diff options
Diffstat (limited to 'thirdparty/zstd/zstd.h')
| -rw-r--r-- | thirdparty/zstd/zstd.h | 236 |
1 files changed, 170 insertions, 66 deletions
diff --git a/thirdparty/zstd/zstd.h b/thirdparty/zstd/zstd.h index a1910ee223..72080ea87e 100644 --- a/thirdparty/zstd/zstd.h +++ b/thirdparty/zstd/zstd.h @@ -15,6 +15,7 @@ extern "C" { #define ZSTD_H_235446 /* ====== Dependency ======*/ +#include <limits.h> /* INT_MAX */ #include <stddef.h> /* size_t */ @@ -71,7 +72,7 @@ extern "C" { /*------ Version ------*/ #define ZSTD_VERSION_MAJOR 1 #define ZSTD_VERSION_MINOR 4 -#define ZSTD_VERSION_RELEASE 1 +#define ZSTD_VERSION_RELEASE 4 #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 */ @@ -196,9 +197,13 @@ 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, @@ -233,7 +238,7 @@ ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, * 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(). * @@ -261,18 +266,26 @@ typedef enum { /* compression parameters * Note: When compressing with a ZSTD_CDict these parameters are superseded - * by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict() - * for more info (superseded-by-cdict).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 resets all other compression parameters to default */ + /* 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. @@ -283,13 +296,13 @@ typedef enum { * 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, @@ -344,7 +357,7 @@ typedef enum { 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) */ @@ -363,7 +376,7 @@ typedef enum { * 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. @@ -386,6 +399,7 @@ typedef enum { * 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. @@ -396,6 +410,7 @@ typedef enum { ZSTD_c_experimentalParam4=1001, ZSTD_c_experimentalParam5=1002, ZSTD_c_experimentalParam6=1003, + ZSTD_c_experimentalParam7=1004 } ZSTD_cParameter; typedef struct { @@ -793,12 +808,17 @@ ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, 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); @@ -925,7 +945,7 @@ ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); * 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); @@ -969,7 +989,7 @@ ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); * 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. @@ -1014,8 +1034,8 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); * 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 @@ -1063,6 +1083,8 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); /* 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 @@ -1073,6 +1095,24 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); 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 */ @@ -1101,21 +1141,12 @@ typedef enum { 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; @@ -1126,7 +1157,7 @@ typedef enum { * 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 @@ -1142,6 +1173,12 @@ typedef enum { * 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 @@ -1150,6 +1187,7 @@ typedef 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 { @@ -1158,7 +1196,7 @@ typedef enum { * 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; @@ -1210,20 +1248,38 @@ ZSTDLIB_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcS * 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. */ + * 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. Unlike ZSTD_estimateCStreamSize*(), + * this estimate does not include space for a window buffer, so this estimate + * is guaranteed to be enough for single-shot compressions, but not streaming + * compressions. It will however assume the input may be arbitrarily large, + * which is the 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(). + * + * Note: only single-threaded compression is supported. This function 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); @@ -1334,7 +1390,8 @@ ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictS * 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() : @@ -1361,7 +1418,9 @@ ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 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, @@ -1369,7 +1428,9 @@ ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx, 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, @@ -1441,6 +1502,12 @@ ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* pre * 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. @@ -1613,8 +1680,13 @@ ZSTDLIB_API size_t ZSTD_decompressStream_simpleArgs ( * 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); @@ -1623,42 +1695,66 @@ ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLe * * 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: @@ -1673,6 +1769,7 @@ ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const * 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); @@ -1718,8 +1815,10 @@ ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx); * 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: * @@ -1727,14 +1826,17 @@ ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dic * 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); @@ -1908,8 +2010,8 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); /*! 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 @@ -1920,12 +2022,14 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); + 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. |