d085385e60
Release notes: https://github.com/facebook/zstd/releases/tag/v1.5.0
(cherry picked from commit 5bea1370f0)
1345 lines
61 KiB
C
1345 lines
61 KiB
C
/*
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* Copyright (c) Przemyslaw Skibinski, 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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#include "zstd_compress_internal.h"
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#include "hist.h"
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#include "zstd_opt.h"
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#define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats */
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#define ZSTD_FREQ_DIV 4 /* log factor when using previous stats to init next stats */
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#define ZSTD_MAX_PRICE (1<<30)
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#define ZSTD_PREDEF_THRESHOLD 1024 /* if srcSize < ZSTD_PREDEF_THRESHOLD, symbols' cost is assumed static, directly determined by pre-defined distributions */
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/*-*************************************
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* Price functions for optimal parser
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***************************************/
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#if 0 /* approximation at bit level */
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# define BITCOST_ACCURACY 0
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# define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY)
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# define WEIGHT(stat) ((void)opt, ZSTD_bitWeight(stat))
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#elif 0 /* fractional bit accuracy */
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# define BITCOST_ACCURACY 8
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# define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY)
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# define WEIGHT(stat,opt) ((void)opt, ZSTD_fracWeight(stat))
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#else /* opt==approx, ultra==accurate */
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# define BITCOST_ACCURACY 8
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# define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY)
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# define WEIGHT(stat,opt) (opt ? ZSTD_fracWeight(stat) : ZSTD_bitWeight(stat))
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#endif
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MEM_STATIC U32 ZSTD_bitWeight(U32 stat)
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{
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return (ZSTD_highbit32(stat+1) * BITCOST_MULTIPLIER);
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}
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MEM_STATIC U32 ZSTD_fracWeight(U32 rawStat)
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{
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U32 const stat = rawStat + 1;
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U32 const hb = ZSTD_highbit32(stat);
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U32 const BWeight = hb * BITCOST_MULTIPLIER;
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U32 const FWeight = (stat << BITCOST_ACCURACY) >> hb;
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U32 const weight = BWeight + FWeight;
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assert(hb + BITCOST_ACCURACY < 31);
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return weight;
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}
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#if (DEBUGLEVEL>=2)
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/* debugging function,
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* @return price in bytes as fractional value
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* for debug messages only */
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MEM_STATIC double ZSTD_fCost(U32 price)
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{
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return (double)price / (BITCOST_MULTIPLIER*8);
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}
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#endif
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static int ZSTD_compressedLiterals(optState_t const* const optPtr)
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{
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return optPtr->literalCompressionMode != ZSTD_lcm_uncompressed;
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}
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static void ZSTD_setBasePrices(optState_t* optPtr, int optLevel)
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{
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if (ZSTD_compressedLiterals(optPtr))
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optPtr->litSumBasePrice = WEIGHT(optPtr->litSum, optLevel);
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optPtr->litLengthSumBasePrice = WEIGHT(optPtr->litLengthSum, optLevel);
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optPtr->matchLengthSumBasePrice = WEIGHT(optPtr->matchLengthSum, optLevel);
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optPtr->offCodeSumBasePrice = WEIGHT(optPtr->offCodeSum, optLevel);
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}
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/* ZSTD_downscaleStat() :
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* reduce all elements in table by a factor 2^(ZSTD_FREQ_DIV+malus)
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* return the resulting sum of elements */
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static U32 ZSTD_downscaleStat(unsigned* table, U32 lastEltIndex, int malus)
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{
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U32 s, sum=0;
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DEBUGLOG(5, "ZSTD_downscaleStat (nbElts=%u)", (unsigned)lastEltIndex+1);
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assert(ZSTD_FREQ_DIV+malus > 0 && ZSTD_FREQ_DIV+malus < 31);
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for (s=0; s<lastEltIndex+1; s++) {
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table[s] = 1 + (table[s] >> (ZSTD_FREQ_DIV+malus));
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sum += table[s];
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}
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return sum;
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}
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/* ZSTD_rescaleFreqs() :
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* if first block (detected by optPtr->litLengthSum == 0) : init statistics
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* take hints from dictionary if there is one
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* or init from zero, using src for literals stats, or flat 1 for match symbols
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* otherwise downscale existing stats, to be used as seed for next block.
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*/
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static void
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ZSTD_rescaleFreqs(optState_t* const optPtr,
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const BYTE* const src, size_t const srcSize,
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int const optLevel)
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{
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int const compressedLiterals = ZSTD_compressedLiterals(optPtr);
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DEBUGLOG(5, "ZSTD_rescaleFreqs (srcSize=%u)", (unsigned)srcSize);
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optPtr->priceType = zop_dynamic;
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if (optPtr->litLengthSum == 0) { /* first block : init */
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if (srcSize <= ZSTD_PREDEF_THRESHOLD) { /* heuristic */
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DEBUGLOG(5, "(srcSize <= ZSTD_PREDEF_THRESHOLD) => zop_predef");
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optPtr->priceType = zop_predef;
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}
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assert(optPtr->symbolCosts != NULL);
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if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) {
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/* huffman table presumed generated by dictionary */
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optPtr->priceType = zop_dynamic;
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if (compressedLiterals) {
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unsigned lit;
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assert(optPtr->litFreq != NULL);
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optPtr->litSum = 0;
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for (lit=0; lit<=MaxLit; lit++) {
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U32 const scaleLog = 11; /* scale to 2K */
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U32 const bitCost = HUF_getNbBits(optPtr->symbolCosts->huf.CTable, lit);
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assert(bitCost <= scaleLog);
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optPtr->litFreq[lit] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/;
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optPtr->litSum += optPtr->litFreq[lit];
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} }
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{ unsigned ll;
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FSE_CState_t llstate;
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FSE_initCState(&llstate, optPtr->symbolCosts->fse.litlengthCTable);
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optPtr->litLengthSum = 0;
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for (ll=0; ll<=MaxLL; ll++) {
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U32 const scaleLog = 10; /* scale to 1K */
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U32 const bitCost = FSE_getMaxNbBits(llstate.symbolTT, ll);
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assert(bitCost < scaleLog);
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optPtr->litLengthFreq[ll] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/;
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optPtr->litLengthSum += optPtr->litLengthFreq[ll];
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} }
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{ unsigned ml;
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FSE_CState_t mlstate;
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FSE_initCState(&mlstate, optPtr->symbolCosts->fse.matchlengthCTable);
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optPtr->matchLengthSum = 0;
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for (ml=0; ml<=MaxML; ml++) {
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U32 const scaleLog = 10;
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U32 const bitCost = FSE_getMaxNbBits(mlstate.symbolTT, ml);
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assert(bitCost < scaleLog);
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optPtr->matchLengthFreq[ml] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/;
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optPtr->matchLengthSum += optPtr->matchLengthFreq[ml];
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} }
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{ unsigned of;
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FSE_CState_t ofstate;
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FSE_initCState(&ofstate, optPtr->symbolCosts->fse.offcodeCTable);
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optPtr->offCodeSum = 0;
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for (of=0; of<=MaxOff; of++) {
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U32 const scaleLog = 10;
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U32 const bitCost = FSE_getMaxNbBits(ofstate.symbolTT, of);
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assert(bitCost < scaleLog);
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optPtr->offCodeFreq[of] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/;
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optPtr->offCodeSum += optPtr->offCodeFreq[of];
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} }
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} else { /* not a dictionary */
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assert(optPtr->litFreq != NULL);
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if (compressedLiterals) {
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unsigned lit = MaxLit;
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HIST_count_simple(optPtr->litFreq, &lit, src, srcSize); /* use raw first block to init statistics */
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optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1);
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}
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{ unsigned ll;
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for (ll=0; ll<=MaxLL; ll++)
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optPtr->litLengthFreq[ll] = 1;
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}
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optPtr->litLengthSum = MaxLL+1;
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{ unsigned ml;
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for (ml=0; ml<=MaxML; ml++)
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optPtr->matchLengthFreq[ml] = 1;
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}
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optPtr->matchLengthSum = MaxML+1;
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{ unsigned of;
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for (of=0; of<=MaxOff; of++)
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optPtr->offCodeFreq[of] = 1;
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}
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optPtr->offCodeSum = MaxOff+1;
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}
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} else { /* new block : re-use previous statistics, scaled down */
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if (compressedLiterals)
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optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1);
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optPtr->litLengthSum = ZSTD_downscaleStat(optPtr->litLengthFreq, MaxLL, 0);
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optPtr->matchLengthSum = ZSTD_downscaleStat(optPtr->matchLengthFreq, MaxML, 0);
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optPtr->offCodeSum = ZSTD_downscaleStat(optPtr->offCodeFreq, MaxOff, 0);
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}
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ZSTD_setBasePrices(optPtr, optLevel);
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}
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/* ZSTD_rawLiteralsCost() :
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* price of literals (only) in specified segment (which length can be 0).
