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8509f22aac
Add the zstd library from Linux kernel (only decompression support). There are minimal changes to build with U-Boot, otherwise the files are identical to Linux commit dc35da16 from March 2018, the files had not been touched since in kernel. Also SPDX lincese tags were added. Signed-off-by: Marek Behún <marek.behun@nic.cz>
1148 lines
48 KiB
C
1148 lines
48 KiB
C
/* SPDX-License-Identifier: (GPL-2.0 or BSD-3-Clause-Clear) */
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/*
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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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#ifndef ZSTD_H
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#define ZSTD_H
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/* ====== Dependency ======*/
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#include <linux/types.h> /* size_t */
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/*-*****************************************************************************
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* Introduction
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*
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* zstd, short for Zstandard, is a fast lossless compression algorithm,
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* targeting real-time compression scenarios at zlib-level and better
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* compression ratios. The zstd compression library provides in-memory
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* compression and decompression functions. The library supports compression
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* levels from 1 up to ZSTD_maxCLevel() which is 22. Levels >= 20, labeled
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* ultra, should be used with caution, as they require more memory.
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* Compression can be done in:
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* - a single step, reusing a context (described as Explicit memory management)
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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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* compression with a dictionary 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 Fast dictionary API)
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******************************************************************************/
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/*====== Helper functions ======*/
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/**
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* enum ZSTD_ErrorCode - zstd error codes
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*
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* Functions that return size_t can be checked for errors using ZSTD_isError()
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* and the ZSTD_ErrorCode can be extracted using ZSTD_getErrorCode().
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*/
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typedef enum {
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ZSTD_error_no_error,
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ZSTD_error_GENERIC,
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ZSTD_error_prefix_unknown,
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ZSTD_error_version_unsupported,
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ZSTD_error_parameter_unknown,
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ZSTD_error_frameParameter_unsupported,
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ZSTD_error_frameParameter_unsupportedBy32bits,
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ZSTD_error_frameParameter_windowTooLarge,
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ZSTD_error_compressionParameter_unsupported,
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ZSTD_error_init_missing,
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ZSTD_error_memory_allocation,
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ZSTD_error_stage_wrong,
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ZSTD_error_dstSize_tooSmall,
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ZSTD_error_srcSize_wrong,
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ZSTD_error_corruption_detected,
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ZSTD_error_checksum_wrong,
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ZSTD_error_tableLog_tooLarge,
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ZSTD_error_maxSymbolValue_tooLarge,
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ZSTD_error_maxSymbolValue_tooSmall,
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ZSTD_error_dictionary_corrupted,
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ZSTD_error_dictionary_wrong,
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ZSTD_error_dictionaryCreation_failed,
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ZSTD_error_maxCode
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} ZSTD_ErrorCode;
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/**
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* ZSTD_maxCLevel() - maximum compression level available
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*
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* Return: Maximum compression level available.
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*/
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int ZSTD_maxCLevel(void);
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/**
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* ZSTD_compressBound() - maximum compressed size in worst case scenario
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* @srcSize: The size of the data to compress.
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*
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* Return: The maximum compressed size in the worst case scenario.
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*/
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size_t ZSTD_compressBound(size_t srcSize);
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/**
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* ZSTD_isError() - tells if a size_t function result is an error code
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* @code: The function result to check for error.
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*
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* Return: Non-zero iff the code is an error.
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*/
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static __attribute__((unused)) unsigned int ZSTD_isError(size_t code)
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{
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return code > (size_t)-ZSTD_error_maxCode;
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}
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/**
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* ZSTD_getErrorCode() - translates an error function result to a ZSTD_ErrorCode
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* @functionResult: The result of a function for which ZSTD_isError() is true.
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*
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* Return: The ZSTD_ErrorCode corresponding to the functionResult or 0
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* if the functionResult isn't an error.
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*/
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static __attribute__((unused)) ZSTD_ErrorCode ZSTD_getErrorCode(
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size_t functionResult)
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{
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if (!ZSTD_isError(functionResult))
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return (ZSTD_ErrorCode)0;
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return (ZSTD_ErrorCode)(0 - functionResult);
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}
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/**
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* enum ZSTD_strategy - zstd compression search strategy
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*
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* From faster to stronger.
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*/
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typedef enum {
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ZSTD_fast,
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ZSTD_dfast,
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ZSTD_greedy,
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ZSTD_lazy,
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ZSTD_lazy2,
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ZSTD_btlazy2,
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ZSTD_btopt,
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ZSTD_btopt2
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} ZSTD_strategy;
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/**
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* struct ZSTD_compressionParameters - zstd compression parameters
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* @windowLog: Log of the largest match distance. Larger means more
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* compression, and more memory needed during decompression.
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* @chainLog: Fully searched segment. Larger means more compression, slower,
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* and more memory (useless for fast).
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* @hashLog: Dispatch table. Larger means more compression,
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* slower, and more memory.
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* @searchLog: Number of searches. Larger means more compression and slower.
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* @searchLength: Match length searched. Larger means faster decompression,
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* sometimes less compression.
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* @targetLength: Acceptable match size for optimal parser (only). Larger means
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* more compression, and slower.
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* @strategy: The zstd compression strategy.
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*/
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typedef struct {
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unsigned int windowLog;
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unsigned int chainLog;
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unsigned int hashLog;
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unsigned int searchLog;
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unsigned int searchLength;
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unsigned int targetLength;
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ZSTD_strategy strategy;
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} ZSTD_compressionParameters;
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/**
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* struct ZSTD_frameParameters - zstd frame parameters
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* @contentSizeFlag: Controls whether content size will be present in the frame
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* header (when known).
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* @checksumFlag: Controls whether a 32-bit checksum is generated at the end
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* of the frame for error detection.
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* @noDictIDFlag: Controls whether dictID will be saved into the frame header
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* when using dictionary compression.
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*
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* The default value is all fields set to 0.
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*/
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typedef struct {
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unsigned int contentSizeFlag;
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unsigned int checksumFlag;
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unsigned int noDictIDFlag;
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} ZSTD_frameParameters;
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/**
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* struct ZSTD_parameters - zstd parameters
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* @cParams: The compression parameters.
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* @fParams: The frame parameters.
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*/
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typedef struct {
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ZSTD_compressionParameters cParams;
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ZSTD_frameParameters fParams;
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} ZSTD_parameters;
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/**
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* ZSTD_getCParams() - returns ZSTD_compressionParameters for selected level
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* @compressionLevel: The compression level from 1 to ZSTD_maxCLevel().
