|  | /* | 
|  | * 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 https://github.com/facebook/zstd. | 
|  | * An additional grant of patent rights can be found in the PATENTS file in the | 
|  | * same directory. | 
|  | * | 
|  | * This program is free software; you can redistribute it and/or modify it under | 
|  | * the terms of the GNU General Public License version 2 as published by the | 
|  | * Free Software Foundation. This program is dual-licensed; you may select | 
|  | * either version 2 of the GNU General Public License ("GPL") or BSD license | 
|  | * ("BSD"). | 
|  | */ | 
|  |  | 
|  | #ifndef ZSTD_H | 
|  | #define ZSTD_H | 
|  |  | 
|  | /* ======   Dependency   ======*/ | 
|  | #include <linux/types.h>   /* size_t */ | 
|  |  | 
|  |  | 
|  | /*-***************************************************************************** | 
|  | * 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, labeled | 
|  | * ultra, should be used with caution, as they require more memory. | 
|  | * Compression can be done in: | 
|  | *  - 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) | 
|  | ******************************************************************************/ | 
|  |  | 
|  | /*======  Helper functions  ======*/ | 
|  |  | 
|  | /** | 
|  | * enum ZSTD_ErrorCode - zstd error codes | 
|  | * | 
|  | * Functions that return size_t can be checked for errors using ZSTD_isError() | 
|  | * and the ZSTD_ErrorCode can be extracted using ZSTD_getErrorCode(). | 
|  | */ | 
|  | typedef enum { | 
|  | ZSTD_error_no_error, | 
|  | ZSTD_error_GENERIC, | 
|  | ZSTD_error_prefix_unknown, | 
|  | ZSTD_error_version_unsupported, | 
|  | ZSTD_error_parameter_unknown, | 
|  | ZSTD_error_frameParameter_unsupported, | 
|  | ZSTD_error_frameParameter_unsupportedBy32bits, | 
|  | ZSTD_error_frameParameter_windowTooLarge, | 
|  | ZSTD_error_compressionParameter_unsupported, | 
|  | ZSTD_error_init_missing, | 
|  | ZSTD_error_memory_allocation, | 
|  | ZSTD_error_stage_wrong, | 
|  | ZSTD_error_dstSize_tooSmall, | 
|  | ZSTD_error_srcSize_wrong, | 
|  | ZSTD_error_corruption_detected, | 
|  | ZSTD_error_checksum_wrong, | 
|  | ZSTD_error_tableLog_tooLarge, | 
|  | ZSTD_error_maxSymbolValue_tooLarge, | 
|  | ZSTD_error_maxSymbolValue_tooSmall, | 
|  | ZSTD_error_dictionary_corrupted, | 
|  | ZSTD_error_dictionary_wrong, | 
|  | ZSTD_error_dictionaryCreation_failed, | 
|  | ZSTD_error_maxCode | 
|  | } ZSTD_ErrorCode; | 
|  |  | 
|  | /** | 
|  | * ZSTD_maxCLevel() - maximum compression level available | 
|  | * | 
|  | * Return: Maximum compression level available. | 
|  | */ | 
|  | int ZSTD_maxCLevel(void); | 
|  | /** | 
|  | * ZSTD_compressBound() - maximum compressed size in worst case scenario | 
|  | * @srcSize: The size of the data to compress. | 
|  | * | 
|  | * Return:   The maximum compressed size in the worst case scenario. | 
|  | */ | 
|  | size_t ZSTD_compressBound(size_t srcSize); | 
|  | /** | 
|  | * ZSTD_isError() - tells if a size_t function result is an error code | 
|  | * @code:  The function result to check for error. | 
|  | * | 
|  | * Return: Non-zero iff the code is an error. | 
|  | */ | 
|  | static __attribute__((unused)) unsigned int ZSTD_isError(size_t code) | 
|  | { | 
|  | return code > (size_t)-ZSTD_error_maxCode; | 
|  | } | 
|  | /** | 
|  | * ZSTD_getErrorCode() - translates an error function result to a ZSTD_ErrorCode | 
|  | * @functionResult: The result of a function for which ZSTD_isError() is true. | 
|  | * | 
|  | * Return:          The ZSTD_ErrorCode corresponding to the functionResult or 0 | 
|  | *                  if the functionResult isn't an error. | 
|  | */ | 
|  | static __attribute__((unused)) ZSTD_ErrorCode ZSTD_getErrorCode( | 
|  | size_t functionResult) | 
|  | { | 
|  | if (!ZSTD_isError(functionResult)) | 
|  | return (ZSTD_ErrorCode)0; | 
|  | return (ZSTD_ErrorCode)(0 - functionResult); | 
|  | } | 
|  |  | 
|  | /** | 
|  | * enum ZSTD_strategy - zstd compression search strategy | 
|  | * | 
|  | * From faster to stronger. | 
|  | */ | 
|  | typedef enum { | 
|  | ZSTD_fast, | 
|  | ZSTD_dfast, | 
|  | ZSTD_greedy, | 
|  | ZSTD_lazy, | 
|  | ZSTD_lazy2, | 
|  | ZSTD_btlazy2, | 
|  | ZSTD_btopt, | 
|  | ZSTD_btopt2 | 
|  | } ZSTD_strategy; | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_compressionParameters - zstd compression parameters | 
|  | * @windowLog:    Log of the largest match distance. Larger means more | 
|  | *                compression, and more memory needed during decompression. | 
|  | * @chainLog:     Fully searched segment. Larger means more compression, slower, | 
|  | *                and more memory (useless for fast). | 
|  | * @hashLog:      Dispatch table. Larger means more compression, | 
|  | *                slower, and more memory. | 
|  | * @searchLog:    Number of searches. Larger means more compression and slower. | 
|  | * @searchLength: Match length searched. Larger means faster decompression, | 
|  | *                sometimes less compression. | 
|  | * @targetLength: Acceptable match size for optimal parser (only). Larger means | 
|  | *                more compression, and slower. | 
|  | * @strategy:     The zstd compression strategy. | 
|  | */ | 
|  | typedef struct { | 
|  | unsigned int windowLog; | 
|  | unsigned int chainLog; | 
|  | unsigned int hashLog; | 
|  | unsigned int searchLog; | 
|  | unsigned int searchLength; | 
|  | unsigned int targetLength; | 
|  | ZSTD_strategy strategy; | 
|  | } ZSTD_compressionParameters; | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_frameParameters - zstd frame parameters | 
|  | * @contentSizeFlag: Controls whether content size will be present in the frame | 
