0a0a212934
There was a flaw in the formula which compared literal cost with match cost : at a given position, a non-null literal suite is going to be part of next sequence, while if position ends a previous match, to immediately start another match, next sequence will have a litlength of zero. A litlength of zero has a non-null cost. It follows that literals cost should be compared to match cost + litlength==0. Not doing so gave a structural advantage to matches, which would be selected more often. I believe that's what led to the creation of the strange heuristic which added a complex cost to matches. The heuristic was actually compensating. It was probably created through multiple trials, settling for best outcome on a given scenario (I suspect silesia.tar). The problem with this heuristic is that it's hard to understand, and unfortunately, any future change in the parser would impact the way it should be calculated and its effects. The "proper" formula makes it possible to remove this heuristic. Now, the problem is : in a head to head comparison, it's sometimes better, sometimes worse. Note that all differences are small (< 0.01 ratio). In general, the newer formula is better for smaller files (for example, calgary.tar and enwik7). I suspect that's because starting statistics are pretty poor (another area of improvement). However, for silesia.tar specifically, it's worse at level 22 (while being better at level 17, so even compression level has an impact ...). It's a pity that zstd -22 gets worse on silesia.tar. That being said, I like that the new code gets rid of strange variables, which were introducing complexity for any future evolution (faster variants being in mind). Therefore, in spite of this detrimental side effect, I tend to be in favor of it.
773 lines
32 KiB
C
773 lines
32 KiB
C
/*
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* Copyright (c) 2016-present, 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 "zstd_opt.h"
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#include "zstd_lazy.h" /* ZSTD_updateTree, ZSTD_updateTree_extDict */
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#define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats. Also used for matchSum (?) */
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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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/*-*************************************
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* Price functions for optimal parser
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***************************************/
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static void ZSTD_setLog2Prices(optState_t* optPtr)
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{
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optPtr->log2litSum = ZSTD_highbit32(optPtr->litSum+1);
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optPtr->log2litLengthSum = ZSTD_highbit32(optPtr->litLengthSum+1);
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optPtr->log2matchLengthSum = ZSTD_highbit32(optPtr->matchLengthSum+1);
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optPtr->log2offCodeSum = ZSTD_highbit32(optPtr->offCodeSum+1);
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}
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static void ZSTD_rescaleFreqs(optState_t* const optPtr,
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const BYTE* const src, size_t const srcSize)
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{
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optPtr->staticPrices = 0;
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if (optPtr->litLengthSum == 0) { /* first init */
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unsigned u;
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if (srcSize <= 1024) optPtr->staticPrices = 1;
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assert(optPtr->litFreq!=NULL);
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for (u=0; u<=MaxLit; u++)
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optPtr->litFreq[u] = 0;
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for (u=0; u<srcSize; u++)
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optPtr->litFreq[src[u]]++;
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optPtr->litSum = 0;
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for (u=0; u<=MaxLit; u++) {
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optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> ZSTD_FREQ_DIV);
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optPtr->litSum += optPtr->litFreq[u];
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}
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for (u=0; u<=MaxLL; u++)
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optPtr->litLengthFreq[u] = 1;
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optPtr->litLengthSum = MaxLL+1;
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for (u=0; u<=MaxML; u++)
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optPtr->matchLengthFreq[u] = 1;
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optPtr->matchLengthSum = MaxML+1;
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for (u=0; u<=MaxOff; u++)
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optPtr->offCodeFreq[u] = 1;
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optPtr->offCodeSum = (MaxOff+1);
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} else {
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unsigned u;
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optPtr->litSum = 0;
