/*
- * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
#define ZSTD_H_235446
/* ====== Dependency ======*/
+#include <limits.h> /* INT_MAX */
#include <stddef.h> /* size_t */
#endif
-/*******************************************************************************************************
+/*******************************************************************************
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 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.
+ 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 memory management)
+ - 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 in:
+
+ 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 Fast 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 shall never be used with a dynamic library.
- They are not "stable", their definition may change in the future. Only static linking is allowed.
-*********************************************************************************************************/
+ 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 3
-#define ZSTD_VERSION_RELEASE 1
+#define ZSTD_VERSION_MINOR 4
+#define ZSTD_VERSION_RELEASE 5
#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
-ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< useful to check dll version */
+ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< to check runtime library version */
#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)
-ZSTDLIB_API const char* ZSTD_versionString(void); /* v1.3.0 */
+ZSTDLIB_API const char* ZSTD_versionString(void); /* requires v1.3.0+ */
+
+/* *************************************
+ * 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)
+
/***************************************
ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,
const void* src, size_t compressedSize);
-/*! ZSTD_getFrameContentSize() : v1.3.0
+/*! 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 the frame in `src`, if known
+ * @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".
* 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 done with ZSTD_compress()
+ * 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.
/*! 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 in the same return value (0),
- * while ZSTD_getFrameContentSize() distinguishes them.
- *
- * 'src' is the start of a zstd compressed frame.
- * @return : content size to be decompressed, as a 64-bits value _if known and not empty_, 0 otherwise. */
+ * 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. */
ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
+/*! ZSTD_findFrameCompressedSize() :
+ * `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 ======*/
-ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
-ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case scenario */
+#define ZSTD_COMPRESSBOUND(srcSize) ((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 */
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 */
+ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
/***************************************
-* Explicit memory management
+* Explicit context
***************************************/
/*= Compression context
* When compressing many times,
- * it is recommended to allocate a context just once, and re-use it for each successive compression operation.
+ * it is recommended to allocate a context just 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 in multi-threaded environments. */
+ * 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);
/*! ZSTD_compressCCtx() :
- * Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()). */
-ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* ctx,
+ * 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.
+ */
+ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
int compressionLevel);
ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
/*! ZSTD_decompressDCtx() :
- * Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()) */
-ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* ctx,
+ * 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);
-/**************************
-* Simple dictionary API
-***************************/
-/*! ZSTD_compress_usingDict() :
- * Compression using a predefined Dictionary (see dictBuilder/zdict.h).
- * Note : This function loads the dictionary, resulting in significant startup delay.
- * Note : 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);
+/***************************************
+* Advanced compression API
+***************************************/
-/*! ZSTD_decompress_usingDict() :
- * Decompression using a predefined Dictionary (see dictBuilder/zdict.h).
- * Dictionary must be identical to the one used during compression.
- * Note : This function loads the dictionary, resulting in significant startup delay.
- * 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);
+/* 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 "simple" one-shot variants such as ZSTD_compressCCtx()__ .
+ *
+ * It's possible to reset all parameters to "default" using ZSTD_CCtx_reset().
+ *
+ * This API supercedes all other "advanced" API entry points in the experimental section.
+ * In the future, we expect to remove from experimental API entry points which are redundant with this API.
+ */
-/**********************************
- * Bulk processing dictionary API
- *********************************/
-typedef struct ZSTD_CDict_s ZSTD_CDict;
+/* 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;
-/*! ZSTD_createCDict() :
- * When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
- * ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
- * 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, since its content is copied within CDict */
-ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
- int compressionLevel);
-/*! ZSTD_freeCDict() :
- * Function frees memory allocated by ZSTD_createCDict(). */
-ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
+typedef enum {
-/*! ZSTD_compress_usingCDict() :
- * Compression using a digested Dictionary.
- * Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
- * Note that compression level is decided during dictionary creation.
- * 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);
+ /* 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". */
+
+ /* 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. */
+ 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) */
-typedef struct ZSTD_DDict_s ZSTD_DDict;
+ /* multi-threading parameters */
+ /* These parameters are only useful if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD).
+ * They return an error otherwise. */
+ ZSTD_c_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel.
+ * When nbWorkers >= 1, triggers asynchronous mode when used with ZSTD_compressStream*() :
+ * ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller,
+ * while compression work is performed in parallel, within worker threads.
+ * (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, 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 1 MB, 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_targetCBlockSize
+ * ZSTD_c_srcSizeHint
+ * 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,
+ ZSTD_c_experimentalParam6=1003,
+ ZSTD_c_experimentalParam7=1004
+} ZSTD_cParameter;
-/*! 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);
+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_freeDDict() :
- * Function frees memory allocated with ZSTD_createDDict() */
-ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict);
+/*! 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_decompress_usingDDict() :
- * Decompression using a digested Dictionary.
- * Faster startup than ZSTD_decompress_usingDict(), 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);
+/*! 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 removes any reference to any dictionary too.
+ * 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.
+ * Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
+ * @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
+***************************************/
+
+/* 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
+ * 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_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);
/****************************
* 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 in situations where many streaming operations will be achieved consecutively,
-* since it will play nicer with system's memory, by re-using already allocated memory.
-* Use one separate ZSTD_CStream per thread for parallel execution.
+* It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory.
*
-* Start a new compression by initializing ZSTD_CStream.
-* Use ZSTD_initCStream() to start a new compression operation.
-* Use ZSTD_initCStream_usingDict() or ZSTD_initCStream_usingCDict() for a compression which requires a dictionary (experimental section)
+* For parallel execution, use one separate ZSTD_CStream per thread.
*
-* Use ZSTD_compressStream() repetitively to consume input stream.
-* The function will automatically update both `pos` fields.
-* Note that it may not consume the entire input, in which case `pos < size`,
-* and it's up to the caller to present again remaining data.