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* @estimatedSrcSize: The estimated source size to compress or 0 if unknown.
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* @dictSize: The dictionary size or 0 if a dictionary isn't being used.
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*
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* Return: The selected ZSTD_compressionParameters.
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*/
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ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel,
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unsigned long long estimatedSrcSize, size_t dictSize);
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/**
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* ZSTD_getParams() - returns ZSTD_parameters for selected level
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* @compressionLevel: The compression level from 1 to ZSTD_maxCLevel().
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* @estimatedSrcSize: The estimated source size to compress or 0 if unknown.
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* @dictSize: The dictionary size or 0 if a dictionary isn't being used.
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*
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* The same as ZSTD_getCParams() except also selects the default frame
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* parameters (all zero).
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*
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* Return: The selected ZSTD_parameters.
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*/
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ZSTD_parameters ZSTD_getParams(int compressionLevel,
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unsigned long long estimatedSrcSize, size_t dictSize);
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/*-*************************************
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* Explicit memory management
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**************************************/
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/**
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* ZSTD_CCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_CCtx
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* @cParams: The compression parameters to be used for compression.
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*
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* If multiple compression parameters might be used, the caller must call
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* ZSTD_CCtxWorkspaceBound() for each set of parameters and use the maximum
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* size.
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*
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* Return: A lower bound on the size of the workspace that is passed to
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* ZSTD_initCCtx().
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*/
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size_t ZSTD_CCtxWorkspaceBound(ZSTD_compressionParameters cParams);
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/**
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* struct ZSTD_CCtx - the zstd compression context
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*
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* When compressing many times it is recommended to allocate a context just once
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* and reuse it for each successive compression operation.
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*/
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typedef struct ZSTD_CCtx_s ZSTD_CCtx;
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/**
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* ZSTD_initCCtx() - initialize a zstd compression context
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* @workspace: The workspace to emplace the context into. It must outlive
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* the returned context.
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* @workspaceSize: The size of workspace. Use ZSTD_CCtxWorkspaceBound() to
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* determine how large the workspace must be.
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*
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* Return: A compression context emplaced into workspace.
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*/
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ZSTD_CCtx *ZSTD_initCCtx(void *workspace, size_t workspaceSize);
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/**
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* ZSTD_compressCCtx() - compress src into dst
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* @ctx: The context. Must have been initialized with a workspace at
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* least as large as ZSTD_CCtxWorkspaceBound(params.cParams).
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* @dst: The buffer to compress src into.
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* @dstCapacity: The size of the destination buffer. May be any size, but
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* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
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* @src: The data to compress.
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* @srcSize: The size of the data to compress.
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* @params: The parameters to use for compression. See ZSTD_getParams().
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*
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* Return: The compressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_compressCCtx(ZSTD_CCtx *ctx, void *dst, size_t dstCapacity,
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const void *src, size_t srcSize, ZSTD_parameters params);
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/**
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* ZSTD_DCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_DCtx
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*
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* Return: A lower bound on the size of the workspace that is passed to
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* ZSTD_initDCtx().
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*/
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size_t ZSTD_DCtxWorkspaceBound(void);
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/**
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* struct ZSTD_DCtx - the zstd decompression context
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*
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* When decompressing many times it is recommended to allocate a context just
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* once and reuse it for each successive decompression operation.
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*/
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typedef struct ZSTD_DCtx_s ZSTD_DCtx;
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/**
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* ZSTD_initDCtx() - initialize a zstd decompression context
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* @workspace: The workspace to emplace the context into. It must outlive
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* the returned context.
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* @workspaceSize: The size of workspace. Use ZSTD_DCtxWorkspaceBound() to
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* determine how large the workspace must be.
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*
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* Return: A decompression context emplaced into workspace.
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*/
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ZSTD_DCtx *ZSTD_initDCtx(void *workspace, size_t workspaceSize);
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/**
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* ZSTD_decompressDCtx() - decompress zstd compressed src into dst
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* @ctx: The decompression context.
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* @dst: The buffer to decompress src into.
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* @dstCapacity: The size of the destination buffer. Must be at least as large
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* as the decompressed size. If the caller cannot upper bound the
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* decompressed size, then it's better to use the streaming API.
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* @src: The zstd compressed data to decompress. Multiple concatenated
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* frames and skippable frames are allowed.
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* @srcSize: The exact size of the data to decompress.
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*
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* Return: The decompressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_decompressDCtx(ZSTD_DCtx *ctx, 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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/**
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* ZSTD_compress_usingDict() - compress src into dst using a dictionary
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* @ctx: The context. Must have been initialized with a workspace at
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* least as large as ZSTD_CCtxWorkspaceBound(params.cParams).
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* @dst: The buffer to compress src into.
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* @dstCapacity: The size of the destination buffer. May be any size, but
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* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
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* @src: The data to compress.
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* @srcSize: The size of the data to compress.
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* @dict: The dictionary to use for compression.
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* @dictSize: The size of the dictionary.
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* @params: The parameters to use for compression. See ZSTD_getParams().
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*
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* Compression using a predefined dictionary. The same dictionary must be used
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* during decompression.
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*
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* Return: The compressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_compress_usingDict(ZSTD_CCtx *ctx, void *dst, size_t dstCapacity,
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const void *src, size_t srcSize, const void *dict, size_t dictSize,
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ZSTD_parameters params);
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/**
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* ZSTD_decompress_usingDict() - decompress src into dst using a dictionary
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* @ctx: The decompression context.
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* @dst: The buffer to decompress src into.
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* @dstCapacity: The size of the destination buffer. Must be at least as large
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* as the decompressed size. If the caller cannot upper bound the
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* decompressed size, then it's better to use the streaming API.
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* @src: The zstd compressed data to decompress. Multiple concatenated
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* frames and skippable frames are allowed.
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* @srcSize: The exact size of the data to decompress.
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* @dict: The dictionary to use for decompression. The same dictionary
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* must've been used to compress the data.
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* @dictSize: The size of the dictionary.
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*
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* Return: The decompressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_decompress_usingDict(ZSTD_DCtx *ctx, void *dst, size_t dstCapacity,
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const void *src, size_t srcSize, const void *dict, size_t dictSize);
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/*-**************************
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* Fast dictionary API
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***************************/
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/**
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* ZSTD_CDictWorkspaceBound() - memory needed to initialize a ZSTD_CDict
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* @cParams: The compression parameters to be used for compression.
