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/*
* Copyright ( c ) 2016 - present , 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 .
*/
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# include "zstd_compress_internal.h"
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# include "zstd_lazy.h"
/*-*************************************
* Binary Tree search
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void
ZSTD_updateDUBT ( ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * iend ,
U32 mls )
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{
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const ZSTD_compressionParameters * const cParams = & ms - > cParams ;
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U32 * const hashTable = ms - > hashTable ;
U32 const hashLog = cParams - > hashLog ;
U32 * const bt = ms - > chainTable ;
U32 const btLog = cParams - > chainLog - 1 ;
U32 const btMask = ( 1 < < btLog ) - 1 ;
const BYTE * const base = ms - > window . base ;
U32 const target = ( U32 ) ( ip - base ) ;
U32 idx = ms - > nextToUpdate ;
if ( idx ! = target )
DEBUGLOG ( 7 , " ZSTD_updateDUBT, from %u to %u (dictLimit:%u) " ,
idx , target , ms - > window . dictLimit ) ;
assert ( ip + 8 < = iend ) ; /* condition for ZSTD_hashPtr */
( void ) iend ;
assert ( idx > = ms - > window . dictLimit ) ; /* condition for valid base+idx */
for ( ; idx < target ; idx + + ) {
size_t const h = ZSTD_hashPtr ( base + idx , hashLog , mls ) ; /* assumption : ip + 8 <= iend */
U32 const matchIndex = hashTable [ h ] ;
U32 * const nextCandidatePtr = bt + 2 * ( idx & btMask ) ;
U32 * const sortMarkPtr = nextCandidatePtr + 1 ;
DEBUGLOG ( 8 , " ZSTD_updateDUBT: insert %u " , idx ) ;
hashTable [ h ] = idx ; /* Update Hash Table */
* nextCandidatePtr = matchIndex ; /* update BT like a chain */
* sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK ;
}
ms - > nextToUpdate = target ;
}
/** ZSTD_insertDUBT1() :
* sort one already inserted but unsorted position
* assumption : current > = btlow = = ( current - btmask )
* doesn ' t fail */
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static void
ZSTD_insertDUBT1 ( ZSTD_matchState_t * ms ,
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U32 current , const BYTE * inputEnd ,
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U32 nbCompares , U32 btLow ,
const ZSTD_dictMode_e dictMode )
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{
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const ZSTD_compressionParameters * const cParams = & ms - > cParams ;
U32 * const bt = ms - > chainTable ;
U32 const btLog = cParams - > chainLog - 1 ;
U32 const btMask = ( 1 < < btLog ) - 1 ;
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size_t commonLengthSmaller = 0 , commonLengthLarger = 0 ;
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const BYTE * const base = ms - > window . base ;
const BYTE * const dictBase = ms - > window . dictBase ;
const U32 dictLimit = ms - > window . dictLimit ;
const BYTE * const ip = ( current > = dictLimit ) ? base + current : dictBase + current ;
const BYTE * const iend = ( current > = dictLimit ) ? inputEnd : dictBase + dictLimit ;
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const BYTE * const dictEnd = dictBase + dictLimit ;
const BYTE * const prefixStart = base + dictLimit ;
const BYTE * match ;
U32 * smallerPtr = bt + 2 * ( current & btMask ) ;
U32 * largerPtr = smallerPtr + 1 ;
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U32 matchIndex = * smallerPtr ; /* this candidate is unsorted : next sorted candidate is reached through *smallerPtr, while *largerPtr contains previous unsorted candidate (which is already saved and can be overwritten) */
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U32 dummy32 ; /* to be nullified at the end */
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U32 const windowValid = ms - > window . lowLimit ;
U32 const maxDistance = 1U < < cParams - > windowLog ;
U32 const windowLow = ( current - windowValid > maxDistance ) ? current - maxDistance : windowValid ;
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DEBUGLOG ( 8 , " ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u) " ,
current , dictLimit , windowLow ) ;
assert ( current > = btLow ) ;
assert ( ip < iend ) ; /* condition for ZSTD_count */
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while ( nbCompares - - & & ( matchIndex > windowLow ) ) {
U32 * const nextPtr = bt + 2 * ( matchIndex & btMask ) ;
size_t matchLength = MIN ( commonLengthSmaller , commonLengthLarger ) ; /* guaranteed minimum nb of common bytes */
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assert ( matchIndex < current ) ;
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/* note : all candidates are now supposed sorted,
* but it ' s still possible to have nextPtr [ 1 ] = = ZSTD_DUBT_UNSORTED_MARK
* when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */
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if ( ( dictMode ! = ZSTD_extDict )
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| | ( matchIndex + matchLength > = dictLimit ) /* both in current segment*/
| | ( current < dictLimit ) /* both in extDict */ ) {
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const BYTE * const mBase = ( ( dictMode ! = ZSTD_extDict )
| | ( matchIndex + matchLength > = dictLimit ) ) ?