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for (u=0; u<=MaxLit; u++) {
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optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> (ZSTD_FREQ_DIV+1));
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optPtr->litSum += optPtr->litFreq[u];
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}
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optPtr->litLengthSum = 0;
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for (u=0; u<=MaxLL; u++) {
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optPtr->litLengthFreq[u] = 1 + (optPtr->litLengthFreq[u]>>(ZSTD_FREQ_DIV+1));
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optPtr->litLengthSum += optPtr->litLengthFreq[u];
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}
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optPtr->matchLengthSum = 0;
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for (u=0; u<=MaxML; u++) {
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optPtr->matchLengthFreq[u] = 1 + (optPtr->matchLengthFreq[u]>>ZSTD_FREQ_DIV);
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optPtr->matchLengthSum += optPtr->matchLengthFreq[u];
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}
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optPtr->offCodeSum = 0;
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for (u=0; u<=MaxOff; u++) {
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optPtr->offCodeFreq[u] = 1 + (optPtr->offCodeFreq[u]>>ZSTD_FREQ_DIV);
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optPtr->offCodeSum += optPtr->offCodeFreq[u];
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}
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}
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ZSTD_setLog2Prices(optPtr);
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}
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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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{
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if (optPtr->staticPrices) return (litLength*6); /* 6 bit per literal - no statistic used */
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if (litLength == 0) return 0;
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/* literals */
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{ U32 u;
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U32 cost = litLength * optPtr->log2litSum;
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for (u=0; u < litLength; u++)
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cost -= ZSTD_highbit32(optPtr->litFreq[literals[u]]+1);
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return cost;
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}
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}
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static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr)
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{
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if (optPtr->staticPrices) return ZSTD_highbit32((U32)litLength+1);
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/* literal Length */
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{ U32 const llCode = ZSTD_LLcode(litLength);
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U32 const price = LL_bits[llCode] + optPtr->log2litLengthSum - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
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return price;
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}
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}
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static U32 ZSTD_fullLiteralsCost(const BYTE* const literals, U32 const litLength,
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const optState_t* const optPtr)
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{
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return ZSTD_rawLiteralsCost(literals, litLength, optPtr)
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+ ZSTD_litLengthPrice(litLength, optPtr);
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}
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static int ZSTD_litLengthContribution(U32 const litLength, const optState_t* const optPtr)
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{
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if (optPtr->staticPrices) return ZSTD_highbit32(litLength+1);
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/* literal Length */
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{ U32 const llCode = ZSTD_LLcode(litLength);
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int const contribution = LL_bits[llCode]
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+ ZSTD_highbit32(optPtr->litLengthFreq[0]+1)
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- ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
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#if 1
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return contribution;
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#else
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return MAX(0, contribution); /* sometimes better, sometimes not ... */
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#endif
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}
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}
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static int ZSTD_literalsContribution(const BYTE* const literals, U32 const litLength,
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const optState_t* const optPtr)