-* @return : a size hint, preferred nb of bytes to use as input for next function call
-* or an error code, which can be tested using ZSTD_isError().
-* Note 1 : it's just a hint, to help latency a little, any other value will work fine.
-* Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize()
+* 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 remains within internal buffer, using ZSTD_flushStream().
-* `output->pos` will be updated.
-* Note that some content might still be left within internal buffer if `output->size` is too small.
-* @return : nb of bytes still present within internal buffer (0 if it's empty)
+* 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().
*
-* ZSTD_endStream() instructs to finish a frame.
+* 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.
-* ZSTD_endStream() may not be able to flush full data if `output->size` is too small.
-* In which case, call again ZSTD_endStream() to complete the flush.
+* 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,
- or >0 if some data is still present within internal buffer
- (value is minimum size estimation for remaining data to flush, but it could be more)
+* >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 versions <= v1.2.0 */
+ /* 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);
/*===== 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() :
+ * 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.
+ * - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
+ * - When nbWorkers>=1, function is non-blocking : it just acquires a copy of input, and distributes jobs to internal worker threads, flush 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.
+ */
+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.
+ * It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2().
+ * It is redundant, but remains fully supported.
+ * Advanced parameters and dictionary compression can only be used through the
+ * new API.
+ ******************************************************************************/
+
+/*!
+ * 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);
+ */
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);
-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 in all circumstances. */
-
-
/*-***************************************************************************
* Streaming decompression - HowTo
* 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,
-* or ZSTD_initDStream_usingDict() if decompression requires a dictionary.
-* @return : recommended first input size
+* 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.
-* @return : 0 when a frame is completely decoded and fully flushed,
-* an error code, which can be tested using ZSTD_isError(),
-* any other value > 0, which means there is still some decoding to do to complete current frame.
-* The return value is a suggested next input size (a hint to improve latency) that will never load more than the current frame.
+* 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) */
- /* Continue to distinguish them for compatibility with versions <= v1.2.0 */
+ /* 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);
/*===== Streaming decompression functions =====*/
+
+/* 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);
+
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. */
-#endif /* ZSTD_H_235446 */
+/**************************
+* 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 dictBuilder/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);
-/****************************************************************************************
- * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS
- * The definitions in this section are considered experimental.
- * They should never be used with a dynamic library, as prototypes may change in the future.
+/***********************************
+ * 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(). */
+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() */
+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() :
+ * 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_fromDDict() :
+ * 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() :
+ * 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 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
+ *
+ * This API allows dictionaries to be used with ZSTD_compress2(),
+ * ZSTD_compressStream2(), and ZSTD_decompress(). Dictionaries are sticky, and
+ * only reset with the context is reset with ZSTD_reset_parameters or
+ * ZSTD_reset_session_and_parameters. Prefixes are single-use.
+ ******************************************************************************/
+
+
+/*! ZSTD_CCtx_loadDictionary() :
+ * 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.
+ * To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters).
+ * 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. */
+ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
+
+/*! ZSTD_CCtx_refCDict() :
+ * Reference a prepared dictionary, to be used for all next compressed frames.
+ * Note that compression parameters are enforced from within CDict,
+ * and supersede any compression parameter previously set within CCtx.
+ * The parameters ignored are labled 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() :
+ * 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).
+ * @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() :
+ * Create an internal DDict from dict buffer,
+ * to be used to decompress next frames.
+ * The dictionary remains valid for all future frames, until explicitly invalidated.
+ * @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() :
+ * Reference a prepared dictionary, to be used to decompress next frames.
+ * The dictionary remains active for decompression of future frames using same DCtx.
+ * @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ * Note 1 : Currently, only one dictionary can be managed.
+ * Referencing a new dictionary effectively "discards" any previous one.
+ * 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() :
+ * 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_*() :
+ * 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
-/* --- Constants ---*/
-#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */
-#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
-#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* v0.7+ */
-
-#define ZSTD_WINDOWLOG_MAX_32 27
-#define ZSTD_WINDOWLOG_MAX_64 27
-#define ZSTD_WINDOWLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
-#define ZSTD_WINDOWLOG_MIN 10
-#define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX
-#define ZSTD_HASHLOG_MIN 6
-#define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1)
-#define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
-#define ZSTD_HASHLOG3_MAX 17
-#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
-#define ZSTD_SEARCHLOG_MIN 1
-#define ZSTD_SEARCHLENGTH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */
-#define ZSTD_SEARCHLENGTH_MIN 3 /* only for ZSTD_btopt, other strategies are limited to 4 */
-#define ZSTD_TARGETLENGTH_MIN 4
-#define ZSTD_TARGETLENGTH_MAX 999
-#define ZSTD_LDM_MINMATCH_MIN 4
-#define ZSTD_LDM_MINMATCH_MAX 4096
-#define ZSTD_LDM_BUCKETSIZELOG_MAX 8
-
-#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */
-#define ZSTD_FRAMEHEADERSIZE_MIN 6
-static const size_t ZSTD_frameHeaderSize_prefix = 5; /* minimum input size to know frame header size */
-static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
-static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
-static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */
-
-
-/*--- Advanced types ---*/
-typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2,
- ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; /* from faster to stronger */
+/****************************************************************************************
+ * 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_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 64