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* does not include price of literalLength symbol */
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static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength,
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const optState_t* const optPtr,
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int optLevel)
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{
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if (litLength == 0) return 0;
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if (!ZSTD_compressedLiterals(optPtr))
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return (litLength << 3) * BITCOST_MULTIPLIER; /* Uncompressed - 8 bytes per literal. */
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if (optPtr->priceType == zop_predef)
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return (litLength*6) * BITCOST_MULTIPLIER; /* 6 bit per literal - no statistic used */
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/* dynamic statistics */
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{ U32 price = litLength * optPtr->litSumBasePrice;
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U32 u;
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for (u=0; u < litLength; u++) {
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assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice); /* literal cost should never be negative */
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price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel);
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}
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return price;
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}
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}
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/* ZSTD_litLengthPrice() :
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* cost of literalLength symbol */
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static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr, int optLevel)
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{
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if (optPtr->priceType == zop_predef) return WEIGHT(litLength, optLevel);
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/* dynamic statistics */
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{ U32 const llCode = ZSTD_LLcode(litLength);
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return (LL_bits[llCode] * BITCOST_MULTIPLIER)
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+ optPtr->litLengthSumBasePrice
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- WEIGHT(optPtr->litLengthFreq[llCode], optLevel);
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}
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}
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/* ZSTD_getMatchPrice() :
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* Provides the cost of the match part (offset + matchLength) of a sequence
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* Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence.
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* optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */
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FORCE_INLINE_TEMPLATE U32
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ZSTD_getMatchPrice(U32 const offset,
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U32 const matchLength,
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const optState_t* const optPtr,
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int const optLevel)
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{
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U32 price;
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U32 const offCode = ZSTD_highbit32(offset+1);
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U32 const mlBase = matchLength - MINMATCH;
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assert(matchLength >= MINMATCH);
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if (optPtr->priceType == zop_predef) /* fixed scheme, do not use statistics */
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return WEIGHT(mlBase, optLevel) + ((16 + offCode) * BITCOST_MULTIPLIER);
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/* dynamic statistics */
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price = (offCode * BITCOST_MULTIPLIER) + (optPtr->offCodeSumBasePrice - WEIGHT(optPtr->offCodeFreq[offCode], optLevel));
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if ((optLevel<2) /*static*/ && offCode >= 20)
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price += (offCode-19)*2 * BITCOST_MULTIPLIER; /* handicap for long distance offsets, favor decompression speed */
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/* match Length */
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{ U32 const mlCode = ZSTD_MLcode(mlBase);
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price += (ML_bits[mlCode] * BITCOST_MULTIPLIER) + (optPtr->matchLengthSumBasePrice - WEIGHT(optPtr->matchLengthFreq[mlCode], optLevel));
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}
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price += BITCOST_MULTIPLIER / 5; /* heuristic : make matches a bit more costly to favor less sequences -> faster decompression speed */
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DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price);
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return price;
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}
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/* ZSTD_updateStats() :
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* assumption : literals + litLengtn <= iend */
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static void ZSTD_updateStats(optState_t* const optPtr,
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U32 litLength, const BYTE* literals,
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U32 offsetCode, U32 matchLength)
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{
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/* literals */
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if (ZSTD_compressedLiterals(optPtr)) {
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U32 u;
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for (u=0; u < litLength; u++)
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optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD;
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optPtr->litSum += litLength*ZSTD_LITFREQ_ADD;
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}
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/* literal Length */
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{ U32 const llCode = ZSTD_LLcode(litLength);
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optPtr->litLengthFreq[llCode]++;
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optPtr->litLengthSum++;
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}
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/* match offset code (0-2=>repCode; 3+=>offset+2) */
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{ U32 const offCode = ZSTD_highbit32(offsetCode+1);
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assert(offCode <= MaxOff);
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optPtr->offCodeFreq[offCode]++;
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optPtr->offCodeSum++;
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}
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/* match Length */
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{ U32 const mlBase = matchLength - MINMATCH;
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U32 const mlCode = ZSTD_MLcode(mlBase);
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optPtr->matchLengthFreq[mlCode]++;
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optPtr->matchLengthSum++;
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}
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}
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/* ZSTD_readMINMATCH() :
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* function safe only for comparisons
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* assumption : memPtr must be at least 4 bytes before end of buffer */
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MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length)
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{
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switch (length)
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{
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default :
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case 4 : return MEM_read32(memPtr);
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case 3 : if (MEM_isLittleEndian())
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return MEM_read32(memPtr)<<8;
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else
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return MEM_read32(memPtr)>>8;
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}
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}
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/* Update hashTable3 up to ip (excluded)
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Assumption : always within prefix (i.e. not within extDict) */
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static U32 ZSTD_insertAndFindFirstIndexHash3 (ZSTD_matchState_t* ms,
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U32* nextToUpdate3,
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const BYTE* const ip)
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{
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U32* const hashTable3 = ms->hashTable3;
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U32 const hashLog3 = ms->hashLog3;
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const BYTE* const base = ms->window.base;
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U32 idx = *nextToUpdate3;
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U32 const target = (U32)(ip - base);
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size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3);
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assert(hashLog3 > 0);
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while(idx < target) {
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hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx;
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idx++;
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}
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*nextToUpdate3 = target;
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return hashTable3[hash3];
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}
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/*-*************************************
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* Binary Tree search
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***************************************/
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/** ZSTD_insertBt1() : add one or multiple positions to tree.
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* ip : assumed <= iend-8 .