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{
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int const contribution = ZSTD_rawLiteralsCost(literals, litLength, optPtr)
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+ ZSTD_litLengthContribution(litLength, optPtr);
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return contribution;
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}
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/* ZSTD_getMatchPrice() :
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* optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */
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FORCE_INLINE_TEMPLATE U32 ZSTD_getMatchPrice(
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U32 const offset, 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->staticPrices) /* fixed scheme, do not use statistics */
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return ZSTD_highbit32((U32)mlBase+1) + 16 + offCode;
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price = offCode + optPtr->log2offCodeSum - ZSTD_highbit32(optPtr->offCodeFreq[offCode]+1);
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if ((optLevel<2) /*static*/ && offCode >= 20) price += (offCode-19)*2; /* 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] + optPtr->log2matchLengthSum - ZSTD_highbit32(optPtr->matchLengthFreq[mlCode]+1);
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}
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//price += optPtr->factor;
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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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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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{ 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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/* function safe only for comparisons */
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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_CCtx* const cctx, const BYTE* const ip)
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{
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U32* const hashTable3 = cctx->hashTable3;
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U32 const hashLog3 = cctx->hashLog3;
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const BYTE* const base = cctx->base;
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U32 idx = cctx->nextToUpdate3;
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U32 const target = cctx->nextToUpdate3 = (U32)(ip - base);
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size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3);
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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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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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FORCE_INLINE_TEMPLATE
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U32 ZSTD_insertBtAndGetAllMatches (
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ZSTD_CCtx* zc,
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const BYTE* const ip, const BYTE* const iLimit, int const extDict,
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U32 nbCompares, U32 const mls, U32 const sufficient_len,
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U32 rep[ZSTD_REP_NUM], U32 const ll0,
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ZSTD_match_t* matches, const U32 lengthToBeat)
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{
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const BYTE* const base = zc->base;
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U32 const current = (U32)(ip-base);
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U32 const hashLog = zc->appliedParams.cParams.hashLog;
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U32 const minMatch = (mls==3) ? 3 : 4;
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U32* const hashTable = zc->hashTable;
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size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
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U32 matchIndex = hashTable[h];
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U32* const bt = zc->chainTable;
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U32 const btLog = zc->appliedParams.cParams.chainLog - 1;
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U32 const btMask= (1U << btLog) - 1;
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size_t commonLengthSmaller=0, commonLengthLarger=0;
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const BYTE* const dictBase = zc->dictBase;
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U32 const dictLimit = zc->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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U32 const btLow = btMask >= current ? 0 : current - btMask;
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U32 const windowLow = zc->lowLimit;
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U32* smallerPtr = bt + 2*(current&btMask);
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U32* largerPtr = bt + 2*(current&btMask) + 1;
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U32 matchEndIdx = current+8+1; /* farthest referenced position of any match => detects repetitive patterns */
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U32 dummy32; /* to be nullified at the end */
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U32 mnum = 0;