+#define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX
+#define ZSTD_SRCSIZEHINT_MIN 0
+#define ZSTD_SRCSIZEHINT_MAX INT_MAX
+
+/* internal */
+#define ZSTD_HASHLOG3_MAX 17
+
+
+/* --- Advanced types --- */
+
+typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
+
+typedef struct {
+ unsigned int matchPos; /* Match pos in dst */
+ /* If seqDef.offset > 3, then this is seqDef.offset - 3
+ * If seqDef.offset < 3, then this is the corresponding repeat offset
+ * But if seqDef.offset < 3 and litLength == 0, this is the
+ * repeat offset before the corresponding repeat offset
+ * And if seqDef.offset == 3 and litLength == 0, this is the
+ * most recent repeat offset - 1
+ */
+ unsigned int offset;
+ unsigned int litLength; /* Literal length */
+ unsigned int matchLength; /* Match length */
+ /* 0 when seq not rep and seqDef.offset otherwise
+ * when litLength == 0 this will be <= 4, otherwise <= 3 like normal
+ */
+ unsigned int rep;
+} 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 searchLength; /**< 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;
+ 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 {
- unsigned contentSizeFlag; /**< 1: content size will be in frame header (when known) */
- unsigned checksumFlag; /**< 1: generate a 32-bits checksum at end of frame, for error detection */
- unsigned noDictIDFlag; /**< 1: no dictID will be saved into frame header (if dictionary compression) */
+ 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_frameParameters fParams;
} ZSTD_parameters;
-typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
+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;
-/*= Custom memory allocation functions */
-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;
-/* use this constant to defer to stdlib's functions */
-static const ZSTD_customMem ZSTD_defaultCMem = { NULL, NULL, NULL };
+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 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;
/***************************************
* Frame size functions
***************************************/
-/*! ZSTD_findFrameCompressedSize() :
- * `src` should point to the start of a ZSTD encoded frame or skippable frame
- * `srcSize` must be at least as large as the frame
- * @return : the compressed size of the first frame starting at `src`,
- * suitable to pass 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);
-
/*! ZSTD_findDecompressedSize() :
- * `src` should point the start of a series of ZSTD encoded and/or skippable frames
+ * `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 exactly at `srcSize` bytes after `src`)
+ * (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
* however it does mean that all frame data must be present and valid. */
ZSTDLIB_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 occured: 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_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize);
+
/*! ZSTD_frameHeaderSize() :
-* `src` should point to the start of a ZSTD frame
-* `srcSize` must be >= ZSTD_frameHeaderSize_prefix.
-* @return : size of the Frame Header */
+ * srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
+ * @return : size of the Frame Header,
+ * or an error code (if srcSize is too small) */
ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
+/*! ZSTD_getSequences() :
+ * Extract sequences from the sequence store
+ * zc can be used to insert custom compression params.
+ * This function invokes ZSTD_compress2
+ * @return : number of sequences extracted
+ */
+ZSTDLIB_API size_t ZSTD_getSequences(ZSTD_CCtx* zc, ZSTD_Sequence* outSeqs,
+ size_t outSeqsSize, const void* src, size_t srcSize);
+
/***************************************
-* Context memory usage
+* Memory management
***************************************/
-/*! ZSTD_sizeof_*() :
- * These functions give the current memory usage of selected object.
- * Object memory usage can evolve if it's re-used multiple times. */
-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);
-
/*! ZSTD_estimate*() :
* These functions make it possible to estimate memory usage
* of a future {D,C}Ctx, before its creation.
- * ZSTD_estimateCCtxSize() 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_estimateCCtxSize_advanced_usingCParams() can provide a tighter estimation.
- * ZSTD_estimateCCtxSize_advanced_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
- * ZSTD_estimateCCtxSize_advanced_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbThreads is > 1.
- * Note : CCtx estimation is only correct for single-threaded compression */
+ *
+ * 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.
+ *
+ * Note 2 : only single-threaded compression is supported.
+ * ZSTD_estimateCCtxSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1.
+ */
ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel);
-ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced_usingCParams(ZSTD_compressionParameters cParams);
-ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced_usingCCtxParams(const ZSTD_CCtx_params* params);
+ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams);
+ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params);
ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
/*! 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_advanced_usingCParams() can provide a tighter estimation.
- * ZSTD_estimateCStreamSize_advanced_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
- * ZSTD_estimateCStreamSize_advanced_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbThreads is set to a value > 1.
- * Note : CStream estimation is only correct for single-threaded compression.
+ * 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();
* 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_API size_t ZSTD_estimateCStreamSize(int compressionLevel);
-ZSTDLIB_API size_t ZSTD_estimateCStreamSize_advanced_usingCParams(ZSTD_compressionParameters cParams);
-ZSTDLIB_API size_t ZSTD_estimateCStreamSize_advanced_usingCCtxParams(const ZSTD_CCtx_params* params);
+ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams);
+ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
-typedef enum {
- ZSTD_dlm_byCopy = 0, /* Copy dictionary content internally. */
- ZSTD_dlm_byRef, /* Reference dictionary content -- the dictionary buffer must outlives its users. */
-} ZSTD_dictLoadMethod_e;
+/*! 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_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel);
+ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod);
+ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod);
+
+/*! 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.
+ */
+ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize);
+ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */
+
+ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize);
+ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
+
+ZSTDLIB_API const ZSTD_CDict* ZSTD_initStaticCDict(
+ void* workspace, size_t workspaceSize,
+ const void* dict, size_t dictSize,
+ ZSTD_dictLoadMethod_e dictLoadMethod,
+ ZSTD_dictContentType_e dictContentType,
+ ZSTD_compressionParameters cParams);
+
+ZSTDLIB_API const ZSTD_DDict* ZSTD_initStaticDDict(
+ 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;
+static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */
+
+ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
+ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
+ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
+ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
+
+ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
+ ZSTD_dictLoadMethod_e dictLoadMethod,
+ ZSTD_dictContentType_e dictContentType,
+ ZSTD_compressionParameters cParams,
+ ZSTD_customMem customMem);
+
+ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
+ ZSTD_dictLoadMethod_e dictLoadMethod,
+ ZSTD_dictContentType_e dictContentType,
+ ZSTD_customMem customMem);
-/*! ZSTD_estimate?DictSize() :
- * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict().
