*! ZSTD_versionNumber() :
* Return runtime library version, the value is (MAJOR*100*100 + MINOR*100 + RELEASE). */
ZSTDLIB_API unsigned ZSTD_versionNumber(void);
#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)
/*! ZSTD_versionString() :
* Return runtime library version, like "1.4.5". Requires v1.3.0+. */
ZSTDLIB_API const char* ZSTD_versionString(void);
/* *************************************
* Default constant
***************************************/
#ifndef ZSTD_CLEVEL_DEFAULT
# define ZSTD_CLEVEL_DEFAULT 3
#endif
/* *************************************
* Constants
***************************************/
/* 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`.
* NOTE: Providing `dstCapacity >= ZSTD_compressBound(srcSize)` guarantees that zstd will have
* enough space to successfully compress the data.
* @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. */
ZSTD_DEPRECATED("Replaced by ZSTD_getFrameContentSize")
ZSTDLIB_API
unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
/*! ZSTD_findFrameCompressedSize() : Requires v1.4.0+
* `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 ======*/
/* 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) ? 0xFF00FF00FF00FF00ULL : 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
*/
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 */
ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed, requires v1.4.0+ */
ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
ZSTDLIB_API int ZSTD_defaultCLevel(void); /*!< default compression level, specified by ZSTD_CLEVEL_DEFAULT, requires v1.5.0+ */
/***************************************
* Explicit context
***************************************/
/*= Compression context
* When compressing many times,
* it is recommended to allocate a context just once,
* and reuse it for each successive compression operation.
* This will make workload friendlier for system's memory.
* 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.
*/
typedef struct ZSTD_CCtx_s ZSTD_CCtx;
ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void);
ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); /* accept NULL pointer */
/*! ZSTD_compressCCtx() :
* Same as ZSTD_compress(), using an explicit ZSTD_CCtx.
* Important : in order to mirror `ZSTD_compress()` behavior,
* this function compresses at the requested compression level,
* __ignoring any other advanced parameter__ .
* If any advanced parameter was set using the advanced API,
* they will all be reset. Only `compressionLevel` remains.
*/
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 reuse 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);
ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); /* accept NULL pointer */
/*! ZSTD_decompressDCtx() :
* Same as ZSTD_decompress(),
* requires an allocated ZSTD_DCtx.
* Compatible with sticky parameters (see below).
*/
ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize);
/*********************************************
* Advanced compression API (Requires v1.4.0+)
**********************************************/
/* 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*()` !
* __They do not apply to one-shot variants such as ZSTD_compressCCtx()__ .
*
* It's possible to reset all parameters to "default" using ZSTD_CCtx_reset().
*
* This API supersedes all other "advanced" API entry points in the experimental section.
* In the future, we expect to remove API entry points from experimental 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
* 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).
* 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.
* 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'. */
/* 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 */
ZSTD_c_windowLog=101, /* Maximum allowed back-reference distance, expressed as power of 2.
* This will set a memory budget for streaming decompression,
* with larger values requiring more memory
* and typically compressing more.
* 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
* requires explicitly allowing such size at streaming decompression stage. */
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.
* This parameter is useless for "fast" strategy.
* 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.
* This parameter is useless for "fast" and "dFast" strategies.
* 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". */
ZSTD_c_targetCBlockSize=130, /* v1.5.6+
* Attempts to fit compressed block size into approximatively targetCBlockSize.
* Bound by ZSTD_TARGETCBLOCKSIZE_MIN and ZSTD_TARGETCBLOCKSIZE_MAX.
* Note that it's not a guarantee, just a convergence target (default:0).
* No target when targetCBlockSize == 0.
* This is helpful in low bandwidth streaming environments to improve end-to-end latency,
* when a client can make use of partial documents (a prominent example being Chrome).
* Note: this parameter is stable since v1.5.6.
* It was present as an experimental parameter in earlier versions,
* but it's not recommended using it with earlier library versions
* due to massive performance regressions.
*/
/* 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
* 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+) */
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(),
* For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
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 */
/* 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.
*/
ZSTD_c_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel.
* When nbWorkers >= 1, triggers asynchronous mode when invoking ZSTD_compressStream*() :
* ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller,
* while compression is performed in parallel, within worker thread(s).
* (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.
* Default value is `0`, aka "single-threaded mode" : no worker is spawned,
* compression is performed inside Caller's thread, and all invocations are blocking */
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.
* Job size must be a minimum of overlap size, or ZSTDMT_JOBSIZE_MIN (= 512 KB), whichever is largest.
