contrib/zstd/lib/zstd.h in extzstd-0.3 vs contrib/zstd/lib/zstd.h in extzstd-0.3.1

- old
+ new

@@ -1,7 +1,7 @@ /* - * 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 * LICENSE file in the root directory of this source tree) and the GPLv2 (found * in the COPYING file in the root directory of this source tree). @@ -13,10 +13,11 @@ #ifndef ZSTD_H_235446 #define ZSTD_H_235446 /* ====== Dependency ======*/ +#include <limits.h> /* INT_MAX */ #include <stddef.h> /* size_t */ /* ===== ZSTDLIB_API : control library symbols visibility ===== */ #ifndef ZSTDLIB_VISIBILITY @@ -69,31 +70,31 @@ *******************************************************************************/ /*------ Version ------*/ #define ZSTD_VERSION_MAJOR 1 #define ZSTD_VERSION_MINOR 4 -#define ZSTD_VERSION_RELEASE 0 +#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); /**< 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); /* requires v1.3.0+ */ -/*************************************** -* Default constant -***************************************/ +/* ************************************* + * Default constant + ***************************************/ #ifndef ZSTD_CLEVEL_DEFAULT # define ZSTD_CLEVEL_DEFAULT 3 #endif -/*************************************** -* Constants -***************************************/ +/* ************************************* + * 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 */ @@ -181,21 +182,30 @@ /*************************************** * 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(), using an explicit ZSTD_CCtx - * The function will compress at requested compression level, - * ignoring any other parameter */ + * 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); @@ -226,11 +236,11 @@ /* 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() + * __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. @@ -254,39 +264,50 @@ typedef enum { /* compression parameters * Note: When compressing with a ZSTD_CDict these parameters are superseded - * by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict() - * for more info (superseded-by-cdict). */ - ZSTD_c_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table + * 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 sets all default values of other compression parameters */ + * 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 window size at decompression stage if using streaming. */ + * 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 when using "fast" strategy. + * 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 when using "fast" and "dFast" strategies. + * 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. @@ -337,11 +358,11 @@ /* 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 variants, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */ + * For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */ ZSTD_c_checksumFlag=201, /* A 32-bits checksum of content is written at end of frame (default:0) */ ZSTD_c_dictIDFlag=202, /* When applicable, dictionary's ID is written into frame header (default:1) */ /* multi-threading parameters */ /* These parameters are only useful if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD). @@ -356,11 +377,11 @@ * 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 */ + * 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. @@ -378,19 +399,23 @@ * 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; typedef struct { size_t error; int lowerBound; @@ -495,15 +520,17 @@ * 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_c_format + * 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_experimentalParam1=1000, + ZSTD_d_experimentalParam2=1001 } ZSTD_dParameter; /*! ZSTD_dParam_getBounds() : * All parameters must belong to an interval with lower and upper bounds, @@ -655,38 +682,54 @@ 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 in all circumstances. */ +ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */ -/******************************************************************************* - * This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and - * ZSTD_compressStream2(). It is redundant, but is still fully supported. + +/* ***************************************************************************** + * 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 number of bytes left to flush (if non-zero and not an error). + * 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). */ +/*! 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). */ +/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */ ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); /*-*************************************************************************** * Streaming decompression - HowTo @@ -723,11 +766,11 @@ /*===== Streaming decompression functions =====*/ /* This function is redundant with the advanced API and equivalent to: * - * ZSTD_DCtx_reset(zds); + * 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); @@ -768,16 +811,21 @@ * Bulk processing dictionary API **********************************/ typedef struct ZSTD_CDict_s ZSTD_CDict; /*! ZSTD_createCDict() : - * When compressing multiple messages / blocks using the same dictionary, it's recommended to load it only once. - * ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup cost. + * 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. - * Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate `dictBuffer` content. - * Note : A ZSTD_CDict can be created from an empty dictBuffer, but it is inefficient when used to compress small data. */ + * @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(). */ @@ -900,11 +948,11 @@ * 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_dm_rawContent). + * 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() : @@ -944,11 +992,11 @@ * @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_dm_rawContent). + * 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, @@ -967,11 +1015,11 @@ 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. @@ -989,12 +1037,12 @@ * 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 5 /* minimum input size required to query frame