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* @return : nb of positions added */
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static U32 ZSTD_insertBt1(
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ZSTD_matchState_t* ms,
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const BYTE* const ip, const BYTE* const iend,
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U32 const mls, const int extDict)
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{
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const ZSTD_compressionParameters* const cParams = &ms->cParams;
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U32* const hashTable = ms->hashTable;
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U32 const hashLog = cParams->hashLog;
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size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
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U32* const bt = ms->chainTable;
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U32 const btLog = cParams->chainLog - 1;
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U32 const btMask = (1 << btLog) - 1;
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U32 matchIndex = hashTable[h];
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size_t commonLengthSmaller=0, commonLengthLarger=0;
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const BYTE* const base = ms->window.base;
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const BYTE* const dictBase = ms->window.dictBase;
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const U32 dictLimit = ms->window.dictLimit;
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const BYTE* const dictEnd = dictBase + dictLimit;
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const BYTE* const prefixStart = base + dictLimit;
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const BYTE* match;
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const U32 curr = (U32)(ip-base);
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const U32 btLow = btMask >= curr ? 0 : curr - btMask;
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U32* smallerPtr = bt + 2*(curr&btMask);
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U32* largerPtr = smallerPtr + 1;
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U32 dummy32; /* to be nullified at the end */
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U32 const windowLow = ms->window.lowLimit;
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U32 matchEndIdx = curr+8+1;
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size_t bestLength = 8;
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U32 nbCompares = 1U << cParams->searchLog;
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#ifdef ZSTD_C_PREDICT
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U32 predictedSmall = *(bt + 2*((curr-1)&btMask) + 0);
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U32 predictedLarge = *(bt + 2*((curr-1)&btMask) + 1);
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predictedSmall += (predictedSmall>0);
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predictedLarge += (predictedLarge>0);
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#endif /* ZSTD_C_PREDICT */
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DEBUGLOG(8, "ZSTD_insertBt1 (%u)", curr);
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assert(ip <= iend-8); /* required for h calculation */
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hashTable[h] = curr; /* Update Hash Table */
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assert(windowLow > 0);
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while (nbCompares-- && (matchIndex >= windowLow)) {
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U32* const nextPtr = bt + 2*(matchIndex & btMask);
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size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
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assert(matchIndex < curr);
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#ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */
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const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */
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if (matchIndex == predictedSmall) {
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/* no need to check length, result known */
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*smallerPtr = matchIndex;
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if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
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smallerPtr = nextPtr+1; /* new "smaller" => larger of match */
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matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
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predictedSmall = predictPtr[1] + (predictPtr[1]>0);
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continue;
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}
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if (matchIndex == predictedLarge) {
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*largerPtr = matchIndex;
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if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */
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largerPtr = nextPtr;
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matchIndex = nextPtr[0];
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predictedLarge = predictPtr[0] + (predictPtr[0]>0);
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continue;
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}
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#endif
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if (!extDict || (matchIndex+matchLength >= dictLimit)) {
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assert(matchIndex+matchLength >= dictLimit); /* might be wrong if actually extDict */
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match = base + matchIndex;
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matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
|
|
} else {
|
|
match = dictBase + matchIndex;
|
|
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
|
|
if (matchIndex+matchLength >= dictLimit)
|
|
match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
|
|
}
|
|
|
|
if (matchLength > bestLength) {
|
|
bestLength = matchLength;
|
|
if (matchLength > matchEndIdx - matchIndex)
|
|
matchEndIdx = matchIndex + (U32)matchLength;
|
|
}
|
|
|
|
if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
|
|
break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */
|
|
}
|
|
|
|
if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */
|
|
/* match is smaller than current */
|
|
*smallerPtr = matchIndex; /* update smaller idx */
|
|
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
|
|
if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */
|
|
smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */
|
|
matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */
|
|
} else {
|
|
/* match is larger than current */
|
|
*largerPtr = matchIndex;
|
|
commonLengthLarger = matchLength;
|
|
if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */
|
|
largerPtr = nextPtr;
|
|
matchIndex = nextPtr[0];
|
|
} }
|
|
|
|
*smallerPtr = *largerPtr = 0;
|
|
{ U32 positions = 0;
|
|
if (bestLength > 384) positions = MIN(192, (U32)(bestLength - 384)); /* speed optimization */
|
|
assert(matchEndIdx > curr + 8);
|
|
return MAX(positions, matchEndIdx - (curr + 8));
|
|
}
|
|
}
|
|
|
|
FORCE_INLINE_TEMPLATE
|
|
void ZSTD_updateTree_internal(
|
|
ZSTD_matchState_t* ms,
|
|
const BYTE* const ip, const BYTE* const iend,
|
|
const U32 mls, const ZSTD_dictMode_e dictMode)
|
|
{
|
|
const BYTE* const base = ms->window.base;
|
|
U32 const target = (U32)(ip - base);
|
|
U32 idx = ms->nextToUpdate;
|
|
DEBUGLOG(6, "ZSTD_updateTree_internal, from %u to %u (dictMode:%u)",
|
|
idx, target, dictMode);
|
|
|
|
while(idx < target) {
|
|
U32 const forward = ZSTD_insertBt1(ms, base+idx, iend, mls, dictMode == ZSTD_extDict);
|
|
assert(idx < (U32)(idx + forward));
|
|
idx += forward;
|
|
}
|
|
assert((size_t)(ip - base) <= (size_t)(U32)(-1));
|
|
assert((size_t)(iend - base) <= (size_t)(U32)(-1));
|
|
ms->nextToUpdate = target;
|
|
}
|
|
|
|
void ZSTD_updateTree(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend) {
|
|
ZSTD_updateTree_internal(ms, ip, iend, ms->cParams.minMatch, ZSTD_noDict);
|
|
}
|
|
|
|
FORCE_INLINE_TEMPLATE
|
|
U32 ZSTD_insertBtAndGetAllMatches (
|
|
ZSTD_match_t* matches, /* store result (found matches) in this table (presumed large enough) */
|
|
ZSTD_matchState_t* ms,
|
|
U32* nextToUpdate3,
|
|
const BYTE* const ip, const BYTE* const iLimit, const ZSTD_dictMode_e dictMode,
|
|
const U32 rep[ZSTD_REP_NUM],
|
|
U32 const ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */
|
|
const U32 lengthToBeat,
|
|
U32 const mls /* template */)
|
|
{
|
|
const ZSTD_compressionParameters* const cParams = &ms->cParams;
|
|
U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1);
|
|
const BYTE* const base = ms->window.base;
|
|
U32 const curr = (U32)(ip-base);
|
|
U32 const hashLog = cParams->hashLog;
|
|
U32 const minMatch = (mls==3) ? 3 : 4;
|
|
U32* const hashTable = ms->hashTable;
|
|
size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
|
|
U32 matchIndex = hashTable[h];
|
|
U32* const bt = ms->chainTable;
|
|
U32 const btLog = cParams->chainLog - 1;
|
|
U32 const btMask= (1U << btLog) - 1;
|
|
size_t commonLengthSmaller=0, commonLengthLarger=0;
|
|
const BYTE* const dictBase = ms->window.dictBase;
|
|
U32 const dictLimit = ms->window.dictLimit;
|
|
const BYTE* const dictEnd = dictBase + dictLimit;
|
|
const BYTE* const prefixStart = base + dictLimit;
|
|
U32 const btLow = (btMask >= curr) ? 0 : curr - btMask;
|
|
U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog);
|
|
U32 const matchLow = windowLow ? windowLow : 1;
|
|
U32* smallerPtr = bt + 2*(curr&btMask);
|
|
U32* largerPtr = bt + 2*(curr&btMask) + 1;
|
|
U32 matchEndIdx = curr+8+1; /* farthest referenced position of any match => detects repetitive patterns */
|
|
U32 dummy32; /* to be nullified at the end */
|
|
U32 mnum = 0;
|
|
U32 nbCompares = 1U << cParams->searchLog;
|
|
|
|
const ZSTD_matchState_t* dms = dictMode == ZSTD_dictMatchState ? ms->dictMatchState : NULL;
|
|
const ZSTD_compressionParameters* const dmsCParams =
|
|
dictMode == ZSTD_dictMatchState ? &dms->cParams : NULL;
|
|
const BYTE* const dmsBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL;
|
|
const BYTE* const dmsEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL;
|
|
U32 const dmsHighLimit = dictMode == ZSTD_dictMatchState ? (U32)(dmsEnd - dmsBase) : 0;
|
|
U32 const dmsLowLimit = dictMode == ZSTD_dictMatchState ? dms->window.lowLimit : 0;
|
|
U32 const dmsIndexDelta = dictMode == ZSTD_dictMatchState ? windowLow - dmsHighLimit : 0;
|
|
U32 const dmsHashLog = dictMode == ZSTD_dictMatchState ? dmsCParams->hashLog : hashLog;
|
|
U32 const dmsBtLog = dictMode == ZSTD_dictMatchState ? dmsCParams->chainLog - 1 : btLog;
|
|
U32 const dmsBtMask = dictMode == ZSTD_dictMatchState ? (1U << dmsBtLog) - 1 : 0;
|
|
U32 const dmsBtLow = dictMode == ZSTD_dictMatchState && dmsBtMask < dmsHighLimit - dmsLowLimit ? dmsHighLimit - dmsBtMask : dmsLowLimit;
|
|
|
|
size_t bestLength = lengthToBeat-1;
|
|
DEBUGLOG(8, "ZSTD_insertBtAndGetAllMatches: current=%u", curr);
|
|
|
|
/* check repCode */
|
|
assert(ll0 <= 1); /* necessarily 1 or 0 */
|
|
{ U32 const lastR = ZSTD_REP_NUM + ll0;
|
|
U32 repCode;
|
|
for (repCode = ll0; repCode < lastR; repCode++) {
|
|
U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
|
|
U32 const repIndex = curr - repOffset;
|
|
U32 repLen = 0;
|
|
assert(curr >= dictLimit);
|
|
if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < curr-dictLimit) { /* equivalent to `curr > repIndex >= dictLimit` */
|
|
/* We must validate the repcode offset because when we're using a dictionary the
|
|
* valid offset range shrinks when the dictionary goes out of bounds.