* The minimum size is automatically and transparently enforced. */
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
* ZSTD_c_srcSizeHint
* ZSTD_c_enableDedicatedDictSearch
* ZSTD_c_stableInBuffer
* ZSTD_c_stableOutBuffer
* ZSTD_c_blockDelimiters
* ZSTD_c_validateSequences
* ZSTD_c_useBlockSplitter
* ZSTD_c_useRowMatchFinder
* ZSTD_c_prefetchCDictTables
* ZSTD_c_enableSeqProducerFallback
* ZSTD_c_maxBlockSize
* 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,
/* was ZSTD_c_experimentalParam6=1003; is now ZSTD_c_targetCBlockSize */
ZSTD_c_experimentalParam7=1004,
ZSTD_c_experimentalParam8=1005,
ZSTD_c_experimentalParam9=1006,
ZSTD_c_experimentalParam10=1007,
ZSTD_c_experimentalParam11=1008,
ZSTD_c_experimentalParam12=1009,
ZSTD_c_experimentalParam13=1010,
ZSTD_c_experimentalParam14=1011,
ZSTD_c_experimentalParam15=1012,
ZSTD_c_experimentalParam16=1013,
ZSTD_c_experimentalParam17=1014,
ZSTD_c_experimentalParam18=1015,
ZSTD_c_experimentalParam19=1016
} 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".
* This also removes any reference to any dictionary or external sequence producer.
* 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.
* (note that this entry point doesn't even expose a compression level parameter).
* 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.
* 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.
* @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);
/***********************************************
* Advanced decompression API (Requires v1.4.0+)
************************************************/
/* 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 :
* ZSTD_d_format
* ZSTD_d_stableOutBuffer
* ZSTD_d_forceIgnoreChecksum
* ZSTD_d_refMultipleDDicts
* ZSTD_d_disableHuffmanAssembly
* ZSTD_d_maxBlockSize
* Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
* note : never ever use experimentalParam? names directly
*/
ZSTD_d_experimentalParam1=1000,
ZSTD_d_experimentalParam2=1001,
ZSTD_d_experimentalParam3=1002,
ZSTD_d_experimentalParam4=1003,
ZSTD_d_experimentalParam5=1004,
ZSTD_d_experimentalParam6=1005
} 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 reuse 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 reuse 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);
ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); /* accept NULL pointer */
/*===== 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;
/*! ZSTD_compressStream2() : Requires v1.4.0+
* 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.
* - endOp must be a valid directive
* - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
* - 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,
* 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.
* - note: if an operation ends with an error, it may leave @cctx in an undefined state.
* Therefore, it's UB to invoke ZSTD_compressStream2() of ZSTD_compressStream() on such a state.
* In order to be re-employed after an error, a state must be reset,
* which can be done explicitly (ZSTD_CCtx_reset()),
* or is sometimes implied by methods starting a new compression job (ZSTD_initCStream(), ZSTD_compressCCtx())
*/
ZSTDLIB_API size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
ZSTD_outBuffer* output,
ZSTD_inBuffer* input,
ZSTD_EndDirective endOp);
/* 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.
*/
ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */
ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */
/* *****************************************************************************
* This following is a legacy streaming API, available since v1.0+ .
* It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2().
* It is redundant, but remains fully supported.
******************************************************************************/
/*!
* 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);
*
* Note that ZSTD_initCStream() clears any previously set dictionary. Use the new API
* to compress with a dictionary.
*/
ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
/*!
* 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()
* returns the minimum nb of bytes left to flush (if non-zero and not an error).
*/
ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */
ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */
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 reused 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);
ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); /* accept NULL pointer */
/*===== Streaming decompression functions =====*/
/*! ZSTD_initDStream() :
* Initialize/reset DStream state for new decompression operation.
* Call before new decompression operation using same DStream.
*
* Note : This function is redundant with the advanced API and equivalent to:
* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
* ZSTD_DCtx_refDDict(zds, NULL);
*/
ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds);
/*! 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.
*
* Note: when an operation returns with an error code, the @zds state may be left in undefined state.
* It's UB to invoke `ZSTD_decompressStream()` on such a state.
* In order to re-use such a state, it must be first reset,
* which can be done explicitly (`ZSTD_DCtx_reset()`),
* or is implied for operations starting some new decompression job (`ZSTD_initDStream`, `ZSTD_decompressDCtx()`, `ZSTD_decompress_usingDict()`)
*/
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),
* or a buffer with specified information (see zdict.h).
* 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() :
* 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.
* ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
* @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. */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
int compressionLevel);
/*! ZSTD_freeCDict() :
* Function frees memory allocated by ZSTD_createCDict().