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size_t bestLength = lengthToBeat-1;
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DEBUGLOG(7, "ZSTD_insertBtAndGetAllMatches");
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/* check repCode */
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{ U32 const lastR = ZSTD_REP_NUM + ll0;
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U32 repCode;
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for (repCode = ll0; repCode < lastR; repCode++) {
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U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
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U32 const repIndex = current - repOffset;
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U32 repLen = 0;
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assert(current >= dictLimit);
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if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) { /* equivalent to `current > repIndex >= dictLimit` */
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if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) {
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repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
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}
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} else { /* repIndex < dictLimit || repIndex >= current */
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const BYTE* const repMatch = dictBase + repIndex;
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assert(current >= windowLow);
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if ( extDict /* this case only valid in extDict mode */
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&& ( ((repOffset-1) /*intentional overflow*/ < current - windowLow) /* equivalent to `current > repIndex >= windowLow` */
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& (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */)
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&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
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repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch;
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} }
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/* save longer solution */
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if (repLen > bestLength) {
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DEBUGLOG(8, "found rep-match %u of length %u",
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repCode - ll0, (U32)repLen);
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bestLength = repLen;
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matches[mnum].off = repCode - ll0;
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matches[mnum].len = (U32)repLen;
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mnum++;
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if ( (repLen > sufficient_len)
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| (ip+repLen == iLimit) ) { /* best possible */
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return mnum;
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} } } }
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/* HC3 match finder */
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if ((mls == 3) /*static*/ && (bestLength < mls)) {
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U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3 (zc, ip);
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if ((matchIndex3 > windowLow)
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& (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) {
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size_t mlen;
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if ((!extDict) /*static*/ || (matchIndex3 >= dictLimit)) {
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const BYTE* const match = base + matchIndex3;
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mlen = ZSTD_count(ip, match, iLimit);
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} else {
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const BYTE* const match = dictBase + matchIndex3;
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mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart);
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}
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/* save best solution */
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if (mlen >= mls /* == 3 > bestLength */) {
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DEBUGLOG(8, "found small match with hlog3, of length %u",
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(U32)mlen);
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bestLength = mlen;
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assert(current > matchIndex3);
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assert(mnum==0); /* no prior solution */
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matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE;
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matches[0].len = (U32)mlen;
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mnum = 1;
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if ( (mlen > sufficient_len) |
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(ip+mlen == iLimit) ) { /* best possible length */
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zc->nextToUpdate = current+1; /* skip insertion */
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return 1;
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} } } }