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*
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* Return: A lower bound on the size of the workspace that is passed to
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* ZSTD_initCDict().
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*/
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size_t ZSTD_CDictWorkspaceBound(ZSTD_compressionParameters cParams);
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/**
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* struct ZSTD_CDict - a digested dictionary to be used for compression
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*/
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typedef struct ZSTD_CDict_s ZSTD_CDict;
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/**
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* ZSTD_initCDict() - initialize a digested dictionary for compression
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* @dictBuffer: The dictionary to digest. The buffer is referenced by the
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* ZSTD_CDict so it must outlive the returned ZSTD_CDict.
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* @dictSize: The size of the dictionary.
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* @params: The parameters to use for compression. See ZSTD_getParams().
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* @workspace: The workspace. It must outlive the returned ZSTD_CDict.
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* @workspaceSize: The workspace size. Must be at least
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* ZSTD_CDictWorkspaceBound(params.cParams).
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*
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* When compressing multiple messages / blocks with the same dictionary it is
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* recommended to load it just once. The ZSTD_CDict merely references the
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* dictBuffer, so it must outlive the returned ZSTD_CDict.
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*
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* Return: The digested dictionary emplaced into workspace.
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*/
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ZSTD_CDict *ZSTD_initCDict(const void *dictBuffer, size_t dictSize,
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ZSTD_parameters params, void *workspace, size_t workspaceSize);
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/**
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* ZSTD_compress_usingCDict() - compress src into dst using a ZSTD_CDict
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* @ctx: The context. Must have been initialized with a workspace at
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* least as large as ZSTD_CCtxWorkspaceBound(cParams) where
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* cParams are the compression parameters used to initialize the
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* cdict.
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* @dst: The buffer to compress src into.
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* @dstCapacity: The size of the destination buffer. May be any size, but
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* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
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* @src: The data to compress.
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* @srcSize: The size of the data to compress.
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* @cdict: The digested dictionary to use for compression.
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* @params: The parameters to use for compression. See ZSTD_getParams().
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*
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* Compression using a digested dictionary. The same dictionary must be used
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* during decompression.
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*
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* Return: The compressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_compress_usingCDict(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
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const void *src, size_t srcSize, const ZSTD_CDict *cdict);
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/**
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* ZSTD_DDictWorkspaceBound() - memory needed to initialize a ZSTD_DDict
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*
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* Return: A lower bound on the size of the workspace that is passed to
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* ZSTD_initDDict().
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*/
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size_t ZSTD_DDictWorkspaceBound(void);
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/**
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* struct ZSTD_DDict - a digested dictionary to be used for decompression
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*/
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typedef struct ZSTD_DDict_s ZSTD_DDict;
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/**
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* ZSTD_initDDict() - initialize a digested dictionary for decompression
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* @dictBuffer: The dictionary to digest. The buffer is referenced by the
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* ZSTD_DDict so it must outlive the returned ZSTD_DDict.
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* @dictSize: The size of the dictionary.
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* @workspace: The workspace. It must outlive the returned ZSTD_DDict.
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* @workspaceSize: The workspace size. Must be at least
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* ZSTD_DDictWorkspaceBound().
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*
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* When decompressing multiple messages / blocks with the same dictionary it is
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* recommended to load it just once. The ZSTD_DDict merely references the
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* dictBuffer, so it must outlive the returned ZSTD_DDict.
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*
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* Return: The digested dictionary emplaced into workspace.
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*/
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ZSTD_DDict *ZSTD_initDDict(const void *dictBuffer, size_t dictSize,
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void *workspace, size_t workspaceSize);
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/**
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* ZSTD_decompress_usingDDict() - decompress src into dst using a ZSTD_DDict
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* @ctx: The decompression context.
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* @dst: The buffer to decompress src into.
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* @dstCapacity: The size of the destination buffer. Must be at least as large
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* as the decompressed size. If the caller cannot upper bound the
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* decompressed size, then it's better to use the streaming API.
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* @src: The zstd compressed data to decompress. Multiple concatenated
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* frames and skippable frames are allowed.
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* @srcSize: The exact size of the data to decompress.
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* @ddict: The digested dictionary to use for decompression. The same
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* dictionary must've been used to compress the data.
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*
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* Return: The decompressed size or an error, which can be checked using
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* ZSTD_isError().
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*/
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size_t ZSTD_decompress_usingDDict(ZSTD_DCtx *dctx, void *dst,
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size_t dstCapacity, 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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/**
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* struct ZSTD_inBuffer - input buffer for streaming
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* @src: Start of the input buffer.
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* @size: Size of the input buffer.
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* @pos: Position where reading stopped. Will be updated.
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* Necessarily 0 <= pos <= size.
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*/
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typedef struct ZSTD_inBuffer_s {
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const void *src;
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size_t size;
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size_t pos;
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} ZSTD_inBuffer;
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/**
|
|
* struct ZSTD_outBuffer - output buffer for streaming
|
|
* @dst: Start of the output buffer.
|
|
* @size: Size of the output buffer.
|
|
* @pos: Position where writing stopped. Will be updated.
|
|
* Necessarily 0 <= pos <= size.
|
|
*/
|
|
typedef struct ZSTD_outBuffer_s {
|
|
void *dst;
|
|
size_t size;
|
|
size_t pos;
|
|
} ZSTD_outBuffer;
|
|
|
|
|
|
|
|
/*-*****************************************************************************
|
|
* Streaming compression - HowTo
|
|
*
|
|
* A ZSTD_CStream object is required to track streaming operation.
|
|
* Use ZSTD_initCStream() to initialize a ZSTD_CStream object.
|
|
* ZSTD_CStream objects can be reused multiple times on consecutive compression
|
|
* operations. It is recommended to re-use ZSTD_CStream in situations where many
|
|
* streaming operations will be achieved consecutively. Use one separate
|
|
* ZSTD_CStream per thread for parallel execution.
|
|
*
|
|
* Use ZSTD_compressStream() repetitively to consume input stream.
|
|
* The function will automatically update both `pos` fields.
|
|
* Note that it may not consume the entire input, in which case `pos < size`,
|
|
* and it's up to the caller to present again remaining data.
|
|
* It returns a hint for the preferred number of bytes to use as an input for
|
|
* the next function call.
|
|
*
|
|
* At any moment, it's possible to flush whatever data remains within internal
|
|
* buffer, using ZSTD_flushStream(). `output->pos` will be updated. There might
|
|
* still be some content left within the internal buffer if `output->size` is
|
|
* too small. It returns the number of bytes left in the internal buffer and
|
|
* must be called until it returns 0.
