470 lines
24 KiB
C
470 lines
24 KiB
C
/*
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zstd - standard compression library
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Header File
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Copyright (C) 2014-2016, Yann Collet.
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BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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You can contact the author at :
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- zstd source repository : https://github.com/Cyan4973/zstd
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*/
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#ifndef ZSTD_H_235446
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#define ZSTD_H_235446
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*====== Dependency ======*/
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#include <stddef.h> /* size_t */
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/*====== Export for Windows ======*/
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/*!
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* ZSTD_DLL_EXPORT :
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* Enable exporting of functions when building a Windows DLL
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*/
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#if defined(_WIN32) && defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
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# define ZSTDLIB_API __declspec(dllexport)
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#else
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# define ZSTDLIB_API
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#endif
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/*====== Version ======*/
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#define ZSTD_VERSION_MAJOR 0
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#define ZSTD_VERSION_MINOR 8
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#define ZSTD_VERSION_RELEASE 0
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#define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE
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#define ZSTD_QUOTE(str) #str
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#define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str)
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#define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION)
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#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
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ZSTDLIB_API unsigned ZSTD_versionNumber (void);
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/* *************************************
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* Simple API
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***************************************/
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/*! ZSTD_compress() :
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Compresses `src` buffer into already allocated `dst`.
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Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
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@return : the number of bytes written into `dst` (<= `dstCapacity),
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or an error code if it fails (which can be tested using ZSTD_isError()) */
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ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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int compressionLevel);
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/*! ZSTD_getDecompressedSize() :
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* @return : decompressed size if known, 0 otherwise.
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note 1 : decompressed size could be wrong or intentionally modified !
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always ensure results fit within application's authorized limits !
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note 2 : when `0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more. */
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unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
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/*! ZSTD_decompress() :
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`compressedSize` : must be the _exact_ size of compressed input, otherwise decompression will fail.
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`dstCapacity` must be equal or larger than originalSize.
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@return : the number of bytes decompressed into `dst` (<= `dstCapacity`),
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or an errorCode if it fails (which can be tested using ZSTD_isError()) */
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ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,
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const void* src, size_t compressedSize);
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/*====== Helper functions ======*/
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ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
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ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case scenario */
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ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */
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ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */
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/*-*************************************
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* Explicit memory management
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***************************************/
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/** Compression context */
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typedef struct ZSTD_CCtx_s ZSTD_CCtx; /*< incomplete type */
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ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void);
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ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx);
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/** ZSTD_compressCCtx() :
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Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()) */
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ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel);
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/** Decompression context */
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typedef struct ZSTD_DCtx_s ZSTD_DCtx; /*< incomplete type */
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ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void);
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ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
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/** ZSTD_decompressDCtx() :
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* Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()) */
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ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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/*-************************
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* Simple dictionary API
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***************************/
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/*! ZSTD_compress_usingDict() :
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* Compression using a predefined Dictionary (see dictBuilder/zdict.h).
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* Note : This function load the dictionary, resulting in a significant startup time. */
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ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const void* dict,size_t dictSize,
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int compressionLevel);
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/*! ZSTD_decompress_usingDict() :
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* Decompression using a predefined Dictionary (see dictBuilder/zdict.h).
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* Dictionary must be identical to the one used during compression.
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* Note : This function load the dictionary, resulting in a significant startup time */
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ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const void* dict,size_t dictSize);
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/*-**************************
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* Fast Dictionary API
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****************************/
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/*! ZSTD_createCDict() :
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* Create a digested dictionary, ready to start compression operation without startup delay.
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* `dict` can be released after creation */
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typedef struct ZSTD_CDict_s ZSTD_CDict;
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ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionLevel);
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ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
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/*! ZSTD_compress_usingCDict() :
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* Compression using a digested Dictionary.
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* Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
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* Note that compression level is decided during dictionary creation */
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ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const ZSTD_CDict* cdict);
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/*! ZSTD_createDDict() :
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* Create a digested dictionary, ready to start decompression operation without startup delay.
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* `dict` can be released after creation */
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typedef struct ZSTD_DDict_s ZSTD_DDict;
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ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize);
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ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict);
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/*! ZSTD_decompress_usingDDict() :
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* Decompression using a digested Dictionary
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* Faster startup than ZSTD_decompress_usingDict(), recommended when same dictionary is used multiple times. */
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ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const ZSTD_DDict* ddict);
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#ifdef ZSTD_STATIC_LINKING_ONLY
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/* ====================================================================================
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* The definitions in this section are considered experimental.