- * ZSTD_estimateCStreamSize_advanced_usingCParams() makes it possible to control precisely compression parameters, like ZSTD_createCDict_advanced().
- * Note : dictionary created by reference using ZSTD_dlm_byRef are smaller
- */
-ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel);
-ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod);
-ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod);
/***************************************
* Advanced compression functions
***************************************/
-/*! ZSTD_createCCtx_advanced() :
- * Create a ZSTD compression context using external alloc and free functions */
-ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
-
-/*! ZSTD_initStaticCCtx() : initialize a fixed-size zstd compression context
- * workspace: The memory area to emplace the context into.
- * Provided pointer must 8-bytes aligned.
- * It must outlive context usage.
- * workspaceSize: Use ZSTD_estimateCCtxSize() or ZSTD_estimateCStreamSize()
- * to determine how large workspace must be to support scenario.
- * @return : pointer to ZSTD_CCtx*, or NULL if error (size too small)
- * Note : zstd will never resize nor malloc() when using a static cctx.
- * If it needs more memory than available, it will simply error out.
- * Note 2 : there is no corresponding "free" function.
- * Since workspace was allocated externally, it must be freed externally too.
- * Limitation 1 : currently not compatible with internal CDict creation, such as
- * ZSTD_CCtx_loadDictionary() or ZSTD_initCStream_usingDict().
- * Limitation 2 : currently not compatible with multi-threading
- */
-ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize);
-
/*! ZSTD_createCDict_byReference() :
* Create a digested dictionary for compression
- * Dictionary content is simply referenced, and therefore stays in dictBuffer.
- * It is important that dictBuffer outlives CDict, it must remain read accessible throughout the lifetime of CDict */
+ * Dictionary content is just referenced, not duplicated.
+ * As a consequence, `dictBuffer` **must** outlive CDict,
+ * and its content must remain unmodified throughout the lifetime of CDict.
+ * note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
-typedef enum { ZSTD_dm_auto=0, /* dictionary is "full" if it starts with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */
- ZSTD_dm_rawContent, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */
- ZSTD_dm_fullDict /* refuses to load a dictionary if it does not respect Zstandard's specification */
-} ZSTD_dictMode_e;
-/*! ZSTD_createCDict_advanced() :
- * Create a ZSTD_CDict using external alloc and free, and customized compression parameters */
-ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
- ZSTD_dictLoadMethod_e dictLoadMethod,
- ZSTD_dictMode_e dictMode,
- ZSTD_compressionParameters cParams,
- ZSTD_customMem customMem);
-
-/*! ZSTD_initStaticCDict_advanced() :
- * Generate a digested dictionary in provided memory area.
- * workspace: The memory area to emplace the dictionary into.
- * Provided pointer must 8-bytes aligned.
- * It must outlive dictionary usage.
- * workspaceSize: Use ZSTD_estimateCDictSize()
- * to determine how large workspace must be.
- * cParams : use ZSTD_getCParams() to transform a compression level
- * into its relevants cParams.
- * @return : pointer to ZSTD_CDict*, or NULL if error (size too small)
- * Note : there is no corresponding "free" function.
- * Since workspace was allocated externally, it must be freed externally.
- */
-ZSTDLIB_API ZSTD_CDict* ZSTD_initStaticCDict(
- void* workspace, size_t workspaceSize,
- const void* dict, size_t dictSize,
- ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictMode_e dictMode,
- ZSTD_compressionParameters cParams);
-
/*! ZSTD_getCParams() :
-* @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize.
-* `estimatedSrcSize` value is optional, select 0 if not known */
+ * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize.
+ * `estimatedSrcSize` value is optional, select 0 if not known */
ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
/*! 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 (0) */
+ * 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 */
ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
/*! ZSTD_checkCParams() :
-* Ensure param values remain within authorized range */
+ * Ensure param values remain within authorized range.
+ * @return 0 on success, or an error code (can be checked with ZSTD_isError()) */
ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
/*! ZSTD_adjustCParams() :
* optimize params for a given `srcSize` and `dictSize`.
- * both values are optional, select `0` if unknown. */
+ * `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) */
ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
/*! ZSTD_compress_advanced() :
-* Same as ZSTD_compress_usingDict(), with fine-tune control over each compression parameter */
-ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* cctx,
- void* dst, size_t dstCapacity,
- const void* src, size_t srcSize,
- const void* dict,size_t dictSize,
- ZSTD_parameters params);
+ * Note : this function is now DEPRECATED.
+ * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters.
+ * This prototype will be marked as deprecated and generate compilation warning on reaching v1.5.x */
+ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx,
+ void* dst, size_t dstCapacity,
+ const void* src, size_t srcSize,
+ const void* dict,size_t dictSize,
+ ZSTD_parameters params);
/*! ZSTD_compress_usingCDict_advanced() :
-* Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */
+ * Note : this function is now REDUNDANT.
+ * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters.
+ * This prototype will be marked as deprecated and generate compilation warning in some future version */
ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx,
- void* dst, size_t dstCapacity,
- const void* src, size_t srcSize,
- const ZSTD_CDict* cdict, ZSTD_frameParameters fParams);
+ 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` */
+ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
+
+/*! 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 ?) */
+ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
+
+/*! 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 ?) */
+ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
+
+/* === 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
+
+/* Controls how the literals are compressed (default is auto).
+ * The value must be of type ZSTD_literalCompressionMode_e.
+ * See ZSTD_literalCompressionMode_t enum definition for details.
+ */
+#define ZSTD_c_literalCompressionMode ZSTD_c_experimentalParam5
+
+/* 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
+
+/* 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
+
+/*! 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()).