|
|
*
|
|
* ZSTD_endStream() instructs to finish a frame. It will perform a flush and
|
|
* write frame epilogue. The epilogue is required for decoders to consider a
|
|
* frame completed. Similar to ZSTD_flushStream(), it may not be able to flush
|
|
* the full content if `output->size` is too small. In which case, call again
|
|
* ZSTD_endStream() to complete the flush. It returns the number of bytes left
|
|
* in the internal buffer and must be called until it returns 0.
|
|
******************************************************************************/
|
|
|
|
/**
|
|
* ZSTD_CStreamWorkspaceBound() - memory needed to initialize a ZSTD_CStream
|
|
* @cParams: The compression parameters to be used for compression.
|
|
*
|
|
* Return: A lower bound on the size of the workspace that is passed to
|
|
* ZSTD_initCStream() and ZSTD_initCStream_usingCDict().
|
|
*/
|
|
size_t ZSTD_CStreamWorkspaceBound(ZSTD_compressionParameters cParams);
|
|
|
|
/**
|
|
* struct ZSTD_CStream - the zstd streaming compression context
|
|
*/
|
|
typedef struct ZSTD_CStream_s ZSTD_CStream;
|
|
|
|
/*===== ZSTD_CStream management functions =====*/
|
|
/**
|
|
* ZSTD_initCStream() - initialize a zstd streaming compression context
|
|
* @params: The zstd compression parameters.
|
|
* @pledgedSrcSize: If params.fParams.contentSizeFlag == 1 then the caller must
|
|
* pass the source size (zero means empty source). Otherwise,
|
|
* the caller may optionally pass the source size, or zero if
|
|
* unknown.
|
|
* @workspace: The workspace to emplace the context into. It must outlive
|
|
* the returned context.
|
|
* @workspaceSize: The size of workspace.
|
|
* Use ZSTD_CStreamWorkspaceBound(params.cParams) to determine
|
|
* how large the workspace must be.
|
|
*
|
|
* Return: The zstd streaming compression context.
|
|
*/
|
|
ZSTD_CStream *ZSTD_initCStream(ZSTD_parameters params,
|
|
unsigned long long pledgedSrcSize, void *workspace,
|
|
size_t workspaceSize);
|
|
|
|
/**
|
|
* ZSTD_initCStream_usingCDict() - initialize a streaming compression context
|
|
* @cdict: The digested dictionary to use for compression.
|
|
* @pledgedSrcSize: Optionally the source size, or zero if unknown.
|
|
* @workspace: The workspace to emplace the context into. It must outlive
|
|
* the returned context.
|
|
* @workspaceSize: The size of workspace. Call ZSTD_CStreamWorkspaceBound()
|
|
* with the cParams used to initialize the cdict to determine
|
|
* how large the workspace must be.
|
|
*
|
|
* Return: The zstd streaming compression context.
|
|
*/
|
|
ZSTD_CStream *ZSTD_initCStream_usingCDict(const ZSTD_CDict *cdict,
|
|
unsigned long long pledgedSrcSize, void *workspace,
|
|
size_t workspaceSize);
|
|
|
|
/*===== Streaming compression functions =====*/
|
|
/**
|
|
* ZSTD_resetCStream() - reset the context using parameters from creation
|
|
* @zcs: The zstd streaming compression context to reset.
|
|
* @pledgedSrcSize: Optionally the source size, or zero if unknown.
|
|
*
|
|
* Resets the context using the parameters from creation. Skips dictionary
|
|
* loading, since it can be reused. If `pledgedSrcSize` is non-zero the frame
|
|
* content size is always written into the frame header.
|
|
*
|
|
* Return: Zero or an error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_resetCStream(ZSTD_CStream *zcs, unsigned long long pledgedSrcSize);
|
|
/**
|
|
* ZSTD_compressStream() - streaming compress some of input into output
|
|
* @zcs: The zstd streaming compression context.
|
|
* @output: Destination buffer. `output->pos` is updated to indicate how much
|
|
* compressed data was written.
|
|
* @input: Source buffer. `input->pos` is updated to indicate how much data was
|
|
* read. Note that it may not consume the entire input, in which case
|
|
* `input->pos < input->size`, and it's up to the caller to present
|
|
* remaining data again.
|
|
*
|
|
* The `input` and `output` buffers may be any size. Guaranteed to make some
|
|
* forward progress if `input` and `output` are not empty.
|
|
*
|
|
* Return: A hint for the number of bytes to use as the input for the next
|
|
* function call or an error, which can be checked using
|
|
* ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_compressStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output,
|
|
ZSTD_inBuffer *input);
|
|
/**
|
|
* ZSTD_flushStream() - flush internal buffers into output
|
|
* @zcs: The zstd streaming compression context.
|
|
* @output: Destination buffer. `output->pos` is updated to indicate how much
|
|
* compressed data was written.
|
|
*
|
|
* ZSTD_flushStream() must be called until it returns 0, meaning all the data
|
|
* has been flushed. Since ZSTD_flushStream() causes a block to be ended,
|
|
* calling it too often will degrade the compression ratio.
|
|
*
|
|
* Return: The number of bytes still present within internal buffers or an
|
|
* error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_flushStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output);
|
|
/**
|
|
* ZSTD_endStream() - flush internal buffers into output and end the frame
|
|
* @zcs: The zstd streaming compression context.
|
|
* @output: Destination buffer. `output->pos` is updated to indicate how much
|
|
* compressed data was written.
|
|
*
|
|
* ZSTD_endStream() must be called until it returns 0, meaning all the data has
|
|
* been flushed and the frame epilogue has been written.
|
|
*
|
|
* Return: The number of bytes still present within internal buffers or an
|
|
* error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_endStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output);
|
|
|
|
/**
|
|
* ZSTD_CStreamInSize() - recommended size for the input buffer
|
|
*
|
|
* Return: The recommended size for the input buffer.
|
|
*/
|
|
size_t ZSTD_CStreamInSize(void);
|
|
/**
|
|
* ZSTD_CStreamOutSize() - recommended size for the output buffer
|
|
*
|
|
* When the output buffer is at least this large, it is guaranteed to be large
|
|
* enough to flush at least one complete compressed block.
|
|
*
|
|
* Return: The recommended size for the output buffer.