base : dictBase ;
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assert ( ( matchIndex + matchLength > = dictLimit ) /* might be wrong if extDict is incorrectly set to 0 */
| | ( current < dictLimit ) ) ;
match = mBase + matchIndex ;
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matchLength + = ZSTD_count ( ip + matchLength , match + matchLength , iend ) ;
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} else {
match = dictBase + matchIndex ;
matchLength + = ZSTD_count_2segments ( ip + matchLength , match + matchLength , iend , dictEnd , prefixStart ) ;
if ( matchIndex + matchLength > = dictLimit )
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match = base + matchIndex ; /* preparation for next read of match[matchLength] */
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}
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DEBUGLOG ( 8 , " ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes " ,
current , matchIndex , ( U32 ) matchLength ) ;
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if ( ip + matchLength = = iend ) { /* equal : no way to know if inf or sup */
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break ; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */
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}
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if ( match [ matchLength ] < ip [ matchLength ] ) { /* necessarily within buffer */
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/* match is smaller than current */
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* 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 */
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DEBUGLOG ( 8 , " ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u " ,
matchIndex , btLow , nextPtr [ 1 ] ) ;
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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 */
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} else {
/* match is larger than current */
* largerPtr = matchIndex ;
commonLengthLarger = matchLength ;
if ( matchIndex < = btLow ) { largerPtr = & dummy32 ; break ; } /* beyond tree size, stop searching */
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DEBUGLOG ( 8 , " ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u " ,
matchIndex , btLow , nextPtr [ 0 ] ) ;
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largerPtr = nextPtr ;
matchIndex = nextPtr [ 0 ] ;
} }
* smallerPtr = * largerPtr = 0 ;
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}
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static size_t
ZSTD_DUBT_findBetterDictMatch (
ZSTD_matchState_t * ms ,
const BYTE * const ip , const BYTE * const iend ,
size_t * offsetPtr ,
size_t bestLength ,
U32 nbCompares ,
U32 const mls ,
const ZSTD_dictMode_e dictMode )
{
const ZSTD_matchState_t * const dms = ms - > dictMatchState ;
const ZSTD_compressionParameters * const dmsCParams = & dms - > cParams ;
const U32 * const dictHashTable = dms - > hashTable ;
U32 const hashLog = dmsCParams - > hashLog ;
size_t const h = ZSTD_hashPtr ( ip , hashLog , mls ) ;
U32 dictMatchIndex = dictHashTable [ h ] ;
const BYTE * const base = ms - > window . base ;
const BYTE * const prefixStart = base + ms - > window . dictLimit ;
U32 const current = ( U32 ) ( ip - base ) ;
const BYTE * const dictBase = dms - > window . base ;
const BYTE * const dictEnd = dms - > window . nextSrc ;
U32 const dictHighLimit = ( U32 ) ( dms - > window . nextSrc - dms - > window . base ) ;
U32 const dictLowLimit = dms - > window . lowLimit ;
U32 const dictIndexDelta = ms - > window . lowLimit - dictHighLimit ;
U32 * const dictBt = dms - > chainTable ;
U32 const btLog = dmsCParams - > chainLog - 1 ;
U32 const btMask = ( 1 < < btLog ) - 1 ;
U32 const btLow = ( btMask > = dictHighLimit - dictLowLimit ) ? dictLowLimit : dictHighLimit - btMask ;
size_t commonLengthSmaller = 0 , commonLengthLarger = 0 ;
( void ) dictMode ;
assert ( dictMode = = ZSTD_dictMatchState ) ;
while ( nbCompares - - & & ( dictMatchIndex > dictLowLimit ) ) {
U32 * const nextPtr = dictBt + 2 * ( dictMatchIndex & btMask ) ;
size_t matchLength = MIN ( commonLengthSmaller , commonLengthLarger ) ; /* guaranteed minimum nb of common bytes */
const BYTE * match = dictBase + dictMatchIndex ;
matchLength + = ZSTD_count_2segments ( ip + matchLength , match + matchLength , iend , dictEnd , prefixStart ) ;
if ( dictMatchIndex + matchLength > = dictHighLimit )
match = base + dictMatchIndex + dictIndexDelta ; /* to prepare for next usage of match[matchLength] */
if ( matchLength > bestLength ) {
U32 matchIndex = dictMatchIndex + dictIndexDelta ;
if ( ( 4 * ( int ) ( matchLength - bestLength ) ) > ( int ) ( ZSTD_highbit32 ( current - matchIndex + 1 ) - ZSTD_highbit32 ( ( U32 ) offsetPtr [ 0 ] + 1 ) ) ) {
DEBUGLOG ( 9 , " ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u) " ,
current , ( U32 ) bestLength , ( U32 ) matchLength , ( U32 ) * offsetPtr , ZSTD_REP_MOVE + current - matchIndex , dictMatchIndex , matchIndex ) ;
bestLength = matchLength , * offsetPtr = ZSTD_REP_MOVE + current - matchIndex ;
}
if ( ip + matchLength = = iend ) { /* reached end of input : ip[matchLength] is not valid, no way to know if it's larger or smaller than match */
break ; /* drop, to guarantee consistency (miss a little bit of compression) */
}
}
if ( match [ matchLength ] < ip [ matchLength ] ) {
if ( dictMatchIndex < = btLow ) { break ; } /* beyond tree size, stop the search */
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 */
if ( dictMatchIndex < = btLow ) { break ; } /* beyond tree size, stop the search */
commonLengthLarger = matchLength ;
dictMatchIndex = nextPtr [ 0 ] ;
}
}
if ( bestLength > = MINMATCH ) {
U32 const mIndex = current - ( ( U32 ) * offsetPtr - ZSTD_REP_MOVE ) ; ( void ) mIndex ;
DEBUGLOG ( 8 , " ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u) " ,
