facebook
/
zstd
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
zstd/lib/compress/zstd_opt.c

923 lines
39 KiB
C
Raw Blame History

/*
* Copyright (c) 2016-present, Przemyslaw Skibinski, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
#include "zstd_compress_internal.h"
#include "zstd_opt.h"
#define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats. Also used for matchSum (?) */
#define ZSTD_FREQ_DIV 4 /* log factor when using previous stats to init next stats */
#define ZSTD_MAX_PRICE (1<<30)
/*-*************************************
* Price functions for optimal parser
***************************************/
static void ZSTD_setLog2Prices(optState_t* optPtr)
{
optPtr->log2litSum = ZSTD_highbit32(optPtr->litSum+1);
optPtr->log2litLengthSum = ZSTD_highbit32(optPtr->litLengthSum+1);
optPtr->log2matchLengthSum = ZSTD_highbit32(optPtr->matchLengthSum+1);
optPtr->log2offCodeSum = ZSTD_highbit32(optPtr->offCodeSum+1);
}
static void ZSTD_rescaleFreqs(optState_t* const optPtr,
const BYTE* const src, size_t const srcSize)
{
optPtr->staticPrices = 0;
if (optPtr->litLengthSum == 0) { /* first init */
unsigned u;
if (srcSize <= 1024) optPtr->staticPrices = 1;
assert(optPtr->litFreq!=NULL);
for (u=0; u<=MaxLit; u++)
optPtr->litFreq[u] = 0;
for (u=0; u<srcSize; u++)
optPtr->litFreq[src[u]]++;
optPtr->litSum = 0;
for (u=0; u<=MaxLit; u++) {
optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> ZSTD_FREQ_DIV);
optPtr->litSum += optPtr->litFreq[u];
}
for (u=0; u<=MaxLL; u++)
optPtr->litLengthFreq[u] = 1;
optPtr->litLengthSum = MaxLL+1;
for (u=0; u<=MaxML; u++)
optPtr->matchLengthFreq[u] = 1;
optPtr->matchLengthSum = MaxML+1;
for (u=0; u<=MaxOff; u++)
optPtr->offCodeFreq[u] = 1;
optPtr->offCodeSum = (MaxOff+1);
} else {
unsigned u;
optPtr->litSum = 0;
for (u=0; u<=MaxLit; u++) {
optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> (ZSTD_FREQ_DIV+1));
optPtr->litSum += optPtr->litFreq[u];
}
optPtr->litLengthSum = 0;
for (u=0; u<=MaxLL; u++) {
optPtr->litLengthFreq[u] = 1 + (optPtr->litLengthFreq[u]>>(ZSTD_FREQ_DIV+1));
optPtr->litLengthSum += optPtr->litLengthFreq[u];
}
optPtr->matchLengthSum = 0;
for (u=0; u<=MaxML; u++) {
optPtr->matchLengthFreq[u] = 1 + (optPtr->matchLengthFreq[u]>>ZSTD_FREQ_DIV);
optPtr->matchLengthSum += optPtr->matchLengthFreq[u];
}
optPtr->offCodeSum = 0;
for (u=0; u<=MaxOff; u++) {
optPtr->offCodeFreq[u] = 1 + (optPtr->offCodeFreq[u]>>ZSTD_FREQ_DIV);
optPtr->offCodeSum += optPtr->offCodeFreq[u];
}
}
ZSTD_setLog2Prices(optPtr);
}
/* ZSTD_rawLiteralsCost() :
* cost of literals (only) in given segment (which length can be null)
* does not include cost of literalLength symbol */
static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength,
const optState_t* const optPtr)
{
if (optPtr->staticPrices) return (litLength*6); /* 6 bit per literal - no statistic used */
if (litLength == 0) return 0;
/* literals */
{ U32 u;
U32 cost = litLength * optPtr->log2litSum;
for (u=0; u < litLength; u++)
cost -= ZSTD_highbit32(optPtr->litFreq[literals[u]]+1);
return cost;
}
}
/* ZSTD_litLengthPrice() :
* cost of literalLength symbol */
static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr)
{
if (optPtr->staticPrices) return ZSTD_highbit32((U32)litLength+1);
/* literal Length */
{ U32 const llCode = ZSTD_LLcode(litLength);
U32 const price = LL_bits[llCode] + optPtr->log2litLengthSum - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
return price;
}
}
/* ZSTD_litLengthPrice() :
* cost of the literal part of a sequence,
* including literals themselves, and literalLength symbol */
static U32 ZSTD_fullLiteralsCost(const BYTE* const literals, U32 const litLength,
const optState_t* const optPtr)
{
return ZSTD_rawLiteralsCost(literals, litLength, optPtr)
+ ZSTD_litLengthPrice(litLength, optPtr);
}
/* ZSTD_litLengthContribution() :
* @return ( cost(litlength) - cost(0) )
* this value can then be added to rawLiteralsCost()
* to provide a cost which is directly comparable to a match ending at same position */
static int ZSTD_litLengthContribution(U32 const litLength, const optState_t* const optPtr)
{
if (optPtr->staticPrices) return ZSTD_highbit32(litLength+1);
/* literal Length */
{ U32 const llCode = ZSTD_LLcode(litLength);
int const contribution = LL_bits[llCode]
+ ZSTD_highbit32(optPtr->litLengthFreq[0]+1)
- ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
#if 1
return contribution;
#else
return MAX(0, contribution); /* sometimes better, sometimes not ... */
#endif
}
}
/* ZSTD_literalsContribution() :
* creates a fake cost for the literals part of a sequence
* which can be compared to the ending cost of a match
* should a new match start at this position */
static int ZSTD_literalsContribution(const BYTE* const literals, U32 const litLength,
const optState_t* const optPtr)
{
int const contribution = ZSTD_rawLiteralsCost(literals, litLength, optPtr)
+ ZSTD_litLengthContribution(litLength, optPtr);
return contribution;
}
/* ZSTD_getMatchPrice() :
* Provides the cost of the match part (offset + matchLength) of a sequence
* Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence.
* optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */
FORCE_INLINE_TEMPLATE U32 ZSTD_getMatchPrice(
U32 const offset, U32 const matchLength,
const optState_t* const optPtr,
int const optLevel)
{
U32 price;
U32 const offCode = ZSTD_highbit32(offset+1);
U32 const mlBase = matchLength - MINMATCH;
assert(matchLength >= MINMATCH);
if (optPtr->staticPrices) /* fixed scheme, do not use statistics */
return ZSTD_highbit32((U32)mlBase+1) + 16 + offCode;
price = offCode + optPtr->log2offCodeSum - ZSTD_highbit32(optPtr->offCodeFreq[offCode]+1);
if ((optLevel<2) /*static*/ && offCode >= 20) price += (offCode-19)*2; /* handicap for long distance offsets, favor decompression speed */
/* match Length */
{ U32 const mlCode = ZSTD_MLcode(mlBase);
price += ML_bits[mlCode] + optPtr->log2matchLengthSum - ZSTD_highbit32(optPtr->matchLengthFreq[mlCode]+1);
}
DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price);
return price;
}
static void ZSTD_updateStats(optState_t* const optPtr,
U32 litLength, const BYTE* literals,
U32 offsetCode, U32 matchLength)
{
/* literals */
{ U32 u;
for (u=0; u < litLength; u++)
optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD;
optPtr->litSum += litLength*ZSTD_LITFREQ_ADD;
}
/* literal Length */
{ U32 const llCode = ZSTD_LLcode(litLength);
optPtr->litLengthFreq[llCode]++;
optPtr->litLengthSum++;
}
/* match offset code (0-2=>repCode; 3+=>offset+2) */
{ U32 const offCode = ZSTD_highbit32(offsetCode+1);
assert(offCode <= MaxOff);
optPtr->offCodeFreq[offCode]++;
optPtr->offCodeSum++;
}
/* match Length */
{ U32 const mlBase = matchLength - MINMATCH;
U32 const mlCode = ZSTD_MLcode(mlBase);
optPtr->matchLengthFreq[mlCode]++;
optPtr->matchLengthSum++;
}
}
/* ZSTD_readMINMATCH() :
* function safe only for comparisons
* assumption : memPtr must be at least 4 bytes before end of buffer */
MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length)
{
switch (length)
{
default :
case 4 : return MEM_read32(memPtr);
case 3 : if (MEM_isLittleEndian())
return MEM_read32(memPtr)<<8;
else
return MEM_read32(memPtr)>>8;
}
}
/* Update hashTable3 up to ip (excluded)
Assumption : always within prefix (i.e. not within extDict) */
static U32 ZSTD_insertAndFindFirstIndexHash3 (ZSTD_matchState_t* ms, const BYTE* const ip)
{
U32* const hashTable3 = ms->hashTable3;
U32 const hashLog3 = ms->hashLog3;
const BYTE* const base = ms->base;
U32 idx = ms->nextToUpdate3;
U32 const target = ms->nextToUpdate3 = (U32)(ip - base);
size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3);
while(idx < target) {
hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx;
idx++;
}
return hashTable3[hash3];
}
/*-*************************************
* Binary Tree search
***************************************/
/** ZSTD_insertBt1() : add one or multiple positions to tree.
* ip : assumed <= iend-8 .