|
|
*/
|
|
if ((repIndex >= windowLow) & (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) {
|
|
repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
|
|
}
|
|
} else { /* repIndex < dictLimit || repIndex >= curr */
|
|
const BYTE* const repMatch = dictMode == ZSTD_dictMatchState ?
|
|
dmsBase + repIndex - dmsIndexDelta :
|
|
dictBase + repIndex;
|
|
assert(curr >= windowLow);
|
|
if ( dictMode == ZSTD_extDict
|
|
&& ( ((repOffset-1) /*intentional overflow*/ < curr - windowLow) /* equivalent to `curr > repIndex >= windowLow` */
|
|
& (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */)
|
|
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
|
|
repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch;
|
|
}
|
|
if (dictMode == ZSTD_dictMatchState
|
|
&& ( ((repOffset-1) /*intentional overflow*/ < curr - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `curr > repIndex >= dmsLowLimit` */
|
|
& ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */
|
|
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
|
|
repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch;
|
|
} }
|
|
/* save longer solution */
|
|
if (repLen > bestLength) {
|
|
DEBUGLOG(8, "found repCode %u (ll0:%u, offset:%u) of length %u",
|
|
repCode, ll0, repOffset, repLen);
|
|
bestLength = repLen;
|
|
matches[mnum].off = repCode - ll0;
|
|
matches[mnum].len = (U32)repLen;
|
|
mnum++;
|
|
if ( (repLen > sufficient_len)
|
|
| (ip+repLen == iLimit) ) { /* best possible */
|
|
return mnum;
|
|
} } } }
|
|
|
|
/* HC3 match finder */
|
|
if ((mls == 3) /*static*/ && (bestLength < mls)) {
|
|
U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, nextToUpdate3, ip);
|
|
if ((matchIndex3 >= matchLow)
|
|
& (curr - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) {
|
|
size_t mlen;
|
|
if ((dictMode == ZSTD_noDict) /*static*/ || (dictMode == ZSTD_dictMatchState) /*static*/ || (matchIndex3 >= dictLimit)) {
|
|
const BYTE* const match = base + matchIndex3;
|
|
mlen = ZSTD_count(ip, match, iLimit);
|
|
} else {
|
|
const BYTE* const match = dictBase + matchIndex3;
|
|
mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart);
|
|
}
|
|
|
|
/* save best solution */
|
|
if (mlen >= mls /* == 3 > bestLength */) {
|
|
DEBUGLOG(8, "found small match with hlog3, of length %u",
|
|
(U32)mlen);
|
|
bestLength = mlen;
|
|
assert(curr > matchIndex3);
|
|
assert(mnum==0); /* no prior solution */
|
|
matches[0].off = (curr - matchIndex3) + ZSTD_REP_MOVE;
|
|
matches[0].len = (U32)mlen;
|
|
mnum = 1;
|
|
if ( (mlen > sufficient_len) |
|
|
(ip+mlen == iLimit) ) { /* best possible length */
|
|
ms->nextToUpdate = curr+1; /* skip insertion */
|
|
return 1;
|
|
} } }
|
|
/* no dictMatchState lookup: dicts don't have a populated HC3 table */
|
|
}
|
|
|
|
hashTable[h] = curr; /* Update Hash Table */
|
|
|
|
while (nbCompares-- && (matchIndex >= matchLow)) {
|
|
U32* const nextPtr = bt + 2*(matchIndex & btMask);
|
|
const BYTE* match;
|
|
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
|
|
assert(curr > matchIndex);
|
|
|
|
if ((dictMode == ZSTD_noDict) || (dictMode == ZSTD_dictMatchState) || (matchIndex+matchLength >= dictLimit)) {
|
|
assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */
|
|
match = base + matchIndex;
|
|
if (matchIndex >= dictLimit) assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */
|
|
matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit);
|
|
} else {
|
|
match = dictBase + matchIndex;
|
|
assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */
|
|
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart);
|
|
if (matchIndex+matchLength >= dictLimit)
|
|
match = base + matchIndex; /* prepare for match[matchLength] read */
|
|
}
|
|
|
|
if (matchLength > bestLength) {
|
|
DEBUGLOG(8, "found match of length %u at distance %u (offCode=%u)",
|
|
(U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE);
|
|
assert(matchEndIdx > matchIndex);
|
|
if (matchLength > matchEndIdx - matchIndex)
|
|
matchEndIdx = matchIndex + (U32)matchLength;
|
|
bestLength = matchLength;
|
|
matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE;
|
|
matches[mnum].len = (U32)matchLength;
|
|
mnum++;
|
|
if ( (matchLength > ZSTD_OPT_NUM)
|
|
| (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) {
|
|
if (dictMode == ZSTD_dictMatchState) nbCompares = 0; /* break should also skip searching dms */
|
|
break; /* drop, to preserve bt consistency (miss a little bit of compression) */
|
|
}
|
|
}
|
|
|
|
if (match[matchLength] < ip[matchLength]) {
|
|
/* match smaller than current */
|
|
*smallerPtr = matchIndex; /* update smaller idx */
|
|
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
|
|
if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
|
|
smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */
|
|
matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */
|
|
} else {
|
|
*largerPtr = matchIndex;
|
|
commonLengthLarger = matchLength;
|
|
if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */
|
|
largerPtr = nextPtr;
|
|
matchIndex = nextPtr[0];
|
|
} }
|
|
|
|
*smallerPtr = *largerPtr = 0;
|
|
|
|
if (dictMode == ZSTD_dictMatchState && nbCompares) {
|
|
size_t const dmsH = ZSTD_hashPtr(ip, dmsHashLog, mls);
|
|
U32 dictMatchIndex = dms->hashTable[dmsH];
|