current , ( U32 ) bestLength , ( U32 ) * offsetPtr , mIndex ) ;
}
return bestLength ;
}
static size_t
ZSTD_DUBT_findBestMatch ( ZSTD_matchState_t * ms ,
const BYTE * const ip , const BYTE * const iend ,
size_t * offsetPtr ,
U32 const mls ,
const ZSTD_dictMode_e dictMode )
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{
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const ZSTD_compressionParameters * const cParams = & ms - > cParams ;
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U32 * const hashTable = ms - > hashTable ;
U32 const hashLog = cParams - > hashLog ;
size_t const h = ZSTD_hashPtr ( ip , hashLog , mls ) ;
U32 matchIndex = hashTable [ h ] ;
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const BYTE * const base = ms - > window . base ;
U32 const current = ( U32 ) ( ip - base ) ;
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U32 const windowLow = ZSTD_getLowestMatchIndex ( ms , current , cParams - > windowLog ) ;
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U32 * const bt = ms - > chainTable ;
U32 const btLog = cParams - > chainLog - 1 ;
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U32 const btMask = ( 1 < < btLog ) - 1 ;
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U32 const btLow = ( btMask > = current ) ? 0 : current - btMask ;
U32 const unsortLimit = MAX ( btLow , windowLow ) ;
U32 * nextCandidate = bt + 2 * ( matchIndex & btMask ) ;
U32 * unsortedMark = bt + 2 * ( matchIndex & btMask ) + 1 ;
U32 nbCompares = 1U < < cParams - > searchLog ;
U32 nbCandidates = nbCompares ;
U32 previousCandidate = 0 ;
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DEBUGLOG ( 7 , " ZSTD_DUBT_findBestMatch (%u) " , current ) ;
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assert ( ip < = iend - 8 ) ; /* required for h calculation */
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/* reach end of unsorted candidates list */
while ( ( matchIndex > unsortLimit )
& & ( * unsortedMark = = ZSTD_DUBT_UNSORTED_MARK )
& & ( nbCandidates > 1 ) ) {
DEBUGLOG ( 8 , " ZSTD_DUBT_findBestMatch: candidate %u is unsorted " ,
matchIndex ) ;
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* unsortedMark = previousCandidate ; /* the unsortedMark becomes a reversed chain, to move up back to original position */
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previousCandidate = matchIndex ;
matchIndex = * nextCandidate ;
nextCandidate = bt + 2 * ( matchIndex & btMask ) ;
unsortedMark = bt + 2 * ( matchIndex & btMask ) + 1 ;
nbCandidates - - ;
}
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/* nullify last candidate if it's still unsorted
* simplification , detrimental to compression ratio , beneficial for speed */
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if ( ( matchIndex > unsortLimit )
& & ( * unsortedMark = = ZSTD_DUBT_UNSORTED_MARK ) ) {
DEBUGLOG ( 7 , " ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u " ,
matchIndex ) ;
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* nextCandidate = * unsortedMark = 0 ;
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}
/* batch sort stacked candidates */
matchIndex = previousCandidate ;
while ( matchIndex ) { /* will end on matchIndex == 0 */
U32 * const nextCandidateIdxPtr = bt + 2 * ( matchIndex & btMask ) + 1 ;
U32 const nextCandidateIdx = * nextCandidateIdxPtr ;
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ZSTD_insertDUBT1 ( ms , matchIndex , iend ,
nbCandidates , unsortLimit , dictMode ) ;
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matchIndex = nextCandidateIdx ;
nbCandidates + + ;
}
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/* find longest match */
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{ size_t commonLengthSmaller = 0 , commonLengthLarger = 0 ;
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const BYTE * const dictBase = ms - > window . dictBase ;
const U32 dictLimit = ms - > window . dictLimit ;
const BYTE * const dictEnd = dictBase + dictLimit ;
const BYTE * const prefixStart = base + dictLimit ;
U32 * smallerPtr = bt + 2 * ( current & btMask ) ;
U32 * largerPtr = bt + 2 * ( current & btMask ) + 1 ;
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U32 matchEndIdx = current + 8 + 1 ;
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U32 dummy32 ; /* to be nullified at the end */
size_t bestLength = 0 ;
matchIndex = hashTable [ h ] ;
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 ;
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if ( ( dictMode ! = ZSTD_extDict ) | | ( matchIndex + matchLength > = dictLimit ) ) {
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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] */
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}
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if ( matchLength > bestLength ) {
if ( matchLength > matchEndIdx - matchIndex )
matchEndIdx = matchIndex + ( U32 ) matchLength ;
if ( ( 4 * ( int ) ( matchLength - bestLength ) ) > ( int ) ( ZSTD_highbit32 ( current - matchIndex + 1 ) - ZSTD_highbit32 ( ( U32 ) offsetPtr [ 0 ] + 1 ) ) )
bestLength = matchLength , * offsetPtr = ZSTD_REP_MOVE + current - matchIndex ;
if ( ip + matchLength = = iend ) { /* equal : no way to know if inf or sup */
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if ( dictMode = = ZSTD_dictMatchState ) {
nbCompares = 0 ; /* in addition to avoiding checking any
* further in this loop , make sure we
* skip checking in the dictionary . */
}
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break ; /* drop, to guarantee consistency (miss a little bit of compression) */
}
}
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if ( match [ matchLength ] < ip [ matchLength ] ) {
/* 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 the search */
smallerPtr = nextPtr + 1 ; /* new "smaller" => larger of match */
