/* * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. * All rights reserved. * * This source code is licensed under the BSD-style license found in the * LICENSE file in the root directory of this source tree. An additional grant * of patent rights can be found in the PATENTS file in the same directory. */ #if defined (__cplusplus) extern "C" { #endif #ifndef ZSTD_H_235446 #define ZSTD_H_235446 /* ====== Dependency ======*/ #include /* size_t */ /* ===== ZSTDLIB_API : control library symbols visibility ===== */ #ifndef ZSTDLIB_VISIBILITY # if defined(__GNUC__) && (__GNUC__ >= 4) # define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) # else # define ZSTDLIB_VISIBILITY # endif #endif #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) # define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) # define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ #else # define ZSTDLIB_API ZSTDLIB_VISIBILITY #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. Compression can be done in: - a single step (described as Simple API) - a single step, reusing a context (described as Explicit memory management) - unbounded multiple steps (described as Streaming compression) The compression ratio achievable on small data can be highly improved using a dictionary in: - a single step (described as Simple dictionary API) - a single step, reusing a dictionary (described as Fast 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. *********************************************************************************************************/ /*------ Version ------*/ #define ZSTD_VERSION_MAJOR 1 #define ZSTD_VERSION_MINOR 3 #define ZSTD_VERSION_RELEASE 1 #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 */ #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 */ /*************************************** * Simple API ***************************************/ /*! ZSTD_compress() : * Compresses `src` content as a single zstd compressed frame into already allocated `dst`. * 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_compress( void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel); /*! ZSTD_decompress() : * `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. * `dstCapacity` is an upper bound of originalSize to regenerate. * If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data. * @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), * or an errorCode if it fails (which can be tested using ZSTD_isError()). */ ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, const void* src, size_t compressedSize); /*! ZSTD_getFrameContentSize() : 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 * - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined * - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) * note 1 : a 0 return value means the frame is valid but "empty". * note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode. * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. * In which case, it's necessary to use streaming mode to decompress data. * Optionally, application can rely on some implicit limit, * as ZSTD_decompress() only needs an upper bound of decompressed size. * (For example, data could be necessarily cut into blocks <= 16 KB). * note 3 : decompressed size is always present when compression is done with ZSTD_compress() * note 4 : decompressed size can be very large (64-bits value), * potentially larger than what local system can handle as a single memory segment. * In which case, it's necessary to use streaming mode to decompress data. * note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. * Always ensure return value fits within application's authorized limits. * Each application can set its own limits. * note 6 : This function replaces ZSTD_getDecompressedSize() */ #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) #define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); /*! ZSTD_getDecompressedSize() : * NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize(). * Both functions work the same way, * but ZSTD_getDecompressedSize() blends * "empty", "unknown" and "error" results 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. */ ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(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 */ 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 */ /*************************************** * Explicit memory management ***************************************/ /*= Compression context * When compressing many times, * 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. */ 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, void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel); /*= Decompression context * When decompressing many times, * it is recommended to allocate a context only once, * and re-use it for each successive compression operation. * This will make workload friendlier for system's memory. * Use one context per thread for parallel execution. */ typedef struct ZSTD_DCtx_s ZSTD_DCtx; ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void); 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, 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); /*! 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); /********************************** * Bulk processing dictionary API *********************************/ typedef struct ZSTD_CDict_s ZSTD_CDict; /*! 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); /*! 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); 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. * 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); /**************************** * Streaming ****************************/ typedef struct ZSTD_inBuffer_s { const void* src; /**< start of input buffer */ size_t size; /**< size of input buffer */ size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */ } ZSTD_inBuffer; typedef struct ZSTD_outBuffer_s { void* dst; /**< start of output buffer */ size_t size; /**< size of output buffer */ size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */ } ZSTD_outBuffer; /*-*********************************************************************** * Streaming compression - HowTo * * A ZSTD_CStream object is required to track streaming operation. * Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources. * ZSTD_CStream objects can be reused multiple times on consecutive compression operations. * It is recommended to re-use ZSTD_CStream 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. * * 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) * * 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() * * 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) * or an error code, which can be tested using ZSTD_isError(). * * ZSTD_endStream() 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. * @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) * 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 */ /*===== ZSTD_CStream management functions =====*/ ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); /*===== Streaming compression functions =====*/ ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 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 * * A ZSTD_DStream object is required to track streaming operations. * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. * ZSTD_DStream objects can be re-used multiple times. * * Use ZSTD_initDStream() to start a new decompression operation, * or ZSTD_initDStream_usingDict() if decompression requires a dictionary. * @return : recommended first input size * * 