|
const U32* const dmsBt = dms->chainTable;
|
|
commonLengthSmaller = commonLengthLarger = 0;
|
|
while (nbCompares-- && (dictMatchIndex > dmsLowLimit)) {
|
|
const U32* const nextPtr = dmsBt + 2*(dictMatchIndex & dmsBtMask);
|
|
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
|
|
const BYTE* match = dmsBase + dictMatchIndex;
|
|
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart);
|
|
if (dictMatchIndex+matchLength >= dmsHighLimit)
|
|
match = base + dictMatchIndex + dmsIndexDelta; /* to prepare for next usage of match[matchLength] */
|
|
|
|
if (matchLength > bestLength) {
|
|
matchIndex = dictMatchIndex + dmsIndexDelta;
|
|
DEBUGLOG(8, "found dms match of length %u at distance %u (offCode=%u)",
|
|
(U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE);
|
|
if (matchLength > matchEndIdx - matchIndex)
|
|
matchEndIdx = matchIndex + (U32)matchLength;
|
|
bestLength = matchLength;
|
|
matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE;
|
|
matches[mnum].len = (U32)matchLength;
|
|
mnum++;
|
|
if ( (matchLength > ZSTD_OPT_NUM)
|
|
| (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) {
|
|
break; /* drop, to guarantee consistency (miss a little bit of compression) */
|
|
}
|
|
}
|
|
|
|
if (dictMatchIndex <= dmsBtLow) { break; } /* beyond tree size, stop the search */
|
|
if (match[matchLength] < ip[matchLength]) {
|
|
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
|
|
dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
|
|
} else {
|
|
/* match is larger than current */
|
|
commonLengthLarger = matchLength;
|
|
dictMatchIndex = nextPtr[0];
|
|
}
|
|
}
|
|
}
|
|
|
|
assert(matchEndIdx > curr+8);
|
|
ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
|
|
return mnum;
|
|
}
|
|
|
|
|
|
FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches (
|
|
ZSTD_match_t* matches, /* store result (match found, increasing size) in this table */
|
|
ZSTD_matchState_t* ms,
|
|
U32* nextToUpdate3,
|
|
const BYTE* ip, const BYTE* const iHighLimit, const ZSTD_dictMode_e dictMode,
|
|
const U32 rep[ZSTD_REP_NUM],
|
|
U32 const ll0,
|
|
U32 const lengthToBeat)
|
|
{
|
|
const ZSTD_compressionParameters* const cParams = &ms->cParams;
|
|
U32 const matchLengthSearch = cParams->minMatch;
|
|
DEBUGLOG(8, "ZSTD_BtGetAllMatches");
|
|
if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
|
|
ZSTD_updateTree_internal(ms, ip, iHighLimit, matchLengthSearch, dictMode);
|
|
switch(matchLengthSearch)
|
|
{
|
|
case 3 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 3);
|
|
default :
|
|
case 4 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 4);
|
|
case 5 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 5);
|
|
case 7 :
|
|
case 6 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 6);
|
|
}
|
|
}
|
|
|
|
/*************************
|
|
* LDM helper functions *
|
|
*************************/
|
|
|
|
/* Struct containing info needed to make decision about ldm inclusion */
|
|
typedef struct {
|
|
rawSeqStore_t seqStore; /* External match candidates store for this block */
|
|
U32 startPosInBlock; /* Start position of the current match candidate */
|
|
U32 endPosInBlock; /* End position of the current match candidate */
|
|
U32 offset; /* Offset of the match candidate */
|
|
} ZSTD_optLdm_t;
|
|
|
|
/* ZSTD_optLdm_skipRawSeqStoreBytes():
|
|
* Moves forward in rawSeqStore by nbBytes, which will update the fields 'pos' and 'posInSequence'.
|
|
*/
|
|
static void ZSTD_optLdm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes) {
|
|
U32 currPos = (U32)(rawSeqStore->posInSequence + nbBytes);
|
|
while (currPos && rawSeqStore->pos < rawSeqStore->size) {
|
|
rawSeq currSeq = rawSeqStore->seq[rawSeqStore->pos];
|
|
if (currPos >= currSeq.litLength + currSeq.matchLength) {
|
|
currPos -= currSeq.litLength + currSeq.matchLength;
|
|
rawSeqStore->pos++;
|
|
} else {
|
|
rawSeqStore->posInSequence = currPos;
|
|
break;
|
|
}
|
|
}
|
|
if (currPos == 0 || rawSeqStore->pos == rawSeqStore->size) {
|
|
rawSeqStore->posInSequence = 0;
|
|
}
|
|
}
|
|
|
|
/* ZSTD_opt_getNextMatchAndUpdateSeqStore():
|
|
* Calculates the beginning and end of the next match in the current block.
|
|
* Updates 'pos' and 'posInSequence' of the ldmSeqStore.
|
|
*/
|
|
static void ZSTD_opt_getNextMatchAndUpdateSeqStore(ZSTD_optLdm_t* optLdm, U32 currPosInBlock,
|
|
U32 blockBytesRemaining) {
|
|
rawSeq currSeq;
|
|
U32 currBlockEndPos;
|
|
U32 literalsBytesRemaining;
|
|
U32 matchBytesRemaining;
|
|
|
|
/* Setting match end position to MAX to ensure we never use an LDM during this block */
|
|
if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) {
|
|
optLdm->startPosInBlock = UINT_MAX;
|
|
optLdm->endPosInBlock = UINT_MAX;
|
|
return;
|
|
}
|
|
/* Calculate appropriate bytes left in matchLength and litLength after adjusting
|
|
based on ldmSeqStore->posInSequence */
|
|
currSeq = optLdm->seqStore.seq[optLdm->seqStore.pos];
|
|
assert(optLdm->seqStore.posInSequence <= currSeq.litLength + currSeq.matchLength);
|
|
currBlockEndPos = currPosInBlock + blockBytesRemaining;
|
|
literalsBytesRemaining = (optLdm->seqStore.posInSequence < currSeq.litLength) ?
|
|
currSeq.litLength - (U32)optLdm->seqStore.posInSequence :
|
|
0;
|
|
matchBytesRemaining = (literalsBytesRemaining == 0) ?