|
|
*/
|
|
size_t ZSTD_CStreamOutSize(void);
|
|
|
|
|
|
|
|
/*-*****************************************************************************
|
|
* Streaming decompression - HowTo
|
|
*
|
|
* A ZSTD_DStream object is required to track streaming operations.
|
|
* Use ZSTD_initDStream() to initialize a ZSTD_DStream object.
|
|
* ZSTD_DStream objects can be re-used multiple times.
|
|
*
|
|
* Use ZSTD_decompressStream() repetitively to consume your input.
|
|
* The function will update both `pos` fields.
|
|
* If `input->pos < input->size`, some input has not been consumed.
|
|
* It's up to the caller to present again remaining data.
|
|
* If `output->pos < output->size`, decoder has flushed everything it could.
|
|
* Returns 0 iff a frame is completely decoded and fully flushed.
|
|
* Otherwise it returns a suggested next input size that will never load more
|
|
* than the current frame.
|
|
******************************************************************************/
|
|
|
|
/**
|
|
* ZSTD_DStreamWorkspaceBound() - memory needed to initialize a ZSTD_DStream
|
|
* @maxWindowSize: The maximum window size allowed for compressed frames.
|
|
*
|
|
* Return: A lower bound on the size of the workspace that is passed to
|
|
* ZSTD_initDStream() and ZSTD_initDStream_usingDDict().
|
|
*/
|
|
size_t ZSTD_DStreamWorkspaceBound(size_t maxWindowSize);
|
|
|
|
/**
|
|
* struct ZSTD_DStream - the zstd streaming decompression context
|
|
*/
|
|
typedef struct ZSTD_DStream_s ZSTD_DStream;
|
|
/*===== ZSTD_DStream management functions =====*/
|
|
/**
|
|
* ZSTD_initDStream() - initialize a zstd streaming decompression context
|
|
* @maxWindowSize: The maximum window size allowed for compressed frames.
|
|
* @workspace: The workspace to emplace the context into. It must outlive
|
|
* the returned context.
|
|
* @workspaceSize: The size of workspace.
|
|
* Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine
|
|
* how large the workspace must be.
|
|
*
|
|
* Return: The zstd streaming decompression context.
|
|
*/
|
|
ZSTD_DStream *ZSTD_initDStream(size_t maxWindowSize, void *workspace,
|
|
size_t workspaceSize);
|
|
/**
|
|
* ZSTD_initDStream_usingDDict() - initialize streaming decompression context
|
|
* @maxWindowSize: The maximum window size allowed for compressed frames.
|
|
* @ddict: The digested dictionary to use for decompression.
|
|
* @workspace: The workspace to emplace the context into. It must outlive
|
|
* the returned context.
|
|
* @workspaceSize: The size of workspace.
|
|
* Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine
|
|
* how large the workspace must be.
|
|
*
|
|
* Return: The zstd streaming decompression context.
|
|
*/
|
|
ZSTD_DStream *ZSTD_initDStream_usingDDict(size_t maxWindowSize,
|
|
const ZSTD_DDict *ddict, void *workspace, size_t workspaceSize);
|
|
|
|
/*===== Streaming decompression functions =====*/
|
|
/**
|
|
* ZSTD_resetDStream() - reset the context using parameters from creation
|
|
* @zds: The zstd streaming decompression context to reset.
|
|
*
|
|
* Resets the context using the parameters from creation. Skips dictionary
|
|
* loading, since it can be reused.
|
|
*
|
|
* Return: Zero or an error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_resetDStream(ZSTD_DStream *zds);
|
|
/**
|
|
* ZSTD_decompressStream() - streaming decompress some of input into output
|
|
* @zds: The zstd streaming decompression context.
|
|
* @output: Destination buffer. `output.pos` is updated to indicate how much
|
|
* decompressed data was written.
|
|
* @input: Source buffer. `input.pos` is updated to indicate how much data was
|
|
* read. Note that it may not consume the entire input, in which case
|
|
* `input.pos < input.size`, and it's up to the caller to present
|
|
* remaining data again.
|
|
*
|
|
* The `input` and `output` buffers may be any size. Guaranteed to make some
|
|
* forward progress if `input` and `output` are not empty.
|
|
* ZSTD_decompressStream() will not consume the last byte of the frame until
|
|
* the entire frame is flushed.
|
|
*
|
|
* Return: Returns 0 iff a frame is completely decoded and fully flushed.
|
|
* Otherwise returns a hint for the number of bytes to use as the input
|
|
* for the next function call or an error, which can be checked using
|
|
* ZSTD_isError(). The size hint will never load more than the frame.
|
|
*/
|
|
size_t ZSTD_decompressStream(ZSTD_DStream *zds, ZSTD_outBuffer *output,
|
|
ZSTD_inBuffer *input);
|
|
|
|
/**
|
|
* ZSTD_DStreamInSize() - recommended size for the input buffer
|
|
*
|
|
* Return: The recommended size for the input buffer.
|
|
*/
|
|
size_t ZSTD_DStreamInSize(void);
|
|
/**
|
|
* ZSTD_DStreamOutSize() - recommended size for the output buffer
|
|
*
|
|
* When the output buffer is at least this large, it is guaranteed to be large
|
|
* enough to flush at least one complete decompressed block.
|
|
*
|
|
* Return: The recommended size for the output buffer.
|
|
*/
|
|
size_t ZSTD_DStreamOutSize(void);
|
|
|
|
|
|
/* --- Constants ---*/
|
|
#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */
|
|
#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
|
|
|
|
#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
|
|
#define ZSTD_CONTENTSIZE_ERROR (0ULL - 2)
|
|
|
|
#define ZSTD_WINDOWLOG_MAX_32 27
|
|
#define ZSTD_WINDOWLOG_MAX_64 27
|
|
#define ZSTD_WINDOWLOG_MAX \
|
|
((unsigned int)(sizeof(size_t) == 4 \
|
|
? ZSTD_WINDOWLOG_MAX_32 \
|
|
: ZSTD_WINDOWLOG_MAX_64))
|
|
#define ZSTD_WINDOWLOG_MIN 10
|
|
#define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX
|
|
#define ZSTD_HASHLOG_MIN 6
|
|
#define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1)
|
|
#define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
|
|
#define ZSTD_HASHLOG3_MAX 17
|
|
#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
|
|
#define ZSTD_SEARCHLOG_MIN 1
|
|
/* only for ZSTD_fast, other strategies are limited to 6 */
|
|
#define ZSTD_SEARCHLENGTH_MAX 7
|
|
/* only for ZSTD_btopt, other strategies are limited to 4 */
|
|
#define ZSTD_SEARCHLENGTH_MIN 3
|
|
#define ZSTD_TARGETLENGTH_MIN 4
|
|
#define ZSTD_TARGETLENGTH_MAX 999
|
|
|
|
/* for static allocation */
|
|
#define ZSTD_FRAMEHEADERSIZE_MAX 18
|
|
#define ZSTD_FRAMEHEADERSIZE_MIN 6
|
|
static const size_t ZSTD_frameHeaderSize_prefix = 5;
|
|
static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
|
|
static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
|
|
/* magic number + skippable frame length */
|
|
static const size_t ZSTD_skippableHeaderSize = 8;
|
|
|
|
|
|
/*-*************************************
|
|
* Compressed size functions
|
|
**************************************/
|
|
|
|
/**
|
|
* ZSTD_findFrameCompressedSize() - returns the size of a compressed frame
|
|
* @src: Source buffer. It should point to the start of a zstd encoded frame
|
|
* or a skippable frame.
