1565 lines
94 KiB
C
1565 lines
94 KiB
C
/*
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* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#if defined (__cplusplus)
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extern "C" {
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#endif
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#ifndef ZSTD_H_235446
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#define ZSTD_H_235446
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/* ====== Dependency ======*/
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#include <stddef.h> /* size_t */
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/* ===== ZSTDLIB_API : control library symbols visibility ===== */
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#ifndef ZSTDLIB_VISIBILITY
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# if defined(__GNUC__) && (__GNUC__ >= 4)
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# define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default")))
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# else
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# define ZSTDLIB_VISIBILITY
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# endif
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#endif
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#if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
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# define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY
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#elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
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# define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
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#else
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# define ZSTDLIB_API ZSTDLIB_VISIBILITY
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#endif
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/*******************************************************************************
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Introduction
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zstd, short for Zstandard, is a fast lossless compression algorithm, targeting
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real-time compression scenarios at zlib-level and better compression ratios.
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The zstd compression library provides in-memory compression and decompression
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functions.
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The library supports regular compression levels from 1 up to ZSTD_maxCLevel(),
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which is currently 22. Levels >= 20, labeled `--ultra`, should be used with
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caution, as they require more memory. The library also offers negative
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compression levels, which extend the range of speed vs. ratio preferences.
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The lower the level, the faster the speed (at the cost of compression).
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Compression can be done in:
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- a single step (described as Simple API)
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- a single step, reusing a context (described as Explicit context)
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- unbounded multiple steps (described as Streaming compression)
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The compression ratio achievable on small data can be highly improved using
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a dictionary. Dictionary compression can be performed in:
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- a single step (described as Simple dictionary API)
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- a single step, reusing a dictionary (described as Bulk-processing
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dictionary API)
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Advanced experimental functions can be accessed using
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`#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h.
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Advanced experimental APIs should never be used with a dynamically-linked
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library. They are not "stable"; their definitions or signatures may change in
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the future. Only static linking is allowed.
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*******************************************************************************/
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/*------ Version ------*/
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#define ZSTD_VERSION_MAJOR 1
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#define ZSTD_VERSION_MINOR 3
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#define ZSTD_VERSION_RELEASE 8
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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); /**< useful to check dll version */
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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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ZSTDLIB_API const char* ZSTD_versionString(void); /* v1.3.0+ */
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/***************************************
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* Default constant
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***************************************/
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#ifndef ZSTD_CLEVEL_DEFAULT
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# define ZSTD_CLEVEL_DEFAULT 3
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#endif
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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` content as a single zstd compressed frame into already allocated `dst`.
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* Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
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* @return : compressed size 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_decompress() :
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* `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames.
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* `dstCapacity` is an upper bound of originalSize to regenerate.
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* If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
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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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/*! ZSTD_getFrameContentSize() : added in v1.3.0
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* `src` should point to the start of a ZSTD encoded frame.
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* `srcSize` must be at least as large as the frame header.
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* hint : any size >= `ZSTD_frameHeaderSize_max` is large enough.
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* @return : - decompressed size of `src` frame content, if known
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* - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
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* - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small)
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* note 1 : a 0 return value means the frame is valid but "empty".
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* note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode.
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* When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
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* In which case, it's necessary to use streaming mode to decompress data.
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* Optionally, application can rely on some implicit limit,
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* as ZSTD_decompress() only needs an upper bound of decompressed size.
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* (For example, data could be necessarily cut into blocks <= 16 KB).
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* note 3 : decompressed size is always present when compression is completed using single-pass functions,
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* such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict().
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* note 4 : decompressed size can be very large (64-bits value),
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* potentially larger than what local system can handle as a single memory segment.
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* In which case, it's necessary to use streaming mode to decompress data.
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* note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified.
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* Always ensure return value fits within application's authorized limits.
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* Each application can set its own limits.
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* note 6 : This function replaces ZSTD_getDecompressedSize() */
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#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
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#define ZSTD_CONTENTSIZE_ERROR (0ULL - 2)
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ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
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/*! ZSTD_getDecompressedSize() :
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* NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize().
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* Both functions work the same way, but ZSTD_getDecompressedSize() blends
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* "empty", "unknown" and "error" results to the same return value (0),
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* while ZSTD_getFrameContentSize() gives them separate return values.
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* @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */
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ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
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/*====== Helper functions ======*/
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#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */
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ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass 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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ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
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/***************************************
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* Explicit context
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***************************************/
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/*= Compression context
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* When compressing many times,
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* it is recommended to allocate a context just once, and re-use it for each successive compression operation.
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* This will make workload friendlier for system's memory.
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* Use one context per thread for parallel execution in multi-threaded environments. */
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typedef struct ZSTD_CCtx_s ZSTD_CCtx;
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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,
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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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/*= Decompression context
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* When decompressing many times,
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* it is recommended to allocate a context only once,
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* and re-use it for each successive compression operation.
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* This will make workload friendlier for system's memory.
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* Use one context per thread for parallel execution. */
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typedef struct ZSTD_DCtx_s ZSTD_DCtx;
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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,
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void* dst, size_t dstCapacity,
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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 loads the dictionary, resulting in significant startup delay.
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* Note : When `dict == NULL || dictSize < 8` no dictionary is used. */
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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 loads the dictionary, resulting in significant startup delay.
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* Note : When `dict == NULL || dictSize < 8` no dictionary is used. */
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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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* Bulk processing dictionary API
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*********************************/
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typedef struct ZSTD_CDict_s ZSTD_CDict;
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/*! ZSTD_createCDict() :
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* When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
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* ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
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* ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
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* `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict
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* Note : A ZSTD_CDict can be created with an empty dictionary, but it is inefficient for small data. */
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ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
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int compressionLevel);
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/*! ZSTD_freeCDict() :
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* Function frees memory allocated by ZSTD_createCDict(). */
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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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* Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
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* Note : ZSTD_compress_usingCDict() can be used with a ZSTD_CDict created from an empty dictionary.
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* But it is inefficient for small data, and it is recommended to use ZSTD_compressCCtx(). */
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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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typedef struct ZSTD_DDict_s ZSTD_DDict;
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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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* dictBuffer can be released after DDict creation, as its content is copied inside DDict */
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ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize);
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/*! ZSTD_freeDDict() :
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* Function frees memory allocated with ZSTD_createDDict() */
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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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/****************************
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* Streaming
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****************************/
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typedef struct ZSTD_inBuffer_s {
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const void* src; /**< start of input buffer */
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size_t size; /**< size of input buffer */
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size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */
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} ZSTD_inBuffer;
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typedef struct ZSTD_outBuffer_s {
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void* dst; /**< start of output buffer */
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size_t size; /**< size of output buffer */
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size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */
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} ZSTD_outBuffer;
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/*-***********************************************************************
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* Streaming compression - HowTo
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*
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* A ZSTD_CStream object is required to track streaming operation.
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* Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources.
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* ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
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* It is recommended to re-use ZSTD_CStream in situations where many streaming operations will be achieved consecutively,
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* since it will play nicer with system's memory, by re-using already allocated memory.
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* Use one separate ZSTD_CStream per thread for parallel execution.
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*
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* Start a new compression by initializing ZSTD_CStream context.
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* Use ZSTD_initCStream() to start a new compression operation.
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* Use variants ZSTD_initCStream_usingDict() or ZSTD_initCStream_usingCDict() for streaming with dictionary (experimental section)
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*
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* Use ZSTD_compressStream() as many times as necessary to consume input stream.
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* The function will automatically update both `pos` fields within `input` and `output`.
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* Note that the function may not consume the entire input,
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* for example, because the output buffer is already full,
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* in which case `input.pos < input.size`.
