mirror of
https://github.com/facebook/zstd.git
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745 lines
30 KiB
C
745 lines
30 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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/* This header contains definitions
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* that shall **only** be used by modules within lib/compress.
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*/
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#ifndef ZSTD_COMPRESS_H
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#define ZSTD_COMPRESS_H
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/*-*************************************
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* Dependencies
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***************************************/
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#include "zstd_internal.h"
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#ifdef ZSTD_MULTITHREAD
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# include "zstdmt_compress.h"
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#endif
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*-*************************************
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* Constants
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***************************************/
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#define kSearchStrength 8
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#define HASH_READ_SIZE 8
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#define ZSTD_DUBT_UNSORTED_MARK 1 /* For btlazy2 strategy, index 1 now means "unsorted".
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It could be confused for a real successor at index "1", if sorted as larger than its predecessor.
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It's not a big deal though : candidate will just be sorted again.
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Additionnally, candidate position 1 will be lost.
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But candidate 1 cannot hide a large tree of candidates, so it's a minimal loss.
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The benefit is that ZSTD_DUBT_UNSORTED_MARK cannot be misdhandled after table re-use with a different strategy */
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/*-*************************************
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* Context memory management
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***************************************/
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typedef enum { ZSTDcs_created=0, ZSTDcs_init, ZSTDcs_ongoing, ZSTDcs_ending } ZSTD_compressionStage_e;
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typedef enum { zcss_init=0, zcss_load, zcss_flush } ZSTD_cStreamStage;
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typedef struct ZSTD_prefixDict_s {
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const void* dict;
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size_t dictSize;
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ZSTD_dictContentType_e dictContentType;
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} ZSTD_prefixDict;
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typedef struct {
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U32 CTable[HUF_CTABLE_SIZE_U32(255)];
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HUF_repeat repeatMode;
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} ZSTD_hufCTables_t;
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typedef struct {
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FSE_CTable offcodeCTable[FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff)];
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FSE_CTable matchlengthCTable[FSE_CTABLE_SIZE_U32(MLFSELog, MaxML)];
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FSE_CTable litlengthCTable[FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL)];
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FSE_repeat offcode_repeatMode;
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FSE_repeat matchlength_repeatMode;
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FSE_repeat litlength_repeatMode;
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} ZSTD_fseCTables_t;
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typedef struct {
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ZSTD_hufCTables_t huf;
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ZSTD_fseCTables_t fse;
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} ZSTD_entropyCTables_t;
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typedef struct {
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U32 off;
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U32 len;
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} ZSTD_match_t;
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typedef struct {
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int price;
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U32 off;
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U32 mlen;
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U32 litlen;
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U32 rep[ZSTD_REP_NUM];
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} ZSTD_optimal_t;
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typedef enum { zop_dynamic=0, zop_predef, zop_static } ZSTD_OptPrice_e;
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typedef struct {
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/* All tables are allocated inside cctx->workspace by ZSTD_resetCCtx_internal() */
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U32* litFreq; /* table of literals statistics, of size 256 */
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U32* litLengthFreq; /* table of litLength statistics, of size (MaxLL+1) */
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U32* matchLengthFreq; /* table of matchLength statistics, of size (MaxML+1) */
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U32* offCodeFreq; /* table of offCode statistics, of size (MaxOff+1) */
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ZSTD_match_t* matchTable; /* list of found matches, of size ZSTD_OPT_NUM+1 */
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ZSTD_optimal_t* priceTable; /* All positions tracked by optimal parser, of size ZSTD_OPT_NUM+1 */
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U32 litSum; /* nb of literals */
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U32 litLengthSum; /* nb of litLength codes */
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U32 matchLengthSum; /* nb of matchLength codes */
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U32 offCodeSum; /* nb of offset codes */
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/* begin updated by ZSTD_setLog2Prices */
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U32 log2litSum; /* pow2 to compare log2(litfreq) to */
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U32 log2litLengthSum; /* pow2 to compare log2(llfreq) to */
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U32 log2matchLengthSum; /* pow2 to compare log2(mlfreq) to */
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U32 log2offCodeSum; /* pow2 to compare log2(offreq) to */