matchIndex = nextPtr [ 1 ] ; /* new matchIndex larger than previous (closer to current) */
} else {
/* match is larger than current */
* largerPtr = matchIndex ;
commonLengthLarger = matchLength ;
if ( matchIndex < = btLow ) { largerPtr = & dummy32 ; break ; } /* beyond tree size, stop the search */
largerPtr = nextPtr ;
matchIndex = nextPtr [ 0 ] ;
} }
* smallerPtr = * largerPtr = 0 ;
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if ( dictMode = = ZSTD_dictMatchState & & nbCompares ) {
bestLength = ZSTD_DUBT_findBetterDictMatch (
ms , ip , iend ,
offsetPtr , bestLength , nbCompares ,
mls , dictMode ) ;
}
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assert ( matchEndIdx > current + 8 ) ; /* ensure nextToUpdate is increased */
ms - > nextToUpdate = matchEndIdx - 8 ; /* skip repetitive patterns */
if ( bestLength > = MINMATCH ) {
U32 const mIndex = current - ( ( U32 ) * offsetPtr - ZSTD_REP_MOVE ) ; ( void ) mIndex ;
DEBUGLOG ( 8 , " ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u) " ,
current , ( U32 ) bestLength , ( U32 ) * offsetPtr , mIndex ) ;
}
return bestLength ;
}
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}
/** ZSTD_BtFindBestMatch() : Tree updater, providing best match */
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FORCE_INLINE_TEMPLATE size_t
ZSTD_BtFindBestMatch ( ZSTD_matchState_t * ms ,
const BYTE * const ip , const BYTE * const iLimit ,
size_t * offsetPtr ,
const U32 mls /* template */ ,
const ZSTD_dictMode_e dictMode )
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{
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DEBUGLOG ( 7 , " ZSTD_BtFindBestMatch " ) ;
if ( ip < ms - > window . base + ms - > nextToUpdate ) return 0 ; /* skipped area */
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ZSTD_updateDUBT ( ms , ip , iLimit , mls ) ;
return ZSTD_DUBT_findBestMatch ( ms , ip , iLimit , offsetPtr , mls , dictMode ) ;
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}
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static size_t
ZSTD_BtFindBestMatch_selectMLS ( ZSTD_matchState_t * ms ,
const BYTE * ip , const BYTE * const iLimit ,
size_t * offsetPtr )
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{
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switch ( ms - > cParams . minMatch )
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{
default : /* includes case 3 */
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case 4 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_noDict ) ;
case 5 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_noDict ) ;
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case 7 :
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case 6 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_noDict ) ;
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}
}
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static size_t ZSTD_BtFindBestMatch_dictMatchState_selectMLS (
ZSTD_matchState_t * ms ,
const BYTE * ip , const BYTE * const iLimit ,
size_t * offsetPtr )
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{
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switch ( ms - > cParams . minMatch )
{
default : /* includes case 3 */
case 4 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_dictMatchState ) ;
case 5 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_dictMatchState ) ;
case 7 :
case 6 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_dictMatchState ) ;
}
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}
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static size_t ZSTD_BtFindBestMatch_extDict_selectMLS (
ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * const iLimit ,
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size_t * offsetPtr )
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{
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switch ( ms - > cParams . minMatch )
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{
default : /* includes case 3 */
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case 4 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_extDict ) ;
case 5 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_extDict ) ;
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case 7 :
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case 6 : return ZSTD_BtFindBestMatch ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_extDict ) ;
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}
}
/* *********************************
* Hash Chain
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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# define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)]
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/* Update chains up to ip (excluded)
Assumption : always within prefix ( i . e . not within extDict ) */
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static U32 ZSTD_insertAndFindFirstIndex_internal (
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ZSTD_matchState_t * ms ,
const ZSTD_compressionParameters * const cParams ,
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const BYTE * ip , U32 const mls )
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{
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U32 * const hashTable = ms - > hashTable ;
const U32 hashLog = cParams - > hashLog ;
U32 * const chainTable = ms - > chainTable ;
const U32 chainMask = ( 1 < < cParams - > chainLog ) - 1 ;
const BYTE * const base = ms - > window . base ;
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const U32 target = ( U32 ) ( ip - base ) ;
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U32 idx = ms - > nextToUpdate ;
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while ( idx < target ) { /* catch up */
size_t const h = ZSTD_hashPtr ( base + idx , hashLog , mls ) ;