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* The caller must check if input has been entirely consumed.
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* If not, the caller must make some room to receive more compressed data,
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* typically by emptying output buffer, or allocating a new output buffer,
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* and then present again remaining input data.
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* @return : a size hint, preferred nb of bytes to use as input for next function call
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* or an error code, which can be tested using ZSTD_isError().
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* Note 1 : it's just a hint, to help latency a little, any other value will work fine.
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* Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize()
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*
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* At any moment, it's possible to flush whatever data might remain stuck within internal buffer,
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* using ZSTD_flushStream(). `output->pos` will be updated.
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* Note that, if `output->size` is too small, a single invocation of ZSTD_flushStream() might not be enough (return code > 0).
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* In which case, make some room to receive more compressed data, and call again ZSTD_flushStream().
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* @return : 0 if internal buffers are entirely flushed,
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* >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
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* or an error code, which can be tested using ZSTD_isError().
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*
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* ZSTD_endStream() 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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* flush() operation is the same, and follows same rules as ZSTD_flushStream().
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* @return : 0 if frame fully completed and fully flushed,
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* >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
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* or an error code, which can be tested using ZSTD_isError().
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*
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* *******************************************************************/
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typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */
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/* Continue to distinguish them for compatibility with older versions <= v1.2.0 */
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/*===== ZSTD_CStream management functions =====*/
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ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void);
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ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
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/*===== Streaming compression functions =====*/
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ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
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ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
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ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
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ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
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ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */
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ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */
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/*-***************************************************************************
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* Streaming decompression - HowTo
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*
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* A ZSTD_DStream object is required to track streaming operations.
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* Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources.
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* ZSTD_DStream objects can be re-used multiple times.
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*
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* Use ZSTD_initDStream() to start a new decompression operation,
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* or ZSTD_initDStream_usingDict() if decompression requires a dictionary.
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* @return : recommended first input size
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*
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* Use ZSTD_decompressStream() repetitively to consume your input.
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* The function will update both `pos` fields.
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* If `input.pos < input.size`, some input has not been consumed.
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* It's up to the caller to present again remaining data.
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* The function tries to flush all data decoded immediately, repecting buffer sizes.
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* If `output.pos < output.size`, decoder has flushed everything it could.
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* But if `output.pos == output.size`, there is no such guarantee,
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* it's likely that some decoded data was not flushed and still remains within internal buffers.
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* In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.
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* When no additional input is provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX.
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* @return : 0 when a frame is completely decoded and fully flushed,
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* or an error code, which can be tested using ZSTD_isError(),
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* or any other value > 0, which means there is still some decoding or flushing to do to complete current frame :
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* the return value is a suggested next input size (a hint for better latency)
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* that will never load more than the current frame.
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* *******************************************************************************/
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typedef ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */
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/* For compatibility with versions <= v1.2.0, prefer differentiating them. */
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/*===== ZSTD_DStream management functions =====*/
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ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void);
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ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds);
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/*===== Streaming decompression functions =====*/
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ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds);
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ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
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ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */
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ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */
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#endif /* ZSTD_H_235446 */
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|
|
|
|
|
|
|
|
|
#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
|
|
#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
|
|
|
|
/****************************************************************************************
|
|
* ADVANCED AND EXPERIMENTAL FUNCTIONS
|
|
****************************************************************************************
|
|
* The definitions in this section are considered experimental.
|
|
* They should never be used with a dynamic library, as prototypes may change in the future.
|
|
* They are provided for advanced scenarios.
|
|
* Use them only in association with static linking.
|
|
* ***************************************************************************************/
|
|
|
|
ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed */
|
|
|
|
/* --- Constants ---*/
|
|
#define ZSTD_MAGICNUMBER 0xFD2FB528 /* v0.8+ */
|
|
#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* v0.7+ */
|
|
#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
|
|
|
|
#define ZSTD_BLOCKSIZELOG_MAX 17
|
|
#define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) /* define, for static allocation */
|
|
|
|
#define ZSTD_WINDOWLOG_MAX_32 30
|
|
#define ZSTD_WINDOWLOG_MAX_64 31
|
|
#define ZSTD_WINDOWLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
|
|
#define ZSTD_WINDOWLOG_MIN 10
|
|
#define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30)
|
|
#define ZSTD_HASHLOG_MIN 6
|
|
#define ZSTD_CHAINLOG_MAX_32 29
|
|
#define ZSTD_CHAINLOG_MAX_64 30
|
|
#define ZSTD_CHAINLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64))
|
|
#define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
|
|
#define ZSTD_HASHLOG3_MAX 17
|
|
#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
|
|
#define ZSTD_SEARCHLOG_MIN 1
|
|
#define ZSTD_SEARCHLENGTH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */
|
|
#define ZSTD_SEARCHLENGTH_MIN 3 /* only for ZSTD_btopt, other strategies are limited to 4 */
|
|
#define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX
|
|
#define ZSTD_TARGETLENGTH_MIN 0 /* note : comparing this constant to an unsigned results in a tautological test */
|
|
#define ZSTD_LDM_MINMATCH_MAX 4096
|
|
#define ZSTD_LDM_MINMATCH_MIN 4
|
|
#define ZSTD_LDM_BUCKETSIZELOG_MAX 8
|
|
|
|
#define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size to know frame header size */
|
|
#define ZSTD_FRAMEHEADERSIZE_MIN 6
|
|
#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */
|
|
static const size_t ZSTD_frameHeaderSize_prefix = ZSTD_FRAMEHEADERSIZE_PREFIX;
|
|
static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
|
|
static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
|
|
static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */
|
|
|
|
|
|
|
|
/* --- Advanced types --- */
|
|
typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2,
|
|
ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; /* from faster to stronger */
|
|
|
|
typedef struct {
|
|
unsigned windowLog; /**< largest match distance : larger == more compression, more memory needed during decompression */
|
|
unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */
|
|
unsigned hashLog; /**< dispatch table : larger == faster, more memory */
|
|
unsigned searchLog; /**< nb of searches : larger == more compression, slower */
|
|
unsigned searchLength; /**< match length searched : larger == faster decompression, sometimes less compression */
|
|
unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */
|
|
ZSTD_strategy strategy;
|
|
} ZSTD_compressionParameters;
|
|
|
|
typedef struct {
|
|
unsigned contentSizeFlag; /**< 1: content size will be in frame header (when known) */
|
|
unsigned checksumFlag; /**< 1: generate a 32-bits checksum at end of frame, for error detection */
|
|
unsigned noDictIDFlag; /**< 1: no dictID will be saved into frame header (if dictionary compression) */
|
|
} ZSTD_frameParameters;
|
|
|
|
typedef struct {
|
|
ZSTD_compressionParameters cParams;
|
|
ZSTD_frameParameters fParams;
|
|
} ZSTD_parameters;
|
|
|
|
typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
|
|
|
|
typedef enum {
|
|
ZSTD_dct_auto = 0, /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */
|
|
ZSTD_dct_rawContent, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */
|
|
ZSTD_dct_fullDict /* refuses to load a dictionary if it does not respect Zstandard's specification */
|
|
} ZSTD_dictContentType_e;
|
|
|
|
typedef enum {
|
|
ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */
|
|
ZSTD_dlm_byRef, /**< Reference dictionary content -- the dictionary buffer must outlive its users. */
|
|
} ZSTD_dictLoadMethod_e;
|
|
|
|
|
|
|
|
/***************************************
|
|
* Frame size functions
|
|
***************************************/
|
|
|
|
/*! ZSTD_findFrameCompressedSize() :
|
|
* `src` should point to the start of a ZSTD encoded frame or skippable frame
|
|
* `srcSize` must be >= first frame size
|
|
* @return : the compressed size of the first frame starting at `src`,
|
|
* suitable to pass to `ZSTD_decompress` or similar,
|
|
* or an error code if input is invalid */
|
|
ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
|
|
|
|
/*! ZSTD_findDecompressedSize() :
|
|
* `src` should point the start of a series of ZSTD encoded and/or skippable frames
|
|
* `srcSize` must be the _exact_ size of this series
|
|
* (i.e. there should be a frame boundary exactly at `srcSize` bytes after `src`)
|
|
* @return : - decompressed size of all data in all successive frames
|
|
* - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN
|
|
* - if an error occurred: ZSTD_CONTENTSIZE_ERROR
|
|
*
|
|
* note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode.