|  | *                   header (when known). | 
|  | * @checksumFlag:    Controls whether a 32-bit checksum is generated at the end | 
|  | *                   of the frame for error detection. | 
|  | * @noDictIDFlag:    Controls whether dictID will be saved into the frame header | 
|  | *                   when using dictionary compression. | 
|  | * | 
|  | * The default value is all fields set to 0. | 
|  | */ | 
|  | typedef struct { | 
|  | unsigned int contentSizeFlag; | 
|  | unsigned int checksumFlag; | 
|  | unsigned int noDictIDFlag; | 
|  | } ZSTD_frameParameters; | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_parameters - zstd parameters | 
|  | * @cParams: The compression parameters. | 
|  | * @fParams: The frame parameters. | 
|  | */ | 
|  | typedef struct { | 
|  | ZSTD_compressionParameters cParams; | 
|  | ZSTD_frameParameters fParams; | 
|  | } ZSTD_parameters; | 
|  |  | 
|  | /** | 
|  | * ZSTD_getCParams() - returns ZSTD_compressionParameters for selected level | 
|  | * @compressionLevel: The compression level from 1 to ZSTD_maxCLevel(). | 
|  | * @estimatedSrcSize: The estimated source size to compress or 0 if unknown. | 
|  | * @dictSize:         The dictionary size or 0 if a dictionary isn't being used. | 
|  | * | 
|  | * Return:            The selected ZSTD_compressionParameters. | 
|  | */ | 
|  | ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, | 
|  | unsigned long long estimatedSrcSize, size_t dictSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_getParams() - returns ZSTD_parameters for selected level | 
|  | * @compressionLevel: The compression level from 1 to ZSTD_maxCLevel(). | 
|  | * @estimatedSrcSize: The estimated source size to compress or 0 if unknown. | 
|  | * @dictSize:         The dictionary size or 0 if a dictionary isn't being used. | 
|  | * | 
|  | * The same as ZSTD_getCParams() except also selects the default frame | 
|  | * parameters (all zero). | 
|  | * | 
|  | * Return:            The selected ZSTD_parameters. | 
|  | */ | 
|  | ZSTD_parameters ZSTD_getParams(int compressionLevel, | 
|  | unsigned long long estimatedSrcSize, size_t dictSize); | 
|  |  | 
|  | /*-************************************* | 
|  | * Explicit memory management | 
|  | **************************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_CCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_CCtx | 
|  | * @cParams: The compression parameters to be used for compression. | 
|  | * | 
|  | * If multiple compression parameters might be used, the caller must call | 
|  | * ZSTD_CCtxWorkspaceBound() for each set of parameters and use the maximum | 
|  | * size. | 
|  | * | 
|  | * Return:   A lower bound on the size of the workspace that is passed to | 
|  | *           ZSTD_initCCtx(). | 
|  | */ | 
|  | size_t ZSTD_CCtxWorkspaceBound(ZSTD_compressionParameters cParams); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_CCtx - the zstd compression context | 
|  | * | 
|  | * When compressing many times it is recommended to allocate a context just once | 
|  | * and reuse it for each successive compression operation. | 
|  | */ | 
|  | typedef struct ZSTD_CCtx_s ZSTD_CCtx; | 
|  | /** | 
|  | * ZSTD_initCCtx() - initialize a zstd compression context | 
|  | * @workspace:     The workspace to emplace the context into. It must outlive | 
|  | *                 the returned context. | 
|  | * @workspaceSize: The size of workspace. Use ZSTD_CCtxWorkspaceBound() to | 
|  | *                 determine how large the workspace must be. | 
|  | * | 
|  | * Return:         A compression context emplaced into workspace. | 
|  | */ | 
|  | ZSTD_CCtx *ZSTD_initCCtx(void *workspace, size_t workspaceSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_compressCCtx() - compress src into dst | 
|  | * @ctx:         The context. Must have been initialized with a workspace at | 
|  | *               least as large as ZSTD_CCtxWorkspaceBound(params.cParams). | 
|  | * @dst:         The buffer to compress src into. | 
|  | * @dstCapacity: The size of the destination buffer. May be any size, but | 
|  | *               ZSTD_compressBound(srcSize) is guaranteed to be large enough. | 
|  | * @src:         The data to compress. | 
|  | * @srcSize:     The size of the data to compress. | 
|  | * @params:      The parameters to use for compression. See ZSTD_getParams(). | 
|  | * | 
|  | * Return:       The compressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_compressCCtx(ZSTD_CCtx *ctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize, ZSTD_parameters params); | 
|  |  | 
|  | /** | 
|  | * ZSTD_DCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_DCtx | 
|  | * | 
|  | * Return: A lower bound on the size of the workspace that is passed to | 
|  | *         ZSTD_initDCtx(). | 
|  | */ | 
|  | size_t ZSTD_DCtxWorkspaceBound(void); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_DCtx - the zstd decompression context | 
|  | * | 
|  | * When decompressing many times it is recommended to allocate a context just | 
|  | * once and reuse it for each successive decompression operation. | 
|  | */ | 
|  | typedef struct ZSTD_DCtx_s ZSTD_DCtx; | 
|  | /** | 
|  | * ZSTD_initDCtx() - initialize a zstd decompression context | 
|  | * @workspace:     The workspace to emplace the context into. It must outlive | 
|  | *                 the returned context. | 
|  | * @workspaceSize: The size of workspace. Use ZSTD_DCtxWorkspaceBound() to | 
|  | *                 determine how large the workspace must be. | 
|  | * | 
|  | * Return:         A decompression context emplaced into workspace. | 
|  | */ | 
|  | ZSTD_DCtx *ZSTD_initDCtx(void *workspace, size_t workspaceSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_decompressDCtx() - decompress zstd compressed src into dst | 