NEXT_IN_CHAIN ( idx , chainMask ) = hashTable [ h ] ;
hashTable [ h ] = idx ;
idx + + ;
}
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ms - > nextToUpdate = target ;
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return hashTable [ ZSTD_hashPtr ( ip , hashLog , mls ) ] ;
}
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U32 ZSTD_insertAndFindFirstIndex ( ZSTD_matchState_t * ms , const BYTE * ip ) {
const ZSTD_compressionParameters * const cParams = & ms - > cParams ;
return ZSTD_insertAndFindFirstIndex_internal ( ms , cParams , ip , ms - > cParams . minMatch ) ;
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}
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/* inlining is important to hardwire a hot branch (template emulation) */
FORCE_INLINE_TEMPLATE
size_t ZSTD_HcFindBestMatch_generic (
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ZSTD_matchState_t * ms ,
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const BYTE * const ip , const BYTE * const iLimit ,
size_t * offsetPtr ,
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const U32 mls , const ZSTD_dictMode_e dictMode )
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{
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const ZSTD_compressionParameters * const cParams = & ms - > cParams ;
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U32 * const chainTable = ms - > chainTable ;
const U32 chainSize = ( 1 < < cParams - > chainLog ) ;
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const U32 chainMask = chainSize - 1 ;
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const BYTE * const base = ms - > window . base ;
const BYTE * const dictBase = ms - > window . dictBase ;
const U32 dictLimit = ms - > window . dictLimit ;
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const BYTE * const prefixStart = base + dictLimit ;
const BYTE * const dictEnd = dictBase + dictLimit ;
const U32 current = ( U32 ) ( ip - base ) ;
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const U32 maxDistance = 1U < < cParams - > windowLog ;
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const U32 lowestValid = ms - > window . lowLimit ;
const U32 withinMaxDistance = ( current - lowestValid > maxDistance ) ? current - maxDistance : lowestValid ;
const U32 isDictionary = ( ms - > loadedDictEnd ! = 0 ) ;
const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance ;
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const U32 minChain = current > chainSize ? current - chainSize : 0 ;
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U32 nbAttempts = 1U < < cParams - > searchLog ;
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size_t ml = 4 - 1 ;
/* HC4 match finder */
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U32 matchIndex = ZSTD_insertAndFindFirstIndex_internal ( ms , cParams , ip , mls ) ;
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for ( ; ( matchIndex > lowLimit ) & ( nbAttempts > 0 ) ; nbAttempts - - ) {
size_t currentMl = 0 ;
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if ( ( dictMode ! = ZSTD_extDict ) | | matchIndex > = dictLimit ) {
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const BYTE * const match = base + matchIndex ;
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assert ( matchIndex > = dictLimit ) ; /* ensures this is true if dictMode != ZSTD_extDict */
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if ( match [ ml ] = = ip [ ml ] ) /* potentially better */
currentMl = ZSTD_count ( ip , match , iLimit ) ;
} else {
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const BYTE * const match = dictBase + matchIndex ;
assert ( match + 4 < = dictEnd ) ;
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if ( MEM_read32 ( match ) = = MEM_read32 ( ip ) ) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments ( ip + 4 , match + 4 , iLimit , dictEnd , prefixStart ) + 4 ;
}
/* save best solution */
if ( currentMl > ml ) {
ml = currentMl ;
* offsetPtr = current - matchIndex + ZSTD_REP_MOVE ;
if ( ip + currentMl = = iLimit ) break ; /* best possible, avoids read overflow on next attempt */
}
if ( matchIndex < = minChain ) break ;
matchIndex = NEXT_IN_CHAIN ( matchIndex , chainMask ) ;
}
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if ( dictMode = = ZSTD_dictMatchState ) {
const ZSTD_matchState_t * const dms = ms - > dictMatchState ;
const U32 * const dmsChainTable = dms - > chainTable ;
const U32 dmsChainSize = ( 1 < < dms - > cParams . chainLog ) ;
const U32 dmsChainMask = dmsChainSize - 1 ;
const U32 dmsLowestIndex = dms - > window . dictLimit ;
const BYTE * const dmsBase = dms - > window . base ;
const BYTE * const dmsEnd = dms - > window . nextSrc ;
const U32 dmsSize = ( U32 ) ( dmsEnd - dmsBase ) ;
const U32 dmsIndexDelta = dictLimit - dmsSize ;
const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0 ;
matchIndex = dms - > hashTable [ ZSTD_hashPtr ( ip , dms - > cParams . hashLog , mls ) ] ;
for ( ; ( matchIndex > dmsLowestIndex ) & ( nbAttempts > 0 ) ; nbAttempts - - ) {
size_t currentMl = 0 ;
const BYTE * const match = dmsBase + matchIndex ;
assert ( match + 4 < = dmsEnd ) ;
if ( MEM_read32 ( match ) = = MEM_read32 ( ip ) ) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments ( ip + 4 , match + 4 , iLimit , dmsEnd , prefixStart ) + 4 ;
/* save best solution */
if ( currentMl > ml ) {
ml = currentMl ;
* offsetPtr = current - ( matchIndex + dmsIndexDelta ) + ZSTD_REP_MOVE ;
if ( ip + currentMl = = iLimit ) break ; /* best possible, avoids read overflow on next attempt */
}
if ( matchIndex < = dmsMinChain ) break ;
matchIndex = dmsChainTable [ matchIndex & dmsChainMask ] ;
}
}
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return ml ;
}
FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_selectMLS (
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ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * const iLimit ,