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/* end : updated by ZSTD_setLog2Prices */
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ZSTD_OptPrice_e priceType; /* prices can be determined dynamically, or follow dictionary statistics, or a pre-defined cost structure */
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const ZSTD_entropyCTables_t* symbolCosts; /* pre-calculated dictionary statistics */
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} optState_t;
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typedef struct {
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ZSTD_entropyCTables_t entropy;
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U32 rep[ZSTD_REP_NUM];
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} ZSTD_compressedBlockState_t;
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typedef struct {
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BYTE const* nextSrc; /* next block here to continue on current prefix */
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BYTE const* base; /* All regular indexes relative to this position */
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BYTE const* dictBase; /* extDict indexes relative to this position */
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U32 dictLimit; /* below that point, need extDict */
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U32 lowLimit; /* below that point, no more data */
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} ZSTD_window_t;
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typedef struct ZSTD_matchState_t ZSTD_matchState_t;
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struct ZSTD_matchState_t {
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ZSTD_window_t window; /* State for window round buffer management */
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U32 loadedDictEnd; /* index of end of dictionary */
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U32 nextToUpdate; /* index from which to continue table update */
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U32 nextToUpdate3; /* index from which to continue table update */
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U32 hashLog3; /* dispatch table : larger == faster, more memory */
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U32* hashTable;
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U32* hashTable3;
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U32* chainTable;
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optState_t opt; /* optimal parser state */
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const ZSTD_matchState_t *dictMatchState;
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};
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typedef struct {
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ZSTD_compressedBlockState_t* prevCBlock;
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ZSTD_compressedBlockState_t* nextCBlock;
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ZSTD_matchState_t matchState;
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} ZSTD_blockState_t;
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typedef struct {
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U32 offset;
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U32 checksum;
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} ldmEntry_t;
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typedef struct {
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ZSTD_window_t window; /* State for the window round buffer management */
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ldmEntry_t* hashTable;
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BYTE* bucketOffsets; /* Next position in bucket to insert entry */
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U64 hashPower; /* Used to compute the rolling hash.
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* Depends on ldmParams.minMatchLength */
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} ldmState_t;
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typedef struct {
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U32 enableLdm; /* 1 if enable long distance matching */
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U32 hashLog; /* Log size of hashTable */
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U32 bucketSizeLog; /* Log bucket size for collision resolution, at most 8 */
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U32 minMatchLength; /* Minimum match length */
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U32 hashEveryLog; /* Log number of entries to skip */
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U32 windowLog; /* Window log for the LDM */
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} ldmParams_t;
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typedef struct {
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U32 offset;
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U32 litLength;
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U32 matchLength;
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} rawSeq;
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typedef struct {
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rawSeq* seq; /* The start of the sequences */
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size_t pos; /* The position where reading stopped. <= size. */
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size_t size; /* The number of sequences. <= capacity. */
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size_t capacity; /* The capacity starting from `seq` pointer */
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} rawSeqStore_t;
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struct ZSTD_CCtx_params_s {
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ZSTD_format_e format;
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ZSTD_compressionParameters cParams;
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ZSTD_frameParameters fParams;
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int compressionLevel;
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int disableLiteralCompression;
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int forceWindow; /* force back-references to respect limit of
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* 1<<wLog, even for dictionary */
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/* Multithreading: used to pass parameters to mtctx */
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unsigned nbWorkers;
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unsigned jobSize;
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unsigned overlapSizeLog;
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/* Long distance matching parameters */
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ldmParams_t ldmParams;
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/* Internal use, for createCCtxParams() and freeCCtxParams() only */
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ZSTD_customMem customMem;
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}; /* typedef'd to ZSTD_CCtx_params within "zstd.h" */
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struct ZSTD_CCtx_s {
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ZSTD_compressionStage_e stage;