|  | * @ctx:         The decompression context. | 
|  | * @dst:         The buffer to decompress src into. | 
|  | * @dstCapacity: The size of the destination buffer. Must be at least as large | 
|  | *               as the decompressed size. If the caller cannot upper bound the | 
|  | *               decompressed size, then it's better to use the streaming API. | 
|  | * @src:         The zstd compressed data to decompress. Multiple concatenated | 
|  | *               frames and skippable frames are allowed. | 
|  | * @srcSize:     The exact size of the data to decompress. | 
|  | * | 
|  | * Return:       The decompressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_decompressDCtx(ZSTD_DCtx *ctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize); | 
|  |  | 
|  | /*-************************ | 
|  | * Simple dictionary API | 
|  | **************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_compress_usingDict() - compress src into dst using a dictionary | 
|  | * @ctx:         The context. Must have been initialized with a workspace at | 
|  | *               least as large as ZSTD_CCtxWorkspaceBound(params.cParams). | 
|  | * @dst:         The buffer to compress src into. | 
|  | * @dstCapacity: The size of the destination buffer. May be any size, but | 
|  | *               ZSTD_compressBound(srcSize) is guaranteed to be large enough. | 
|  | * @src:         The data to compress. | 
|  | * @srcSize:     The size of the data to compress. | 
|  | * @dict:        The dictionary to use for compression. | 
|  | * @dictSize:    The size of the dictionary. | 
|  | * @params:      The parameters to use for compression. See ZSTD_getParams(). | 
|  | * | 
|  | * Compression using a predefined dictionary. The same dictionary must be used | 
|  | * during decompression. | 
|  | * | 
|  | * Return:       The compressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | 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, | 
|  | ZSTD_parameters params); | 
|  |  | 
|  | /** | 
|  | * ZSTD_decompress_usingDict() - decompress src into dst using a dictionary | 
|  | * @ctx:         The decompression context. | 
|  | * @dst:         The buffer to decompress src into. | 
|  | * @dstCapacity: The size of the destination buffer. Must be at least as large | 
|  | *               as the decompressed size. If the caller cannot upper bound the | 
|  | *               decompressed size, then it's better to use the streaming API. | 
|  | * @src:         The zstd compressed data to decompress. Multiple concatenated | 
|  | *               frames and skippable frames are allowed. | 
|  | * @srcSize:     The exact size of the data to decompress. | 
|  | * @dict:        The dictionary to use for decompression. The same dictionary | 
|  | *               must've been used to compress the data. | 
|  | * @dictSize:    The size of the dictionary. | 
|  | * | 
|  | * Return:       The decompressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_decompress_usingDict(ZSTD_DCtx *ctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize, const void *dict, size_t dictSize); | 
|  |  | 
|  | /*-************************** | 
|  | * Fast dictionary API | 
|  | ***************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_CDictWorkspaceBound() - memory needed to initialize a ZSTD_CDict | 
|  | * @cParams: The compression parameters to be used for compression. | 
|  | * | 
|  | * Return:   A lower bound on the size of the workspace that is passed to | 
|  | *           ZSTD_initCDict(). | 
|  | */ | 
|  | size_t ZSTD_CDictWorkspaceBound(ZSTD_compressionParameters cParams); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_CDict - a digested dictionary to be used for compression | 
|  | */ | 
|  | typedef struct ZSTD_CDict_s ZSTD_CDict; | 
|  |  | 
|  | /** | 
|  | * ZSTD_initCDict() - initialize a digested dictionary for compression | 
|  | * @dictBuffer:    The dictionary to digest. The buffer is referenced by the | 
|  | *                 ZSTD_CDict so it must outlive the returned ZSTD_CDict. | 
|  | * @dictSize:      The size of the dictionary. | 
|  | * @params:        The parameters to use for compression. See ZSTD_getParams(). | 
|  | * @workspace:     The workspace. It must outlive the returned ZSTD_CDict. | 
|  | * @workspaceSize: The workspace size. Must be at least | 
|  | *                 ZSTD_CDictWorkspaceBound(params.cParams). | 
|  | * | 
|  | * When compressing multiple messages / blocks with the same dictionary it is | 
|  | * recommended to load it just once. The ZSTD_CDict merely references the | 
|  | * dictBuffer, so it must outlive the returned ZSTD_CDict. | 
|  | * | 
|  | * Return:         The digested dictionary emplaced into workspace. | 
|  | */ | 
|  | ZSTD_CDict *ZSTD_initCDict(const void *dictBuffer, size_t dictSize, | 
|  | ZSTD_parameters params, void *workspace, size_t workspaceSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_compress_usingCDict() - compress src into dst using a ZSTD_CDict | 
|  | * @ctx:         The context. Must have been initialized with a workspace at | 
|  | *               least as large as ZSTD_CCtxWorkspaceBound(cParams) where | 
|  | *               cParams are the compression parameters used to initialize the | 
|  | *               cdict. | 
|  | * @dst:         The buffer to compress src into. | 
|  | * @dstCapacity: The size of the destination buffer. May be any size, but | 
|  | *               ZSTD_compressBound(srcSize) is guaranteed to be large enough. | 
|  | * @src:         The data to compress. | 
|  | * @srcSize:     The size of the data to compress. | 
|  | * @cdict:       The digested dictionary to use for compression. | 