header size */ -#define ZSTD_FRAMEHEADERSIZE_MIN 6 +#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 @@ -1035,19 +1083,43 @@ #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 minMatch; /**< match length searched : larger == faster decompression, sometimes less compression */ @@ -1072,36 +1144,27 @@ ZSTD_dct_fullDict = 2 /* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */ } ZSTD_dictContentType_e; typedef enum { ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */ - ZSTD_dlm_byRef = 1, /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ + ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ } ZSTD_dictLoadMethod_e; typedef enum { - /* Opened question : should we have a format ZSTD_f_auto ? - * Today, it would mean exactly the same as ZSTD_f_zstd1. - * But, in the future, should several formats become supported, - * on the compression side, it would mean "default format". - * On the decompression side, it would mean "automatic format detection", - * so that ZSTD_f_zstd1 would mean "accept *only* zstd frames". - * Since meaning is a little different, another option could be to define different enums for compression and decompression. - * This question could be kept for later, when there are actually multiple formats to support, - * but there is also the question of pinning enum values, and pinning value `0` is especially important */ 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. + 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 two ways: + * 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 @@ -1113,27 +1176,34 @@ * 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_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */ } ZSTD_literalCompressionMode_e; /*************************************** * Frame size functions @@ -1160,11 +1230,11 @@ * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to * read each contained frame header. This is fast as most of the data is skipped, * however it does mean that all frame data must be present and valid. */ ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); -/** ZSTD_decompressBound() : +/*! 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 @@ -1181,24 +1251,47 @@ * 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); + /*************************************** * Memory management ***************************************/ /*! 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_usingCParams() can provide a tighter estimation. - * ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. - * ZSTD_estimateCCtxSize_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 : CCtx size 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_usingCParams(ZSTD_compressionParameters cParams); ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); @@ -1305,11 +1398,12 @@ /*! ZSTD_createCDict_byReference() : * Create a digested dictionary for compression * 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. */ + * 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); /*! ZSTD_getCParams() : * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. * `estimatedSrcSize` value is optional, select 0 if not known */ @@ -1332,19 +1426,23 @@ * 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 compression parameters (by structure) */ + * 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); @@ -1407,10 +1505,21 @@ * 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()). */ @@ -1541,10 +1650,41 @@ /* 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_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. @@ -1579,56 +1719,85 @@ * 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); +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_dm_auto (treated as a full zstd dictionary if + * 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); +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); - * ZSTD_CCtx_setZstdParams(zcs, params); // Set the zstd params and leave the rest as-is + * // 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); * - * pledgedSrcSize must be correct. If srcSize is not known at init time, use - * value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. + * 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); +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: + * This function is DEPRECATED, and is approximately equivalent to: * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); - * ZSTD_CCtx_setZstdFrameParams(zcs, fParams); // Set the zstd frame params and leave the rest as-is + * // 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); +ZSTDLIB_API size_t +ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, + const ZSTD_CDict* cdict, + ZSTD_frameParameters fParams, + unsigned long long pledgedSrcSize); /*! ZSTD_resetCStream() : * This function is deprecated, and is equivalent to: * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); @@ -1639,10 +1808,11 @@ * If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN. * If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. * For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs, * but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead. * @return : 0, or an error code (which can be tested using ZSTD_isError()) + * 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 { @@ -1684,27 +1854,32 @@ * * 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); /********************************************************************* @@ -1841,11 +2016,11 @@ unsigned headerSize; unsigned dictID; unsigned checksumFlag; } ZSTD_frameHeader; -/** ZSTD_getFrameHeader() : +/*! 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 */ @@ -1874,27 +2049,29 @@ /** 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 + Use ZSTD_createCCtx() and ZSTD_createDCtx() - It is necessary to init context before starting + compression : any ZSTD_compressBegin*() variant, including with dictionary + decompression : any ZSTD_decompressBegin*() variant, including with dictionary + copyCCtx() and copyDCtx() can be used too - 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, really consider using 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. */