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size_t * offsetPtr )
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{
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switch ( ms - > cParams . minMatch )
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{
default : /* includes case 3 */
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case 4 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_noDict ) ;
case 5 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_noDict ) ;
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case 7 :
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case 6 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_noDict ) ;
}
}
static size_t ZSTD_HcFindBestMatch_dictMatchState_selectMLS (
ZSTD_matchState_t * ms ,
const BYTE * ip , const BYTE * const iLimit ,
size_t * offsetPtr )
{
switch ( ms - > cParams . minMatch )
{
default : /* includes case 3 */
case 4 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_dictMatchState ) ;
case 5 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_dictMatchState ) ;
case 7 :
case 6 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_dictMatchState ) ;
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}
}
FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_extDict_selectMLS (
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ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * const iLimit ,
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size_t * offsetPtr )
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{
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switch ( ms - > cParams . minMatch )
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{
default : /* includes case 3 */
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case 4 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 4 , ZSTD_extDict ) ;
case 5 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 5 , ZSTD_extDict ) ;
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case 7 :
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case 6 : return ZSTD_HcFindBestMatch_generic ( ms , ip , iLimit , offsetPtr , 6 , ZSTD_extDict ) ;
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}
}
/* *******************************
* Common parser - lazy strategy
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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typedef enum { search_hashChain , search_binaryTree } searchMethod_e ;
FORCE_INLINE_TEMPLATE size_t
ZSTD_compressBlock_lazy_generic (
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ZSTD_matchState_t * ms , seqStore_t * seqStore ,
U32 rep [ ZSTD_REP_NUM ] ,
const void * src , size_t srcSize ,
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const searchMethod_e searchMethod , const U32 depth ,
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ZSTD_dictMode_e const dictMode )
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{
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 ;
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const BYTE * const base = ms - > window . base ;
const U32 prefixLowestIndex = ms - > window . dictLimit ;
const BYTE * const prefixLowest = base + prefixLowestIndex ;
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typedef size_t ( * searchMax_f ) (
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ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * iLimit , size_t * offsetPtr ) ;
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searchMax_f const searchMax = dictMode = = ZSTD_dictMatchState ?
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( searchMethod = = search_binaryTree ? ZSTD_BtFindBestMatch_dictMatchState_selectMLS
: ZSTD_HcFindBestMatch_dictMatchState_selectMLS ) :
( searchMethod = = search_binaryTree ? ZSTD_BtFindBestMatch_selectMLS
: ZSTD_HcFindBestMatch_selectMLS ) ;
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U32 offset_1 = rep [ 0 ] , offset_2 = rep [ 1 ] , savedOffset = 0 ;
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const ZSTD_matchState_t * const dms = ms - > dictMatchState ;
const U32 dictLowestIndex = dictMode = = ZSTD_dictMatchState ?
dms - > window . dictLimit : 0 ;
const BYTE * const dictBase = dictMode = = ZSTD_dictMatchState ?
dms - > window . base : NULL ;
const BYTE * const dictLowest = dictMode = = ZSTD_dictMatchState ?
dictBase + dictLowestIndex : NULL ;
const BYTE * const dictEnd = dictMode = = ZSTD_dictMatchState ?
dms - > window . nextSrc : NULL ;
const U32 dictIndexDelta = dictMode = = ZSTD_dictMatchState ?
prefixLowestIndex - ( U32 ) ( dictEnd - dictBase ) :
0 ;
const U32 dictAndPrefixLength = ( U32 ) ( ip - prefixLowest + dictEnd - dictLowest ) ;
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/* init */
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ip + = ( dictAndPrefixLength = = 0 ) ;
if ( dictMode = = ZSTD_noDict ) {
U32 const maxRep = ( U32 ) ( ip - prefixLowest ) ;
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if ( offset_2 > maxRep ) savedOffset = offset_2 , offset_2 = 0 ;
if ( offset_1 > maxRep ) savedOffset = offset_1 , offset_1 = 0 ;
}
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if ( dictMode = = ZSTD_dictMatchState ) {
/* dictMatchState repCode checks don't currently handle repCode == 0
* disabling . */
assert ( offset_1 < = dictAndPrefixLength ) ;
assert ( offset_2 < = dictAndPrefixLength ) ;
}
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/* Match Loop */
while ( ip < ilimit ) {
size_t matchLength = 0 ;
size_t offset = 0 ;
const BYTE * start = ip + 1 ;
/* check repCode */
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if ( dictMode = = ZSTD_dictMatchState ) {
const U32 repIndex = ( U32 ) ( ip - base ) + 1 - offset_1 ;
const BYTE * repMatch = ( dictMode = = ZSTD_dictMatchState
& & repIndex < prefixLowestIndex ) ?