|  | * @params:      The parameters to use for compression. See ZSTD_getParams(). | 
|  | * | 
|  | * Compression using a digested dictionary. The same dictionary must be used | 
|  | * during decompression. | 
|  | * | 
|  | * Return:       The compressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_compress_usingCDict(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize, const ZSTD_CDict *cdict); | 
|  |  | 
|  |  | 
|  | /** | 
|  | * ZSTD_DDictWorkspaceBound() - memory needed to initialize a ZSTD_DDict | 
|  | * | 
|  | * Return:  A lower bound on the size of the workspace that is passed to | 
|  | *          ZSTD_initDDict(). | 
|  | */ | 
|  | size_t ZSTD_DDictWorkspaceBound(void); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_DDict - a digested dictionary to be used for decompression | 
|  | */ | 
|  | typedef struct ZSTD_DDict_s ZSTD_DDict; | 
|  |  | 
|  | /** | 
|  | * ZSTD_initDDict() - initialize a digested dictionary for decompression | 
|  | * @dictBuffer:    The dictionary to digest. The buffer is referenced by the | 
|  | *                 ZSTD_DDict so it must outlive the returned ZSTD_DDict. | 
|  | * @dictSize:      The size of the dictionary. | 
|  | * @workspace:     The workspace. It must outlive the returned ZSTD_DDict. | 
|  | * @workspaceSize: The workspace size. Must be at least | 
|  | *                 ZSTD_DDictWorkspaceBound(). | 
|  | * | 
|  | * When decompressing multiple messages / blocks with the same dictionary it is | 
|  | * recommended to load it just once. The ZSTD_DDict merely references the | 
|  | * dictBuffer, so it must outlive the returned ZSTD_DDict. | 
|  | * | 
|  | * Return:         The digested dictionary emplaced into workspace. | 
|  | */ | 
|  | ZSTD_DDict *ZSTD_initDDict(const void *dictBuffer, size_t dictSize, | 
|  | void *workspace, size_t workspaceSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_decompress_usingDDict() - decompress src into dst using a ZSTD_DDict | 
|  | * @ctx:         The decompression context. | 
|  | * @dst:         The buffer to decompress src into. | 
|  | * @dstCapacity: The size of the destination buffer. Must be at least as large | 
|  | *               as the decompressed size. If the caller cannot upper bound the | 
|  | *               decompressed size, then it's better to use the streaming API. | 
|  | * @src:         The zstd compressed data to decompress. Multiple concatenated | 
|  | *               frames and skippable frames are allowed. | 
|  | * @srcSize:     The exact size of the data to decompress. | 
|  | * @ddict:       The digested dictionary to use for decompression. The same | 
|  | *               dictionary must've been used to compress the data. | 
|  | * | 
|  | * Return:       The decompressed size or an error, which can be checked using | 
|  | *               ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_decompress_usingDDict(ZSTD_DCtx *dctx, void *dst, | 
|  | size_t dstCapacity, const void *src, size_t srcSize, | 
|  | const ZSTD_DDict *ddict); | 
|  |  | 
|  |  | 
|  | /*-************************** | 
|  | * Streaming | 
|  | ***************************/ | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_inBuffer - input buffer for streaming | 
|  | * @src:  Start of the input buffer. | 
|  | * @size: Size of the input buffer. | 
|  | * @pos:  Position where reading stopped. Will be updated. | 
|  | *        Necessarily 0 <= pos <= size. | 
|  | */ | 
|  | typedef struct ZSTD_inBuffer_s { | 
|  | const void *src; | 
|  | size_t size; | 
|  | size_t pos; | 
|  | } ZSTD_inBuffer; | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_outBuffer - output buffer for streaming | 
|  | * @dst:  Start of the output buffer. | 
|  | * @size: Size of the output buffer. | 
|  | * @pos:  Position where writing stopped. Will be updated. | 
|  | *        Necessarily 0 <= pos <= size. | 
|  | */ | 
|  | typedef struct ZSTD_outBuffer_s { | 
|  | void *dst; | 
|  | size_t size; | 
|  | size_t pos; | 
|  | } ZSTD_outBuffer; | 
|  |  | 
|  |  | 
|  |  | 
|  | /*-***************************************************************************** | 
|  | * Streaming compression - HowTo | 
|  | * | 
|  | * A ZSTD_CStream object is required to track streaming operation. | 
|  | * Use ZSTD_initCStream() to initialize a ZSTD_CStream object. | 
|  | * 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. Use one separate | 
|  | * ZSTD_CStream per thread for parallel execution. | 
|  | * | 
|  | * 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. | 
|  | * It returns a hint for the preferred number of bytes to use as an input for | 
|  | * the next function call. | 
|  | * | 
|  | * At any moment, it's possible to flush whatever data remains within internal | 
|  | * buffer, using ZSTD_flushStream(). `output->pos` will be updated. There might | 
|  | * still be some content left within the internal buffer if `output->size` is | 
|  | * too small. It returns the number of bytes left in the internal buffer and | 
|  | * must be called until it returns 0. | 
|  | * | 
|  | * 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. It returns the number of bytes left | 
|  | * in the internal buffer and must be called until it returns 0. | 
|  | ******************************************************************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_CStreamWorkspaceBound() - memory needed to initialize a ZSTD_CStream | 
|  | * @cParams: The compression parameters to be used for compression. | 
|  | * | 
|  | * Return:   A lower bound on the size of the workspace that is passed to | 
|  | *           ZSTD_initCStream() and ZSTD_initCStream_usingCDict(). | 
|  | */ | 