|
|
* When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
|
|
* In which case, it's necessary to use streaming mode to decompress data.
|
|
* note 2 : decompressed size is always present when compression is done with ZSTD_compress()
|
|
* note 3 : decompressed size can be very large (64-bits value),
|
|
* potentially larger than what local system can handle as a single memory segment.
|
|
* In which case, it's necessary to use streaming mode to decompress data.
|
|
* note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified.
|
|
* Always ensure result fits within application's authorized limits.
|
|
* Each application can set its own limits.
|
|
* note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to
|
|
* read each contained frame header. This is fast as most of the data is skipped,
|
|
* however it does mean that all frame data must be present and valid. */
|
|
ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
|
|
|
|
/*! ZSTD_frameHeaderSize() :
|
|
* srcSize must be >= ZSTD_frameHeaderSize_prefix.
|
|
* @return : size of the Frame Header,
|
|
* or an error code (if srcSize is too small) */
|
|
ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
|
|
|
|
|
|
/***************************************
|
|
* Memory management
|
|
***************************************/
|
|
|
|
/*! ZSTD_sizeof_*() :
|
|
* These functions give the current memory usage of selected object.
|
|
* Object memory usage can evolve when re-used. */
|
|
ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
|
|
ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
|
|
ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs);
|
|
ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds);
|
|
ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);
|
|
ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
/*! ZSTD_estimate*() :
|
|
* These functions make it possible to estimate memory usage
|
|
* of a future {D,C}Ctx, before its creation.
|
|
* ZSTD_estimateCCtxSize() will provide a budget large enough for any compression level up to selected one.
|
|
* It will also consider src size to be arbitrarily "large", which is worst case.
|
|
* If srcSize is known to always be small, ZSTD_estimateCCtxSize_usingCParams() can provide a tighter estimation.
|
|
* ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
|
|
* ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbWorkers is >= 1.
|
|
* Note : CCtx size estimation is only correct for single-threaded compression. */
|
|
ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel);
|
|
ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams);
|
|
ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params);
|
|
ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
|
|
|
|
/*! ZSTD_estimateCStreamSize() :
|
|
* ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one.
|
|
* It will also consider src size to be arbitrarily "large", which is worst case.
|
|
* If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation.
|
|
* ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
|
|
* ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbWorkers is >= 1.
|
|
* Note : CStream size estimation is only correct for single-threaded compression.
|
|
* ZSTD_DStream memory budget depends on window Size.
|
|
* This information can be passed manually, using ZSTD_estimateDStreamSize,
|
|
* or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame();
|
|
* Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
|
|
* an internal ?Dict will be created, which additional size is not estimated here.
|
|
* In this case, get total size by adding ZSTD_estimate?DictSize */
|
|
ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel);
|
|
ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams);
|
|
ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params);
|
|
ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize);
|
|
ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
|
|
|
|
/*! ZSTD_estimate?DictSize() :
|
|
* ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict().
|
|
* ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced().
|
|
* Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel);
|
|
ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod);
|
|
ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod);
|
|
|
|
/*! ZSTD_initStatic*() :
|
|
* Initialize an object using a pre-allocated fixed-size buffer.
|
|
* workspace: The memory area to emplace the object into.
|
|
* Provided pointer *must be 8-bytes aligned*.
|
|
* Buffer must outlive object.
|
|
* workspaceSize: Use ZSTD_estimate*Size() to determine
|
|
* how large workspace must be to support target scenario.
|
|
* @return : pointer to object (same address as workspace, just different type),
|
|
* or NULL if error (size too small, incorrect alignment, etc.)
|
|
* Note : zstd will never resize nor malloc() when using a static buffer.
|
|
* If the object requires more memory than available,
|
|
* zstd will just error out (typically ZSTD_error_memory_allocation).
|
|
* Note 2 : there is no corresponding "free" function.
|
|
* Since workspace is allocated externally, it must be freed externally too.
|
|
* Note 3 : cParams : use ZSTD_getCParams() to convert a compression level
|
|
* into its associated cParams.
|
|
* Limitation 1 : currently not compatible with internal dictionary creation, triggered by
|
|
* ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict().
|
|
* Limitation 2 : static cctx currently not compatible with multi-threading.
|
|
* Limitation 3 : static dctx is incompatible with legacy support.
|
|
*/
|
|
ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize);
|
|
ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */
|
|
|
|
ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize);
|
|
ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
|
|
|
|
ZSTDLIB_API const ZSTD_CDict* ZSTD_initStaticCDict(
|
|
void* workspace, size_t workspaceSize,
|
|
const void* dict, size_t dictSize,
|
|
ZSTD_dictLoadMethod_e dictLoadMethod,
|
|
ZSTD_dictContentType_e dictContentType,
|
|
ZSTD_compressionParameters cParams);
|
|
|
|
ZSTDLIB_API const ZSTD_DDict* ZSTD_initStaticDDict(
|
|
void* workspace, size_t workspaceSize,
|
|
const void* dict, size_t dictSize,
|
|
ZSTD_dictLoadMethod_e dictLoadMethod,
|
|
ZSTD_dictContentType_e dictContentType);
|
|
|
|
/*! Custom memory allocation :
|
|
* These prototypes make it possible to pass your own allocation/free functions.
|
|
* ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below.
|
|
* All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones.
|
|
*/
|
|
typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size);
|
|
typedef void (*ZSTD_freeFunction) (void* opaque, void* address);
|
|
typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem;
|
|
static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */
|
|
|
|
ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
|
|
ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
|
|
ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
|
|
ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
|
|
|
|
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
|
|
ZSTD_dictLoadMethod_e dictLoadMethod,
|
|
ZSTD_dictContentType_e dictContentType,
|
|
ZSTD_compressionParameters cParams,
|
|
ZSTD_customMem customMem);
|
|
|
|
ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
|
|
ZSTD_dictLoadMethod_e dictLoadMethod,
|
|
ZSTD_dictContentType_e dictContentType,
|
|
ZSTD_customMem customMem);
|
|
|
|
|
|
|
|
/***************************************
|
|
* Advanced compression functions
|
|
***************************************/
|
|
|
|
/*! ZSTD_createCDict_byReference() :
|
|
* Create a digested dictionary for compression
|
|
* Dictionary content is simply referenced, and therefore stays in dictBuffer.
|
|
* It is important that dictBuffer outlives CDict, it must remain read accessible throughout the lifetime of CDict */
|
|
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
|
|
|
|
/*! ZSTD_getCParams() :
|
|
* @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize.
|
|
* `estimatedSrcSize` value is optional, select 0 if not known */
|
|
ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
|
|
|
|
/*! ZSTD_getParams() :
|
|
* same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`.
|
|
* All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 */
|
|
ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
|
|
|
|
/*! ZSTD_checkCParams() :
|
|
* Ensure param values remain within authorized range */
|
|
ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
|
|
|
|
/*! ZSTD_adjustCParams() :
|
|
* optimize params for a given `srcSize` and `dictSize`.