dictBase + ( repIndex - dictIndexDelta ) :
base + repIndex ;
if ( ( ( U32 ) ( ( prefixLowestIndex - 1 ) - repIndex ) > = 3 /* intentional underflow */ )
& & ( MEM_read32 ( repMatch ) = = MEM_read32 ( ip + 1 ) ) ) {
const BYTE * repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend ;
matchLength = ZSTD_count_2segments ( ip + 1 + 4 , repMatch + 4 , iend , repMatchEnd , prefixLowest ) + 4 ;
if ( depth = = 0 ) goto _storeSequence ;
}
}
if ( dictMode = = ZSTD_noDict
& & ( ( offset_1 > 0 ) & ( MEM_read32 ( ip + 1 - offset_1 ) = = MEM_read32 ( ip + 1 ) ) ) ) {
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matchLength = ZSTD_count ( ip + 1 + 4 , ip + 1 + 4 - offset_1 , iend ) + 4 ;
if ( depth = = 0 ) goto _storeSequence ;
}
/* first search (depth 0) */
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{ size_t offsetFound = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offsetFound ) ;
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if ( ml2 > matchLength )
matchLength = ml2 , start = ip , offset = offsetFound ;
}
if ( matchLength < 4 ) {
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ip + = ( ( ip - anchor ) > > kSearchStrength ) + 1 ; /* jump faster over incompressible sections */
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continue ;
}
/* let's try to find a better solution */
if ( depth > = 1 )
while ( ip < ilimit ) {
ip + + ;
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if ( ( dictMode = = ZSTD_noDict )
& & ( offset ) & & ( ( offset_1 > 0 ) & ( MEM_read32 ( ip ) = = MEM_read32 ( ip - offset_1 ) ) ) ) {
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size_t const mlRep = ZSTD_count ( ip + 4 , ip + 4 - offset_1 , iend ) + 4 ;
int const gain2 = ( int ) ( mlRep * 3 ) ;
int const gain1 = ( int ) ( matchLength * 3 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
if ( ( mlRep > = 4 ) & & ( gain2 > gain1 ) )
matchLength = mlRep , offset = 0 , start = ip ;
}
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if ( dictMode = = ZSTD_dictMatchState ) {
const U32 repIndex = ( U32 ) ( ip - base ) - offset_1 ;
const BYTE * repMatch = repIndex < prefixLowestIndex ?
dictBase + ( repIndex - dictIndexDelta ) :
base + repIndex ;
if ( ( ( U32 ) ( ( prefixLowestIndex - 1 ) - repIndex ) > = 3 /* intentional underflow */ )
& & ( MEM_read32 ( repMatch ) = = MEM_read32 ( ip ) ) ) {
const BYTE * repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend ;
size_t const mlRep = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repMatchEnd , prefixLowest ) + 4 ;
int const gain2 = ( int ) ( mlRep * 3 ) ;
int const gain1 = ( int ) ( matchLength * 3 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
if ( ( mlRep > = 4 ) & & ( gain2 > gain1 ) )
matchLength = mlRep , offset = 0 , start = ip ;
}
}
{ size_t offset2 = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offset2 ) ;
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int const gain2 = ( int ) ( ml2 * 4 - ZSTD_highbit32 ( ( U32 ) offset2 + 1 ) ) ; /* raw approx */
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 4 ) ;
if ( ( ml2 > = 4 ) & & ( gain2 > gain1 ) ) {
matchLength = ml2 , offset = offset2 , start = ip ;
continue ; /* search a better one */
} }
/* let's find an even better one */
if ( ( depth = = 2 ) & & ( ip < ilimit ) ) {
ip + + ;
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if ( ( dictMode = = ZSTD_noDict )
& & ( offset ) & & ( ( offset_1 > 0 ) & ( MEM_read32 ( ip ) = = MEM_read32 ( ip - offset_1 ) ) ) ) {
size_t const mlRep = ZSTD_count ( ip + 4 , ip + 4 - offset_1 , iend ) + 4 ;
int const gain2 = ( int ) ( mlRep * 4 ) ;
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int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
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if ( ( mlRep > = 4 ) & & ( gain2 > gain1 ) )
matchLength = mlRep , offset = 0 , start = ip ;
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}
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if ( dictMode = = ZSTD_dictMatchState ) {
const U32 repIndex = ( U32 ) ( ip - base ) - offset_1 ;
const BYTE * repMatch = repIndex < prefixLowestIndex ?
dictBase + ( repIndex - dictIndexDelta ) :
base + repIndex ;
if ( ( ( U32 ) ( ( prefixLowestIndex - 1 ) - repIndex ) > = 3 /* intentional underflow */ )
& & ( MEM_read32 ( repMatch ) = = MEM_read32 ( ip ) ) ) {
const BYTE * repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend ;
size_t const mlRep = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repMatchEnd , prefixLowest ) + 4 ;
int const gain2 = ( int ) ( mlRep * 4 ) ;
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
if ( ( mlRep > = 4 ) & & ( gain2 > gain1 ) )
matchLength = mlRep , offset = 0 , start = ip ;
}
}
{ size_t offset2 = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offset2 ) ;
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int const gain2 = ( int ) ( ml2 * 4 - ZSTD_highbit32 ( ( U32 ) offset2 + 1 ) ) ; /* raw approx */
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 7 ) ;
if ( ( ml2 > = 4 ) & & ( gain2 > gain1 ) ) {
matchLength = ml2 , offset = offset2 , start = ip ;
continue ;
} } }
break ; /* nothing found : store previous solution */
}
/* NOTE:
* start [ - offset + ZSTD_REP_MOVE - 1 ] is undefined behavior .
* ( - offset + ZSTD_REP_MOVE - 1 ) is unsigned , and is added to start , which
* overflows the pointer , which is undefined behavior .