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int cParamsChanged; /* == 1 if cParams(except wlog) or compression level are changed in requestedParams. Triggers transmission of new params to ZSTDMT (if available) then reset to 0. */
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int bmi2; /* == 1 if the CPU supports BMI2 and 0 otherwise. CPU support is determined dynamically once per context lifetime. */
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ZSTD_CCtx_params requestedParams;
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ZSTD_CCtx_params appliedParams;
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U32 dictID;
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void* workSpace;
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size_t workSpaceSize;
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size_t blockSize;
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unsigned long long pledgedSrcSizePlusOne; /* this way, 0 (default) == unknown */
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unsigned long long consumedSrcSize;
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unsigned long long producedCSize;
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XXH64_state_t xxhState;
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ZSTD_customMem customMem;
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size_t staticSize;
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seqStore_t seqStore; /* sequences storage ptrs */
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ldmState_t ldmState; /* long distance matching state */
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rawSeq* ldmSequences; /* Storage for the ldm output sequences */
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size_t maxNbLdmSequences;
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rawSeqStore_t externSeqStore; /* Mutable reference to external sequences */
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ZSTD_blockState_t blockState;
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U32* entropyWorkspace; /* entropy workspace of HUF_WORKSPACE_SIZE bytes */
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/* streaming */
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char* inBuff;
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size_t inBuffSize;
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size_t inToCompress;
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size_t inBuffPos;
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size_t inBuffTarget;
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char* outBuff;
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size_t outBuffSize;
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size_t outBuffContentSize;
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size_t outBuffFlushedSize;
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ZSTD_cStreamStage streamStage;
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U32 frameEnded;
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/* Dictionary */
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ZSTD_CDict* cdictLocal;
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const ZSTD_CDict* cdict;
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ZSTD_prefixDict prefixDict; /* single-usage dictionary */
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/* Multi-threading */
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#ifdef ZSTD_MULTITHREAD
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ZSTDMT_CCtx* mtctx;
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#endif
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};
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typedef enum { ZSTD_dtlm_fast, ZSTD_dtlm_full } ZSTD_dictTableLoadMethod_e;
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typedef enum { ZSTD_noDict = 0, ZSTD_extDict = 1, ZSTD_dictMatchState = 2 } ZSTD_dictMode_e;
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typedef size_t (*ZSTD_blockCompressor) (
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ZSTD_matchState_t* bs, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
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ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize);
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ZSTD_blockCompressor ZSTD_selectBlockCompressor(ZSTD_strategy strat, ZSTD_dictMode_e dictMode);
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MEM_STATIC U32 ZSTD_LLcode(U32 litLength)
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{
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static const BYTE LL_Code[64] = { 0, 1, 2, 3, 4, 5, 6, 7,
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8, 9, 10, 11, 12, 13, 14, 15,
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16, 16, 17, 17, 18, 18, 19, 19,
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20, 20, 20, 20, 21, 21, 21, 21,
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22, 22, 22, 22, 22, 22, 22, 22,
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23, 23, 23, 23, 23, 23, 23, 23,
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24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24 };
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static const U32 LL_deltaCode = 19;
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return (litLength > 63) ? ZSTD_highbit32(litLength) + LL_deltaCode : LL_Code[litLength];
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}
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/* ZSTD_MLcode() :
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* note : mlBase = matchLength - MINMATCH;
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* because it's the format it's stored in seqStore->sequences */
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MEM_STATIC U32 ZSTD_MLcode(U32 mlBase)
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{
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static const BYTE ML_Code[128] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
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32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37,
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38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39,
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40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40,
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41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
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42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
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42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42 };
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static const U32 ML_deltaCode = 36;
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return (mlBase > 127) ? ZSTD_highbit32(mlBase) + ML_deltaCode : ML_Code[mlBase];
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}
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/*! ZSTD_storeSeq() :
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* Store a sequence (literal length, literals, offset code and match length code) into seqStore_t.
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* `offsetCode` : distance to match + 3 (values 1-3 are repCodes).