|
|
* both values are optional, select `0` if unknown. */
|
|
ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
|
|
|
|
/*! ZSTD_compress_advanced() :
|
|
* Same as ZSTD_compress_usingDict(), with fine-tune control over each compression parameter */
|
|
ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* cctx,
|
|
void* dst, size_t dstCapacity,
|
|
const void* src, size_t srcSize,
|
|
const void* dict,size_t dictSize,
|
|
ZSTD_parameters params);
|
|
|
|
/*! ZSTD_compress_usingCDict_advanced() :
|
|
* Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */
|
|
ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx,
|
|
void* dst, size_t dstCapacity,
|
|
const void* src, size_t srcSize,
|
|
const ZSTD_CDict* cdict, ZSTD_frameParameters fParams);
|
|
|
|
|
|
/*--- Advanced decompression functions ---*/
|
|
|
|
/*! ZSTD_isFrame() :
|
|
* Tells if the content of `buffer` starts with a valid Frame Identifier.
|
|
* Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
|
|
* Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled.
|
|
* Note 3 : Skippable Frame Identifiers are considered valid. */
|
|
ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size);
|
|
|
|
/*! ZSTD_createDDict_byReference() :
|
|
* Create a digested dictionary, ready to start decompression operation without startup delay.
|
|
* Dictionary content is referenced, and therefore stays in dictBuffer.
|
|
* It is important that dictBuffer outlives DDict,
|
|
* it must remain read accessible throughout the lifetime of DDict */
|
|
ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize);
|
|
|
|
|
|
/*! ZSTD_getDictID_fromDict() :
|
|
* Provides the dictID stored within dictionary.
|
|
* if @return == 0, the dictionary is not conformant with Zstandard specification.
|
|
* It can still be loaded, but as a content-only dictionary. */
|
|
ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize);
|
|
|
|
/*! ZSTD_getDictID_fromDDict() :
|
|
* Provides the dictID of the dictionary loaded into `ddict`.
|
|
* If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
|
|
* Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */
|
|
ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict);
|
|
|
|
/*! ZSTD_getDictID_fromFrame() :
|
|
* Provides the dictID required to decompressed the frame stored within `src`.
|
|
* If @return == 0, the dictID could not be decoded.
|
|
* This could for one of the following reasons :
|
|
* - The frame does not require a dictionary to be decoded (most common case).
|
|
* - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.
|
|
* Note : this use case also happens when using a non-conformant dictionary.
|
|
* - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`).
|
|
* - This is not a Zstandard frame.
|
|
* When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. */
|
|
ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
|
|
|
|
|
|
/********************************************************************
|
|
* Advanced streaming functions
|
|
********************************************************************/
|
|
|
|
/*===== Advanced Streaming compression functions =====*/
|
|
ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct. If it is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, "0" also disables frame content size field. It may be enabled in the future. */
|
|
ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/
|
|
ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
|
|
ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. */
|
|
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); /**< note : cdict will just be referenced, and must outlive compression session */
|
|
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize); /**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters. pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. */
|
|
|
|
/*! ZSTD_resetCStream() :
|
|
* start a new compression job, using same parameters from previous job.
|
|
* This is typically useful to skip dictionary loading stage, since it will re-use it in-place.
|
|
* Note that zcs must be init at least once before using ZSTD_resetCStream().
|
|
* If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN.
|
|
* If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end.
|
|
* For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs,
|
|
* but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead.
|
|
* @return : 0, or an error code (which can be tested using ZSTD_isError())
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
|
|
|
|
|
|
typedef struct {
|
|
unsigned long long ingested; /* nb input bytes read and buffered */
|
|
unsigned long long consumed; /* nb input bytes actually compressed */
|
|
unsigned long long produced; /* nb of compressed bytes generated and buffered */
|
|
unsigned long long flushed; /* nb of compressed bytes flushed : not provided; can be tracked from caller side */
|
|
unsigned currentJobID; /* MT only : latest started job nb */
|
|
unsigned nbActiveWorkers; /* MT only : nb of workers actively compressing at probe time */
|
|
} ZSTD_frameProgression;
|
|
|
|
/* ZSTD_getFrameProgression() :
|
|
* tells how much data has been ingested (read from input)
|
|
* consumed (input actually compressed) and produced (output) for current frame.
|
|
* Note : (ingested - consumed) is amount of input data buffered internally, not yet compressed.
|
|
* Aggregates progression inside active worker threads.
|
|
*/
|
|
ZSTDLIB_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx);
|
|
|
|
/*! ZSTD_toFlushNow() :
|
|
* Tell how many bytes are ready to be flushed immediately.
|
|
* Useful for multithreading scenarios (nbWorkers >= 1).
|
|
* Probe the oldest active job, defined as oldest job not yet entirely flushed,
|
|
* and check its output buffer.
|
|
* @return : amount of data stored in oldest job and ready to be flushed immediately.
|
|
* if @return == 0, it means either :
|
|
* + there is no active job (could be checked with ZSTD_frameProgression()), or
|
|
* + oldest job is still actively compressing data,
|
|
* but everything it has produced has also been flushed so far,
|
|
* therefore flushing speed is currently limited by production speed of oldest job
|
|
* irrespective of the speed of concurrent newer jobs.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx);
|
|
|
|
|
|
|
|
/*===== Advanced Streaming decompression functions =====*/
|
|
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;
|
|
ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); /* obsolete : this API will be removed in a future version */
|
|
ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: no dictionary will be used if dict == NULL or dictSize < 8 */
|
|
ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict is referenced, it must outlive decompression session */
|
|
ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); /**< re-use decompression parameters from previous init; saves dictionary loading */
|
|
|
|
|
|
/*********************************************************************
|
|
* Buffer-less and synchronous inner streaming functions
|
|
*
|
|
* This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
|
|
* But it's also a complex one, with several restrictions, documented below.
|
|
* Prefer normal streaming API for an easier experience.
|
|
********************************************************************* */
|
|
|
|
/**
|
|
Buffer-less streaming compression (synchronous mode)
|
|
|
|
A ZSTD_CCtx object is required to track streaming operations.
|
|
Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
|
|
ZSTD_CCtx object can be re-used multiple times within successive compression operations.
|
|
|
|
Start by initializing a context.
|
|
Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression,
|
|
or ZSTD_compressBegin_advanced(), for finer parameter control.
|
|
It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx()
|
|
|
|
Then, consume your input using ZSTD_compressContinue().
|
|
There are some important considerations to keep in mind when using this advanced function :
|
|
- ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only.
|
|
- Interface is synchronous : input is consumed entirely and produces 1+ 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 are considered unfinished (hence corrupted) by compliant decoders.
|
|
|
|
`ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again.
|
|
*/
|
|
|
|
/*===== Buffer-less streaming compression functions =====*/
|
|
ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel);
|
|
ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel);
|
|
ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */
|
|
ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */
|
|
ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); /* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */
|
|
ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */
|
|
|
|
ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
|
|
ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
|
|
|
|
|
|
/*-
|
|
Buffer-less streaming decompression (synchronous mode)
|
|
|
|
A ZSTD_DCtx object is required to track streaming operations.
|
|
Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
|
|
A ZSTD_DCtx object can be re-used multiple times.
|
|
|
|
First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader().
|
|
Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough.
|
|
Data fragment must be large enough to ensure successful decoding.
|
|
`ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough.
|
|
@result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled.
|
|
>0 : `srcSize` is too small, please provide at least @result bytes on next attempt.
|
|
errorCode, which can be tested using ZSTD_isError().
|
|
|
|
It fills a ZSTD_frameHeader structure with important information to correctly decode the frame,
|
|
such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`).
|
|
Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information.
|
|
As a consequence, check that values remain within valid application range.
|
|
For example, do not allocate memory blindly, check that `windowSize` is within expectation.