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. * 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. * *******************************************************************************/ 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 */ /*===== ZSTD_DStream management functions =====*/ ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); /*===== Streaming decompression functions =====*/ 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 */ /**************************************************************************************** * 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. * They are provided for advanced scenarios. * 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_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 */ 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; } 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) */ } ZSTD_frameParameters; typedef struct { ZSTD_compressionParameters cParams; ZSTD_frameParameters fParams; } ZSTD_parameters; typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params; /*= 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 }; /*************************************** * 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 * `srcSize` must be the _exact_ size of this series * (i.e. there should be a frame boundary exactly at `srcSize` bytes after `src`) * @return : - decompressed size of all data in all successive frames * - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN * - if an error occurred: ZSTD_CONTENTSIZE_ERROR * * note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. * In which case, it's necessary to use streaming mode to decompress data. * note 2 : decompressed size is always present when compression is done with ZSTD_compress() * note 3 : decompressed size can be very large (64-bits value), * potentially larger than what local system can handle as a single memory segment. * In which case, it's necessary to use streaming mode to decompress data. * note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. * Always ensure result fits within application's authorized limits. * Each application can set its own limits. * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to * read each contained frame header. This is fast as most of the data is skipped, * however it does mean that all frame data must be present and valid. */ ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(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 */ ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); /*************************************** * Context memory usage ***************************************/ /*! 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() can provide a tighter estimation. * ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. * ZSTD_estimateCCtxSize_advanced_opaque() can be used in tandem with ZSTD_CCtxParam_setParameter(). * Note : CCtx estimation is only correct for single-threaded compression */ ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel); ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams); ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced_opaque(ZSTD_CCtx_params* params); ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); /*! ZSTD_estimate?StreamSize() : * 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() can provide a tighter estimation. * ZSTD_estimateCStreamSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. * ZSTD_estimateCStreamSize_advanced_opaque() can be used in tandem with ZSTD_CCtxParam_setParameter(). * Note : CStream estimation is only correct for single-threaded compression. * ZSTD_DStream memory budget depends on window Size. * This information can be passed manually, using ZSTD_estimateDStreamSize, * or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), * an internal ?Dict will be created, which additional size is not estimated here. * 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(ZSTD_compressionParameters cParams); ZSTDLIB_API size_t ZSTD_estimateCStreamSize_advanced_opaque(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); /*! ZSTD_estimate?DictSize() : * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). * ZSTD_estimateCStreamSize_advanced() makes it possible to control precisely compression parameters, like ZSTD_createCDict_advanced(). * ZSTD_estimateCDictSize_advanced_opaque() allows further compression parameters. ByReference can be set with ZSTD_CCtxParam_setParameter. * Note : dictionary created "byReference" 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, unsigned byReference); ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced_opaque(size_t dictSize, ZSTD_CCtx_params* params); ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, unsigned byReference); /*************************************** * 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); /* !!! To be deprecated !!! */ typedef enum { ZSTD_p_forceWindow, /* Force back-references to remain < windowSize, even when referencing Dictionary content (default:0) */ ZSTD_p_forceRawDict /* Force loading dictionary in "content-only" mode (no header analysis) */ } ZSTD_CCtxParameter; /*! ZSTD_setCCtxParameter() : * Set advanced parameters, selected through enum ZSTD_CCtxParameter * @result : 0, or an error code (which can be tested with ZSTD_isError()) */ ZSTDLIB_API size_t ZSTD_setCCtxParameter(ZSTD_CCtx* cctx, ZSTD_CCtxParameter param, unsigned value); /*! 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 */ 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, unsigned byReference, 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, unsigned byReference, ZSTD_dictMode_e dictMode, ZSTD_compressionParameters cParams); ZSTDLIB_API ZSTD_CDict* ZSTD_initStaticCDict_advanced_opaque( void* workspace, size_t workspaceSize, const void* dict, size_t dictSize, ZSTD_CCtx_params* params); /* TODO */ 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); ZSTDLIB_API size_t ZSTD_initCCtxParams(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); /*! ZSTD_getCParams() : * @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) */ ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); /*! ZSTD_checkCParams() : * Ensure param values remain within authorized range */ 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. */ 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); /*! ZSTD_compress_usingCDict_advanced() : * Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */ 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); /*--- Advanced decompression functions ---*/ /*! ZSTD_isFrame() : * Tells if the content of `buffer` starts with a valid Frame Identifier. * Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. * Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. * Note 3 : Skippable Frame Identifiers are considered valid. */ 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 is important that dictBuffer outlives DDict, * 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, unsigned byReference, 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. */ ZSTDLIB_API ZSTD_DDict* ZSTD_initStaticDDict(void* workspace, size_t workspaceSize, const void* dict, size_t dictSize, unsigned byReference); /*! 