|
|
currSeq.matchLength - ((U32)optLdm->seqStore.posInSequence - currSeq.litLength) :
|
|
currSeq.matchLength;
|
|
|
|
/* If there are more literal bytes than bytes remaining in block, no ldm is possible */
|
|
if (literalsBytesRemaining >= blockBytesRemaining) {
|
|
optLdm->startPosInBlock = UINT_MAX;
|
|
optLdm->endPosInBlock = UINT_MAX;
|
|
ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, blockBytesRemaining);
|
|
return;
|
|
}
|
|
|
|
/* Matches may be < MINMATCH by this process. In that case, we will reject them
|
|
when we are deciding whether or not to add the ldm */
|
|
optLdm->startPosInBlock = currPosInBlock + literalsBytesRemaining;
|
|
optLdm->endPosInBlock = optLdm->startPosInBlock + matchBytesRemaining;
|
|
optLdm->offset = currSeq.offset;
|
|
|
|
if (optLdm->endPosInBlock > currBlockEndPos) {
|
|
/* Match ends after the block ends, we can't use the whole match */
|
|
optLdm->endPosInBlock = currBlockEndPos;
|
|
ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, currBlockEndPos - currPosInBlock);
|
|
} else {
|
|
/* Consume nb of bytes equal to size of sequence left */
|
|
ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, literalsBytesRemaining + matchBytesRemaining);
|
|
}
|
|
}
|
|
|
|
/* ZSTD_optLdm_maybeAddMatch():
|
|
* Adds a match if it's long enough, based on it's 'matchStartPosInBlock'
|
|
* and 'matchEndPosInBlock', into 'matches'. Maintains the correct ordering of 'matches'
|
|
*/
|
|
static void ZSTD_optLdm_maybeAddMatch(ZSTD_match_t* matches, U32* nbMatches,
|
|
ZSTD_optLdm_t* optLdm, U32 currPosInBlock) {
|
|
U32 posDiff = currPosInBlock - optLdm->startPosInBlock;
|
|
/* Note: ZSTD_match_t actually contains offCode and matchLength (before subtracting MINMATCH) */
|
|
U32 candidateMatchLength = optLdm->endPosInBlock - optLdm->startPosInBlock - posDiff;
|
|
U32 candidateOffCode = optLdm->offset + ZSTD_REP_MOVE;
|
|
|
|
/* Ensure that current block position is not outside of the match */
|
|
if (currPosInBlock < optLdm->startPosInBlock
|
|
|| currPosInBlock >= optLdm->endPosInBlock
|
|
|| candidateMatchLength < MINMATCH) {
|
|
return;
|
|
}
|
|
|
|
if (*nbMatches == 0 || ((candidateMatchLength > matches[*nbMatches-1].len) && *nbMatches < ZSTD_OPT_NUM)) {
|
|
DEBUGLOG(6, "ZSTD_optLdm_maybeAddMatch(): Adding ldm candidate match (offCode: %u matchLength %u) at block position=%u",
|
|
candidateOffCode, candidateMatchLength, currPosInBlock);
|
|
matches[*nbMatches].len = candidateMatchLength;
|
|
matches[*nbMatches].off = candidateOffCode;
|
|
(*nbMatches)++;
|
|
}
|
|
}
|
|
|
|
/* ZSTD_optLdm_processMatchCandidate():
|
|
* Wrapper function to update ldm seq store and call ldm functions as necessary.
|
|
*/
|
|
static void ZSTD_optLdm_processMatchCandidate(ZSTD_optLdm_t* optLdm, ZSTD_match_t* matches, U32* nbMatches,
|
|
U32 currPosInBlock, U32 remainingBytes) {
|
|
if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) {
|
|
return;
|
|
}
|
|
|
|
if (currPosInBlock >= optLdm->endPosInBlock) {
|
|
if (currPosInBlock > optLdm->endPosInBlock) {
|
|
/* The position at which ZSTD_optLdm_processMatchCandidate() is called is not necessarily
|
|
* at the end of a match from the ldm seq store, and will often be some bytes
|
|
* over beyond matchEndPosInBlock. As such, we need to correct for these "overshoots"
|
|
*/
|
|
U32 posOvershoot = currPosInBlock - optLdm->endPosInBlock;
|
|
ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, posOvershoot);
|
|
}
|
|
ZSTD_opt_getNextMatchAndUpdateSeqStore(optLdm, currPosInBlock, remainingBytes);
|
|
}
|
|
ZSTD_optLdm_maybeAddMatch(matches, nbMatches, optLdm, currPosInBlock);
|
|
}
|
|
|
|
/*-*******************************
|
|
* Optimal parser
|
|
*********************************/
|
|
|
|
|
|
static U32 ZSTD_totalLen(ZSTD_optimal_t sol)
|
|
{
|
|
return sol.litlen + sol.mlen;
|
|
}
|
|
|
|
#if 0 /* debug */
|
|
|
|
static void
|
|
listStats(const U32* table, int lastEltID)
|
|
{
|
|
int const nbElts = lastEltID + 1;
|
|
int enb;
|
|
for (enb=0; enb < nbElts; enb++) {
|
|
(void)table;
|
|
/* RAWLOG(2, "%3i:%3i, ", enb, table[enb]); */
|
|
RAWLOG(2, "%4i,", table[enb]);
|
|
}
|
|
RAWLOG(2, " \n");
|
|
}
|
|
|
|
#endif
|
|
|
|
FORCE_INLINE_TEMPLATE size_t
|
|
ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
|
|
seqStore_t* seqStore,
|
|
U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize,
|
|
const int optLevel,
|
|
const ZSTD_dictMode_e dictMode)
|
|
{
|
|
optState_t* const optStatePtr = &ms->opt;
|
|
const BYTE* const istart = (const BYTE*)src;
|
|
const BYTE* ip = istart;
|
|
const BYTE* anchor = istart;
|
|
const BYTE* const iend = istart + srcSize;
|
|
const BYTE* const ilimit = iend - 8;
|
|
const BYTE* const base = ms->window.base;
|
|
const BYTE* const prefixStart = base + ms->window.dictLimit;
|
|
const ZSTD_compressionParameters* const cParams = &ms->cParams;
|
|
|
|
U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1);
|
|
U32 const minMatch = (cParams->minMatch == 3) ? 3 : 4;
|
|
U32 nextToUpdate3 = ms->nextToUpdate;
|
|
|
|
ZSTD_optimal_t* const opt = optStatePtr->priceTable;
|
|
ZSTD_match_t* const matches = optStatePtr->matchTable;
|
|
ZSTD_optimal_t lastSequence;
|
|
ZSTD_optLdm_t optLdm;
|
|
|
|
optLdm.seqStore = ms->ldmSeqStore ? *ms->ldmSeqStore : kNullRawSeqStore;
|
|
optLdm.endPosInBlock = optLdm.startPosInBlock = optLdm.offset = 0;
|
|
ZSTD_opt_getNextMatchAndUpdateSeqStore(&optLdm, (U32)(ip-istart), (U32)(iend-ip));
|
|
|
|
/* init */
|
|
DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u",
|
|
(U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate);
|
|
assert(optLevel <= 2);
|
|
ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel);
|
|
ip += (ip==prefixStart);
|
|
|
|
/* Match Loop */
|
|
while (ip < ilimit) {
|
|
U32 cur, last_pos = 0;
|
|
|
|
/* find first match */
|
|
{ U32 const litlen = (U32)(ip - anchor);
|
|
U32 const ll0 = !litlen;
|
|
U32 nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, ip, iend, dictMode, rep, ll0, minMatch);
|
|
ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches,
|
|
(U32)(ip-istart), (U32)(iend - ip));
|
|
if (!nbMatches) { ip++; continue; }
|
|
|
|
/* initialize opt[0] */
|
|
{ U32 i ; for (i=0; i<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; }
|
|
opt[0].mlen = 0; /* means is_a_literal */
|
|
opt[0].litlen = litlen;
|
|
/* We don't need to include the actual price of the literals because
|
|
* it is static for the duration of the forward pass, and is included
|
|
* in every price. We include the literal length to avoid negative
|
|
* prices when we subtract the previous literal length.