|
|
Each application can set its own limits, depending on local restrictions.
|
|
For extended interoperability, it is recommended to support `windowSize` of at least 8 MB.
|
|
|
|
ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes.
|
|
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 distance.
|
|
There are multiple ways to guarantee this condition.
|
|
|
|
The most memory efficient way is to use a round buffer of sufficient size.
|
|
Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(),
|
|
which can @return an error code if required value is too large for current system (in 32-bits mode).
|
|
In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one,
|
|
up to the moment there is not enough room left in the buffer to guarantee decoding another full block,
|
|
which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`.
|
|
At which point, decoding can resume from the beginning of the buffer.
|
|
Note that already decoded data stored in the buffer should be flushed before being overwritten.
|
|
|
|
There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory.
|
|
|
|
Finally, if you control the compression process, you can also ignore all buffer size rules,
|
|
as long as the encoder and decoder progress in "lock-step",
|
|
aka use exactly the same buffer sizes, break contiguity at the same place, etc.
|
|
|
|
Once buffers are setup, start decompression, with ZSTD_decompressBegin().
|
|
If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict().
|
|
|
|
Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
|
|
ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue().
|
|
ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail.
|
|
|
|
@result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity).
|
|
It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item.
|
|
It can also be an error code, which can be tested with ZSTD_isError().
|
|
|
|
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 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_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame.
|
|
For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content.
|
|
*/
|
|
|
|
/*===== Buffer-less streaming decompression functions =====*/
|
|
typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e;
|
|
typedef struct {
|
|
unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */
|
|
unsigned long long windowSize; /* can be very large, up to <= frameContentSize */
|
|
unsigned blockSizeMax;
|
|
ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */
|
|
unsigned headerSize;
|
|
unsigned dictID;
|
|
unsigned checksumFlag;
|
|
} ZSTD_frameHeader;
|
|
/** ZSTD_getFrameHeader() :
|
|
* decode Frame Header, or requires larger `srcSize`.
|
|
* @return : 0, `zfhPtr` is correctly filled,
|
|
* >0, `srcSize` is too small, value is wanted `srcSize` amount,
|
|
* or an error code, which can be tested using ZSTD_isError() */
|
|
ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */
|
|
ZSTDLIB_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */
|
|
|
|
ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
|
|
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
|
|
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
|
|
|
|
ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx);
|
|
ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
|
|
|
|
/* misc */
|
|
ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx);
|
|
typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
|
|
ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
|
|
|
|
|
|
|
|
/* ============================================ */
|
|
/** New advanced API (experimental) */
|
|
/* ============================================ */
|
|
|
|
/* API design :
|
|
* In this advanced API, parameters are pushed one by one into an existing context,
|
|
* using ZSTD_CCtx_set*() functions.
|
|
* Pushed parameters are sticky : they are applied to next job, and any subsequent job.
|
|
* It's possible to reset parameters to "default" using ZSTD_CCtx_reset().
|
|
* Important : "sticky" parameters only work with `ZSTD_compress_generic()` !
|
|
* For any other entry point, "sticky" parameters are ignored !
|
|
*
|
|
* This API is intended to replace all others advanced / experimental API entry points.
|
|
*/
|
|
|
|
/* note on enum design :
|
|
* All enum will be pinned to explicit values before reaching "stable API" status */
|
|
|
|
typedef enum {
|
|
/* Opened question : should we have a format ZSTD_f_auto ?
|
|
* Today, it would mean exactly the same as ZSTD_f_zstd1.
|
|
* But, in the future, should several formats become supported,
|
|
* on the compression side, it would mean "default format".
|
|
* On the decompression side, it would mean "automatic format detection",
|
|
* so that ZSTD_f_zstd1 would mean "accept *only* zstd frames".
|
|
* Since meaning is a little different, another option could be to define different enums for compression and decompression.
|
|
* This question could be kept for later, when there are actually multiple formats to support,
|
|
* but there is also the question of pinning enum values, and pinning value `0` is especially important */
|
|
ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */
|
|
ZSTD_f_zstd1_magicless, /* Variant of zstd frame format, without initial 4-bytes magic number.
|
|
* Useful to save 4 bytes per generated frame.
|
|
* Decoder cannot recognise automatically this format, requiring instructions. */
|
|
} ZSTD_format_e;
|
|
|
|
typedef enum {
|
|
/* Note: this enum and the behavior it controls are effectively internal
|
|
* implementation details of the compressor. They are expected to continue
|
|
* to evolve and should be considered only in the context of extremely
|
|
* advanced performance tuning.
|
|
*
|
|
* Zstd currently supports the use of a CDict in two ways:
|
|
*
|
|
* - The contents of the CDict can be copied into the working context. This
|
|
* means that the compression can search both the dictionary and input
|
|
* while operating on a single set of internal tables. This makes
|
|
* the compression faster per-byte of input. However, the initial copy of
|
|
* the CDict's tables incurs a fixed cost at the beginning of the
|
|
* compression. For small compressions (< 8 KB), that copy can dominate
|
|
* the cost of the compression.
|
|
*
|
|
* - The CDict's tables can be used in-place. In this model, compression is
|
|
* slower per input byte, because the compressor has to search two sets of
|
|
* tables. However, this model incurs no start-up cost (as long as the
|
|
* working context's tables can be reused). For small inputs, this can be
|
|
* faster than copying the CDict's tables.
|
|
*
|
|
* Zstd has a simple internal heuristic that selects which strategy to use
|
|
* at the beginning of a compression. However, if experimentation shows that
|
|
* Zstd is making poor choices, it is possible to override that choice with
|
|
* this enum.
|
|
*/
|
|
ZSTD_dictDefaultAttach = 0, /* Use the default heuristic. */
|
|
ZSTD_dictForceAttach = 1, /* Never copy the dictionary. */
|
|
ZSTD_dictForceCopy = 2, /* Always copy the dictionary. */
|
|
} ZSTD_dictAttachPref_e;
|
|
|
|
typedef enum {
|
|
/* compression format */
|
|
ZSTD_p_format = 10, /* See ZSTD_format_e enum definition.
|
|
* Cast selected format as unsigned for ZSTD_CCtx_setParameter() compatibility. */
|
|
|
|
/* compression parameters */
|
|
ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
|
|
* Default level is ZSTD_CLEVEL_DEFAULT==3.
|
|
* Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
|
|
* Note 1 : it's possible to pass a negative compression level by casting it to unsigned type.
|
|
* Note 2 : setting a level sets all default values of other compression parameters.
|
|
* Note 3 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */
|
|
ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2.
|
|
* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
|
|
* Special: value 0 means "use default windowLog".
|
|
* Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27)
|
|
* requires explicitly allowing such window size during decompression stage. */
|
|
ZSTD_p_hashLog, /* Size of the initial probe table, as a power of 2.
|
|
* Resulting table size is (1 << (hashLog+2)).
|
|
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
|
|
* Larger tables improve compression ratio of strategies <= dFast,
|
|
* and improve speed of strategies > dFast.
|
|
* Special: value 0 means "use default hashLog". */
|
|
ZSTD_p_chainLog, /* Size of the multi-probe search table, as a power of 2.
|
|
* Resulting table size is (1 << (chainLog+2)).
|
|
* Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX.
|
|
* Larger tables result in better and slower compression.
|
|
* This parameter is useless when using "fast" strategy.
|
|
* Note it's still useful when using "dfast" strategy,
|
|
* in which case it defines a secondary probe table.
|
|
* Special: value 0 means "use default chainLog". */
|
|
ZSTD_p_searchLog, /* Number of search attempts, as a power of 2.
|
|
* More attempts result in better and slower compression.
|
|
* This parameter is useless when using "fast" and "dFast" strategies.