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 streaming functions ********************************************************************/ /*===== 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. */ 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 */ 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_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.. * Note that zcs must be init at least once before using ZSTD_resetCStream(). * pledgedSrcSize==0 means "srcSize 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()) */ ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); /*===== 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 */ /********************************************************************* * 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 ********************************************************************* */ /** Buffer-less streaming compression (synchronous mode) A ZSTD_CCtx object is required to track streaming operations. Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. ZSTD_CCtx object can be re-used multiple times within successive compression operations. Start by initializing a context. Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression, or ZSTD_compressBegin_advanced(), for finer parameter control. It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx() 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. - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. Worst case evaluation is provided by ZSTD_compressBound(). ZSTD_compressContinue() doesn't guarantee recover after a failed compression. - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. In which case, it will "discard" the relevant memory section from its history. Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. Without last block mark, frames will be considered unfinished (corrupted) by decoders. `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new frame. */ /*===== 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_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_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); /*- Buffer-less streaming decompression (synchronous mode) A ZSTD_DCtx object is required to track streaming operations. Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. A ZSTD_DCtx object can be re-used multiple times. First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader(). It fills a ZSTD_frameHeader structure with important information to correctly decode the frame, such as minimum rolling buffer size to allocate to decompress data (`windowSize`), and the dictionary ID in use. (Note : content size is optional, it may not be present. 0 means : content size unknown). Note that these values could be wrong, either because of data malformation, or because an attacker is spoofing deliberate false information. As a consequence, check that values remain within valid application range, especially `windowSize`, before allocation. Each application can set its own limit, depending on local restrictions. For extended interoperability, it is recommended to support windowSize of at least 8 MB. Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. Data fragment must be large enough to ensure successful decoding. `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. @result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled. >0 : `srcSize` is too small, please provide at least @result bytes on next attempt. errorCode, which can be tested using ZSTD_isError(). Start decompression, with ZSTD_decompressBegin(). If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). Alternatively, you can copy a prepared context, using ZSTD_copyDCtx(). Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. @result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). It can be zero, which is not an error; it just means ZSTD_decompressContinue() has decoded some metadata item. It can also be an error code, which can be tested with ZSTD_isError(). ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize`. They should preferably be located contiguously, prior to current block. Alternatively, a round buffer of sufficient size is also possible. Sufficient size is determined by frame parameters. ZSTD_decompressContinue() is very sensitive to contiguity, if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, or that previous contiguous segment is large enough to properly handle maximum back-reference. A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. Context can then be reset to start a new decompression. Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). This information is not required to properly decode a frame. == Special case : skippable frames == Skippable frames allow integration of user-defined data into a flow of concatenated frames. Skippable frames will be ignored (skipped) by a decompressor. The format of skippable frames is as follows : a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits c) Frame Content - any content (User Data) of length equal to Frame Size For skippable frames ZSTD_decompressContinue() always returns 0. For skippable frames ZSTD_getFrameHeader() returns fparamsPtr->windowLog==0 what means that a frame is skippable. Note : If fparamsPtr->frameContentSize==0, it is ambiguous: the frame might actually be a Zstd encoded frame with no content. For purposes of decompression, it is valid in both cases to skip the frame using ZSTD_findFrameCompressedSize to find its size in bytes. It also returns Frame Size as fparamsPtr->frameContentSize. */ /*===== Buffer-less streaming decompression functions =====*/ typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e; typedef struct { unsigned long long frameContentSize; /* ZSTD_CONTENTSIZE_UNKNOWN means this field is not available. 0 means "empty" */ unsigned long long windowSize; /* can be very large, up to <= frameContentSize */ ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */ unsigned headerSize; unsigned dictID; unsigned checksumFlag; } ZSTD_frameHeader; ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */ ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx); ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx); ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(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) */ /* dictionary parameters (must be set before ZSTD_CCtx_loadDictionary) */ ZSTD_p_dictMode=300, /* Select how dictionary content must be interpreted. Value must be from type ZSTD_dictMode_e. * default : 0==auto : dictionary will be "full" if it respects specification, otherwise it will be "rawContent" */ ZSTD_p_refDictContent, /* Dictionary content will be referenced, instead of copied (default:0==byCopy). * It requires that dictionary buffer outlives its users */ /* 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_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_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_applyCCtxParams(). * 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_applyCCtxParams() : * 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_applyCCtxParams(ZSTD_CCtx* cctx, ZSTD_CCtx_params* params); /*! 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, * except if ZSTD_p_refDictContent is set before loading. * 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 */ 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 compression jobs. * Note that compression parameters are enforced from within CDict, * and supercede 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 : it's possible to alter ZSTD_p_dictMode using ZSTD_CCtx_setParameter() */ ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize); 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); /** Block functions 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. 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 + 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 !!! + 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<