|
|
* @srcSize: The size of the source buffer. It must be at least as large as the
|
|
* size of the frame.
|
|
*
|
|
* Return: The compressed size of the frame pointed to by `src` or an error,
|
|
* which can be check with ZSTD_isError().
|
|
* Suitable to pass to ZSTD_decompress() or similar functions.
|
|
*/
|
|
size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize);
|
|
|
|
/*-*************************************
|
|
* Decompressed size functions
|
|
**************************************/
|
|
/**
|
|
* ZSTD_getFrameContentSize() - returns the content size in a zstd frame header
|
|
* @src: It should point to the start of a zstd encoded frame.
|
|
* @srcSize: The size of the source buffer. It must be at least as large as the
|
|
* frame header. `ZSTD_frameHeaderSize_max` is always large enough.
|
|
*
|
|
* Return: The frame content size stored in the frame header if known.
|
|
* `ZSTD_CONTENTSIZE_UNKNOWN` if the content size isn't stored in the
|
|
* frame header. `ZSTD_CONTENTSIZE_ERROR` on invalid input.
|
|
*/
|
|
unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
|
|
|
|
/**
|
|
* ZSTD_findDecompressedSize() - returns decompressed size of a series of frames
|
|
* @src: It should point to the start of a series of zstd encoded and/or
|
|
* skippable frames.
|
|
* @srcSize: The exact size of the series of frames.
|
|
*
|
|
* If any zstd encoded frame in the series doesn't have the frame content size
|
|
* set, `ZSTD_CONTENTSIZE_UNKNOWN` is returned. But frame content size is always
|
|
* set when using ZSTD_compress(). The decompressed size can be very large.
|
|
* If the source is untrusted, the decompressed size could be wrong or
|
|
* intentionally modified. Always ensure the result fits within the
|
|
* application's authorized limits. ZSTD_findDecompressedSize() handles multiple
|
|
* frames, and so it must traverse the input to read each frame header. This is
|
|
* efficient as most of the data is skipped, however it does mean that all frame
|
|
* data must be present and valid.
|
|
*
|
|
* Return: Decompressed size of all the data contained in the frames if known.
|
|
* `ZSTD_CONTENTSIZE_UNKNOWN` if the decompressed size is unknown.
|
|
* `ZSTD_CONTENTSIZE_ERROR` if an error occurred.
|
|
*/
|
|
unsigned long long ZSTD_findDecompressedSize(const void *src, size_t srcSize);
|
|
|
|
/*-*************************************
|
|
* Advanced compression functions
|
|
**************************************/
|
|
/**
|
|
* ZSTD_checkCParams() - ensure parameter values remain within authorized range
|
|
* @cParams: The zstd compression parameters.
|
|
*
|
|
* Return: Zero or an error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams);
|
|
|
|
/**
|
|
* ZSTD_adjustCParams() - optimize parameters for a given srcSize and dictSize
|
|
* @srcSize: Optionally the estimated source size, or zero if unknown.
|
|
* @dictSize: Optionally the estimated dictionary size, or zero if unknown.
|
|
*
|
|
* Return: The optimized parameters.
|
|
*/
|
|
ZSTD_compressionParameters ZSTD_adjustCParams(
|
|
ZSTD_compressionParameters cParams, unsigned long long srcSize,
|
|
size_t dictSize);
|
|
|
|
/*--- Advanced decompression functions ---*/
|
|
|
|
/**
|
|
* ZSTD_isFrame() - returns true iff the buffer starts with a valid frame
|
|
* @buffer: The source buffer to check.
|
|
* @size: The size of the source buffer, must be at least 4 bytes.
|
|
*
|
|
* Return: True iff the buffer starts with a zstd or skippable frame identifier.
|
|
*/
|
|
unsigned int ZSTD_isFrame(const void *buffer, size_t size);
|
|
|
|
/**
|
|
* ZSTD_getDictID_fromDict() - returns the dictionary id stored in a dictionary
|
|
* @dict: The dictionary buffer.
|
|
* @dictSize: The size of the dictionary buffer.
|
|
*
|
|
* Return: The dictionary id stored within the dictionary or 0 if the
|
|
* dictionary is not a zstd dictionary. If it returns 0 the
|
|
* dictionary can still be loaded as a content-only dictionary.
|
|
*/
|
|
unsigned int ZSTD_getDictID_fromDict(const void *dict, size_t dictSize);
|
|
|
|
/**
|
|
* ZSTD_getDictID_fromDDict() - returns the dictionary id stored in a ZSTD_DDict
|
|
* @ddict: The ddict to find the id of.
|
|
*
|
|
* Return: The dictionary id stored within `ddict` or 0 if the dictionary is not
|
|
* a zstd dictionary. If it returns 0 `ddict` will be loaded as a
|
|
* content-only dictionary.
|
|
*/
|
|
unsigned int ZSTD_getDictID_fromDDict(const ZSTD_DDict *ddict);
|
|
|
|
/**
|
|
* ZSTD_getDictID_fromFrame() - returns the dictionary id stored in a zstd frame
|
|
* @src: Source buffer. It must be a zstd encoded frame.
|
|
* @srcSize: The size of the source buffer. It must be at least as large as the
|
|
* frame header. `ZSTD_frameHeaderSize_max` is always large enough.