|
|
* Special: value 0 means "use default searchLog". */
|
|
ZSTD_p_minMatch, /* Minimum size of searched matches (note : repCode matches can be smaller).
|
|
* Larger values make faster compression and decompression, but decrease ratio.
|
|
* Must be clamped between ZSTD_SEARCHLENGTH_MIN and ZSTD_SEARCHLENGTH_MAX.
|
|
* Note that currently, for all strategies < btopt, effective minimum is 4.
|
|
* , for all strategies > fast, effective maximum is 6.
|
|
* Special: value 0 means "use default minMatchLength". */
|
|
ZSTD_p_targetLength, /* Impact of this field depends on strategy.
|
|
* For strategies btopt & btultra:
|
|
* Length of Match considered "good enough" to stop search.
|
|
* Larger values make compression stronger, and slower.
|
|
* For strategy fast:
|
|
* Distance between match sampling.
|
|
* Larger values make compression faster, and weaker.
|
|
* Special: value 0 means "use default targetLength". */
|
|
ZSTD_p_compressionStrategy, /* See ZSTD_strategy enum definition.
|
|
* Cast selected strategy as unsigned for ZSTD_CCtx_setParameter() compatibility.
|
|
* The higher the value of selected strategy, the more complex it is,
|
|
* resulting in stronger and slower compression.
|
|
* Special: value 0 means "use default strategy". */
|
|
|
|
ZSTD_p_enableLongDistanceMatching=160, /* Enable long distance matching.
|
|
* This parameter is designed to improve compression ratio
|
|
* for large inputs, by finding large matches at long distance.
|
|
* It increases memory usage and window size.
|
|
* Note: enabling this parameter increases ZSTD_p_windowLog to 128 MB
|
|
* except when expressly set to a different value. */
|
|
ZSTD_p_ldmHashLog, /* Size of the table for long distance matching, as a power of 2.
|
|
* Larger values increase memory usage and compression ratio,
|
|
* but decrease compression speed.
|
|
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
|
|
* default: windowlog - 7.
|
|
* Special: value 0 means "automatically determine hashlog". */
|
|
ZSTD_p_ldmMinMatch, /* Minimum match size for long distance matcher.
|
|
* Larger/too small values usually decrease compression ratio.
|
|
* Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX.
|
|
* Special: value 0 means "use default value" (default: 64). */
|
|
ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution.
|
|
* Larger values improve collision resolution but decrease compression speed.
|
|
* The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX .
|
|
* Special: value 0 means "use default value" (default: 3). */
|
|
ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table.
|
|
* Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN).
|
|
* Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage.
|
|
* Larger values improve compression speed.
|
|
* Deviating far from default value will likely result in a compression ratio decrease.
|
|
* Special: value 0 means "automatically determine hashEveryLog". */
|
|
|
|
/* frame parameters */
|
|
ZSTD_p_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1)
|
|
* Content size must be known at the beginning of compression,
|
|
* it is provided using ZSTD_CCtx_setPledgedSrcSize() */
|
|
ZSTD_p_checksumFlag, /* A 32-bits checksum of content is written at end of frame (default:0) */
|
|
ZSTD_p_dictIDFlag, /* When applicable, dictionary's ID is written into frame header (default:1) */
|
|
|
|
/* multi-threading parameters */
|
|
/* These parameters are only useful if multi-threading is enabled (ZSTD_MULTITHREAD).
|
|
* They return an error otherwise. */
|
|
ZSTD_p_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel.
|
|
* When nbWorkers >= 1, triggers asynchronous mode :
|
|
* ZSTD_compress_generic() consumes some input, flush some output if possible, and immediately gives back control to caller,
|
|
* while compression work is performed in parallel, within worker threads.
|
|
* (note : a strong exception to this rule is when first invocation sets ZSTD_e_end : it becomes a blocking call).
|
|
* More workers improve speed, but also increase memory usage.
|
|
* Default value is `0`, aka "single-threaded mode" : no worker is spawned, compression is performed inside Caller's thread, all invocations are blocking */
|
|
ZSTD_p_jobSize, /* Size of a compression job. This value is enforced only in non-blocking mode.
|
|
* Each compression job is completed in parallel, so this value indirectly controls the nb of active threads.
|
|
* 0 means default, which is dynamically determined based on compression parameters.
|
|
* Job size must be a minimum of overlapSize, or 1 MB, whichever is largest.
|
|
* The minimum size is automatically and transparently enforced */
|
|
ZSTD_p_overlapSizeLog, /* Size of previous input reloaded at the beginning of each job.
|
|
* 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */
|
|
|
|
/* =================================================================== */
|
|
/* experimental parameters - no stability guaranteed */
|
|
/* =================================================================== */
|
|
|
|
ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize,
|
|
* even when referencing into Dictionary content (default:0) */
|
|
ZSTD_p_forceAttachDict, /* Controls whether the contents of a CDict are
|
|
* used in place, or whether they are copied into
|
|
* the working context.
|
|
*
|
|
* Accepts values from the ZSTD_dictAttachPref_e
|
|
* enum. See the comments on that enum for an
|
|
* explanation of the feature.
|
|
*/
|
|
ZSTD_p_rsyncable, /* Enables rsyncable mode, which makes compressed
|
|
* files more rsync friendly by adding periodic
|
|
* synchronization points to the compressed data.
|
|
* The target average block size is
|
|
* ZSTD_p_jobSize / 2. You can modify the job size
|
|
* to increase or decrease the granularity of the
|
|
* synchronization point. Once the jobSize is
|
|
* smaller than the window size, you will start to
|
|
* see degraded compression ratio.
|
|
* NOTE: This only works when multithreading is
|
|
* enabled.
|
|
* NOTE: You probably don't want to use this with
|
|
* long range mode, since that will decrease the
|
|
* effectiveness of the synchronization points,
|
|
* but your milage may vary.
|
|
* NOTE: Rsyncable mode will limit the maximum
|
|
* compression speed to approximately 400 MB/s.
|
|
* If your compression level is already running
|
|
* significantly slower than that (< 200 MB/s),
|
|
* the speed won't be significantly impacted.
|
|
*/
|
|
} ZSTD_cParameter;
|
|
|
|
|
|
/*! ZSTD_CCtx_setParameter() :
|
|
* Set one compression parameter, selected by enum ZSTD_cParameter.
|
|
* Setting a parameter is generally only possible during frame initialization (before starting compression).
|
|
* Exception : when using multi-threading mode (nbThreads >= 1),
|
|
* following parameters can be updated _during_ compression (within same frame):
|
|
* => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy.
|
|
* new parameters will be active on next job, or after a flush().
|
|
* Note : when `value` type is not unsigned (int, or enum), cast it to unsigned for proper type checking.
|
|
* @result : informational value (typically, value being set, correctly clamped),
|
|
* or an error code (which can be tested with ZSTD_isError()). */
|
|
ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value);
|
|
|
|
/*! ZSTD_CCtx_getParameter() :
|
|
* Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned* value);
|
|
|
|
/*! ZSTD_CCtx_setPledgedSrcSize() :
|
|
* Total input data size to be compressed as a single frame.
|
|
* This value will be controlled at the end, and result in error if not respected.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Note 1 : 0 means zero, empty.
|
|
* In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN.
|
|
* ZSTD_CONTENTSIZE_UNKNOWN is default value for any new compression job.
|
|
* Note 2 : If all data is provided and consumed in a single round,
|
|
* this value is overriden by srcSize instead. */
|
|
ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize);
|
|
|
|
/*! ZSTD_CCtx_loadDictionary() :
|
|
* Create an internal CDict from `dict` buffer.