+ */
+ZSTDLIB_API size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int* value);
+
+
+/*! 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.
+ * - ZSTD_freeCCtxParams() : Free the memory.
+ *
+ * This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams()
+ * for static allocation of CCtx for single-threaded compression.
+ */
+ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void);
+ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
+
+/*! ZSTD_CCtxParams_reset() :
+ * Reset params to default values.
+ */
+ZSTDLIB_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params);
+
+/*! ZSTD_CCtxParams_init() :
+ * Initializes the compression parameters of cctxParams according to
+ * compression level. All other parameters are reset to their default values.
+ */
+ZSTDLIB_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel);
+
+/*! ZSTD_CCtxParams_init_advanced() :
+ * Initializes the compression and frame parameters of cctxParams according to
+ * params. All other parameters are reset to their default values.
+ */
+ZSTDLIB_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params);
+
+/*! ZSTD_CCtxParams_setParameter() :
+ * Similar to ZSTD_CCtx_setParameter.
+ * Set one compression parameter, selected by enum ZSTD_cParameter.
+ * Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams().
+ * @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ */
+ZSTDLIB_API size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value);
+
+/*! 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()).
+ */
+ZSTDLIB_API size_t ZSTD_CCtxParams_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value);
+
+/*! 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).
+ */
+ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
+ 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.
+ */
+ZSTDLIB_API size_t ZSTD_compressStream2_simpleArgs (
+ 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 ---*/
+/***************************************
+* Advanced decompression functions
+***************************************/
/*! ZSTD_isFrame() :
* Tells if the content of `buffer` starts with a valid Frame Identifier.
* Note 3 : Skippable Frame Identifiers are considered valid. */
ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size);
-/*! ZSTD_createDCtx_advanced() :
- * Create a ZSTD decompression context using external alloc and free functions */
-ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
-
-/*! ZSTD_initStaticDCtx() : initialize a fixed-size zstd decompression context
- * workspace: The memory area to emplace the context into.
- * Provided pointer must 8-bytes aligned.
- * It must outlive context usage.
- * workspaceSize: Use ZSTD_estimateDCtxSize() or ZSTD_estimateDStreamSize()
- * to determine how large workspace must be to support scenario.
- * @return : pointer to ZSTD_DCtx*, or NULL if error (size too small)
- * Note : zstd will never resize nor malloc() when using a static dctx.
- * If it needs more memory than available, it will simply error out.
- * Note 2 : static dctx is incompatible with legacy support
- * Note 3 : there is no corresponding "free" function.
- * Since workspace was allocated externally, it must be freed externally.
- * Limitation : currently not compatible with internal DDict creation,
- * such as ZSTD_initDStream_usingDict().
- */
-ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize);
-
/*! 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 must remain read accessible throughout the lifetime of DDict */
ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize);
-/*! ZSTD_createDDict_advanced() :
- * Create a ZSTD_DDict using external alloc and free, optionally by reference */
-ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
- ZSTD_dictLoadMethod_e dictLoadMethod,
- ZSTD_customMem customMem);
-
-/*! ZSTD_initStaticDDict() :
- * Generate a digested dictionary in provided memory area.
- * workspace: The memory area to emplace the dictionary into.
- * Provided pointer must 8-bytes aligned.
- * It must outlive dictionary usage.
- * workspaceSize: Use ZSTD_estimateDDictSize()
- * to determine how large workspace must be.
- * @return : pointer to ZSTD_DDict*, or NULL if error (size too small)
- * Note : there is no corresponding "free" function.
- * Since workspace was allocated externally, it must be freed externally.
+/*! 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. */
+ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
+
+/*! 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 ?). */
+ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
+
+/*! 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 ?) */
+ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
+
+/*! 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()).
*/
-ZSTDLIB_API ZSTD_DDict* ZSTD_initStaticDDict(void* workspace, size_t workspaceSize,
- const void* dict, size_t dictSize,
- ZSTD_dictLoadMethod_e dictLoadMethod);
+ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
-/*! ZSTD_getDictID_fromDict() :
- * 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_d_format
+ * experimental parameter,
+ * allowing selection between ZSTD_format_e input compression formats
+ */
+#define ZSTD_d_format ZSTD_d_experimentalParam1
+/* 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.
+ *
+ * When this flags is enabled zstd won't allocate an output buffer, because
+ * 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_getDictID_fromDDict() :
- * 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_DCtx_setFormat() :
+ * 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()). */
+ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
-/*! ZSTD_getDictID_fromFrame() :
- * 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 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);
+/*! 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.
+ */
+ZSTDLIB_API size_t ZSTD_decompressStream_simpleArgs (
+ 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 =====*/
-ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
-ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */
-ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct, a size of 0 means unknown. for a frame size of 0 use initCStream_advanced */
-ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/
-ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
- ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize is optional and can be 0 (meaning unknown). note: if the contentSizeFlag is set, pledgedSrcSize == 0 means the source size is actually 0. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. */
-ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); /**< note : cdict will just be referenced, and must outlive compression session */
-ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize); /**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters */
+/**! ZSTD_initCStream_srcSize() :
+ * This function is deprecated, and 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);
+ * 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.
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t
+ZSTD_initCStream_srcSize(ZSTD_CStream* zcs,
+ int compressionLevel,
+ unsigned long long pledgedSrcSize);
+
+/**! ZSTD_initCStream_usingDict() :
+ * This function is deprecated, and is equivalent to:
+ * 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.
+ * Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if
+ * it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t
+ZSTD_initCStream_usingDict(ZSTD_CStream* zcs,
+ const void* dict, size_t dictSize,
+ int compressionLevel);
+
+/**! ZSTD_initCStream_advanced() :
+ * This function is deprecated, and is approximately equivalent to:
+ * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
+ * // Pseudocode: Set each zstd parameter and leave the rest as-is.