|  | size_t ZSTD_CStreamWorkspaceBound(ZSTD_compressionParameters cParams); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_CStream - the zstd streaming compression context | 
|  | */ | 
|  | typedef struct ZSTD_CStream_s ZSTD_CStream; | 
|  |  | 
|  | /*===== ZSTD_CStream management functions =====*/ | 
|  | /** | 
|  | * ZSTD_initCStream() - initialize a zstd streaming compression context | 
|  | * @params:         The zstd compression parameters. | 
|  | * @pledgedSrcSize: If params.fParams.contentSizeFlag == 1 then the caller must | 
|  | *                  pass the source size (zero means empty source). Otherwise, | 
|  | *                  the caller may optionally pass the source size, or zero if | 
|  | *                  unknown. | 
|  | * @workspace:      The workspace to emplace the context into. It must outlive | 
|  | *                  the returned context. | 
|  | * @workspaceSize:  The size of workspace. | 
|  | *                  Use ZSTD_CStreamWorkspaceBound(params.cParams) to determine | 
|  | *                  how large the workspace must be. | 
|  | * | 
|  | * Return:          The zstd streaming compression context. | 
|  | */ | 
|  | ZSTD_CStream *ZSTD_initCStream(ZSTD_parameters params, | 
|  | unsigned long long pledgedSrcSize, void *workspace, | 
|  | size_t workspaceSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_initCStream_usingCDict() - initialize a streaming compression context | 
|  | * @cdict:          The digested dictionary to use for compression. | 
|  | * @pledgedSrcSize: Optionally the source size, or zero if unknown. | 
|  | * @workspace:      The workspace to emplace the context into. It must outlive | 
|  | *                  the returned context. | 
|  | * @workspaceSize:  The size of workspace. Call ZSTD_CStreamWorkspaceBound() | 
|  | *                  with the cParams used to initialize the cdict to determine | 
|  | *                  how large the workspace must be. | 
|  | * | 
|  | * Return:          The zstd streaming compression context. | 
|  | */ | 
|  | ZSTD_CStream *ZSTD_initCStream_usingCDict(const ZSTD_CDict *cdict, | 
|  | unsigned long long pledgedSrcSize, void *workspace, | 
|  | size_t workspaceSize); | 
|  |  | 
|  | /*===== Streaming compression functions =====*/ | 
|  | /** | 
|  | * ZSTD_resetCStream() - reset the context using parameters from creation | 
|  | * @zcs:            The zstd streaming compression context to reset. | 
|  | * @pledgedSrcSize: Optionally the source size, or zero if unknown. | 
|  | * | 
|  | * Resets the context using the parameters from creation. Skips dictionary | 
|  | * loading, since it can be reused. If `pledgedSrcSize` is non-zero the frame | 
|  | * content size is always written into the frame header. | 
|  | * | 
|  | * Return:          Zero or an error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_resetCStream(ZSTD_CStream *zcs, unsigned long long pledgedSrcSize); | 
|  | /** | 
|  | * ZSTD_compressStream() - streaming compress some of input into output | 
|  | * @zcs:    The zstd streaming compression context. | 
|  | * @output: Destination buffer. `output->pos` is updated to indicate how much | 
|  | *          compressed data was written. | 
|  | * @input:  Source buffer. `input->pos` is updated to indicate how much data was | 
|  | *          read. Note that it may not consume the entire input, in which case | 
|  | *          `input->pos < input->size`, and it's up to the caller to present | 
|  | *          remaining data again. | 
|  | * | 
|  | * The `input` and `output` buffers may be any size. Guaranteed to make some | 
|  | * forward progress if `input` and `output` are not empty. | 
|  | * | 
|  | * Return:  A hint for the number of bytes to use as the input for the next | 
|  | *          function call or an error, which can be checked using | 
|  | *          ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_compressStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output, | 
|  | ZSTD_inBuffer *input); | 
|  | /** | 
|  | * ZSTD_flushStream() - flush internal buffers into output | 
|  | * @zcs:    The zstd streaming compression context. | 
|  | * @output: Destination buffer. `output->pos` is updated to indicate how much | 
|  | *          compressed data was written. | 
|  | * | 
|  | * ZSTD_flushStream() must be called until it returns 0, meaning all the data | 
|  | * has been flushed. Since ZSTD_flushStream() causes a block to be ended, | 
|  | * calling it too often will degrade the compression ratio. | 
|  | * | 
|  | * Return:  The number of bytes still present within internal buffers or an | 
|  | *          error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_flushStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output); | 
|  | /** | 
|  | * ZSTD_endStream() - flush internal buffers into output and end the frame | 
|  | * @zcs:    The zstd streaming compression context. | 
|  | * @output: Destination buffer. `output->pos` is updated to indicate how much | 
|  | *          compressed data was written. | 
|  | * | 
|  | * ZSTD_endStream() must be called until it returns 0, meaning all the data has | 
|  | * been flushed and the frame epilogue has been written. | 
|  | * | 
|  | * Return:  The number of bytes still present within internal buffers or an | 
|  | *          error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_endStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output); | 
|  |  | 
|  | /** | 
|  | * ZSTD_CStreamInSize() - recommended size for the input buffer | 
|  | * | 
|  | * Return: The recommended size for the input buffer. | 
|  | */ | 
|  | size_t ZSTD_CStreamInSize(void); | 
|  | /** | 
|  | * ZSTD_CStreamOutSize() - recommended size for the output buffer | 
|  | * | 