|
|
* Decompression will have to use same dictionary.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Special: Adding a NULL (or 0-size) dictionary invalidates previous dictionary,
|
|
* meaning "return to no-dictionary mode".
|
|
* Note 1 : Dictionary will be used for all future compression jobs.
|
|
* To return to "no-dictionary" situation, load a NULL dictionary
|
|
* Note 2 : Loading a dictionary involves building tables, which are dependent on compression parameters.
|
|
* For this reason, compression parameters cannot be changed anymore after loading a dictionary.
|
|
* It's also a CPU consuming operation, with non-negligible impact on latency.
|
|
* Note 3 :`dict` content will be copied internally.
|
|
* Use ZSTD_CCtx_loadDictionary_byReference() to reference dictionary content instead.
|
|
* In such a case, dictionary buffer must outlive its users.
|
|
* Note 4 : Use ZSTD_CCtx_loadDictionary_advanced()
|
|
* to precisely select how dictionary content must be interpreted. */
|
|
ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
|
|
ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
|
|
ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
|
|
|
|
|
|
/*! ZSTD_CCtx_refCDict() :
|
|
* Reference a prepared dictionary, to be used for all next compression jobs.
|
|
* Note that compression parameters are enforced from within CDict,
|
|
* and supercede any compression parameter previously set within CCtx.
|
|
* The dictionary will remain valid for future compression jobs using same CCtx.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Special : adding a NULL CDict means "return to no-dictionary mode".
|
|
* Note 1 : Currently, only one dictionary can be managed.
|
|
* Adding a new dictionary effectively "discards" any previous one.
|
|
* Note 2 : CDict is just referenced, its lifetime must outlive CCtx. */
|
|
ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
|
|
|
|
/*! ZSTD_CCtx_refPrefix() :
|
|
* Reference a prefix (single-usage dictionary) for next compression job.
|
|
* Decompression will need same prefix to properly regenerate data.
|
|
* Compressing with a prefix is similar in outcome as performing a diff and compressing it,
|
|
* but performs much faster, especially during decompression (compression speed is tunable with compression level).
|
|
* Note that prefix is **only used once**. Tables are discarded at end of compression job (ZSTD_e_end).
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
|
|
* Note 1 : Prefix buffer is referenced. It **must** outlive compression job.
|
|
* Its contain must remain unmodified up to end of compression (ZSTD_e_end).
|
|
* Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
|
|
* ensure that the window size is large enough to contain the entire source.
|
|
* See ZSTD_p_windowLog.
|
|
* Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
|
|
* It's a CPU consuming operation, with non-negligible impact on latency.
|
|
* If there is a need to use same prefix multiple times, consider loadDictionary instead.
|
|
* Note 4 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
|
|
* Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. */
|
|
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
|
|
const void* prefix, size_t prefixSize);
|
|
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx,
|
|
const void* prefix, size_t prefixSize,
|
|
ZSTD_dictContentType_e dictContentType);
|
|
|
|
/*! ZSTD_CCtx_reset() :
|
|
* Return a CCtx to clean state.
|
|
* Useful after an error, or to interrupt an ongoing compression job and start a new one.
|
|
* Any internal data not yet flushed is cancelled.
|
|
* The parameters and dictionary are kept unchanged, to reset them use ZSTD_CCtx_resetParameters().
|
|
*/
|
|
ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx);
|
|
|
|
/*! ZSTD_CCtx_resetParameters() :
|
|
* All parameters are back to default values (compression level is ZSTD_CLEVEL_DEFAULT).
|
|
* Dictionary (if any) is dropped.
|
|
* Resetting parameters is only possible during frame initialization (before starting compression).
|
|
* To reset the context use ZSTD_CCtx_reset().
|
|
* @return 0 or an error code (which can be checked with ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtx_resetParameters(ZSTD_CCtx* cctx);
|
|
|
|
|
|
|
|
typedef enum {
|
|
ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */
|
|
ZSTD_e_flush, /* flush any data provided so far,
|
|
* it creates (at least) one new block, that can be decoded immediately on reception;
|
|
* frame will continue: any future data can still reference previously compressed data, improving compression. */
|
|
ZSTD_e_end /* flush any remaining data and close current frame.
|
|
* any additional data starts a new frame.
|
|
* each frame is independent (does not reference any content from previous frame). */
|
|
} ZSTD_EndDirective;
|
|
|
|
/*! ZSTD_compress_generic() :
|
|
* Behave about the same as ZSTD_compressStream. To note :
|
|
* - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter()
|
|
* - Compression parameters cannot be changed once compression is started.
|
|
* - outpot->pos must be <= dstCapacity, input->pos must be <= srcSize
|
|
* - outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
|
|
* - In single-thread mode (default), function is blocking : it completed its job before returning to caller.
|
|
* - In multi-thread mode, function is non-blocking : it just acquires a copy of input, and distribute job to internal worker threads,
|
|
* and then immediately returns, just indicating that there is some data remaining to be flushed.
|
|
* The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
|
|
* - Exception : in multi-threading mode, if the first call requests a ZSTD_e_end directive, it is blocking : it will complete compression before giving back control to caller.
|
|
* - @return provides a minimum amount of data remaining to be flushed from internal buffers
|
|
* or an error code, which can be tested using ZSTD_isError().
|
|
* if @return != 0, flush is not fully completed, there is still some data left within internal buffers.
|
|
* This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers.
|
|
* For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed.
|
|
* - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0),
|
|
* only ZSTD_e_end or ZSTD_e_flush operations are allowed.
|
|
* Before starting a new compression job, or changing compression parameters,
|
|
* it is required to fully flush internal buffers.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
|
|
ZSTD_outBuffer* output,
|
|
ZSTD_inBuffer* input,
|
|
ZSTD_EndDirective endOp);
|
|
|
|
|
|
/*! ZSTD_compress_generic_simpleArgs() :
|
|
* Same as ZSTD_compress_generic(),
|
|
* but using only integral types as arguments.
|
|
* Argument list is larger than ZSTD_{in,out}Buffer,
|
|
* but can be helpful for binders from dynamic languages
|
|
* which have troubles handling structures containing memory pointers.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_compress_generic_simpleArgs (
|
|
ZSTD_CCtx* cctx,
|
|
void* dst, size_t dstCapacity, size_t* dstPos,
|
|
const void* src, size_t srcSize, size_t* srcPos,
|
|
ZSTD_EndDirective endOp);
|
|
|
|
|
|
/*! ZSTD_CCtx_params :
|
|
* Quick howto :
|
|
* - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure
|
|
* - ZSTD_CCtxParam_setParameter() : Push parameters one by one into
|
|
* an existing ZSTD_CCtx_params structure.
|
|
* This is similar to
|
|
* ZSTD_CCtx_setParameter().
|
|
* - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to
|
|
* an existing CCtx.
|
|
* These parameters will be applied to
|
|
* all subsequent compression jobs.
|
|
* - ZSTD_compress_generic() : Do compression using the CCtx.
|
|
* - ZSTD_freeCCtxParams() : Free the memory.
|
|
*
|
|
* This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams()
|
|
* for static allocation for single-threaded compression.
|
|
*/
|
|
ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void);
|
|
ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
|
/*! ZSTD_CCtxParams_reset() :
|
|
* Reset params to default values.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params);
|
|
|
|
/*! ZSTD_CCtxParams_init() :
|
|
* Initializes the compression parameters of cctxParams according to
|
|
* compression level. All other parameters are reset to their default values.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel);
|
|
|
|
/*! ZSTD_CCtxParams_init_advanced() :
|
|
* Initializes the compression and frame parameters of cctxParams according to
|
|
* params. All other parameters are reset to their default values.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params);
|
|
|
|
|
|
/*! ZSTD_CCtxParam_setParameter() :
|
|
* Similar to ZSTD_CCtx_setParameter.