+ * for ((param, value) : params) {
+ * ZSTD_CCtx_setParameter(zcs, param, value);
+ * }
+ * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
+ * ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
+ *
+ * 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.
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t
+ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
+ const void* dict, size_t dictSize,
+ ZSTD_parameters params,
+ unsigned long long pledgedSrcSize);
+
+/**! ZSTD_initCStream_usingCDict() :
+ * This function is deprecated, and equivalent to:
+ * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
+ * ZSTD_CCtx_refCDict(zcs, cdict);
+ *
+ * note : cdict will just be referenced, and must outlive compression session
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);
+
+/**! ZSTD_initCStream_usingCDict_advanced() :
+ * This function is DEPRECATED, and is approximately equivalent to:
+ * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
+ * // Pseudocode: Set each zstd frame parameter and leave the rest as-is.
+ * for ((fParam, value) : fParams) {
+ * ZSTD_CCtx_setParameter(zcs, fParam, value);
+ * }
+ * 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.
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t
+ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs,
+ const ZSTD_CDict* cdict,
+ ZSTD_frameParameters fParams,
+ unsigned long long pledgedSrcSize);
/*! ZSTD_resetCStream() :
- * start a new compression job, using same parameters from previous job.
- * This is typically useful to skip dictionary loading stage, since it will re-use it in-place..
+ * This function is deprecated, and is equivalent to:
+ * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
+ * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
+ *
+ * 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().
- * pledgedSrcSize==0 means "srcSize unknown".
+ * 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.
- * @return : 0, or an error code (which can be tested using ZSTD_isError()) */
+ * 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())
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
+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.
+ */
+ZSTDLIB_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx);
+
+/*! 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.
+ */
+ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx);
+
+
/*===== Advanced Streaming decompression functions =====*/
-typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;
-ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
-ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
-ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue);
-ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: a dict will not be used if dict == NULL or dictSize < 8 */
-ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict will just be referenced, and must outlive decompression session */
-ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); /**< re-use decompression parameters from previous init; saves dictionary loading */
+/**
+ * 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
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize);
+
+/**
+ * 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
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);
+
+/**
+ * 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
+ * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
+ */
+ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds);
/*********************************************************************
* Buffer-less and synchronous inner streaming functions
*
* This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
-* But it's also a complex one, with many restrictions (documented below).
-* Prefer using normal streaming API for an easier experience
+* But it's also a complex one, with several restrictions, documented below.
+* Prefer normal streaming API for an easier experience.
********************************************************************* */
/**
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 buffer only.
- - Interface is synchronous : input is consumed entirely and produce 1+ (or more) compressed blocks.
+ - 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.
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 will be considered unfinished (corrupted) by decoders.
+ Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders.
- `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new frame.
+ `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again.
*/
/*===== Buffer-less streaming compression functions =====*/
ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel);
ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel);
-ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize is optional and can be 0 (meaning unknown). note: if the contentSizeFlag is set, pledgedSrcSize == 0 means the source size is actually 0 */
+ZSTDLIB_API 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 */
ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */
-ZSTDLIB_API 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=0 means null-size */
-ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize can be 0, indicating unknown size. if it is non-zero, it must be accurate. for 0 size frames, use compressBegin_advanced */
+ZSTDLIB_API 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 */
+ZSTDLIB_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 */
ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
unsigned dictID;
unsigned checksumFlag;
} 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_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_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format);
ZSTDLIB_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 */
ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
-/*=== New advanced API (experimental, and compression only) ===*/
-
-/* notes on API design :
- * In this proposal, parameters are pushed one by one into an existing CCtx,
- * and then applied on all subsequent compression jobs.
- * When no parameter is ever provided, CCtx is created with compression level ZSTD_CLEVEL_DEFAULT.
- *
- * This API is intended to replace all others experimental API.
- * It can basically do all other use cases, and even new ones.
- * It stands a good chance to become "stable",
- * after a reasonable testing period.
- */
-
-/* note on naming convention :
- * Initially, the API favored names like ZSTD_setCCtxParameter() .
- * In this proposal, convention is changed towards ZSTD_CCtx_setParameter() .
- * The main driver is that it identifies more clearly the target object type.
- * It feels clearer in light of potential variants :
- * ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter())
- * ZSTD_DCtx_setParameter() (rather than ZSTD_setDCtxParameter() )
- * Left variant feels easier to distinguish.
- */
-
-/* note on enum design :
- * All enum will be manually set to explicit values before reaching "stable API" status */
-
-typedef enum {
- /* compression parameters */
- ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
- * Default level is ZSTD_CLEVEL_DEFAULT==3.
- * Special: value 0 means "do not change cLevel". */
- ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2.
- * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
- * Special: value 0 means "do not change windowLog". */
- ZSTD_p_hashLog, /* Size of the probe table, as a power of 2.
- * Resulting table size 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 "do not change hashLog". */
- ZSTD_p_chainLog, /* Size of the full-search table, as a power of 2.
- * Resulting table size is (1 << (chainLog+2)).
- * Larger tables result in better and slower compression.
- * This parameter is useless when using "fast" strategy.
- * Special: value 0 means "do not change chainLog". */
- ZSTD_p_searchLog, /* Number of search attempts, as a power of 2.
- * More attempts result in better and slower compression.
- * This parameter is useless when using "fast" and "dFast" strategies.
- * Special: value 0 means "do not change searchLog". */
- ZSTD_p_minMatch, /* Minimum size of searched matches (note : repCode matches can be smaller).
- * Larger values make faster compression and decompression, but decrease ratio.
- * Must be clamped between ZSTD_SEARCHLENGTH_MIN and ZSTD_SEARCHLENGTH_MAX.
- * Note that currently, for all strategies < btopt, effective minimum is 4.
