Mercurial > hg
view contrib/python-zstandard/zstd/zstd.h @ 35654:59c842a3d1e1
hgweb: remove unused second argument of nextPageVarGet()
nextPageVarGet is a function that's used in ajaxScrollInit() to produce URL of
the next page. Before f84b01257e06, its second argument previousVal was a
number on /graph pages, and the code was simply adding 60 to it and returning
the resulting value. Now previousVal can only be a string containing changeset
hash, which can't be used the same way (and in fact isn't used in any way).
author | Anton Shestakov <av6@dwimlabs.net> |
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date | Mon, 15 Jan 2018 19:44:18 +0800 |
parents | c32454d69b85 |
children | b1fb341d8a61 |
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/* * 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 <stddef.h> /* size_t */ /* ===== ZSTDLIB_API : control library symbols visibility ===== */ #if defined(__GNUC__) && (__GNUC__ >= 4) # define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) #else # define ZSTDLIB_VISIBILITY #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 22. Levels >= 20, labelled `--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 compression with 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. These 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 1 #define ZSTD_VERSION_RELEASE 3 #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) #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< library version number; to be used when checking dll version */ /*************************************** * 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 a single compressed frame. `dstCapacity` is an upper bound of originalSize. 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_getDecompressedSize() : * 'src' is the start of a zstd compressed frame. * @return : content size to be decompressed, as a 64-bits value _if known_, 0 otherwise. * note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. * When `return==0`, data to decompress could be any size. * In which case, it's necessary to use streaming mode to decompress data. * Optionally, application can still use ZSTD_decompress() while relying on implied limits. * (For example, data may be necessarily cut into blocks <= 16 KB). * 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 : when `return==0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more. */ 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 */ 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); /**************************** * Fast 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 used by multiple threads concurrently, as its usage is read-only. * `dictBuffer` can be released after ZSTD_CDict creation, as 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. */ 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. * Similar to ZSTD_flushStream(), it may not be able to flush the full content if `output->size` is too small. * In which case, call again ZSTD_endStream() to complete the flush. * @return : nb of bytes still present within internal buffer (0 if it's empty, hence compression completed) * or an error code, which can be tested using ZSTD_isError(). * * *******************************************************************/ typedef struct ZSTD_CStream_s ZSTD_CStream; ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); 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 struct ZSTD_DStream_s ZSTD_DStream; ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); 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 */ #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY /**************************************************************************************** * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS * The definitions in this section are considered experimental. * They should never be used with a dynamic library, as they may change in the future. * They are provided for advanced usages. * Use them only in association with static linking. * ***************************************************************************************/ /* --- Constants ---*/ #define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */ #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U #define ZSTD_WINDOWLOG_MAX_32 25 #define ZSTD_WINDOWLOG_MAX_64 27 #define ZSTD_WINDOWLOG_MAX ((U32)(MEM_32bits() ? 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; static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN; static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX; static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */ /*--- Advanced types ---*/ typedef enum { ZSTD_fast, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2, ZSTD_btlazy2, ZSTD_btopt, ZSTD_btopt2 } 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; /*= 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; /*************************************** * Advanced compression functions ***************************************/ /*! ZSTD_estimateCCtxSize() : * Gives the amount of memory allocated for a ZSTD_CCtx given a set of compression parameters. * `frameContentSize` is an optional parameter, provide `0` if unknown */ ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams); /*! 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_sizeofCCtx() : * Gives the amount of memory used by a given ZSTD_CCtx */ ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); typedef enum { ZSTD_p_forceWindow /* Force back-references to remain < windowSize, even when referencing Dictionary content (default:0)*/ } 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); /*! 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_parameters params, ZSTD_customMem customMem); /*! ZSTD_sizeof_CDict() : * Gives the amount of memory used by a given ZSTD_sizeof_CDict */ ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); /*! 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 of each compression parameter */ ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const void* dict,size_t dictSize, ZSTD_parameters params); /*--- 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_estimateDCtxSize() : * Gives the potential amount of memory allocated to create a ZSTD_DCtx */ ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); /*! 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_sizeof_DCtx() : * Gives the amount of memory used by a given ZSTD_DCtx */ ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); /*! ZSTD_createDDict_byReference() : * Create a digested dictionary, ready to start decompression operation without startup delay. * Dictionary content is simply 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); ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, unsigned byReference, ZSTD_customMem customMem); /*! ZSTD_sizeof_DDict() : * Gives the amount of memory used by a given ZSTD_DDict */ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); /*! 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 used ZSTD_getFrameParams(), 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 size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct */ ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< note: a dict will not be used if dict == NULL or dictSize < 8 */ 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 zero == unknown */ 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_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); /**< re-use compression parameters from previous init; skip dictionary loading stage; zcs must be init at least once before */ ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); /*===== Advanced Streaming decompression functions =====*/ typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e; ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); 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_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); 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 */ ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); /********************************************************************* * Buffer-less and synchronous inner streaming functions * * This is an advanced API, giving full control over buffer management, for users which need direct control over memory. * But it's also a complex one, with many restrictions (documented below). * Prefer using normal streaming API for an easier experience ********************************************************************* */ /** 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); ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict, unsigned long long pledgedSrcSize); 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_getFrameParams(). It fills a ZSTD_frameParams structure which provide important information to correctly decode the frame, such as the minimum rolling buffer size to allocate to decompress data (`windowSize`), and the dictionary ID used. (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 at least 8 MB. Frame parameters are extracted from the beginning of the compressed frame. Data fragment must be large enough to ensure successful decoding, typically `ZSTD_frameHeaderSize_max` bytes. @result : 0 : successful decoding, the `ZSTD_frameParams` 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() or ZSTD_decompressBegin_usingDict(). 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_getFrameParams() returns fparamsPtr->windowLog==0 what means that a frame is skippable. It also returns Frame Size as fparamsPtr->frameContentSize. */ typedef struct { unsigned long long frameContentSize; unsigned windowSize; unsigned dictID; unsigned checksumFlag; } ZSTD_frameParams; /*===== Buffer-less streaming decompression functions =====*/ ZSTDLIB_API size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize); /**< doesn't consume input, see details below */ 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 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); /** 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 : ZSTD_compressBegin() + decompression : ZSTD_decompressBegin() + variants _usingDict() are also allowed + copyCCtx() and copyDCtx() work too - Block size is limited, it must be <= ZSTD_getBlockSizeMax() + If you need to compress more, cut data into multiple blocks + Consider using the regular ZSTD_compress() instead, as frame metadata costs become negligible when source size is large. - 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, decoder must be informed of uncompressed block existence to follow proper history. Use ZSTD_insertBlock() in such a case. */ #define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) /* define, for static allocation */ /*===== Raw zstd block functions =====*/ ZSTDLIB_API size_t ZSTD_getBlockSizeMax(ZSTD_CCtx* cctx); ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); ZSTDLIB_API size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize); /**< insert block into `dctx` history. Useful for uncompressed blocks */ #endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ #if defined (__cplusplus) } #endif