|
|
* Set one compression parameter, selected by enum ZSTD_cParameter.
|
|
* Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams().
|
|
* Note : when `value` is an enum, cast it to unsigned for proper type checking.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value);
|
|
|
|
/*! ZSTD_CCtxParam_getParameter() :
|
|
* Similar to ZSTD_CCtx_getParameter.
|
|
* Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtxParam_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned* value);
|
|
|
|
/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
|
|
* Apply a set of ZSTD_CCtx_params to the compression context.
|
|
* This can be done even after compression is started,
|
|
* if nbWorkers==0, this will have no impact until a new compression is started.
|
|
* if nbWorkers>=1, new parameters will be picked up at next job,
|
|
* with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
|
|
ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);
|
|
|
|
|
|
/* ==================================== */
|
|
/*=== Advanced decompression API ===*/
|
|
/* ==================================== */
|
|
|
|
/* The following API works the same way as the advanced compression API :
|
|
* a context is created, parameters are pushed into it one by one,
|
|
* then the context can be used to decompress data using an interface similar to the straming API.
|
|
*/
|
|
|
|
/*! ZSTD_DCtx_loadDictionary() :
|
|
* Create an internal DDict from dict buffer,
|
|
* to be used to decompress next frames.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
|
|
* meaning "return to no-dictionary mode".
|
|
* Note 1 : `dict` content will be copied internally.
|
|
* Use ZSTD_DCtx_loadDictionary_byReference()
|
|
* to reference dictionary content instead.
|
|
* In which case, the dictionary buffer must outlive its users.
|
|
* Note 2 : Loading a dictionary involves building tables,
|
|
* which has a non-negligible impact on CPU usage and latency.
|
|
* Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to select
|
|
* how dictionary content will be interpreted and loaded.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
|
|
ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
|
|
ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
|
|
|
|
|
|
/*! ZSTD_DCtx_refDDict() :
|
|
* Reference a prepared dictionary, to be used to decompress next frames.
|
|
* The dictionary remains active for decompression of future frames using same DCtx.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Note 1 : Currently, only one dictionary can be managed.
|
|
* Referencing a new dictionary effectively "discards" any previous one.
|
|
* Special : adding a NULL DDict means "return to no-dictionary mode".
|
|
* Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
|
|
|
|
|
|
/*! ZSTD_DCtx_refPrefix() :
|
|
* Reference a prefix (single-usage dictionary) for next compression job.
|
|
* This is the reverse operation of ZSTD_CCtx_refPrefix(),
|
|
* and must use the same prefix as the one used during compression.
|
|
* Prefix is **only used once**. Reference is discarded at end of frame.
|
|
* End of frame is reached when ZSTD_DCtx_decompress_generic() returns 0.
|
|
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
* Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
|
|
* Note 2 : Prefix buffer is referenced. It **must** outlive decompression job.
|
|
* Prefix buffer must remain unmodified up to the end of frame,
|
|
* reached when ZSTD_DCtx_decompress_generic() returns 0.
|
|
* Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
|
|
* Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode.
|
|
* Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
|
|
* A fulldict prefix is more costly though.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
|
|
const void* prefix, size_t prefixSize);
|
|
ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx,
|
|
const void* prefix, size_t prefixSize,
|
|
ZSTD_dictContentType_e dictContentType);
|
|
|
|
|
|
/*! ZSTD_DCtx_setMaxWindowSize() :
|
|
* Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
|
|
* This is useful to prevent a decoder context from reserving too much memory for itself (potential attack scenario).
|
|
* This parameter is only useful in streaming mode, since no internal buffer is allocated in direct mode.
|
|
* By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_MAX)
|
|
* @return : 0, or an error code (which can be tested using ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
|
|
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|
|
|
/*! ZSTD_DCtx_setFormat() :
|
|
* Instruct the decoder context about what kind of data to decode next.
|
|
* This instruction is mandatory to decode data without a fully-formed header,
|
|
* such ZSTD_f_zstd1_magicless for example.
|
|
* @return : 0, or an error code (which can be tested using ZSTD_isError()).
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
|
|
|
|
|
|
/*! ZSTD_getFrameHeader_advanced() :
|
|
* same as ZSTD_getFrameHeader(),
|
|
* with added capability to select a format (like ZSTD_f_zstd1_magicless) */
|
|
ZSTDLIB_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr,
|
|
const void* src, size_t srcSize, ZSTD_format_e format);
|
|
|
|
|
|
/*! ZSTD_decompress_generic() :
|
|
* Behave the same as ZSTD_decompressStream.
|
|
* Decompression parameters cannot be changed once decompression is started.
|
|
* @return : an error code, which can be tested using ZSTD_isError()
|
|
* if >0, a hint, nb of expected input bytes for next invocation.
|
|
* `0` means : a frame has just been fully decoded and flushed.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
|
|
ZSTD_outBuffer* output,
|
|
ZSTD_inBuffer* input);
|
|
|
|
|
|
/*! ZSTD_decompress_generic_simpleArgs() :
|
|
* Same as ZSTD_decompress_generic(),
|
|
* but using only integral types as arguments.
|
|
* Argument list is larger than ZSTD_{in,out}Buffer,
|
|
* but can be helpful for binders from dynamic languages
|
|
* which have troubles handling structures containing memory pointers.
|
|
*/
|
|
ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs (
|
|
ZSTD_DCtx* dctx,
|
|
void* dst, size_t dstCapacity, size_t* dstPos,
|
|
const void* src, size_t srcSize, size_t* srcPos);
|
|
|
|
|
|
/*! ZSTD_DCtx_reset() :
|
|
* Return a DCtx to clean state.
|
|
* If a decompression was ongoing, any internal data not yet flushed is cancelled.
|
|
* All parameters are back to default values, including sticky ones.
|
|
* Dictionary (if any) is dropped.
|
|
* Parameters can be modified again after a reset.
|
|
*/
|
|
ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx);
|
|
|
|
|
|
|
|
/* ============================ */
|
|
/** Block level API */
|
|
/* ============================ */
|
|
|
|
/*!
|
|
Block functions produce and decode raw zstd blocks, without frame metadata.
|
|
Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
|
|
User will have to take in charge required information to regenerate data, such as compressed and content sizes.
|
|
|
|
A few rules to respect :
|
|
- Compressing and decompressing require a context structure
|
|
+ Use ZSTD_createCCtx() and ZSTD_createDCtx()
|
|
- It is necessary to init context before starting
|
|
+ compression : any ZSTD_compressBegin*() variant, including with dictionary
|
|
+ decompression : any ZSTD_decompressBegin*() variant, including with dictionary
|
|
+ copyCCtx() and copyDCtx() can be used too
|
|
- Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB
|
|
+ If input is larger than a block size, it's necessary to split input data into multiple blocks
|
|
+ For inputs larger than a single block size, consider using the regular ZSTD_compress() instead.
|
|
Frame metadata is not that costly, and quickly becomes negligible as source size grows larger.
|
|
- When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
|
|
In which case, nothing is produced into `dst`.
|
|
+ User must test for such outcome and deal directly with uncompressed data
|
|
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input !!!
|
|
+ In case of multiple successive blocks, should some of them be uncompressed,
|
|
decoder must be informed of their existence in order to follow proper history.
|
|
Use ZSTD_insertBlock() for such a case.
|
|
*/
|
|
|
|
/*===== Raw zstd block functions =====*/
|
|
ZSTDLIB_API size_t ZSTD_getBlockSize (const 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 uncompressed block into `dctx` history. Useful for multi-blocks decompression. */
|
|
|
|
|
|
#endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
|
|
|
|
#if defined (__cplusplus)
|
|
}
|
|
#endif
|