- * Note that currently, for all strategies > fast, effective maximum is 6.
- * Special: value 0 means "do not change minMatchLength". */
- ZSTD_p_targetLength, /* Only useful for strategies >= btopt.
- * Length of Match considered "good enough" to stop search.
- * Larger values make compression stronger and slower.
- * Special: value 0 means "do not change targetLength". */
- ZSTD_p_compressionStrategy, /* See ZSTD_strategy enum definition.
- * Cast selected strategy as unsigned for ZSTD_CCtx_setParameter() compatibility.
- * The higher the value of selected strategy, the more complex it is,
- * resulting in stronger and slower compression.
- * Special: value 0 means "do not change strategy". */
-
- /* frame parameters */
- ZSTD_p_contentSizeFlag=200, /* Content size is written into frame header _whenever known_ (default:1)
- * note that content size must be known at the beginning,
- * it is sent using ZSTD_CCtx_setPledgedSrcSize() */
- ZSTD_p_checksumFlag, /* A 32-bits checksum of content is written at end of frame (default:0) */
- ZSTD_p_dictIDFlag, /* When applicable, dictID of dictionary is provided in frame header (default:1) */
-
- /* multi-threading parameters */
- ZSTD_p_nbThreads=400, /* Select how many threads a compression job can spawn (default:1)
- * More threads improve speed, but also increase memory usage.
- * Can only receive a value > 1 if ZSTD_MULTITHREAD is enabled.
- * Special: value 0 means "do not change nbThreads" */
- ZSTD_p_jobSize, /* Size of a compression job. Each compression job is completed in parallel.
- * 0 means default, which is dynamically determined based on compression parameters.
- * Job size must be a minimum of overlapSize, or 1 KB, whichever is largest
- * The minimum size is automatically and transparently enforced */
- ZSTD_p_overlapSizeLog, /* Size of previous input reloaded at the beginning of each job.
- * 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */
-
- /* advanced parameters - may not remain available after API update */
- ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize,
- * even when referencing into Dictionary content (default:0) */
- ZSTD_p_enableLongDistanceMatching=1200, /* Enable long distance matching.
- * This parameter is designed to improve the compression
- * ratio for large inputs with long distance matches.
- * This increases the memory usage as well as window size.
- * Note: setting this parameter sets all the LDM parameters
- * as well as ZSTD_p_windowLog. It should be set after
- * ZSTD_p_compressionLevel and before ZSTD_p_windowLog and
- * other LDM parameters. Setting the compression level
- * after this parameter overrides the window log, though LDM
- * will remain enabled until explicitly disabled. */
- ZSTD_p_ldmHashLog, /* 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: 20). */
- ZSTD_p_ldmMinMatch, /* Minimum size of searched matches 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 (default: 64). */
- ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution.
- * Larger values usually improve collision resolution but may decrease
- * compression speed.
- * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX (default: 3). */
- ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table.
- * The default is MAX(0, (windowLog - ldmHashLog)) to
- * optimize hash table usage.
- * Larger values improve compression speed. Deviating far from the
- * default value will likely result in a decrease in compression ratio.
- * Must be clamped between 0 and ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN. */
-
-} ZSTD_cParameter;
-
-
-/*! ZSTD_CCtx_setParameter() :
- * Set one compression parameter, selected by enum ZSTD_cParameter.
- * Note : when `value` is an enum, cast it to unsigned for proper type checking.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()). */
-ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value);
-
-/*! ZSTD_CCtx_setPledgedSrcSize() :
- * Total input data size to be compressed as a single frame.
- * This value will be controlled at the end, and result in error if not respected.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- * Note 1 : 0 means zero, empty.
- * In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN.
- * Note that ZSTD_CONTENTSIZE_UNKNOWN is default value for new compression jobs.
- * Note 2 : If all data is provided and consumed in a single round,
- * this value is overriden by srcSize instead. */
-ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize);
-
-/*! ZSTD_CCtx_loadDictionary() :
- * Create an internal CDict from dict buffer.
- * Decompression will have to use same buffer.
- * @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 : `dict` content will be copied internally. Use
- * ZSTD_CCtx_loadDictionary_byReference() to reference dictionary
- * content instead. The dictionary buffer must then outlive its
- * users.
- * Note 2 : Loading a dictionary involves building tables, which are dependent on compression parameters.
- * For this reason, compression parameters cannot be changed anymore after loading a dictionary.
- * It's also a CPU-heavy operation, with non-negligible impact on latency.
- * Note 3 : Dictionary will be used for all future compression jobs.
- * To return to "no-dictionary" situation, load a NULL dictionary
- * Note 5 : Use ZSTD_CCtx_loadDictionary_advanced() to select how dictionary
- * content will be interpreted.
- */
-ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
-ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
-ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictMode_e dictMode);
-
-
-/*! ZSTD_CCtx_refCDict() :
- * Reference a prepared dictionary, to be used for all next compression jobs.
- * Note that compression parameters are enforced from within CDict,
- * and supersede any compression parameter previously set within CCtx.
- * The dictionary will remain valid for future compression jobs using same CCtx.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- * Special : adding a NULL CDict means "return to no-dictionary mode".
- * Note 1 : Currently, only one dictionary can be managed.
- * Adding a new dictionary effectively "discards" any previous one.
- * Note 2 : CDict is just referenced, its lifetime must outlive CCtx.
- */
-ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
-
-/*! ZSTD_CCtx_refPrefix() :
- * Reference a prefix (single-usage dictionary) for next compression job.
- * Decompression need same prefix to properly regenerate data.
- * Prefix is **only used once**. Tables are discarded at end of compression job.
- * Subsequent compression jobs will be done without prefix (if none is explicitly referenced).
- * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_CDict instead.