|
|
*/
|
|
opt[0].price = ZSTD_litLengthPrice(litlen, optStatePtr, optLevel);
|
|
|
|
/* large match -> immediate encoding */
|
|
{ U32 const maxML = matches[nbMatches-1].len;
|
|
U32 const maxOffset = matches[nbMatches-1].off;
|
|
DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffCode=%u at cPos=%u => start new series",
|
|
nbMatches, maxML, maxOffset, (U32)(ip-prefixStart));
|
|
|
|
if (maxML > sufficient_len) {
|
|
lastSequence.litlen = litlen;
|
|
lastSequence.mlen = maxML;
|
|
lastSequence.off = maxOffset;
|
|
DEBUGLOG(6, "large match (%u>%u), immediate encoding",
|
|
maxML, sufficient_len);
|
|
cur = 0;
|
|
last_pos = ZSTD_totalLen(lastSequence);
|
|
goto _shortestPath;
|
|
} }
|
|
|
|
/* set prices for first matches starting position == 0 */
|
|
{ U32 const literalsPrice = opt[0].price + ZSTD_litLengthPrice(0, optStatePtr, optLevel);
|
|
U32 pos;
|
|
U32 matchNb;
|
|
for (pos = 1; pos < minMatch; pos++) {
|
|
opt[pos].price = ZSTD_MAX_PRICE; /* mlen, litlen and price will be fixed during forward scanning */
|
|
}
|
|
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
|
|
U32 const offset = matches[matchNb].off;
|
|
U32 const end = matches[matchNb].len;
|
|
for ( ; pos <= end ; pos++ ) {
|
|
U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel);
|
|
U32 const sequencePrice = literalsPrice + matchPrice;
|
|
DEBUGLOG(7, "rPos:%u => set initial price : %.2f",
|
|
pos, ZSTD_fCost(sequencePrice));
|
|
opt[pos].mlen = pos;
|
|
opt[pos].off = offset;
|
|
opt[pos].litlen = litlen;
|
|
opt[pos].price = sequencePrice;
|
|
} }
|
|
last_pos = pos-1;
|
|
}
|
|
}
|
|
|
|
/* check further positions */
|
|
for (cur = 1; cur <= last_pos; cur++) {
|
|
const BYTE* const inr = ip + cur;
|
|
assert(cur < ZSTD_OPT_NUM);
|
|
DEBUGLOG(7, "cPos:%zi==rPos:%u", inr-istart, cur)
|
|
|
|
/* Fix current position with one literal if cheaper */
|
|
{ U32 const litlen = (opt[cur-1].mlen == 0) ? opt[cur-1].litlen + 1 : 1;
|
|
int const price = opt[cur-1].price
|
|
+ ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel)
|
|
+ ZSTD_litLengthPrice(litlen, optStatePtr, optLevel)
|
|
- ZSTD_litLengthPrice(litlen-1, optStatePtr, optLevel);
|
|
assert(price < 1000000000); /* overflow check */
|
|
if (price <= opt[cur].price) {
|
|
DEBUGLOG(7, "cPos:%zi==rPos:%u : better price (%.2f<=%.2f) using literal (ll==%u) (hist:%u,%u,%u)",
|
|
inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), litlen,
|
|
opt[cur-1].rep[0], opt[cur-1].rep[1], opt[cur-1].rep[2]);
|
|
opt[cur].mlen = 0;
|
|
opt[cur].off = 0;
|
|
opt[cur].litlen = litlen;
|
|
opt[cur].price = price;
|
|
} else {
|
|
DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)",
|
|
inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price),
|
|
opt[cur].rep[0], opt[cur].rep[1], opt[cur].rep[2]);
|
|
}
|
|
}
|
|
|
|
/* Set the repcodes of the current position. We must do it here
|
|
* because we rely on the repcodes of the 2nd to last sequence being
|
|
* correct to set the next chunks repcodes during the backward
|
|
* traversal.
|
|
*/
|
|
ZSTD_STATIC_ASSERT(sizeof(opt[cur].rep) == sizeof(repcodes_t));
|
|
assert(cur >= opt[cur].mlen);
|
|
if (opt[cur].mlen != 0) {
|
|
U32 const prev = cur - opt[cur].mlen;
|
|
repcodes_t newReps = ZSTD_updateRep(opt[prev].rep, opt[cur].off, opt[cur].litlen==0);
|
|
ZSTD_memcpy(opt[cur].rep, &newReps, sizeof(repcodes_t));
|
|
} else {
|
|
ZSTD_memcpy(opt[cur].rep, opt[cur - 1].rep, sizeof(repcodes_t));
|
|
}
|
|
|
|
/* last match must start at a minimum distance of 8 from oend */
|
|
if (inr > ilimit) continue;
|
|
|
|
if (cur == last_pos) break;
|
|
|
|
if ( (optLevel==0) /*static_test*/
|
|
&& (opt[cur+1].price <= opt[cur].price + (BITCOST_MULTIPLIER/2)) ) {
|
|
DEBUGLOG(7, "move to next rPos:%u : price is <=", cur+1);
|
|
continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */
|
|
}
|
|
|
|
{ U32 const ll0 = (opt[cur].mlen != 0);
|
|
U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0;
|
|
U32 const previousPrice = opt[cur].price;
|
|
U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel);
|
|
U32 nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, inr, iend, dictMode, opt[cur].rep, ll0, minMatch);
|
|
U32 matchNb;
|
|
|
|
ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches,
|
|
(U32)(inr-istart), (U32)(iend-inr));
|
|
|
|
if (!nbMatches) {
|
|
DEBUGLOG(7, "rPos:%u : no match found", cur);
|
|
continue;
|
|
}
|
|
|
|
{ U32 const maxML = matches[nbMatches-1].len;
|
|
DEBUGLOG(7, "cPos:%zi==rPos:%u, found %u matches, of maxLength=%u",
|
|
inr-istart, cur, nbMatches, maxML);
|
|
|
|
if ( (maxML > sufficient_len)
|
|
|| (cur + maxML >= ZSTD_OPT_NUM) ) {
|
|
lastSequence.mlen = maxML;
|
|
lastSequence.off = matches[nbMatches-1].off;
|
|
lastSequence.litlen = litlen;
|
|
cur -= (opt[cur].mlen==0) ? opt[cur].litlen : 0; /* last sequence is actually only literals, fix cur to last match - note : may underflow, in which case, it's first sequence, and it's okay */
|
|
last_pos = cur + ZSTD_totalLen(lastSequence);
|
|
if (cur > ZSTD_OPT_NUM) cur = 0; /* underflow => first match */
|
|
goto _shortestPath;
|
|
} }
|
|
|
|
/* set prices using matches found at position == cur */
|
|
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
|
|
U32 const offset = matches[matchNb].off;
|
|
U32 const lastML = matches[matchNb].len;
|
|
U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch;
|
|
U32 mlen;
|
|
|
|
DEBUGLOG(7, "testing match %u => offCode=%4u, mlen=%2u, llen=%2u",
|
|
matchNb, matches[matchNb].off, lastML, litlen);
|
|
|
|
for (mlen = lastML; mlen >= startML; mlen--) { /* scan downward */
|
|
U32 const pos = cur + mlen;
|
|
int const price = basePrice + ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel);
|
|
|
|
if ((pos > last_pos) || (price < opt[pos].price)) {
|
|
DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)",
|
|
pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price));
|
|
while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } /* fill empty positions */
|
|
opt[pos].mlen = mlen;
|
|
opt[pos].off = offset;
|
|
opt[pos].litlen = litlen;
|
|
opt[pos].price = price;
|
|
} else {
|
|
DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)",
|
|
pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price));
|
|
if (optLevel==0) break; /* early update abort; gets ~+10% speed for about -0.01 ratio loss */
|
|
}
|
|
} } }
|
|
} /* for (cur = 1; cur <= last_pos; cur++) */
|
|
|
|
lastSequence = opt[last_pos];
|
|
cur = last_pos > ZSTD_totalLen(lastSequence) ? last_pos - ZSTD_totalLen(lastSequence) : 0; /* single sequence, and it starts before `ip` */
|
|
assert(cur < ZSTD_OPT_NUM); /* control overflow*/
|
|
|
|
_shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
|
|
assert(opt[0].mlen == 0);
|
|
|
|
/* Set the next chunk's repcodes based on the repcodes of the beginning
|
|
* of the last match, and the last sequence. This avoids us having to
|
|
* update them while traversing the sequences.