* If a NULL pointer is passed, no operation is performed. */
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() :
* Function frees memory allocated with ZSTD_createDDict()
* If a NULL pointer is passed, no operation is performed. */
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
*******************************/
/*! ZSTD_getDictID_fromDict() : Requires v1.4.0+
* 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);
/*! 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+
* 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);
/*! ZSTD_getDictID_fromFrame() : Requires v1.4.0+
* 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).
* - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden piece of information.
* 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);
/*******************************************************************************
* Advanced dictionary and prefix API (Requires v1.4.0+)
*
* This API allows dictionaries to be used with ZSTD_compress2(),
* ZSTD_compressStream2(), and ZSTD_decompressDCtx().
* Dictionaries are sticky, they remain valid when same context is reused,
* they only reset when the context is reset
* with ZSTD_reset_parameters or ZSTD_reset_session_and_parameters.
* In contrast, Prefixes are single-use.
******************************************************************************/
/*! ZSTD_CCtx_loadDictionary() : Requires v1.4.0+
* 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".
* 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.
* 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()
* 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.
*/
ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
/*! ZSTD_CCtx_refCDict() : Requires v1.4.0+
* Reference a prepared dictionary, to be used for all future compressed frames.
* Note that compression parameters are enforced from within CDict,
* and supersede any compression parameter previously set within CCtx.
* The parameters ignored are labelled as "superseded-by-cdict" in the ZSTD_cParameter enum docs.
* 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);
/*! ZSTD_CCtx_refPrefix() : Requires v1.4.0+
* 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).
* This method is compatible with LDM (long distance mode).
* @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.
* Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent).
* 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);
/*! ZSTD_DCtx_loadDictionary() : Requires v1.4.0+
* 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.
* @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);
/*! ZSTD_DCtx_refDDict() : Requires v1.4.0+
* Reference a prepared dictionary, to be used to decompress next frames.
* The dictionary remains active for decompression of future frames using same DCtx.
*
* 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().
*
* If called with ZSTD_d_refMultipleDDicts disabled (the default), only one dictionary
* will be managed, and referencing a dictionary effectively "discards" any previous one.
*
* @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);
/*! ZSTD_DCtx_refPrefix() : Requires v1.4.0+
* 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.
* Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent).
* 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 === */
/*! ZSTD_sizeof_*() : Requires v1.4.0+
* 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 */
/* **************************************************************************************
* 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
/* 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
/****************************************************************************************
* 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)
* ***************************************************************************************/
#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)
#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
#define ZSTD_BLOCKSIZE_MAX_MIN (1 << 10) /* The minimum valid max blocksize. Maximum blocksizes smaller than this make compressBound() inaccurate. */
#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)
/* Advanced parameter bounds */
#define ZSTD_TARGETCBLOCKSIZE_MIN 1340 /* suitable to fit into an ethernet / wifi / 4G transport frame */
#define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX
#define ZSTD_SRCSIZEHINT_MIN 0
#define ZSTD_SRCSIZEHINT_MAX INT_MAX
/* --- Advanced types --- */
typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
typedef struct {
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).
*/
} ZSTD_Sequence;
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 */
ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */
} ZSTD_dictLoadMethod_e;
typedef enum {
ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */
ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number.
* Useful to save 4 bytes per generated frame.
* Decoder cannot recognise automatically this format, requiring this instruction. */
} ZSTD_format_e;
typedef enum {
/* Note: this enum controls ZSTD_d_forceIgnoreChecksum */
ZSTD_d_validateChecksum = 0,
ZSTD_d_ignoreChecksum = 1
} ZSTD_forceIgnoreChecksum_e;
typedef enum {
/* Note: this enum controls ZSTD_d_refMultipleDDicts */
ZSTD_rmd_refSingleDDict = 0,
ZSTD_rmd_refMultipleDDicts = 1
} ZSTD_refMultipleDDicts_e;
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.
*
* Zstd currently supports the use of a CDict in three ways:
*
* - 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.
*
* - 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.
*
* 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. */
ZSTD_dictForceLoad = 3 /* Always reload the dictionary */
} 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. */
ZSTD_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */
} ZSTD_literalCompressionMode_e;
typedef enum {
/* 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;
/***************************************
* Frame header and size functions
***************************************/
/*! 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. */
ZSTDLIB_STATIC_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
/*! ZSTD_decompressBound() :
* `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
* - if an error occurred: ZSTD_CONTENTSIZE_ERROR
*
* 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)
*/
ZSTDLIB_STATIC_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize);
/*! ZSTD_frameHeaderSize() :
* srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
* @return : size of the Frame Header,
* or an error code (if srcSize is too small) */
ZSTDLIB_STATIC_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
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);
/*! 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 */ \
))
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;
/*! 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);
/*! ZSTD_generateSequences() :
* WARNING: This function is meant for debugging and informational purposes ONLY!