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* `mlBase` : matchLength - MINMATCH
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*/
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MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const void* literals, U32 offsetCode, size_t mlBase)
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{
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#if defined(ZSTD_DEBUG) && (ZSTD_DEBUG >= 6)
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static const BYTE* g_start = NULL;
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if (g_start==NULL) g_start = (const BYTE*)literals; /* note : index only works for compression within a single segment */
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{ U32 const pos = (U32)((const BYTE*)literals - g_start);
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DEBUGLOG(6, "Cpos%7u :%3u literals, match%3u bytes at dist.code%7u",
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pos, (U32)litLength, (U32)mlBase+MINMATCH, (U32)offsetCode);
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}
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#endif
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/* copy Literals */
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assert(seqStorePtr->lit + litLength <= seqStorePtr->litStart + 128 KB);
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ZSTD_wildcopy(seqStorePtr->lit, literals, litLength);
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seqStorePtr->lit += litLength;
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/* literal Length */
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if (litLength>0xFFFF) {
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assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */
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seqStorePtr->longLengthID = 1;
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seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
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}
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seqStorePtr->sequences[0].litLength = (U16)litLength;
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/* match offset */
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seqStorePtr->sequences[0].offset = offsetCode + 1;
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/* match Length */
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if (mlBase>0xFFFF) {
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assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */
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seqStorePtr->longLengthID = 2;
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seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
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}
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seqStorePtr->sequences[0].matchLength = (U16)mlBase;
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seqStorePtr->sequences++;
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}
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/*-*************************************
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* Match length counter
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***************************************/
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static unsigned ZSTD_NbCommonBytes (size_t val)
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{
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if (MEM_isLittleEndian()) {
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if (MEM_64bits()) {
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# if defined(_MSC_VER) && defined(_WIN64)
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unsigned long r = 0;
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_BitScanForward64( &r, (U64)val );
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return (unsigned)(r>>3);
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# elif defined(__GNUC__) && (__GNUC__ >= 4)
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return (__builtin_ctzll((U64)val) >> 3);
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# else
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static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2,
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0, 3, 1, 3, 1, 4, 2, 7,
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0, 2, 3, 6, 1, 5, 3, 5,
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1, 3, 4, 4, 2, 5, 6, 7,
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7, 0, 1, 2, 3, 3, 4, 6,
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2, 6, 5, 5, 3, 4, 5, 6,
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7, 1, 2, 4, 6, 4, 4, 5,
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7, 2, 6, 5, 7, 6, 7, 7 };
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return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
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# endif
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} else { /* 32 bits */
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# if defined(_MSC_VER)
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unsigned long r=0;
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_BitScanForward( &r, (U32)val );
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return (unsigned)(r>>3);
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# elif defined(__GNUC__) && (__GNUC__ >= 3)
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return (__builtin_ctz((U32)val) >> 3);
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# else
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static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0,
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3, 2, 2, 1, 3, 2, 0, 1,
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3, 3, 1, 2, 2, 2, 2, 0,
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3, 1, 2, 0, 1, 0, 1, 1 };
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return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
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# endif
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}
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} else { /* Big Endian CPU */
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if (MEM_64bits()) {
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# if defined(_MSC_VER) && defined(_WIN64)
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unsigned long r = 0;
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_BitScanReverse64( &r, val );
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return (unsigned)(r>>3);
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# elif defined(__GNUC__) && (__GNUC__ >= 4)
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return (__builtin_clzll(val) >> 3);
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# else
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unsigned r;
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const unsigned n32 = sizeof(size_t)*4; /* calculate this way due to compiler complaining in 32-bits mode */
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if (!(val>>n32)) { r=4; } else { r=0; val>>=n32; }
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if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
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r += (!val);
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return r;
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# endif
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} else { /* 32 bits */
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# if defined(_MSC_VER)
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unsigned long r = 0;
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_BitScanReverse( &r, (unsigned long)val );
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return (unsigned)(r>>3);
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# elif defined(__GNUC__) && (__GNUC__ >= 3)
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return (__builtin_clz((U32)val) >> 3);
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# else
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unsigned r;
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if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
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r += (!val);
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return r;
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# endif
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} }
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}
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MEM_STATIC size_t ZSTD_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* const pInLimit)
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{
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const BYTE* const pStart = pIn;
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const BYTE* const pInLoopLimit = pInLimit - (sizeof(size_t)-1);
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if (pIn < pInLoopLimit) {
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{ size_t const diff = MEM_readST(pMatch) ^ MEM_readST(pIn);
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if (diff) return ZSTD_NbCommonBytes(diff); }
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pIn+=sizeof(size_t); pMatch+=sizeof(size_t);
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while (pIn < pInLoopLimit) {
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size_t const diff = MEM_readST(pMatch) ^ MEM_readST(pIn);
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if (!diff) { pIn+=sizeof(size_t); pMatch+=sizeof(size_t); continue; }
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pIn += ZSTD_NbCommonBytes(diff);
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return (size_t)(pIn - pStart);
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} }
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if (MEM_64bits() && (pIn<(pInLimit-3)) && (MEM_read32(pMatch) == MEM_read32(pIn))) { pIn+=4; pMatch+=4; }
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if ((pIn<(pInLimit-1)) && (MEM_read16(pMatch) == MEM_read16(pIn))) { pIn+=2; pMatch+=2; }
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if ((pIn<pInLimit) && (*pMatch == *pIn)) pIn++;
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return (size_t)(pIn - pStart);
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}
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/** ZSTD_count_2segments() :
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* can count match length with `ip` & `match` in 2 different segments.
