168 lines
8.5 KiB
C
168 lines
8.5 KiB
C
/*
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Buffered version of Zstd compression library
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Copyright (C) 2015-2016, 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 homepage : http://www.zstd.net/
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*/
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#ifndef ZSTD_BUFFERED_H
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#define ZSTD_BUFFERED_H
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/* *************************************
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* Dependencies
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***************************************/
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#include <stddef.h> /* size_t */
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/* ***************************************************************
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* Compiler specifics
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*****************************************************************/
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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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/* *************************************
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* Streaming functions
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***************************************/
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typedef struct ZBUFF_CCtx_s ZBUFF_CCtx;
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ZSTDLIB_API ZBUFF_CCtx* ZBUFF_createCCtx(void);
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ZSTDLIB_API size_t ZBUFF_freeCCtx(ZBUFF_CCtx* cctx);
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ZSTDLIB_API size_t ZBUFF_compressInit(ZBUFF_CCtx* cctx, int compressionLevel);
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ZSTDLIB_API size_t ZBUFF_compressInitDictionary(ZBUFF_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel);
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ZSTDLIB_API size_t ZBUFF_compressContinue(ZBUFF_CCtx* cctx, void* dst, size_t* dstCapacityPtr, const void* src, size_t* srcSizePtr);
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ZSTDLIB_API size_t ZBUFF_compressFlush(ZBUFF_CCtx* cctx, void* dst, size_t* dstCapacityPtr);
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ZSTDLIB_API size_t ZBUFF_compressEnd(ZBUFF_CCtx* cctx, void* dst, size_t* dstCapacityPtr);
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/*-*************************************************
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* Streaming compression - howto
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*
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* A ZBUFF_CCtx object is required to track streaming operation.
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* Use ZBUFF_createCCtx() and ZBUFF_freeCCtx() to create/release resources.
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* ZBUFF_CCtx objects can be reused multiple times.
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*
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* Start by initializing ZBUF_CCtx.
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* Use ZBUFF_compressInit() to start a new compression operation.
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* Use ZBUFF_compressInitDictionary() for a compression which requires a dictionary.
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*
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* Use ZBUFF_compressContinue() repetitively to consume input stream.
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* *srcSizePtr and *dstCapacityPtr can be any size.
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* The function will report how many bytes were read or written within *srcSizePtr and *dstCapacityPtr.
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* Note that it may not consume the entire input, in which case it's up to the caller to present again remaining data.
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* The content of `dst` will be overwritten (up to *dstCapacityPtr) at each call, so save its content if it matters or change @dst .
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* @return : a hint to preferred nb of bytes to use as input for next function call (it's just a hint, to improve latency)
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* or an error code, which can be tested using ZBUFF_isError().
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*
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* At any moment, it's possible to flush whatever data remains within buffer, using ZBUFF_compressFlush().
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* The nb of bytes written into `dst` will be reported into *dstCapacityPtr.
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* Note that the function cannot output more than *dstCapacityPtr,
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* therefore, some content might still be left into internal buffer if *dstCapacityPtr is too small.
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* @return : nb of bytes still present into internal buffer (0 if it's empty)
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* or an error code, which can be tested using ZBUFF_isError().
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*
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* ZBUFF_compressEnd() instructs to finish a frame.
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* It will perform a flush and write frame epilogue.
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* The epilogue is required for decoders to consider a frame completed.
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* Similar to ZBUFF_compressFlush(), it may not be able to output the entire internal buffer content if *dstCapacityPtr is too small.
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* In which case, call again ZBUFF_compressFlush() to complete the flush.
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* @return : nb of bytes still present into internal buffer (0 if it's empty)
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* or an error code, which can be tested using ZBUFF_isError().
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*
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* Hint : recommended buffer sizes (not compulsory) : ZBUFF_recommendedCInSize / ZBUFF_recommendedCOutSize
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* input : ZBUFF_recommendedCInSize==128 KB block size is the internal unit, it improves latency to use this value (skipped buffering).
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* output : ZBUFF_recommendedCOutSize==ZSTD_compressBound(128 KB) + 3 + 3 : ensures it's always possible to write/flush/end a full block. Skip some buffering.
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* By using both, it ensures that input will be entirely consumed, and output will always contain the result, reducing intermediate buffering.
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* **************************************************/
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typedef struct ZBUFF_DCtx_s ZBUFF_DCtx;
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ZSTDLIB_API ZBUFF_DCtx* ZBUFF_createDCtx(void);
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ZSTDLIB_API size_t ZBUFF_freeDCtx(ZBUFF_DCtx* dctx);
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ZSTDLIB_API size_t ZBUFF_decompressInit(ZBUFF_DCtx* dctx);
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ZSTDLIB_API size_t ZBUFF_decompressInitDictionary(ZBUFF_DCtx* dctx, const void* dict, size_t dictSize);
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ZSTDLIB_API size_t ZBUFF_decompressContinue(ZBUFF_DCtx* dctx,
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void* dst, size_t* dstCapacityPtr,
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const void* src, size_t* srcSizePtr);
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/*-***************************************************************************
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* Streaming decompression howto
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*
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* A ZBUFF_DCtx object is required to track streaming operations.
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* Use ZBUFF_createDCtx() and ZBUFF_freeDCtx() to create/release resources.
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* Use ZBUFF_decompressInit() to start a new decompression operation,
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* or ZBUFF_decompressInitDictionary() if decompression requires a dictionary.
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* Note that ZBUFF_DCtx objects can be re-init multiple times.
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*
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* Use ZBUFF_decompressContinue() repetitively to consume your input.
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* *srcSizePtr and *dstCapacityPtr can be any size.
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* The function will report how many bytes were read or written by modifying *srcSizePtr and *dstCapacityPtr.
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* Note that it may not consume the entire input, in which case it's up to the caller to present remaining input again.
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* The content of `dst` will be overwritten (up to *dstCapacityPtr) at each function call, so save its content if it matters, or change `dst`.
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* @return : a hint to preferred nb of bytes to use as input for next function call (it's only a hint, to help latency),
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* or 0 when a frame is completely decoded,
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* or an error code, which can be tested using ZBUFF_isError().
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*
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* Hint : recommended buffer sizes (not compulsory) : ZBUFF_recommendedDInSize() and ZBUFF_recommendedDOutSize()
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* output : ZBUFF_recommendedDOutSize== 128 KB block size is the internal unit, it ensures it's always possible to write a full block when decoded.
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* input : ZBUFF_recommendedDInSize == 128KB + 3;
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* just follow indications from ZBUFF_decompressContinue() to minimize latency. It should always be <= 128 KB + 3 .
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* *******************************************************************************/
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/* *************************************
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* Tool functions
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***************************************/
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ZSTDLIB_API unsigned ZBUFF_isError(size_t errorCode);
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ZSTDLIB_API const char* ZBUFF_getErrorName(size_t errorCode);
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/** Functions below provide recommended buffer sizes for Compression or Decompression operations.
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* These sizes are just hints, they tend to offer better latency */
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ZSTDLIB_API size_t ZBUFF_recommendedCInSize(void);
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ZSTDLIB_API size_t ZBUFF_recommendedCOutSize(void);
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ZSTDLIB_API size_t ZBUFF_recommendedDInSize(void);
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ZSTDLIB_API size_t ZBUFF_recommendedDOutSize(void);
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#if defined (__cplusplus)
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}
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#endif
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#endif /* ZSTD_BUFFERED_H */
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