* Its implementation is flawed, and it will be deleted in a future version.
* It is not guaranteed to succeed, as there are several cases where it will give
* up and fail. You should NOT use this function in production code.
*
* This function is deprecated, and will be removed in a future version.
*
* Generate sequences using ZSTD_compress2(), given a source buffer.
*
* @param zc The compression context to be used for ZSTD_compress2(). Set any
* compression parameters you need on this context.
* @param outSeqs The output sequences buffer of size @p outSeqsSize
* @param outSeqsSize The size of the output sequences buffer.
* ZSTD_sequenceBound(srcSize) is an upper bound on the number
* of sequences that can be generated.
* @param src The source buffer to generate sequences from of size @p srcSize.
* @param srcSize The size of the source buffer.
*
* 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.
*
* @returns The number of sequences generated, necessarily less than
* ZSTD_sequenceBound(srcSize), or an error code that can be checked
* with ZSTD_isError().
*/
ZSTD_DEPRECATED("For debugging only, will be replaced by ZSTD_extractSequences()")
ZSTDLIB_STATIC_API size_t
ZSTD_generateSequences(ZSTD_CCtx* zc,
ZSTD_Sequence* outSeqs, size_t outSeqsSize,
const void* src, size_t srcSize);
/*! ZSTD_mergeBlockDelimiters() :
* Given an array of ZSTD_Sequence, remove all sequences that represent block delimiters/last literals
* by merging them into the literals of the next sequence.
*
* 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
*/
ZSTDLIB_STATIC_API size_t ZSTD_mergeBlockDelimiters(ZSTD_Sequence* sequences, size_t seqsSize);
/*! ZSTD_compressSequences() :
* 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
* 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
* @return : final compressed size, or a ZSTD error code.
*/
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);
/*! ZSTD_writeSkippableFrame() :
* Generates a zstd skippable frame containing data given by src, and writes it to dst buffer.
*
* Skippable frames begin with a 4-byte magic number. There are 16 possible choices of magic number,
* 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.
*/
ZSTDLIB_STATIC_API size_t ZSTD_writeSkippableFrame(void* dst, size_t dstCapacity,
const void* src, size_t srcSize, unsigned magicVariant);
/*! 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);
/***************************************
* Memory management
***************************************/
/*! ZSTD_estimate*() :
* These functions make it possible to estimate memory usage
* of a future {D,C}Ctx, before its creation.
* This is useful in combination with ZSTD_initStatic(),
* which makes it possible to employ a static buffer for ZSTD_CCtx* state.
*
* ZSTD_estimateCCtxSize() will provide a memory budget large enough
* to compress data of any size using one-shot compression ZSTD_compressCCtx() or ZSTD_compress2()
* associated with any compression level up to max specified one.
* The estimate will assume the input may be arbitrarily large,
* which is the worst case.
*
* Note that the size estimation is specific for one-shot compression,
* it is not valid for streaming (see ZSTD_estimateCStreamSize*())
* nor other potential ways of using a ZSTD_CCtx* state.
*
* When srcSize can be bound by a known and rather "small" value,
* this knowledge can be used to provide a tighter budget estimation
* because the ZSTD_CCtx* state will need less memory for small inputs.
* This tighter estimation can be provided by employing 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.
*
* Note : only single-threaded compression is supported.
* ZSTD_estimateCCtxSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1.
*/
ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize(int maxCompressionLevel);
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);
/*! ZSTD_estimateCStreamSize() :
* ZSTD_estimateCStreamSize() will provide a memory budget large enough for streaming compression
* using any compression level up to the max specified one.
* It will also consider src size to be arbitrarily "large", which is a worst case scenario.
* 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_estimateCStreamSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1.
* Note 2 : 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.
*
* ZSTD_DStream memory budget depends on frame's window Size.
* This information can be passed manually, using ZSTD_estimateDStreamSize,
* or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame();
* Any frame requesting a window size larger than max specified one will be rejected.
* Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
* an internal ?Dict will be created, which additional size is not estimated here.
* In this case, get total size by adding ZSTD_estimate?DictSize
*/
ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize(int maxCompressionLevel);
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 maxWindowSize);
ZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
/*! 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.
*/
ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize(size_t dictSize, int