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* convention : on reaching mEnd, match count continue starting from iStart
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*/
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MEM_STATIC size_t
|
|
ZSTD_count_2segments(const BYTE* ip, const BYTE* match,
|
|
const BYTE* iEnd, const BYTE* mEnd, const BYTE* iStart)
|
|
{
|
|
const BYTE* const vEnd = MIN( ip + (mEnd - match), iEnd);
|
|
size_t const matchLength = ZSTD_count(ip, match, vEnd);
|
|
if (match + matchLength != mEnd) return matchLength;
|
|
return matchLength + ZSTD_count(ip+matchLength, iStart, iEnd);
|
|
}
|
|
|
|
|
|
/*-*************************************
|
|
* Hashes
|
|
***************************************/
|
|
static const U32 prime3bytes = 506832829U;
|
|
static U32 ZSTD_hash3(U32 u, U32 h) { return ((u << (32-24)) * prime3bytes) >> (32-h) ; }
|
|
MEM_STATIC size_t ZSTD_hash3Ptr(const void* ptr, U32 h) { return ZSTD_hash3(MEM_readLE32(ptr), h); } /* only in zstd_opt.h */
|
|
|
|
static const U32 prime4bytes = 2654435761U;
|
|
static U32 ZSTD_hash4(U32 u, U32 h) { return (u * prime4bytes) >> (32-h) ; }
|
|
static size_t ZSTD_hash4Ptr(const void* ptr, U32 h) { return ZSTD_hash4(MEM_read32(ptr), h); }
|
|
|
|
static const U64 prime5bytes = 889523592379ULL;
|
|
static size_t ZSTD_hash5(U64 u, U32 h) { return (size_t)(((u << (64-40)) * prime5bytes) >> (64-h)) ; }
|
|
static size_t ZSTD_hash5Ptr(const void* p, U32 h) { return ZSTD_hash5(MEM_readLE64(p), h); }
|
|
|
|
static const U64 prime6bytes = 227718039650203ULL;
|
|
static size_t ZSTD_hash6(U64 u, U32 h) { return (size_t)(((u << (64-48)) * prime6bytes) >> (64-h)) ; }
|
|
static size_t ZSTD_hash6Ptr(const void* p, U32 h) { return ZSTD_hash6(MEM_readLE64(p), h); }
|
|
|
|
static const U64 prime7bytes = 58295818150454627ULL;
|
|
static size_t ZSTD_hash7(U64 u, U32 h) { return (size_t)(((u << (64-56)) * prime7bytes) >> (64-h)) ; }
|
|
static size_t ZSTD_hash7Ptr(const void* p, U32 h) { return ZSTD_hash7(MEM_readLE64(p), h); }
|
|
|
|
static const U64 prime8bytes = 0xCF1BBCDCB7A56463ULL;
|
|
static size_t ZSTD_hash8(U64 u, U32 h) { return (size_t)(((u) * prime8bytes) >> (64-h)) ; }
|
|
static size_t ZSTD_hash8Ptr(const void* p, U32 h) { return ZSTD_hash8(MEM_readLE64(p), h); }
|
|
|
|
MEM_STATIC size_t ZSTD_hashPtr(const void* p, U32 hBits, U32 mls)
|
|
{
|
|
switch(mls)
|
|
{
|
|
default:
|
|
case 4: return ZSTD_hash4Ptr(p, hBits);
|
|
case 5: return ZSTD_hash5Ptr(p, hBits);
|
|
case 6: return ZSTD_hash6Ptr(p, hBits);
|
|
case 7: return ZSTD_hash7Ptr(p, hBits);
|
|
case 8: return ZSTD_hash8Ptr(p, hBits);
|
|
}
|
|
}
|
|
|
|
/*-*************************************
|
|
* Round buffer management
|
|
***************************************/
|
|
/* Max current allowed */
|
|
#define ZSTD_CURRENT_MAX ((3U << 29) + (1U << ZSTD_WINDOWLOG_MAX))
|
|
/* Maximum chunk size before overflow correction needs to be called again */
|
|
#define ZSTD_CHUNKSIZE_MAX \
|
|
( ((U32)-1) /* Maximum ending current index */ \
|
|
- ZSTD_CURRENT_MAX) /* Maximum beginning lowLimit */
|
|
|
|
/**
|
|
* ZSTD_window_clear():
|
|
* Clears the window containing the history by simply setting it to empty.