- * @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 job.
- * Note 2 : Referencing a prefix involves building tables, which are dependent on compression parameters.
- * It's a CPU-heavy operation, with non-negligible impact on latency.
- * Note 3 : By default, the prefix is treated as raw content
- * (ZSTD_dm_rawContent). Use ZSTD_CCtx_refPrefix_advanced() to alter
- * dictMode. */
-ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize);
-ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictMode_e dictMode);
-
-
-
-typedef enum {
- ZSTD_e_continue=0, /* collect more data, encoder transparently decides when to output result, for optimal conditions */
- ZSTD_e_flush, /* flush any data provided so far - frame will continue, future data can still reference previous data for better compression */
- ZSTD_e_end /* flush any remaining data and ends current frame. Any future compression starts a new frame. */
-} ZSTD_EndDirective;
-
-/*! ZSTD_compress_generic() :
- * Behave about the same as ZSTD_compressStream. To note :
- * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter()
- * - Compression parameters cannot be changed once compression is started.
- * - *dstPos must be <= dstCapacity, *srcPos must be <= srcSize
- * - *dspPos and *srcPos will be updated. They are guaranteed to remain below their respective limit.
- * - @return provides the minimum amount of data still to flush from internal buffers
- * or an error code, which can be tested using ZSTD_isError().
- * if @return != 0, flush is not fully completed, there is some data left within internal buffers.
- * - after a ZSTD_e_end directive, if internal buffer is not fully flushed,
- * only ZSTD_e_end or ZSTD_e_flush operations are allowed.
- * It is necessary to fully flush internal buffers
- * before starting a new compression job, or changing compression parameters.
- */
-ZSTDLIB_API size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
- ZSTD_outBuffer* output,
- ZSTD_inBuffer* input,
- ZSTD_EndDirective endOp);
-
-/*! ZSTD_CCtx_reset() :
- * Return a CCtx to clean state.
- * Useful after an error, or to interrupt an ongoing compression job and start a new one.
- * Any internal data not yet flushed is cancelled.
- * Dictionary (if any) is dropped.
- * It's possible to modify compression parameters after a reset.
- */
-ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx); /* Not ready yet ! */
-
-
-/*! ZSTD_compress_generic_simpleArgs() :
- * Same as ZSTD_compress_generic(),
- * but using only integral types as arguments.
- * Argument list is larger and less expressive than ZSTD_{in,out}Buffer,
- * but can be helpful for binders from dynamic languages
- * which have troubles handling structures containing memory pointers.
- */
-size_t ZSTD_compress_generic_simpleArgs (
- ZSTD_CCtx* cctx,
- void* dst, size_t dstCapacity, size_t* dstPos,
- const void* src, size_t srcSize, size_t* srcPos,
- ZSTD_EndDirective endOp);
-
-
-/** ZSTD_CCtx_params
- *
- * - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure
- * - ZSTD_CCtxParam_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 compression jobs.
- * - ZSTD_compress_generic() : Do compression using the CCtx.
- * - ZSTD_freeCCtxParams() : Free the memory.
- *
- * This can be used with ZSTD_estimateCCtxSize_opaque() for static allocation
- * for single-threaded compression.
- */
-ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void);
-
-/*! ZSTD_resetCCtxParams() :
- * Reset params to default, with the default compression level.
- */
-ZSTDLIB_API size_t ZSTD_resetCCtxParams(ZSTD_CCtx_params* params);
-
-/*! ZSTD_initCCtxParams() :
- * Initializes the compression parameters of cctxParams according to
- * compression level. All other parameters are reset to their default values.
- */
-ZSTDLIB_API size_t ZSTD_initCCtxParams(ZSTD_CCtx_params* cctxParams, int compressionLevel);
-
-/*! ZSTD_initCCtxParams_advanced() :
- * Initializes the compression and frame parameters of cctxParams according to
- * params. All other parameters are reset to their default values.
- */
-ZSTDLIB_API size_t ZSTD_initCCtxParams_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params);
-
-ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
-
-/*! ZSTD_CCtxParam_setParameter() :
- * Similar to ZSTD_CCtx_setParameter.
- * Set one compression parameter, selected by enum ZSTD_cParameter.
- * Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams().
- * Note : when `value` is an enum, cast it to unsigned for proper type checking.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- */
-ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value);
-
-/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
- * Apply a set of ZSTD_CCtx_params to the compression context.
- * This must be done before the dictionary is loaded.
- * The pledgedSrcSize is treated as unknown.
- * Multithreading parameters are applied only if nbThreads > 1.
- */
-ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
- ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);
-/**
- Block functions
+/* ============================ */
+/** Block level API */
+/* ============================ */
+/*!
Block functions produce and decode raw zstd blocks, without frame metadata.
- Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
- User will have to take in charge required information to regenerate data, such as compressed and content sizes.
+ Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes).
+ But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes.
A few rules to respect :
- Compressing and decompressing require a context structure
+ compression : any ZSTD_compressBegin*() variant, including with dictionary
+ decompression : any ZSTD_decompressBegin*() variant, including with dictionary
+ copyCCtx() and copyDCtx() can be used too
- - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX
+ - 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
- + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead.
- Frame metadata is not that costly, and quickly becomes negligible as source size grows larger.
- - When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
- In which case, nothing is produced into `dst`.
- + User must test for such outcome and deal directly with uncompressed data
- + ZSTD_decompressBlock() doesn't accept uncompressed data as input !!!
+ + 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_ !!
+ 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.
*/
-#define ZSTD_BLOCKSIZELOG_MAX 17
-#define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) /* define, for static allocation */
/*===== Raw zstd block functions =====*/
ZSTDLIB_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx);
ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
-ZSTDLIB_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 */
+ZSTDLIB_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. */
#endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
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