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hashTable[h] = current; /* Update Hash Table */
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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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const BYTE* match;
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assert(current > matchIndex);
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if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
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assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */
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match = base + matchIndex;
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matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit);
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} else {
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match = dictBase + matchIndex;
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matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart);
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if (matchIndex+matchLength >= dictLimit)
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match = base + matchIndex; /* prepare for match[matchLength] */
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}
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if (matchLength > bestLength) {
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DEBUGLOG(8, "found match of length %u at distance %u",
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(U32)matchLength, current - matchIndex);
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assert(matchEndIdx > matchIndex);
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if (matchLength > matchEndIdx - matchIndex)
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matchEndIdx = matchIndex + (U32)matchLength;
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bestLength = matchLength;
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matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE;
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matches[mnum].len = (U32)matchLength;
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mnum++;
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if (matchLength > ZSTD_OPT_NUM) break;
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if (ip+matchLength == iLimit) { /* equal : no way to know if inf or sup */
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break; /* drop, to preserve bt consistency (miss a little bit of compression) */
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}
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}
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if (match[matchLength] < ip[matchLength]) {
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/* match smaller than current */
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*smallerPtr = matchIndex; /* update smaller idx */
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commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
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if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
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smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */
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matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */
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} else {
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*largerPtr = matchIndex;
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commonLengthLarger = matchLength;
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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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} }
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*smallerPtr = *largerPtr = 0;
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assert(matchEndIdx > current+8);
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zc->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
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return mnum;
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}
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FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches (
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ZSTD_CCtx* zc, /* Index table will be updated */
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const BYTE* ip, const BYTE* const iHighLimit, int const extDict,
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U32 const maxNbAttempts, U32 const matchLengthSearch, U32 const sufficient_len,
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U32 rep[ZSTD_REP_NUM], U32 const ll0,
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ZSTD_match_t* matches, U32 const lengthToBeat)
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{
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DEBUGLOG(7, "ZSTD_BtGetAllMatches");
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if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
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if (extDict) ZSTD_updateTree_extDict(zc, ip, iHighLimit, maxNbAttempts, matchLengthSearch);
|
|
else ZSTD_updateTree(zc, ip, iHighLimit, maxNbAttempts, matchLengthSearch);
|
|
switch(matchLengthSearch)
|
|
{
|
|
case 3 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 3, sufficient_len, rep, ll0, matches, lengthToBeat);
|
|
default :
|
|
case 4 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 4, sufficient_len, rep, ll0, matches, lengthToBeat);
|
|
case 5 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 5, sufficient_len, rep, ll0, matches, lengthToBeat);