|
|
*/
|
|
MEM_STATIC void ZSTD_window_clear(ZSTD_window_t* window)
|
|
{
|
|
size_t const endT = (size_t)(window->nextSrc - window->base);
|
|
U32 const end = (U32)endT;
|
|
|
|
window->lowLimit = end;
|
|
window->dictLimit = end;
|
|
}
|
|
|
|
/**
|
|
* ZSTD_window_hasExtDict():
|
|
* Returns non-zero if the window has a non-empty extDict.
|
|
*/
|
|
MEM_STATIC U32 ZSTD_window_hasExtDict(ZSTD_window_t const window)
|
|
{
|
|
return window.lowLimit < window.dictLimit;
|
|
}
|
|
|
|
/**
|
|
* ZSTD_matchState_dictMode():
|
|
* Inspects the provided matchState and figures out what dictMode should be
|
|
* passed to the compressor.
|
|
*/
|
|
MEM_STATIC ZSTD_dictMode_e ZSTD_matchState_dictMode(const ZSTD_matchState_t *ms)
|
|
{
|
|
return ZSTD_window_hasExtDict(ms->window) ?
|
|
ZSTD_extDict :
|
|
ms->dictMatchState != NULL ?
|
|
ZSTD_dictMatchState :
|
|
ZSTD_noDict;
|
|
}
|
|
|
|
/**
|
|
* ZSTD_window_needOverflowCorrection():
|
|
* Returns non-zero if the indices are getting too large and need overflow
|
|
* protection.
|
|
*/
|
|
MEM_STATIC U32 ZSTD_window_needOverflowCorrection(ZSTD_window_t const window,
|
|
void const* srcEnd)
|
|
{
|
|
U32 const current = (U32)((BYTE const*)srcEnd - window.base);
|
|
return current > ZSTD_CURRENT_MAX;
|
|
}
|
|
|
|
/**
|
|
* ZSTD_window_correctOverflow():
|
|
* Reduces the indices to protect from index overflow.
|
|
* Returns the correction made to the indices, which must be applied to every
|
|
* stored index.
|
|
*
|
|
* The least significant cycleLog bits of the indices must remain the same,
|
|
* which may be 0. Every index up to maxDist in the past must be valid.
|
|
* NOTE: (maxDist & cycleMask) must be zero.
|
|
*/
|
|
MEM_STATIC U32 ZSTD_window_correctOverflow(ZSTD_window_t* window, U32 cycleLog,
|
|
U32 maxDist, void const* src)
|
|
{
|
|
/* preemptive overflow correction:
|
|
* 1. correction is large enough:
|
|
* lowLimit > (3<<29) ==> current > 3<<29 + 1<<windowLog
|
|
* 1<<windowLog <= newCurrent < 1<<chainLog + 1<<windowLog
|
|
*
|
|
* current - newCurrent
|
|
* > (3<<29 + 1<<windowLog) - (1<<windowLog + 1<<chainLog)
|
|
* > (3<<29) - (1<<chainLog)
|
|
* > (3<<29) - (1<<30) (NOTE: chainLog <= 30)
|
|
* > 1<<29
|
|
*
|
|
* 2. (ip+ZSTD_CHUNKSIZE_MAX - cctx->base) doesn't overflow:
|
|
* After correction, current is less than (1<<chainLog + 1<<windowLog).
|
|
* In 64-bit mode we are safe, because we have 64-bit ptrdiff_t.
|
|
* In 32-bit mode we are safe, because (chainLog <= 29), so
|
|
* ip+ZSTD_CHUNKSIZE_MAX - cctx->base < 1<<32.
|
|
* 3. (cctx->lowLimit + 1<<windowLog) < 1<<32:
|
|
* windowLog <= 31 ==> 3<<29 + 1<<windowLog < 7<<29 < 1<<32.