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* They should never be used with a dynamic library, as they may change in the future.
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* They are provided for advanced usages.
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* Use them only in association with static linking.
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* ==================================================================================== */
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/*--- Constants ---*/
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#define ZSTD_MAGICNUMBER 0xFD2FB528 /* v0.8 */
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#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
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#define ZSTD_WINDOWLOG_MAX_32 25
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#define ZSTD_WINDOWLOG_MAX_64 27
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#define ZSTD_WINDOWLOG_MAX ((U32)(MEM_32bits() ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
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#define ZSTD_WINDOWLOG_MIN 18
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#define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1)
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#define ZSTD_CHAINLOG_MIN 4
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#define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX
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#define ZSTD_HASHLOG_MIN 12
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#define ZSTD_HASHLOG3_MAX 17
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#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
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#define ZSTD_SEARCHLOG_MIN 1
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#define ZSTD_SEARCHLENGTH_MAX 7
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#define ZSTD_SEARCHLENGTH_MIN 3
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#define ZSTD_TARGETLENGTH_MIN 4
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#define ZSTD_TARGETLENGTH_MAX 999
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#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */
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static const size_t ZSTD_frameHeaderSize_min = 5;
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static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
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static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */
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/*--- Types ---*/
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typedef enum { ZSTD_fast, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2, ZSTD_btlazy2, ZSTD_btopt } ZSTD_strategy; /*< from faster to stronger */
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typedef struct {
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unsigned windowLog; /*< largest match distance : larger == more compression, more memory needed during decompression */
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unsigned chainLog; /*< fully searched segment : larger == more compression, slower, more memory (useless for fast) */
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unsigned hashLog; /*< dispatch table : larger == faster, more memory */
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unsigned searchLog; /*< nb of searches : larger == more compression, slower */
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unsigned searchLength; /*< match length searched : larger == faster decompression, sometimes less compression */
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unsigned targetLength; /*< acceptable match size for optimal parser (only) : larger == more compression, slower */
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ZSTD_strategy strategy;
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} ZSTD_compressionParameters;
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typedef struct {
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unsigned contentSizeFlag; /*< 1: content size will be in frame header (if known). */
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unsigned checksumFlag; /*< 1: will generate a 22-bits checksum at end of frame, to be used for error detection by decompressor */
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unsigned noDictIDFlag; /*< 1: no dict ID will be saved into frame header (if dictionary compression) */
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} ZSTD_frameParameters;
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typedef struct {
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ZSTD_compressionParameters cParams;
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ZSTD_frameParameters fParams;
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} ZSTD_parameters;
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/* custom memory allocation functions */
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typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size);
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typedef void (*ZSTD_freeFunction) (void* opaque, void* address);
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typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem;
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/*-*************************************
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* Advanced compression functions
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***************************************/
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/*! ZSTD_estimateCCtxSize() :
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* Gives the amount of memory allocated for a ZSTD_CCtx given a set of compression parameters.
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* `frameContentSize` is an optional parameter, provide `0` if unknown */
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ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams);
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/*! ZSTD_createCCtx_advanced() :
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* Create a ZSTD compression context using external alloc and free functions */
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ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
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/*! ZSTD_createCDict_advanced() :
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* Create a ZSTD_CDict using external alloc and free, and customized compression parameters */
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ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
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ZSTD_parameters params, ZSTD_customMem customMem);
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/*! ZSTD_sizeofCCtx() :
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* Gives the amount of memory used by a given ZSTD_CCtx */
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ZSTDLIB_API size_t ZSTD_sizeofCCtx(const ZSTD_CCtx* cctx);
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/*! ZSTD_getParams() :
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* same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of a `ZSTD_compressionParameters`.
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* All fields of `ZSTD_frameParameters` are set to default (0) */
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ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long srcSize, size_t dictSize);
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/*! ZSTD_getCParams() :
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* @return ZSTD_compressionParameters structure for a selected compression level and srcSize.
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* `srcSize` value is optional, select 0 if not known */
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ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long srcSize, size_t dictSize);
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/*! ZSTD_checkCParams() :
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* Ensure param values remain within authorized range */
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ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
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/*! ZSTD_adjustCParams() :
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* optimize params for a given `srcSize` and `dictSize`.