|
|
*/
|
|
if (lastSequence.mlen != 0) {
|
|
repcodes_t reps = ZSTD_updateRep(opt[cur].rep, lastSequence.off, lastSequence.litlen==0);
|
|
ZSTD_memcpy(rep, &reps, sizeof(reps));
|
|
} else {
|
|
ZSTD_memcpy(rep, opt[cur].rep, sizeof(repcodes_t));
|
|
}
|
|
|
|
{ U32 const storeEnd = cur + 1;
|
|
U32 storeStart = storeEnd;
|
|
U32 seqPos = cur;
|
|
|
|
DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)",
|
|
last_pos, cur); (void)last_pos;
|
|
assert(storeEnd < ZSTD_OPT_NUM);
|
|
DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)",
|
|
storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off);
|
|
opt[storeEnd] = lastSequence;
|
|
while (seqPos > 0) {
|
|
U32 const backDist = ZSTD_totalLen(opt[seqPos]);
|
|
storeStart--;
|
|
DEBUGLOG(6, "sequence from rPos=%u copied into pos=%u (llen=%u,mlen=%u,ofc=%u)",
|
|
seqPos, storeStart, opt[seqPos].litlen, opt[seqPos].mlen, opt[seqPos].off);
|
|
opt[storeStart] = opt[seqPos];
|
|
seqPos = (seqPos > backDist) ? seqPos - backDist : 0;
|
|
}
|
|
|
|
/* save sequences */
|
|
DEBUGLOG(6, "sending selected sequences into seqStore")
|
|
{ U32 storePos;
|
|
for (storePos=storeStart; storePos <= storeEnd; storePos++) {
|
|
U32 const llen = opt[storePos].litlen;
|
|
U32 const mlen = opt[storePos].mlen;
|
|
U32 const offCode = opt[storePos].off;
|
|
U32 const advance = llen + mlen;
|
|
DEBUGLOG(6, "considering seq starting at %zi, llen=%u, mlen=%u",
|
|
anchor - istart, (unsigned)llen, (unsigned)mlen);
|
|
|
|
if (mlen==0) { /* only literals => must be last "sequence", actually starting a new stream of sequences */
|
|
assert(storePos == storeEnd); /* must be last sequence */
|
|
ip = anchor + llen; /* last "sequence" is a bunch of literals => don't progress anchor */
|
|
continue; /* will finish */
|
|
}
|
|
|
|
assert(anchor + llen <= iend);
|
|
ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen);
|
|
ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH);
|
|
anchor += advance;
|
|
ip = anchor;
|
|
} }
|
|
ZSTD_setBasePrices(optStatePtr, optLevel);
|
|
}
|
|
} /* while (ip < ilimit) */
|
|
|
|
/* Return the last literals size */
|
|
return (size_t)(iend - anchor);
|
|
}
|
|
|
|
|
|
size_t ZSTD_compressBlock_btopt(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
DEBUGLOG(5, "ZSTD_compressBlock_btopt");
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_noDict);
|
|
}
|
|
|
|
|
|
/* used in 2-pass strategy */
|
|
static U32 ZSTD_upscaleStat(unsigned* table, U32 lastEltIndex, int bonus)
|
|
{
|
|
U32 s, sum=0;
|
|
assert(ZSTD_FREQ_DIV+bonus >= 0);
|
|
for (s=0; s<lastEltIndex+1; s++) {
|
|
table[s] <<= ZSTD_FREQ_DIV+bonus;
|
|
table[s]--;
|
|
sum += table[s];
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
/* used in 2-pass strategy */
|
|
MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr)
|
|
{
|
|
if (ZSTD_compressedLiterals(optPtr))
|
|
optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0);
|
|
optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 0);
|
|
optPtr->matchLengthSum = ZSTD_upscaleStat(optPtr->matchLengthFreq, MaxML, 0);
|
|
optPtr->offCodeSum = ZSTD_upscaleStat(optPtr->offCodeFreq, MaxOff, 0);
|
|
}
|
|
|
|
/* ZSTD_initStats_ultra():
|
|
* make a first compression pass, just to seed stats with more accurate starting values.
|
|
* only works on first block, with no dictionary and no ldm.
|
|
* this function cannot error, hence its contract must be respected.
|
|
*/
|
|
static void
|
|
ZSTD_initStats_ultra(ZSTD_matchState_t* ms,
|
|
seqStore_t* seqStore,
|
|
U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
U32 tmpRep[ZSTD_REP_NUM]; /* updated rep codes will sink here */
|
|
ZSTD_memcpy(tmpRep, rep, sizeof(tmpRep));
|
|
|
|
DEBUGLOG(4, "ZSTD_initStats_ultra (srcSize=%zu)", srcSize);
|
|
assert(ms->opt.litLengthSum == 0); /* first block */
|
|
assert(seqStore->sequences == seqStore->sequencesStart); /* no ldm */
|
|
assert(ms->window.dictLimit == ms->window.lowLimit); /* no dictionary */
|
|
assert(ms->window.dictLimit - ms->nextToUpdate <= 1); /* no prefix (note: intentional overflow, defined as 2-complement) */
|
|
|
|
ZSTD_compressBlock_opt_generic(ms, seqStore, tmpRep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); /* generate stats into ms->opt*/
|
|
|
|
/* invalidate first scan from history */
|
|
ZSTD_resetSeqStore(seqStore);
|
|
ms->window.base -= srcSize;
|
|
ms->window.dictLimit += (U32)srcSize;
|
|
ms->window.lowLimit = ms->window.dictLimit;
|
|
ms->nextToUpdate = ms->window.dictLimit;
|
|
|
|
/* re-inforce weight of collected statistics */
|
|
ZSTD_upscaleStats(&ms->opt);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize);
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra2(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
U32 const curr = (U32)((const BYTE*)src - ms->window.base);
|
|
DEBUGLOG(5, "ZSTD_compressBlock_btultra2 (srcSize=%zu)", srcSize);
|
|
|
|
/* 2-pass strategy:
|
|
* this strategy makes a first pass over first block to collect statistics
|
|
* and seed next round's statistics with it.
|
|
* After 1st pass, function forgets everything, and starts a new block.
|
|
* Consequently, this can only work if no data has been previously loaded in tables,
|
|
* aka, no dictionary, no prefix, no ldm preprocessing.
|
|
* The compression ratio gain is generally small (~0.5% on first block),
|
|
* the cost is 2x cpu time on first block. */
|
|
assert(srcSize <= ZSTD_BLOCKSIZE_MAX);
|
|
if ( (ms->opt.litLengthSum==0) /* first block */
|
|
&& (seqStore->sequences == seqStore->sequencesStart) /* no ldm */
|
|
&& (ms->window.dictLimit == ms->window.lowLimit) /* no dictionary */
|
|
&& (curr == ms->window.dictLimit) /* start of frame, nothing already loaded nor skipped */
|
|
&& (srcSize > ZSTD_PREDEF_THRESHOLD)
|
|
) {
|
|
ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize);
|
|
}
|
|
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btopt_dictMatchState(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_dictMatchState);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra_dictMatchState(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_dictMatchState);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btopt_extDict(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_extDict);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra_extDict(
|
|
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
|
|
const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_extDict);
|
|
}
|
|
|
|
/* note : no btultra2 variant for extDict nor dictMatchState,
|
|
* because btultra2 is not meant to work with dictionaries
|
|
* and is only specific for the first block (no prefix) */
|