|
|
*/
|
|
U32 const cycleMask = (1U << cycleLog) - 1;
|
|
U32 const current = (U32)((BYTE const*)src - window->base);
|
|
U32 const newCurrent = (current & cycleMask) + maxDist;
|
|
U32 const correction = current - newCurrent;
|
|
assert((maxDist & cycleMask) == 0);
|
|
assert(current > newCurrent);
|
|
/* Loose bound, should be around 1<<29 (see above) */
|
|
assert(correction > 1<<28);
|
|
|
|
window->base += correction;
|
|
window->dictBase += correction;
|
|
window->lowLimit -= correction;
|
|
window->dictLimit -= correction;
|
|
|
|
DEBUGLOG(4, "Correction of 0x%x bytes to lowLimit=0x%x", correction,
|
|
window->lowLimit);
|
|
return correction;
|
|
}
|
|
|
|
/**
|
|
* ZSTD_window_enforceMaxDist():
|
|
* Updates lowLimit so that:
|
|
* (srcEnd - base) - lowLimit == maxDist + loadedDictEnd
|
|
* This allows a simple check that index >= lowLimit to see if index is valid.
|
|
* This must be called before a block compression call, with srcEnd as the block
|
|
* source end.
|
|
* If loadedDictEndPtr is not NULL, we set it to zero once we update lowLimit.
|
|
* This is because dictionaries are allowed to be referenced as long as the last
|
|
* byte of the dictionary is in the window, but once they are out of range,
|
|
* they cannot be referenced. If loadedDictEndPtr is NULL, we use
|
|
* loadedDictEnd == 0.
|
|
*/
|
|
MEM_STATIC void ZSTD_window_enforceMaxDist(ZSTD_window_t* window,
|
|
void const* srcEnd, U32 maxDist,
|
|
U32* loadedDictEndPtr,
|
|
const ZSTD_matchState_t** dictMatchStatePtr)
|
|
{
|
|
U32 const current = (U32)((BYTE const*)srcEnd - window->base);
|
|
U32 loadedDictEnd = loadedDictEndPtr != NULL ? *loadedDictEndPtr : 0;
|
|
if (current > maxDist + loadedDictEnd) {
|
|
U32 const newLowLimit = current - maxDist;
|
|
if (window->lowLimit < newLowLimit) window->lowLimit = newLowLimit;
|
|
if (window->dictLimit < window->lowLimit) {
|
|
DEBUGLOG(5, "Update dictLimit from %u to %u", window->dictLimit,
|
|
window->lowLimit);
|
|
window->dictLimit = window->lowLimit;
|
|
}
|
|
if (loadedDictEndPtr)
|
|
*loadedDictEndPtr = 0;
|
|
if (dictMatchStatePtr)
|
|
*dictMatchStatePtr = NULL;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* ZSTD_window_update():
|
|
* Updates the window by appending [src, src + srcSize) to the window.
|
|
* If it is not contiguous, the current prefix becomes the extDict, and we
|
|
* forget about the extDict. Handles overlap of the prefix and extDict.
|
|
* Returns non-zero if the segment is contiguous.
|
|
*/
|
|
MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window,
|
|
void const* src, size_t srcSize)
|
|
{
|
|
BYTE const* const ip = (BYTE const*)src;
|
|
U32 contiguous = 1;
|
|
/* Check if blocks follow each other */
|
|
if (src != window->nextSrc) {
|
|
/* not contiguous */
|
|
size_t const distanceFromBase = (size_t)(window->nextSrc - window->base);
|
|
DEBUGLOG(5, "Non contiguous blocks, new segment starts at %u",
|
|
window->dictLimit);
|
|
window->lowLimit = window->dictLimit;
|
|
assert(distanceFromBase == (size_t)(U32)distanceFromBase); /* should never overflow */
|
|
window->dictLimit = (U32)distanceFromBase;
|
|
window->dictBase = window->base;
|
|
window->base = ip - distanceFromBase;
|
|
// ms->nextToUpdate = window->dictLimit;
|
|
if (window->dictLimit - window->lowLimit < HASH_READ_SIZE) window->lowLimit = window->dictLimit; /* too small extDict */
|
|
contiguous = 0;
|
|
}
|
|
window->nextSrc = ip + srcSize;
|
|
/* if input and dictionary overlap : reduce dictionary (area presumed modified by input) */
|
|
if ( (ip+srcSize > window->dictBase + window->lowLimit)
|
|
& (ip < window->dictBase + window->dictLimit)) {
|
|
ptrdiff_t const highInputIdx = (ip + srcSize) - window->dictBase;
|
|
U32 const lowLimitMax = (highInputIdx > (ptrdiff_t)window->dictLimit) ? window->dictLimit : (U32)highInputIdx;
|
|
window->lowLimit = lowLimitMax;
|
|
}
|
|
return contiguous;
|
|
}
|
|
|
|
#if defined (__cplusplus)
|
|
}
|
|
#endif
|
|
|
|
|
|
/* ==============================================================
|
|
* Private declarations
|
|
* These prototypes shall only be called from within lib/compress
|
|
* ============================================================== */
|
|
|
|
/* ZSTD_getCParamsFromCCtxParams() :
|
|
* cParams are built depending on compressionLevel, src size hints,
|
|
* LDM and manually set compression parameters.