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* both values are optional, select `0` if unknown. */
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ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
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/*! ZSTD_compress_advanced() :
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* Same as ZSTD_compress_usingDict(), with fine-tune control of each compression parameter */
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ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* ctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const void* dict,size_t dictSize,
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ZSTD_parameters params);
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/*--- Advanced Decompression functions ---*/
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/*! ZSTD_estimateDCtxSize() :
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* Gives the potential amount of memory allocated to create a ZSTD_DCtx */
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ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
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/*! ZSTD_createDCtx_advanced() :
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* Create a ZSTD decompression context using external alloc and free functions */
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ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
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/*! ZSTD_sizeofDCtx() :
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* Gives the amount of memory used by a given ZSTD_DCtx */
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ZSTDLIB_API size_t ZSTD_sizeofDCtx(const ZSTD_DCtx* dctx);
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/* ******************************************************************
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* Buffer-less streaming functions (synchronous mode)
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********************************************************************/
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/* This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
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* But it's also a complex one, with a lot of restrictions (documented below).
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* For an easier streaming API, look into common/zbuff.h
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* which removes all restrictions by allocating and managing its own internal buffer */
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ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel);
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ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel);
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ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize);
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ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx);
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ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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/*
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A ZSTD_CCtx object is required to track streaming operations.
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Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
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ZSTD_CCtx object can be re-used multiple times within successive compression operations.
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Start by initializing a context.
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Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression,
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or ZSTD_compressBegin_advanced(), for finer parameter control.
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It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx()
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Then, consume your input using ZSTD_compressContinue().
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There are some important considerations to keep in mind when using this advanced function :
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- ZSTD_compressContinue() has no internal buffer. It uses externally provided buffer only.
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- Interface is synchronous : input is consumed entirely and produce 1+ (or more) compressed blocks.
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- Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario.
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Worst case evaluation is provided by ZSTD_compressBound().
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ZSTD_compressContinue() doesn't guarantee recover after a failed compression.
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- ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog).
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It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks)
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- ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps.
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In which case, it will "discard" the relevant memory section from its history.
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Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum.
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It's possible to use a NULL,0 src content, in which case, it will write a final empty block to end the frame,
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Without last block mark, frames will be considered unfinished (broken) by decoders.
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You can then reuse `ZSTD_CCtx` (ZSTD_compressBegin()) to compress some new frame.
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*/
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typedef struct {
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unsigned long long frameContentSize;
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unsigned windowSize;
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unsigned dictID;
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unsigned checksumFlag;
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} ZSTD_frameParams;
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ZSTDLIB_API size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize); /**< doesn't consume input, see details below */
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ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
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ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
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ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx);
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ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx);
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ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
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ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
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/*
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Buffer-less streaming decompression (synchronous mode)
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A ZSTD_DCtx object is required to track streaming operations.
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Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
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A ZSTD_DCtx object can be re-used multiple times.
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First optional operation is to retrieve frame parameters, using ZSTD_getFrameParams().
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ZSTD_getFrameParams() fills a ZSTD_frameParams structure,
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which can provide the minimum size of rolling buffer required to decompress data (`windowSize`),
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and optionally the final size of uncompressed content.
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(Note : content size is an optional info that may not be present. 0 means : content size unknown).
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These information are extracted from the beginning of the compressed frame.
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Size of data fragment must be large enough to ensure successful decoding, typically ZSTD_frameHeaderSize_max bytes.
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@result : 0 : successful decoding, it means the ZSTD_frameParams structure is correctly filled.
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>0 : `srcSize` is too small, please provide at least @result bytes on next try.
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errorCode, which can be tested using ZSTD_isError().
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Start decompression, with ZSTD_decompressBegin() or ZSTD_decompressBegin_usingDict().
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Alternatively, you can copy a prepared context, using ZSTD_copyDCtx().
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Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
|
|
ZSTD_nextSrcSizeToDecompress() tells how much 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 header.
|
|
|
|
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().
|
|
But 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.
|
|
*/
|
|
|
|
|
|
/* **************************************
|
|
* 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 */
|
|
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_STATIC_LINKING_ONLY */
|
|
|
|
#if defined (__cplusplus)
|
|
}
|
|
#endif
|
|
|
|
#endif /* ZSTD_H_235446 */
|