* @return : nb of positions added */
static U32 ZSTD_insertBt1(
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
const BYTE* const ip, const BYTE* const iend,
U32 const mls, U32 const extDict)
{
U32* const hashTable = ms->hashTable;
U32 const hashLog = cParams->hashLog;
size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
U32* const bt = ms->chainTable;
U32 const btLog = cParams->chainLog - 1;
U32 const btMask = (1 << btLog) - 1;
U32 matchIndex = hashTable[h];
size_t commonLengthSmaller=0, commonLengthLarger=0;
const BYTE* const base = ms->base;
const BYTE* const dictBase = ms->dictBase;
const U32 dictLimit = ms->dictLimit;
const BYTE* const dictEnd = dictBase + dictLimit;
const BYTE* const prefixStart = base + dictLimit;
const BYTE* match;
const U32 current = (U32)(ip-base);
const U32 btLow = btMask >= current ? 0 : current - btMask;
U32* smallerPtr = bt + 2*(current&btMask);
U32* largerPtr = smallerPtr + 1;
U32 dummy32; /* to be nullified at the end */
U32 const windowLow = ms->lowLimit;
U32 matchEndIdx = current+8+1;
size_t bestLength = 8;
U32 nbCompares = 1U << cParams->searchLog;
#ifdef ZSTD_C_PREDICT
U32 predictedSmall = *(bt + 2*((current-1)&btMask) + 0);
U32 predictedLarge = *(bt + 2*((current-1)&btMask) + 1);
predictedSmall += (predictedSmall>0);
predictedLarge += (predictedLarge>0);
#endif /* ZSTD_C_PREDICT */
DEBUGLOG(8, "ZSTD_insertBt1 (%u)", current);
assert(ip <= iend-8); /* required for h calculation */
hashTable[h] = current; /* Update Hash Table */
while (nbCompares-- && (matchIndex > windowLow)) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
assert(matchIndex < current);
#ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */
const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */
if (matchIndex == predictedSmall) {
/* no need to check length, result known */
*smallerPtr = matchIndex;
if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
smallerPtr = nextPtr+1; /* new "smaller" => larger of match */
matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
predictedSmall = predictPtr[1] + (predictPtr[1]>0);
continue;
}
if (matchIndex == predictedLarge) {
*largerPtr = matchIndex;
if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */
largerPtr = nextPtr;
matchIndex = nextPtr[0];
predictedLarge = predictPtr[0] + (predictPtr[0]>0);
continue;
}
#endif
if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
assert(matchIndex+matchLength >= dictLimit); /* might be wrong if extDict is incorrectly set to 0 */
match = base + matchIndex;
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;
if (bestLength > 384) return MIN(192, (U32)(bestLength - 384)); /* speed optimization */
assert(matchEndIdx > current + 8);
return matchEndIdx - (current + 8);
}
FORCE_INLINE_TEMPLATE
void ZSTD_updateTree_internal(
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
const BYTE* const ip, const BYTE* const iend,
const U32 mls, const U32 extDict)
{
const BYTE* const base = ms->base;
U32 const target = (U32)(ip - base);
U32 idx = ms->nextToUpdate;
DEBUGLOG(7, "ZSTD_updateTree_internal, from %u to %u (extDict:%u)",
idx, target, extDict);
while(idx < target)
idx += ZSTD_insertBt1(ms, cParams, base+idx, iend, mls, extDict);
ms->nextToUpdate = target;
}
void ZSTD_updateTree(
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
const BYTE* ip, const BYTE* iend)
{
ZSTD_updateTree_internal(ms, cParams, ip, iend, cParams->searchLength, 0 /*extDict*/);
}
FORCE_INLINE_TEMPLATE
U32 ZSTD_insertBtAndGetAllMatches (
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
const BYTE* const ip, const BYTE* const iLimit, int const extDict,
U32 rep[ZSTD_REP_NUM], U32 const ll0,
ZSTD_match_t* matches, const U32 lengthToBeat, U32 const mls /* template */)
{
U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1);
const BYTE* const base = ms->base;
U32 const current = (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->dictBase;
U32 const dictLimit = ms->dictLimit;
const BYTE* const dictEnd = dictBase + dictLimit;
const BYTE* const prefixStart = base + dictLimit;
U32 const btLow = btMask >= current ? 0 : current - btMask;
U32 const windowLow = ms->lowLimit;
U32* smallerPtr = bt + 2*(current&btMask);
U32* largerPtr = bt + 2*(current&btMask) + 1;
U32 matchEndIdx = current+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;
size_t bestLength = lengthToBeat-1;
DEBUGLOG(7, "ZSTD_insertBtAndGetAllMatches");
/* check repCode */
{ 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 = current - repOffset;
U32 repLen = 0;
assert(current >= dictLimit);
if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) { /* equivalent to `current > repIndex >= dictLimit` */
if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) {
repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
}
} else { /* repIndex < dictLimit || repIndex >= current */
const BYTE* const repMatch = dictBase + repIndex;
assert(current >= windowLow);
if ( extDict /* this case only valid in extDict mode */
&& ( ((repOffset-1) /*intentional overflow*/ < current - windowLow) /* equivalent to `current > 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;
} }