|
|
*
|
|
* Return: The dictionary id required to decompress the frame stored within
|
|
* `src` or 0 if the dictionary id could not be decoded. It can return
|
|
* 0 if the frame does not require a dictionary, the dictionary id
|
|
* wasn't stored in the frame, `src` is not a zstd frame, or `srcSize`
|
|
* is too small.
|
|
*/
|
|
unsigned int ZSTD_getDictID_fromFrame(const void *src, size_t srcSize);
|
|
|
|
/**
|
|
* struct ZSTD_frameParams - zstd frame parameters stored in the frame header
|
|
* @frameContentSize: The frame content size, or 0 if not present.
|
|
* @windowSize: The window size, or 0 if the frame is a skippable frame.
|
|
* @dictID: The dictionary id, or 0 if not present.
|
|
* @checksumFlag: Whether a checksum was used.
|
|
*/
|
|
typedef struct {
|
|
unsigned long long frameContentSize;
|
|
unsigned int windowSize;
|
|
unsigned int dictID;
|
|
unsigned int checksumFlag;
|
|
} ZSTD_frameParams;
|
|
|
|
/**
|
|
* ZSTD_getFrameParams() - extracts parameters from a zstd or skippable frame
|
|
* @fparamsPtr: On success the frame parameters are written here.
|
|
* @src: The source buffer. It must point to a zstd or skippable frame.
|
|
* @srcSize: The size of the source buffer. `ZSTD_frameHeaderSize_max` is
|
|
* always large enough to succeed.
|
|
*
|
|
* Return: 0 on success. If more data is required it returns how many bytes
|
|
* must be provided to make forward progress. Otherwise it returns
|
|
* an error, which can be checked using ZSTD_isError().
|
|
*/
|
|
size_t ZSTD_getFrameParams(ZSTD_frameParams *fparamsPtr, const void *src,
|
|
size_t srcSize);
|
|
|
|
/*-*****************************************************************************
|
|
* Buffer-less and synchronous inner streaming functions
|
|
*
|
|
* This is an advanced API, giving full control over buffer management, for
|
|
* users which need direct control over memory.
|
|
* But it's also a complex one, with many restrictions (documented below).
|
|
* Prefer using normal streaming API for an easier experience
|
|
******************************************************************************/
|
|
|
|
/*-*****************************************************************************
|
|
* Buffer-less streaming compression (synchronous mode)
|
|
*
|
|
* A ZSTD_CCtx object is required to track streaming operations.
|
|
* Use ZSTD_initCCtx() to initialize a context.
|
|
* ZSTD_CCtx object can be re-used multiple times within successive compression
|
|
* operations.
|
|
*
|
|
* Start by initializing a context.
|
|
* Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary
|
|
* compression,
|
|
* or ZSTD_compressBegin_advanced(), for finer parameter control.
|
|
* It's also possible to duplicate a reference context which has already been
|
|
* initialized, using ZSTD_copyCCtx()
|
|
*
|
|
* Then, consume your input using ZSTD_compressContinue().
|
|
* There are some important considerations to keep in mind when using this
|
|
* advanced function :
|
|
* - ZSTD_compressContinue() has no internal buffer. It uses externally provided
|
|
* buffer only.
|
|
* - Interface is synchronous : input is consumed entirely and produce 1+
|
|
* (or more) compressed blocks.
|
|
* - Caller must ensure there is enough space in `dst` to store compressed data
|
|
* under worst case scenario. Worst case evaluation is provided by
|
|
* ZSTD_compressBound().
|
|
* ZSTD_compressContinue() doesn't guarantee recover after a failed
|
|
* compression.
|
|
* - ZSTD_compressContinue() presumes prior input ***is still accessible and
|
|
* unmodified*** (up to maximum distance size, see WindowLog).
|
|
* It remembers all previous contiguous blocks, plus one separated memory
|
|
* segment (which can itself consists of multiple contiguous blocks)
|
|
* - ZSTD_compressContinue() detects that prior input has been overwritten when
|
|
* `src` buffer overlaps. In which case, it will "discard" the relevant memory
|
|
* section from its history.
|
|
*
|
|
* Finish a frame with ZSTD_compressEnd(), which will write the last block(s)
|
|
* and optional checksum. It's possible to use srcSize==0, in which case, it
|
|
* will write a final empty block to end the frame. Without last block mark,
|
|
* frames will be considered unfinished (corrupted) by decoders.
|
|
*
|
|
* `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new
|
|
* frame.
|
|
******************************************************************************/
|
|
|
|
/*===== Buffer-less streaming compression functions =====*/
|
|
size_t ZSTD_compressBegin(ZSTD_CCtx *cctx, int compressionLevel);
|
|
size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx *cctx, const void *dict,
|
|
size_t dictSize, int compressionLevel);
|
|
size_t ZSTD_compressBegin_advanced(ZSTD_CCtx *cctx, const void *dict,
|
|
size_t dictSize, ZSTD_parameters params,
|
|
unsigned long long pledgedSrcSize);
|
|
size_t ZSTD_copyCCtx(ZSTD_CCtx *cctx, const ZSTD_CCtx *preparedCCtx,
|
|
unsigned long long pledgedSrcSize);
|
|
size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx *cctx, const ZSTD_CDict *cdict,
|
|
unsigned long long pledgedSrcSize);
|
|
size_t ZSTD_compressContinue(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
|
|
const void *src, size_t srcSize);
|
|
size_t ZSTD_compressEnd(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
|
|
const void *src, size_t srcSize);
|
|
|
|
|
|
|
|
/*-*****************************************************************************
|
|
* Buffer-less streaming decompression (synchronous mode)
|
|
*
|
|
* A ZSTD_DCtx object is required to track streaming operations.
|
|
* Use ZSTD_initDCtx() to initialize a context.
|
|
* A ZSTD_DCtx object can be re-used multiple times.
|
|
*
|
|
* First typical operation is to retrieve frame parameters, using
|
|
* ZSTD_getFrameParams(). It fills a ZSTD_frameParams structure which provide
|
|
* important information to correctly decode the frame, such as the minimum
|
|
* rolling buffer size to allocate to decompress data (`windowSize`), and the
|
|
* dictionary ID used.
|
|
* Note: content size is optional, it may not be present. 0 means unknown.
|
|
* Note that these values could be wrong, either because of data malformation,
|
|
* or because an attacker is spoofing deliberate false information. As a
|
|
* consequence, check that values remain within valid application range,
|
|
* especially `windowSize`, before allocation. Each application can set its own
|
|
* limit, depending on local restrictions. For extended interoperability, it is
|
|
* recommended to support at least 8 MB.