|  | * When the output buffer is at least this large, it is guaranteed to be large | 
|  | * enough to flush at least one complete compressed block. | 
|  | * | 
|  | * Return: The recommended size for the output buffer. | 
|  | */ | 
|  | size_t ZSTD_CStreamOutSize(void); | 
|  |  | 
|  |  | 
|  |  | 
|  | /*-***************************************************************************** | 
|  | * Streaming decompression - HowTo | 
|  | * | 
|  | * A ZSTD_DStream object is required to track streaming operations. | 
|  | * Use ZSTD_initDStream() to initialize a ZSTD_DStream object. | 
|  | * ZSTD_DStream objects can be re-used multiple times. | 
|  | * | 
|  | * 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. | 
|  | * Returns 0 iff a frame is completely decoded and fully flushed. | 
|  | * Otherwise it returns a suggested next input size that will never load more | 
|  | * than the current frame. | 
|  | ******************************************************************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_DStreamWorkspaceBound() - memory needed to initialize a ZSTD_DStream | 
|  | * @maxWindowSize: The maximum window size allowed for compressed frames. | 
|  | * | 
|  | * Return:         A lower bound on the size of the workspace that is passed to | 
|  | *                 ZSTD_initDStream() and ZSTD_initDStream_usingDDict(). | 
|  | */ | 
|  | size_t ZSTD_DStreamWorkspaceBound(size_t maxWindowSize); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_DStream - the zstd streaming decompression context | 
|  | */ | 
|  | typedef struct ZSTD_DStream_s ZSTD_DStream; | 
|  | /*===== ZSTD_DStream management functions =====*/ | 
|  | /** | 
|  | * ZSTD_initDStream() - initialize a zstd streaming decompression context | 
|  | * @maxWindowSize: The maximum window size allowed for compressed frames. | 
|  | * @workspace:     The workspace to emplace the context into. It must outlive | 
|  | *                 the returned context. | 
|  | * @workspaceSize: The size of workspace. | 
|  | *                 Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine | 
|  | *                 how large the workspace must be. | 
|  | * | 
|  | * Return:         The zstd streaming decompression context. | 
|  | */ | 
|  | ZSTD_DStream *ZSTD_initDStream(size_t maxWindowSize, void *workspace, | 
|  | size_t workspaceSize); | 
|  | /** | 
|  | * ZSTD_initDStream_usingDDict() - initialize streaming decompression context | 
|  | * @maxWindowSize: The maximum window size allowed for compressed frames. | 
|  | * @ddict:         The digested dictionary to use for decompression. | 
|  | * @workspace:     The workspace to emplace the context into. It must outlive | 
|  | *                 the returned context. | 
|  | * @workspaceSize: The size of workspace. | 
|  | *                 Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine | 
|  | *                 how large the workspace must be. | 
|  | * | 
|  | * Return:         The zstd streaming decompression context. | 
|  | */ | 
|  | ZSTD_DStream *ZSTD_initDStream_usingDDict(size_t maxWindowSize, | 
|  | const ZSTD_DDict *ddict, void *workspace, size_t workspaceSize); | 
|  |  | 
|  | /*===== Streaming decompression functions =====*/ | 
|  | /** | 
|  | * ZSTD_resetDStream() - reset the context using parameters from creation | 
|  | * @zds:   The zstd streaming decompression context to reset. | 
|  | * | 
|  | * Resets the context using the parameters from creation. Skips dictionary | 
|  | * loading, since it can be reused. | 
|  | * | 
|  | * Return: Zero or an error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_resetDStream(ZSTD_DStream *zds); | 
|  | /** | 
|  | * ZSTD_decompressStream() - streaming decompress some of input into output | 
|  | * @zds:    The zstd streaming decompression context. | 
|  | * @output: Destination buffer. `output.pos` is updated to indicate how much | 
|  | *          decompressed data was written. | 
|  | * @input:  Source buffer. `input.pos` is updated to indicate how much data was | 
|  | *          read. Note that it may not consume the entire input, in which case | 
|  | *          `input.pos < input.size`, and it's up to the caller to present | 
|  | *          remaining data again. | 
|  | * | 
|  | * The `input` and `output` buffers may be any size. Guaranteed to make some | 
|  | * forward progress if `input` and `output` are not empty. | 
|  | * ZSTD_decompressStream() will not consume the last byte of the frame until | 
|  | * the entire frame is flushed. | 
|  | * | 
|  | * Return:  Returns 0 iff a frame is completely decoded and fully flushed. | 
|  | *          Otherwise returns a hint for the number of bytes to use as the input | 
|  | *          for the next function call or an error, which can be checked using | 
|  | *          ZSTD_isError(). The size hint will never load more than the frame. | 
|  | */ | 
|  | size_t ZSTD_decompressStream(ZSTD_DStream *zds, ZSTD_outBuffer *output, | 
|  | ZSTD_inBuffer *input); | 
|  |  | 
|  | /** | 
|  | * ZSTD_DStreamInSize() - recommended size for the input buffer | 
|  | * | 
|  | * Return: The recommended size for the input buffer. | 
|  | */ | 
|  | size_t ZSTD_DStreamInSize(void); | 
|  | /** | 
|  | * ZSTD_DStreamOutSize() - recommended size for the output buffer | 
|  | * | 
|  | * When the output buffer is at least this large, it is guaranteed to be large | 
|  | * enough to flush at least one complete decompressed block. | 
|  | * | 
|  | * Return: The recommended size for the output buffer. | 
|  | */ | 
|  | size_t ZSTD_DStreamOutSize(void); | 
|  |  | 
|  |  | 
|  | /* --- Constants ---*/ | 
|  | #define ZSTD_MAGICNUMBER            0xFD2FB528   /* >= v0.8.0 */ | 
|  | #define ZSTD_MAGIC_SKIPPABLE_START  0x184D2A50U | 