/* save longer solution */
if (repLen > bestLength) {
DEBUGLOG(8, "found rep-match %u of length %u",
repCode - ll0, (U32)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, ip);
if ((matchIndex3 > windowLow)
& (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) {
size_t mlen;
if ((!extDict) /*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(current > matchIndex3);
assert(mnum==0); /* no prior solution */
matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE;
matches[0].len = (U32)mlen;
mnum = 1;
if ( (mlen > sufficient_len) |
(ip+mlen == iLimit) ) { /* best possible length */
ms->nextToUpdate = current+1; /* skip insertion */
return 1;
} } } }
hashTable[h] = current; /* Update Hash Table */
while (nbCompares-- && (matchIndex > windowLow)) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match;
assert(current > matchIndex);
if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */
match = base + matchIndex;
matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit);
} else {
match = dictBase + matchIndex;
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart);
if (matchIndex+matchLength >= dictLimit)
match = base + matchIndex; /* prepare for match[matchLength] */
}
if (matchLength > bestLength) {
DEBUGLOG(8, "found match of length %u at distance %u",
(U32)matchLength, current - matchIndex);
assert(matchEndIdx > matchIndex);
if (matchLength > matchEndIdx - matchIndex)
matchEndIdx = matchIndex + (U32)matchLength;
bestLength = matchLength;
matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE;
matches[mnum].len = (U32)matchLength;
mnum++;
if (matchLength > ZSTD_OPT_NUM) break;
if (ip+matchLength == iLimit) { /* equal : no way to know if inf or sup */
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;
assert(matchEndIdx > current+8);
ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
return mnum;
}
FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches (
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
const BYTE* ip, const BYTE* const iHighLimit, int const extDict,
U32 rep[ZSTD_REP_NUM], U32 const ll0,
ZSTD_match_t* matches, U32 const lengthToBeat)
{
U32 const matchLengthSearch = cParams->searchLength;
DEBUGLOG(7, "ZSTD_BtGetAllMatches");
if (ip < ms->base + ms->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree_internal(ms, cParams, ip, iHighLimit, matchLengthSearch, extDict);
switch(matchLengthSearch)
{
case 3 : return ZSTD_insertBtAndGetAllMatches(ms, cParams, ip, iHighLimit, extDict, rep, ll0, matches, lengthToBeat, 3);
default :
case 4 : return ZSTD_insertBtAndGetAllMatches(ms, cParams, ip, iHighLimit, extDict, rep, ll0, matches, lengthToBeat, 4);
case 5 : return ZSTD_insertBtAndGetAllMatches(ms, cParams, ip, iHighLimit, extDict, rep, ll0, matches, lengthToBeat, 5);
case 7 :
case 6 : return ZSTD_insertBtAndGetAllMatches(ms, cParams, ip, iHighLimit, extDict, rep, ll0, matches, lengthToBeat, 6);
}
}
/*-*******************************
* 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;
}
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_matchState_t* ms,seqStore_t* seqStore,
U32 rep[ZSTD_REP_NUM],
ZSTD_compressionParameters const* cParams,
const void* src, size_t srcSize,
const int optLevel, const int extDict)
{
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->base;
const BYTE* const prefixStart = base + ms->dictLimit;
U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1);
U32 const minMatch = (cParams->searchLength == 3) ? 3 : 4;
ZSTD_optimal_t* const opt = optStatePtr->priceTable;
ZSTD_match_t* const matches = optStatePtr->matchTable;
cachedLiteralPrice_t cachedLitPrice;
/* init */
DEBUGLOG(5, "ZSTD_compressBlock_opt_generic");
ms->nextToUpdate3 = ms->nextToUpdate;
ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize);
ip += (ip==prefixStart);
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(ms, cParams, ip, iend, extDict, 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(ms, cParams, inr, iend, extDict, 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);
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, &repHistory, sizeof(repHistory));
} 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(seqStore, llen, anchor, offset, mlen-MINMATCH);
anchor = ip;
} }
ZSTD_setLog2Prices(optStatePtr);
} /* while (ip < ilimit) */
/* Return the last literals size */
return iend - anchor;
}
size_t ZSTD_compressBlock_btopt(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
{
DEBUGLOG(5, "ZSTD_compressBlock_btopt");
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 0 /*optLevel*/, 0 /*extDict*/);
}
size_t ZSTD_compressBlock_btultra(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
{
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/);
}
size_t ZSTD_compressBlock_btopt_extDict(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
{
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 0 /*optLevel*/, 1 /*extDict*/);
}
size_t ZSTD_compressBlock_btultra_extDict(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
{
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 2 /*optLevel*/, 1 /*extDict*/);
}
Reference in New Issue View Git Blame Copy Permalink