|
|
* Frame parameters are extracted from the beginning of the compressed frame.
|
|
* Data fragment must be large enough to ensure successful decoding, typically
|
|
* `ZSTD_frameHeaderSize_max` bytes.
|
|
* Result: 0: successful decoding, the `ZSTD_frameParams` structure is filled.
|
|
* >0: `srcSize` is too small, provide at least this many bytes.
|
|
* errorCode, which can be tested using ZSTD_isError().
|
|
*
|
|
* Start decompression, with ZSTD_decompressBegin() or
|
|
* ZSTD_decompressBegin_usingDict(). Alternatively, you can copy a prepared
|
|
* context, using ZSTD_copyDCtx().
|
|
*
|
|
* Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue()
|
|
* alternatively.
|
|
* ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize'
|
|
* to ZSTD_decompressContinue().
|
|
* ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will
|
|
* fail.
|
|
*
|
|
* The result of ZSTD_decompressContinue() is the number of bytes regenerated
|
|
* within 'dst' (necessarily <= dstCapacity). It can be zero, which is not an
|
|
* error; it just means ZSTD_decompressContinue() has decoded some metadata
|
|
* item. It can also be an error code, which can be tested with ZSTD_isError().
|
|
*
|
|
* ZSTD_decompressContinue() needs previous data blocks during decompression, up
|
|
* to `windowSize`. They should preferably be located contiguously, prior to
|
|
* current block. Alternatively, a round buffer of sufficient size is also
|
|
* possible. Sufficient size is determined by frame parameters.
|
|
* ZSTD_decompressContinue() is very sensitive to contiguity, if 2 blocks don't
|
|
* follow each other, make sure that either the compressor breaks contiguity at
|
|
* the same place, or that previous contiguous segment is large enough to
|
|
* properly handle maximum back-reference.
|
|
*
|
|
* A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero.
|
|
* Context can then be reset to start a new decompression.
|
|
*
|
|
* Note: it's possible to know if next input to present is a header or a block,
|
|
* using ZSTD_nextInputType(). This information is not required to properly
|
|
* decode a frame.
|
|
*
|
|
* == Special case: skippable frames ==
|
|
*
|
|
* Skippable frames allow integration of user-defined data into a flow of
|
|
* concatenated frames. Skippable frames will be ignored (skipped) by a
|
|
* decompressor. The format of skippable frames is as follows:
|
|
* a) Skippable frame ID - 4 Bytes, Little endian format, any value from
|
|
* 0x184D2A50 to 0x184D2A5F
|
|
* b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits
|
|
* c) Frame Content - any content (User Data) of length equal to Frame Size
|
|
* For skippable frames ZSTD_decompressContinue() always returns 0.
|
|
* For skippable frames ZSTD_getFrameParams() returns fparamsPtr->windowLog==0
|
|
* what means that a frame is skippable.
|
|
* Note: If fparamsPtr->frameContentSize==0, it is ambiguous: the frame might
|
|
* actually be a zstd encoded frame with no content. For purposes of
|
|
* decompression, it is valid in both cases to skip the frame using
|
|
* ZSTD_findFrameCompressedSize() to find its size in bytes.
|
|
* It also returns frame size as fparamsPtr->frameContentSize.
|
|
******************************************************************************/
|
|
|
|
/*===== Buffer-less streaming decompression functions =====*/
|
|
size_t ZSTD_decompressBegin(ZSTD_DCtx *dctx);
|
|
size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx *dctx, const void *dict,
|
|
size_t dictSize);
|
|
void ZSTD_copyDCtx(ZSTD_DCtx *dctx, const ZSTD_DCtx *preparedDCtx);
|
|
size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx *dctx);
|
|
size_t ZSTD_decompressContinue(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity,
|
|
const void *src, size_t srcSize);
|
|
typedef enum {
|
|
ZSTDnit_frameHeader,
|
|
ZSTDnit_blockHeader,
|
|
ZSTDnit_block,
|
|
ZSTDnit_lastBlock,
|
|
ZSTDnit_checksum,
|
|
ZSTDnit_skippableFrame
|
|
} ZSTD_nextInputType_e;
|
|
ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx *dctx);
|
|
|
|
/*-*****************************************************************************
|
|
* Block functions
|
|
*
|
|
* Block functions produce and decode raw zstd blocks, without frame metadata.
|
|
* Frame metadata cost is typically ~18 bytes, which can be non-negligible for
|
|
* very small blocks (< 100 bytes). User will have to take in charge required
|
|
* information to regenerate data, such as compressed and content sizes.
|
|
*
|
|
* A few rules to respect:
|
|
* - Compressing and decompressing require a context structure
|
|
* + Use ZSTD_initCCtx() and ZSTD_initDCtx()
|
|
* - It is necessary to init context before starting
|
|
* + compression : ZSTD_compressBegin()
|
|
* + decompression : ZSTD_decompressBegin()
|
|
* + variants _usingDict() are also allowed
|
|
* + copyCCtx() and copyDCtx() work too
|
|
* - Block size is limited, it must be <= ZSTD_getBlockSizeMax()
|
|
* + If you need to compress more, cut data into multiple blocks
|
|
* + Consider using the regular ZSTD_compress() instead, as frame metadata
|
|
* costs become negligible when source size is large.
|
|
* - When a block is considered not compressible enough, ZSTD_compressBlock()
|
|
* result will be zero. In which case, nothing is produced into `dst`.
|
|
* + User must test for such outcome and deal directly with uncompressed data
|
|
* + ZSTD_decompressBlock() doesn't accept uncompressed data as input!!!
|
|
* + In case of multiple successive blocks, decoder must be informed of
|
|
* uncompressed block existence to follow proper history. Use
|
|
* ZSTD_insertBlock() in such a case.
|
|
******************************************************************************/
|
|
|
|
/* Define for static allocation */
|
|
#define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024)
|
|
/*===== Raw zstd block functions =====*/
|
|
size_t ZSTD_getBlockSizeMax(ZSTD_CCtx *cctx);
|
|
size_t ZSTD_compressBlock(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
|
|
const void *src, size_t srcSize);
|
|
size_t ZSTD_decompressBlock(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity,
|
|
const void *src, size_t srcSize);
|
|
size_t ZSTD_insertBlock(ZSTD_DCtx *dctx, const void *blockStart,
|
|
size_t blockSize);
|
|
|
|
#endif /* ZSTD_H */
|