|
|
case 7 :
|
|
case 6 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 6, sufficient_len, rep, ll0, matches, lengthToBeat);
|
|
}
|
|
}
|
|
|
|
|
|
/*-*******************************
|
|
* Optimal parser
|
|
*********************************/
|
|
typedef struct repcodes_s {
|
|
U32 rep[3];
|
|
} repcodes_t;
|
|
|
|
repcodes_t ZSTD_updateRep(U32 const rep[3], U32 const offset, U32 const ll0)
|
|
{
|
|
repcodes_t newReps;
|
|
if (offset >= ZSTD_REP_NUM) { /* full offset */
|
|
newReps.rep[2] = rep[1];
|
|
newReps.rep[1] = rep[0];
|
|
newReps.rep[0] = offset - ZSTD_REP_MOVE;
|
|
} else { /* repcode */
|
|
U32 const repCode = offset + ll0;
|
|
if (repCode > 0) { /* note : if repCode==0, no change */
|
|
U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
|
|
newReps.rep[2] = (repCode >= 2) ? rep[1] : rep[2];
|
|
newReps.rep[1] = rep[0];
|
|
newReps.rep[0] = currentOffset;
|
|
} else { /* repCode == 0 */
|
|
memcpy(&newReps, rep, sizeof(newReps));
|
|
}
|
|
}
|
|
return newReps;
|
|
}
|
|
|
|
/* update opt[pos] and last_pos */
|
|
#define SET_PRICE(pos, mlen_, offset_, litlen_, price_, rep_) \
|
|
{ \
|
|
while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } \
|
|
opt[pos].mlen = mlen_; \
|
|
opt[pos].off = offset_; \
|
|
opt[pos].litlen = litlen_; \
|
|
opt[pos].price = price_; \
|
|
memcpy(opt[pos].rep, &rep_, sizeof(rep_)); \
|
|
}
|
|
|
|
typedef struct {
|
|
const BYTE* anchor;
|
|
U32 litlen;
|
|
U32 rawLitCost;
|
|
} cachedLiteralPrice_t;
|
|
|
|
static U32 ZSTD_rawLiteralsCost_cached(
|
|
cachedLiteralPrice_t* const cachedLitPrice,
|
|
const BYTE* const anchor, U32 const litlen,
|
|
const optState_t* const optStatePtr)
|
|
{
|
|
U32 startCost;
|
|
U32 remainingLength;
|
|
const BYTE* startPosition;
|
|
|
|
if (anchor == cachedLitPrice->anchor) {
|
|
startCost = cachedLitPrice->rawLitCost;
|
|
startPosition = anchor + cachedLitPrice->litlen;
|
|
assert(litlen >= cachedLitPrice->litlen);
|
|
remainingLength = litlen - cachedLitPrice->litlen;
|
|
} else {
|
|
startCost = 0;
|
|
startPosition = anchor;
|
|
remainingLength = litlen;
|
|
}
|
|
|
|
{ U32 const rawLitCost = startCost + ZSTD_rawLiteralsCost(startPosition, remainingLength, optStatePtr);
|
|
cachedLitPrice->anchor = anchor;
|
|
cachedLitPrice->litlen = litlen;
|
|
cachedLitPrice->rawLitCost = rawLitCost;
|
|
return rawLitCost;
|
|
}
|
|
}
|
|
|
|
static U32 ZSTD_fullLiteralsCost_cached(
|
|
cachedLiteralPrice_t* const cachedLitPrice,
|
|
const BYTE* const anchor, U32 const litlen,
|
|
const optState_t* const optStatePtr)
|
|
{
|
|
return ZSTD_rawLiteralsCost_cached(cachedLitPrice, anchor, litlen, optStatePtr)
|
|
+ ZSTD_litLengthPrice(litlen, optStatePtr);
|
|
}
|
|
|
|
static int ZSTD_literalsContribution_cached(
|
|
cachedLiteralPrice_t* const cachedLitPrice,
|
|
const BYTE* const anchor, U32 const litlen,
|
|
const optState_t* const optStatePtr)
|
|
{
|
|
int const contribution = ZSTD_rawLiteralsCost_cached(cachedLitPrice, anchor, litlen, optStatePtr)
|
|
+ ZSTD_litLengthContribution(litlen, optStatePtr);
|
|
return contribution;
|
|
}
|
|
|
|
FORCE_INLINE_TEMPLATE
|
|
size_t ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
|
|
const void* src, size_t srcSize,
|
|
const int optLevel, const int extDict)
|
|
{
|
|
seqStore_t* const seqStorePtr = &(ctx->seqStore);
|
|
optState_t* const optStatePtr = &(ctx->optState);
|
|
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 = ctx->base;
|
|
const BYTE* const prefixStart = base + ctx->dictLimit;
|
|
|
|
U32 const maxSearches = 1U << ctx->appliedParams.cParams.searchLog;
|
|
U32 const sufficient_len = MIN(ctx->appliedParams.cParams.targetLength, ZSTD_OPT_NUM -1);
|
|
U32 const mls = ctx->appliedParams.cParams.searchLength;
|
|
U32 const minMatch = (ctx->appliedParams.cParams.searchLength == 3) ? 3 : 4;
|
|
|
|
ZSTD_optimal_t* const opt = optStatePtr->priceTable;
|
|
ZSTD_match_t* const matches = optStatePtr->matchTable;
|
|
cachedLiteralPrice_t cachedLitPrice;
|
|
U32 rep[ZSTD_REP_NUM];
|
|
|
|
/* init */
|
|
DEBUGLOG(5, "ZSTD_compressBlock_opt_generic");
|
|
ctx->nextToUpdate3 = ctx->nextToUpdate;
|
|
ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize);
|
|
ip += (ip==prefixStart);
|
|
{ int i; for (i=0; i<ZSTD_REP_NUM; i++) rep[i]=seqStorePtr->rep[i]; }
|
|
memset(&cachedLitPrice, 0, sizeof(cachedLitPrice));
|
|
|
|
/* Match Loop */
|
|
while (ip < ilimit) {
|
|
U32 cur, last_pos = 0;
|
|
U32 best_mlen, best_off;
|
|
|
|
/* find first match */
|
|
{ U32 const litlen = (U32)(ip - anchor);
|
|
U32 const ll0 = !litlen;
|
|
U32 const nbMatches = ZSTD_BtGetAllMatches(ctx, ip, iend, extDict, maxSearches, mls, sufficient_len, rep, ll0, matches, minMatch);
|
|
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 = 1;
|
|
opt[0].litlen = litlen;
|
|
|
|
/* large match -> immediate encoding */
|
|
{ U32 const maxML = matches[nbMatches-1].len;
|
|
DEBUGLOG(7, "found %u matches of maxLength=%u and offset=%u at cPos=%u => start new serie",
|
|
nbMatches, maxML, matches[nbMatches-1].off, (U32)(ip-prefixStart));
|
|
|
|
if (maxML > sufficient_len) {
|
|
best_mlen = maxML;
|
|
best_off = matches[nbMatches-1].off;
|
|
DEBUGLOG(7, "large match (%u>%u), immediate encoding",
|
|
best_mlen, sufficient_len);
|
|
cur = 0;
|
|
last_pos = 1;
|
|
goto _shortestPath;
|
|
} }
|
|
|
|
/* set prices for first matches starting position == 0 */
|
|
{ U32 const literalsPrice = ZSTD_fullLiteralsCost_cached(&cachedLitPrice, anchor, litlen, optStatePtr);
|
|
U32 pos;
|
|
U32 matchNb;
|
|
for (pos = 0; pos < minMatch; pos++) {
|
|
opt[pos].mlen = 1;
|
|
opt[pos].price = ZSTD_MAX_PRICE;
|
|
}
|
|
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
|
|