|  |  | 
|  | #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) | 
|  | #define ZSTD_CONTENTSIZE_ERROR   (0ULL - 2) | 
|  |  | 
|  | #define ZSTD_WINDOWLOG_MAX_32  27 | 
|  | #define ZSTD_WINDOWLOG_MAX_64  27 | 
|  | #define ZSTD_WINDOWLOG_MAX \ | 
|  | ((unsigned int)(sizeof(size_t) == 4 \ | 
|  | ? ZSTD_WINDOWLOG_MAX_32 \ | 
|  | : ZSTD_WINDOWLOG_MAX_64)) | 
|  | #define ZSTD_WINDOWLOG_MIN 10 | 
|  | #define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX | 
|  | #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 | 
|  | /* only for ZSTD_fast, other strategies are limited to 6 */ | 
|  | #define ZSTD_SEARCHLENGTH_MAX   7 | 
|  | /* only for ZSTD_btopt, other strategies are limited to 4 */ | 
|  | #define ZSTD_SEARCHLENGTH_MIN   3 | 
|  | #define ZSTD_TARGETLENGTH_MIN   4 | 
|  | #define ZSTD_TARGETLENGTH_MAX 999 | 
|  |  | 
|  | /* for static allocation */ | 
|  | #define ZSTD_FRAMEHEADERSIZE_MAX 18 | 
|  | #define ZSTD_FRAMEHEADERSIZE_MIN  6 | 
|  | #define ZSTD_frameHeaderSize_prefix 5 | 
|  | #define ZSTD_frameHeaderSize_min ZSTD_FRAMEHEADERSIZE_MIN | 
|  | #define ZSTD_frameHeaderSize_max ZSTD_FRAMEHEADERSIZE_MAX | 
|  | /* magic number + skippable frame length */ | 
|  | #define ZSTD_skippableHeaderSize 8 | 
|  |  | 
|  |  | 
|  | /*-************************************* | 
|  | * Compressed size functions | 
|  | **************************************/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_findFrameCompressedSize() - returns the size of a compressed frame | 
|  | * @src:     Source buffer. It should point to the start of a zstd encoded frame | 
|  | *           or a skippable frame. | 
|  | * @srcSize: The size of the source buffer. It must be at least as large as the | 
|  | *           size of the frame. | 
|  | * | 
|  | * Return:   The compressed size of the frame pointed to by `src` or an error, | 
|  | *           which can be check with ZSTD_isError(). | 
|  | *           Suitable to pass to ZSTD_decompress() or similar functions. | 
|  | */ | 
|  | size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize); | 
|  |  | 
|  | /*-************************************* | 
|  | * Decompressed size functions | 
|  | **************************************/ | 
|  | /** | 
|  | * ZSTD_getFrameContentSize() - returns the content size in a zstd frame header | 
|  | * @src:     It should point to the start of a zstd encoded frame. | 
|  | * @srcSize: The size of the source buffer. It must be at least as large as the | 
|  | *           frame header. `ZSTD_frameHeaderSize_max` is always large enough. | 
|  | * | 
|  | * Return:   The frame content size stored in the frame header if known. | 
|  | *           `ZSTD_CONTENTSIZE_UNKNOWN` if the content size isn't stored in the | 
|  | *           frame header. `ZSTD_CONTENTSIZE_ERROR` on invalid input. | 
|  | */ | 
|  | unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_findDecompressedSize() - returns decompressed size of a series of frames | 
|  | * @src:     It should point to the start of a series of zstd encoded and/or | 
|  | *           skippable frames. | 
|  | * @srcSize: The exact size of the series of frames. | 
|  | * | 
|  | * If any zstd encoded frame in the series doesn't have the frame content size | 
|  | * set, `ZSTD_CONTENTSIZE_UNKNOWN` is returned. But frame content size is always | 
|  | * set when using ZSTD_compress(). The decompressed size can be very large. | 
|  | * If the source is untrusted, the decompressed size could be wrong or | 
|  | * intentionally modified. Always ensure the result fits within the | 
|  | * application's authorized limits. ZSTD_findDecompressedSize() handles multiple | 
|  | * frames, and so it must traverse the input to read each frame header. This is | 
|  | * efficient as most of the data is skipped, however it does mean that all frame | 
|  | * data must be present and valid. | 
|  | * | 
|  | * Return:   Decompressed size of all the data contained in the frames if known. | 
|  | *           `ZSTD_CONTENTSIZE_UNKNOWN` if the decompressed size is unknown. | 
|  | *           `ZSTD_CONTENTSIZE_ERROR` if an error occurred. | 
|  | */ | 
|  | unsigned long long ZSTD_findDecompressedSize(const void *src, size_t srcSize); | 
|  |  | 
|  | /*-************************************* | 
|  | * Advanced compression functions | 
|  | **************************************/ | 
|  | /** | 
|  | * ZSTD_checkCParams() - ensure parameter values remain within authorized range | 
|  | * @cParams: The zstd compression parameters. | 
|  | * | 
|  | * Return:   Zero or an error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams); | 
|  |  | 
|  | /** | 
|  | * ZSTD_adjustCParams() - optimize parameters for a given srcSize and dictSize | 
|  | * @srcSize:  Optionally the estimated source size, or zero if unknown. | 
|  | * @dictSize: Optionally the estimated dictionary size, or zero if unknown. | 
|  | * | 
|  | * Return:    The optimized parameters. | 
|  | */ | 
|  | ZSTD_compressionParameters ZSTD_adjustCParams( | 
|  | ZSTD_compressionParameters cParams, unsigned long long srcSize, | 
|  | size_t dictSize); | 
|  |  | 
|  | /*--- Advanced decompression functions ---*/ | 
|  |  | 
|  | /** | 
|  | * ZSTD_isFrame() - returns true iff the buffer starts with a valid frame | 
|  | * @buffer: The source buffer to check. | 
|  | * @size:   The size of the source buffer, must be at least 4 bytes. | 
|  | * | 
|  | * Return: True iff the buffer starts with a zstd or skippable frame identifier. | 
|  | */ | 
|  | unsigned int ZSTD_isFrame(const void *buffer, size_t size); | 
|  |  | 
|  | /** | 
|  | * ZSTD_getDictID_fromDict() - returns the dictionary id stored in a dictionary | 