|
|
*/
|
|
ZSTD_compressionParameters ZSTD_getCParamsFromCCtxParams(
|
|
const ZSTD_CCtx_params* CCtxParams, U64 srcSizeHint, size_t dictSize);
|
|
|
|
/*! ZSTD_initCStream_internal() :
|
|
* Private use only. Init streaming operation.
|
|
* expects params to be valid.
|
|
* must receive dict, or cdict, or none, but not both.
|
|
* @return : 0, or an error code */
|
|
size_t ZSTD_initCStream_internal(ZSTD_CStream* zcs,
|
|
const void* dict, size_t dictSize,
|
|
const ZSTD_CDict* cdict,
|
|
ZSTD_CCtx_params params, unsigned long long pledgedSrcSize);
|
|
|
|
/*! ZSTD_compressStream_generic() :
|
|
* Private use only. To be called from zstdmt_compress.c in single-thread mode. */
|
|
size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
|
|
ZSTD_outBuffer* output,
|
|
ZSTD_inBuffer* input,
|
|
ZSTD_EndDirective const flushMode);
|
|
|
|
/*! ZSTD_getCParamsFromCDict() :
|
|
* as the name implies */
|
|
ZSTD_compressionParameters ZSTD_getCParamsFromCDict(const ZSTD_CDict* cdict);
|
|
|
|
/* ZSTD_compressBegin_advanced_internal() :
|
|
* Private use only. To be called from zstdmt_compress.c. */
|
|
size_t ZSTD_compressBegin_advanced_internal(ZSTD_CCtx* cctx,
|
|
const void* dict, size_t dictSize,
|
|
ZSTD_dictContentType_e dictContentType,
|
|
ZSTD_dictTableLoadMethod_e dtlm,
|
|
const ZSTD_CDict* cdict,
|
|
ZSTD_CCtx_params params,
|
|
unsigned long long pledgedSrcSize);
|
|
|
|
/* ZSTD_compress_advanced_internal() :
|
|
* Private use only. To be called from zstdmt_compress.c. */
|
|
size_t ZSTD_compress_advanced_internal(ZSTD_CCtx* cctx,
|
|
void* dst, size_t dstCapacity,
|
|
const void* src, size_t srcSize,
|
|
const void* dict,size_t dictSize,
|
|
ZSTD_CCtx_params params);
|
|
|
|
|
|
/* ZSTD_writeLastEmptyBlock() :
|
|
* output an empty Block with end-of-frame mark to complete a frame
|
|
* @return : size of data written into `dst` (== ZSTD_blockHeaderSize (defined in zstd_internal.h))
|
|
* or an error code if `dstCapcity` is too small (<ZSTD_blockHeaderSize)
|
|
*/
|
|
size_t ZSTD_writeLastEmptyBlock(void* dst, size_t dstCapacity);
|
|
|
|
|
|
/* ZSTD_referenceExternalSequences() :
|
|
* Must be called before starting a compression operation.
|
|
* seqs must parse a prefix of the source.
|
|
* This cannot be used when long range matching is enabled.
|
|
* Zstd will use these sequences, and pass the literals to a secondary block
|
|
* compressor.
|
|
* @return : An error code on failure.
|
|
* NOTE: seqs are not verified! Invalid sequences can cause out-of-bounds memory
|
|
* access and data corruption.
|
|
*/
|
|
size_t ZSTD_referenceExternalSequences(ZSTD_CCtx* cctx, rawSeq* seq, size_t nbSeq);
|
|
|
|
|
|
#endif /* ZSTD_COMPRESS_H */
|