U32 const offset = matches[matchNb].off;
|
|
U32 const end = matches[matchNb].len;
|
|
repcodes_t const repHistory = ZSTD_updateRep(rep, offset, ll0);
|
|
for ( ; pos <= end ; pos++ ) {
|
|
U32 const matchPrice = literalsPrice + ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel);
|
|
DEBUGLOG(7, "rPos:%u => set initial price : %u",
|
|
pos, matchPrice);
|
|
opt[pos].mlen = pos;
|
|
opt[pos].off = offset;
|
|
opt[pos].litlen = litlen;
|
|
opt[pos].price = matchPrice;
|
|
memcpy(opt[pos].rep, &repHistory, sizeof(repHistory));
|
|
} }
|
|
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);
|
|
|
|
/* Fix current position with one literal if cheaper */
|
|
{ U32 const litlen = (opt[cur-1].mlen == 1) ? opt[cur-1].litlen + 1 : 1;
|
|
int price; /* note : contribution can be negative */
|
|
if (cur > litlen) {
|
|
price = opt[cur - litlen].price + ZSTD_literalsContribution(inr-litlen, litlen, optStatePtr);
|
|
} else {
|
|
price = ZSTD_literalsContribution_cached(&cachedLitPrice, anchor, litlen, optStatePtr);
|
|
}
|
|
assert(price < 1000000000); /* overflow check */
|
|
if (price <= opt[cur].price) {
|
|
DEBUGLOG(7, "rPos:%u : better price (%u<%u) using literal",
|
|
cur, price, opt[cur].price);
|
|
opt[cur].mlen = 1;
|
|
opt[cur].off = 0;
|
|
opt[cur].litlen = litlen;
|
|
opt[cur].price = price;
|
|
memcpy(opt[cur].rep, opt[cur-1].rep, sizeof(opt[cur].rep));
|
|
} }
|
|
|
|
/* 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*/
|
|
&& (opt[cur+1].price <= opt[cur].price) )
|
|
continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */
|
|
|
|
{ U32 const ll0 = (opt[cur].mlen != 1);
|
|
U32 const litlen = (opt[cur].mlen == 1) ? opt[cur].litlen : 0;
|
|
U32 const previousPrice = (cur > litlen) ? opt[cur-litlen].price : 0;
|
|
U32 const basePrice = previousPrice + ZSTD_fullLiteralsCost(inr-litlen, litlen, optStatePtr);
|
|
U32 const nbMatches = ZSTD_BtGetAllMatches(ctx, inr, iend, extDict, maxSearches, mls, sufficient_len, opt[cur].rep, ll0, matches, minMatch);
|
|
U32 matchNb;
|
|
if (!nbMatches) continue;
|
|
|
|
{ U32 const maxML = matches[nbMatches-1].len;
|
|
DEBUGLOG(7, "rPos:%u, found %u matches, of maxLength=%u",
|
|
cur, nbMatches, maxML);
|
|
|
|
if ( (maxML > sufficient_len)
|
|
| (cur + maxML >= ZSTD_OPT_NUM) ) {
|
|
best_mlen = maxML;
|
|
best_off = matches[nbMatches-1].off;
|
|
last_pos = cur + 1;
|
|
goto _shortestPath;
|
|
}
|
|
}
|
|
|
|
/* set prices using matches found at position == cur */
|
|
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
|
|
U32 const offset = matches[matchNb].off;
|
|
repcodes_t const repHistory = ZSTD_updateRep(opt[cur].rep, offset, ll0);
|
|
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=%u, mlen=%u, llen=%u",
|
|
matchNb, matches[matchNb].off, lastML, litlen);
|
|
|
|
for (mlen = lastML; mlen >= startML; mlen--) {
|
|
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 => new better price (%u<%u)",
|
|
pos, price, opt[pos].price);
|
|
SET_PRICE(pos, mlen, offset, litlen, price, repHistory); /* note : macro modifies last_pos */
|
|
} else {
|
|
if (optLevel==0) break; /* gets ~+10% speed for about -0.01 ratio loss */
|
|
}
|
|
} } }
|
|
} /* for (cur = 1; cur <= last_pos; cur++) */
|
|
|
|
best_mlen = opt[last_pos].mlen;
|
|
best_off = opt[last_pos].off;
|
|
cur = last_pos - best_mlen;
|
|
|
|
_shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
|
|
assert(opt[0].mlen == 1);
|
|
|
|
/* reverse traversal */
|
|
DEBUGLOG(7, "start reverse traversal (last_pos:%u, cur:%u)",
|
|
last_pos, cur);
|
|
{ U32 selectedMatchLength = best_mlen;
|
|
U32 selectedOffset = best_off;
|
|
U32 pos = cur;
|
|
while (1) {
|
|
U32 const mlen = opt[pos].mlen;
|
|
U32 const off = opt[pos].off;
|
|
opt[pos].mlen = selectedMatchLength;
|
|
opt[pos].off = selectedOffset;
|
|
selectedMatchLength = mlen;
|
|
selectedOffset = off;
|
|
if (mlen > pos) break;
|
|
pos -= mlen;
|
|
} }
|
|
|
|
/* save sequences */
|
|
{ U32 pos;
|
|
for (pos=0; pos < last_pos; ) {
|
|
U32 const llen = (U32)(ip - anchor);
|
|
U32 const mlen = opt[pos].mlen;
|
|
U32 const offset = opt[pos].off;
|
|
if (mlen == 1) { ip++; pos++; continue; } /* literal position => move on */
|
|
pos += mlen; ip += mlen;
|
|
|
|
/* repcodes update : like ZSTD_updateRep(), but update in place */
|
|
if (offset >= ZSTD_REP_NUM) { /* full offset */
|
|
rep[2] = rep[1];
|
|
rep[1] = rep[0];
|
|
rep[0] = offset - ZSTD_REP_MOVE;
|
|
} else { /* repcode */
|
|
U32 const repCode = offset + (llen==0);
|
|
if (repCode) { /* note : if repCode==0, no change */
|
|
U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
|
|
if (repCode >= 2) rep[2] = rep[1];
|
|
rep[1] = rep[0];
|
|
rep[0] = currentOffset;
|
|
}
|
|
}
|
|
|
|
ZSTD_updateStats(optStatePtr, llen, anchor, offset, mlen);
|
|
ZSTD_storeSeq(seqStorePtr, llen, anchor, offset, mlen-MINMATCH);
|
|
anchor = ip;
|
|
} }
|
|
ZSTD_setLog2Prices(optStatePtr);
|
|
} /* while (ip < ilimit) */
|
|
|
|
/* Save reps for next block */
|
|
{ int i; for (i=0; i<ZSTD_REP_NUM; i++) seqStorePtr->repToConfirm[i] = rep[i]; }
|
|
|
|
/* Return the last literals size */
|
|
return iend - anchor;
|
|
}
|
|
|
|
|
|
size_t ZSTD_compressBlock_btopt(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
|
|
{
|
|
DEBUGLOG(5, "ZSTD_compressBlock_btopt");
|
|
return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 0 /*optLevel*/, 0 /*extDict*/);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btopt_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 0 /*optLevel*/, 1 /*extDict*/);
|
|
}
|
|
|
|
size_t ZSTD_compressBlock_btultra_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
|
|
{
|
|
return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 2 /*optLevel*/, 1 /*extDict*/);
|
|
}
|