|  | * @dict:     The dictionary buffer. | 
|  | * @dictSize: The size of the dictionary buffer. | 
|  | * | 
|  | * Return:    The dictionary id stored within the dictionary or 0 if the | 
|  | *            dictionary is not a zstd dictionary. If it returns 0 the | 
|  | *            dictionary can still be loaded as a content-only dictionary. | 
|  | */ | 
|  | unsigned int ZSTD_getDictID_fromDict(const void *dict, size_t dictSize); | 
|  |  | 
|  | /** | 
|  | * ZSTD_getDictID_fromDDict() - returns the dictionary id stored in a ZSTD_DDict | 
|  | * @ddict: The ddict to find the id of. | 
|  | * | 
|  | * Return: The dictionary id stored within `ddict` or 0 if the dictionary is not | 
|  | *         a zstd dictionary. If it returns 0 `ddict` will be loaded as a | 
|  | *         content-only dictionary. | 
|  | */ | 
|  | unsigned int ZSTD_getDictID_fromDDict(const ZSTD_DDict *ddict); | 
|  |  | 
|  | /** | 
|  | * ZSTD_getDictID_fromFrame() - returns the dictionary id stored in a zstd frame | 
|  | * @src:     Source buffer. It must be a zstd encoded frame. | 
|  | * @srcSize: The size of the source buffer. It must be at least as large as the | 
|  | *           frame header. `ZSTD_frameHeaderSize_max` is always large enough. | 
|  | * | 
|  | * Return:   The dictionary id required to decompress the frame stored within | 
|  | *           `src` or 0 if the dictionary id could not be decoded. It can return | 
|  | *           0 if the frame does not require a dictionary, the dictionary id | 
|  | *           wasn't stored in the frame, `src` is not a zstd frame, or `srcSize` | 
|  | *           is too small. | 
|  | */ | 
|  | unsigned int ZSTD_getDictID_fromFrame(const void *src, size_t srcSize); | 
|  |  | 
|  | /** | 
|  | * struct ZSTD_frameParams - zstd frame parameters stored in the frame header | 
|  | * @frameContentSize: The frame content size, or 0 if not present. | 
|  | * @windowSize:       The window size, or 0 if the frame is a skippable frame. | 
|  | * @dictID:           The dictionary id, or 0 if not present. | 
|  | * @checksumFlag:     Whether a checksum was used. | 
|  | */ | 
|  | typedef struct { | 
|  | unsigned long long frameContentSize; | 
|  | unsigned int windowSize; | 
|  | unsigned int dictID; | 
|  | unsigned int checksumFlag; | 
|  | } ZSTD_frameParams; | 
|  |  | 
|  | /** | 
|  | * ZSTD_getFrameParams() - extracts parameters from a zstd or skippable frame | 
|  | * @fparamsPtr: On success the frame parameters are written here. | 
|  | * @src:        The source buffer. It must point to a zstd or skippable frame. | 
|  | * @srcSize:    The size of the source buffer. `ZSTD_frameHeaderSize_max` is | 
|  | *              always large enough to succeed. | 
|  | * | 
|  | * Return:      0 on success. If more data is required it returns how many bytes | 
|  | *              must be provided to make forward progress. Otherwise it returns | 
|  | *              an error, which can be checked using ZSTD_isError(). | 
|  | */ | 
|  | size_t ZSTD_getFrameParams(ZSTD_frameParams *fparamsPtr, const void *src, | 
|  | size_t srcSize); | 
|  |  | 
|  | /*-***************************************************************************** | 
|  | * 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_initCCtx() to initialize a context. | 
|  | * 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  =====*/ | 
|  | size_t ZSTD_compressBegin(ZSTD_CCtx *cctx, int compressionLevel); | 
|  | size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx *cctx, const void *dict, | 
|  | size_t dictSize, int compressionLevel); | 
|  | size_t ZSTD_compressBegin_advanced(ZSTD_CCtx *cctx, const void *dict, | 
|  | size_t dictSize, ZSTD_parameters params, | 
|  | unsigned long long pledgedSrcSize); | 
|  | size_t ZSTD_copyCCtx(ZSTD_CCtx *cctx, const ZSTD_CCtx *preparedCCtx, | 
|  | unsigned long long pledgedSrcSize); | 
|  | size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx *cctx, const ZSTD_CDict *cdict, | 
|  | unsigned long long pledgedSrcSize); | 
|  | size_t ZSTD_compressContinue(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize); | 
|  | 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_initDCtx() to initialize a context. | 
|  | * 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 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 filled. | 
|  | *        >0: `srcSize` is too small, provide at least this many bytes. | 
|  | *        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. | 
|  | * | 
|  | * The 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. | 
|  | * 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  =====*/ | 
|  | size_t ZSTD_decompressBegin(ZSTD_DCtx *dctx); | 
|  | size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx *dctx, const void *dict, | 
|  | size_t dictSize); | 
|  | void   ZSTD_copyDCtx(ZSTD_DCtx *dctx, const ZSTD_DCtx *preparedDCtx); | 
|  | size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx *dctx); | 
|  | 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; | 
|  | 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_initCCtx() and ZSTD_initDCtx() | 
|  | * - 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 for static allocation */ | 
|  | #define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) | 
|  | /*=====   Raw zstd block functions  =====*/ | 
|  | size_t ZSTD_getBlockSizeMax(ZSTD_CCtx *cctx); | 
|  | size_t ZSTD_compressBlock(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize); | 
|  | size_t ZSTD_decompressBlock(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity, | 
|  | const void *src, size_t srcSize); | 
|  | size_t ZSTD_insertBlock(ZSTD_DCtx *dctx, const void *blockStart, | 
|  | size_t blockSize); | 
|  |  | 
|  | #endif  /* ZSTD_H */ |