*/
/* catch up */
if ( offset ) {
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if ( dictMode = = ZSTD_noDict ) {
while ( ( ( start > anchor ) & ( start - ( offset - ZSTD_REP_MOVE ) > prefixLowest ) )
& & ( start [ - 1 ] = = ( start - ( offset - ZSTD_REP_MOVE ) ) [ - 1 ] ) ) /* only search for offset within prefix */
{ start - - ; matchLength + + ; }
}
if ( dictMode = = ZSTD_dictMatchState ) {
U32 const matchIndex = ( U32 ) ( ( start - base ) - ( offset - ZSTD_REP_MOVE ) ) ;
const BYTE * match = ( matchIndex < prefixLowestIndex ) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex ;
const BYTE * const mStart = ( matchIndex < prefixLowestIndex ) ? dictLowest : prefixLowest ;
while ( ( start > anchor ) & & ( match > mStart ) & & ( start [ - 1 ] = = match [ - 1 ] ) ) { start - - ; match - - ; matchLength + + ; } /* catch up */
}
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offset_2 = offset_1 ; offset_1 = ( U32 ) ( offset - ZSTD_REP_MOVE ) ;
}
/* store sequence */
_storeSequence :
{ size_t const litLength = start - anchor ;
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ZSTD_storeSeq ( seqStore , litLength , anchor , iend , ( U32 ) offset , matchLength - MINMATCH ) ;
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anchor = ip = start + matchLength ;
}
/* check immediate repcode */
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if ( dictMode = = ZSTD_dictMatchState ) {
while ( ip < = ilimit ) {
U32 const current2 = ( U32 ) ( ip - base ) ;
U32 const repIndex = current2 - offset_2 ;
const BYTE * repMatch = dictMode = = ZSTD_dictMatchState
& & repIndex < prefixLowestIndex ?
dictBase - dictIndexDelta + repIndex :
base + repIndex ;
if ( ( ( U32 ) ( ( prefixLowestIndex - 1 ) - ( U32 ) repIndex ) > = 3 /* intentional overflow */ )
& & ( MEM_read32 ( repMatch ) = = MEM_read32 ( ip ) ) ) {
const BYTE * const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend ;
matchLength = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repEnd2 , prefixLowest ) + 4 ;
offset = offset_2 ; offset_2 = offset_1 ; offset_1 = ( U32 ) offset ; /* swap offset_2 <=> offset_1 */
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ZSTD_storeSeq ( seqStore , 0 , anchor , iend , 0 , matchLength - MINMATCH ) ;
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ip + = matchLength ;
anchor = ip ;
continue ;
}
break ;
}
}
if ( dictMode = = ZSTD_noDict ) {
while ( ( ( ip < = ilimit ) & ( offset_2 > 0 ) )
& & ( MEM_read32 ( ip ) = = MEM_read32 ( ip - offset_2 ) ) ) {
/* store sequence */
matchLength = ZSTD_count ( ip + 4 , ip + 4 - offset_2 , iend ) + 4 ;
offset = offset_2 ; offset_2 = offset_1 ; offset_1 = ( U32 ) offset ; /* swap repcodes */
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ZSTD_storeSeq ( seqStore , 0 , anchor , iend , 0 , matchLength - MINMATCH ) ;
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ip + = matchLength ;
anchor = ip ;
continue ; /* faster when present ... (?) */
} } }
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/* Save reps for next block */
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rep [ 0 ] = offset_1 ? offset_1 : savedOffset ;
rep [ 1 ] = offset_2 ? offset_2 : savedOffset ;
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/* Return the last literals size */
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return ( size_t ) ( iend - anchor ) ;
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}
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size_t ZSTD_compressBlock_btlazy2 (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_binaryTree , 2 , ZSTD_noDict ) ;
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}
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size_t ZSTD_compressBlock_lazy2 (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 2 , ZSTD_noDict ) ;
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}
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size_t ZSTD_compressBlock_lazy (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 1 , ZSTD_noDict ) ;
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}
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size_t ZSTD_compressBlock_greedy (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 0 , ZSTD_noDict ) ;
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}
size_t ZSTD_compressBlock_btlazy2_dictMatchState (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
void const * src , size_t srcSize )
{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_binaryTree , 2 , ZSTD_dictMatchState ) ;
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}
size_t ZSTD_compressBlock_lazy2_dictMatchState (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
void const * src , size_t srcSize )
{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 2 , ZSTD_dictMatchState ) ;
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}
size_t ZSTD_compressBlock_lazy_dictMatchState (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
void const * src , size_t srcSize )
{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 1 , ZSTD_dictMatchState ) ;
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}
size_t ZSTD_compressBlock_greedy_dictMatchState (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 0 , ZSTD_dictMatchState ) ;
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}
FORCE_INLINE_TEMPLATE
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size_t ZSTD_compressBlock_lazy_extDict_generic (
ZSTD_matchState_t * ms , seqStore_t * seqStore ,
U32 rep [ ZSTD_REP_NUM ] ,
const void * src , size_t srcSize ,
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const searchMethod_e searchMethod , const U32 depth )
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{
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 ;
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const BYTE * const base = ms - > window . base ;
const U32 dictLimit = ms - > window . dictLimit ;
const U32 lowestIndex = ms - > window . lowLimit ;
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const BYTE * const prefixStart = base + dictLimit ;
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const BYTE * const dictBase = ms - > window . dictBase ;
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const BYTE * const dictEnd = dictBase + dictLimit ;
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const BYTE * const dictStart = dictBase + lowestIndex ;
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typedef size_t ( * searchMax_f ) (
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ZSTD_matchState_t * ms ,
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const BYTE * ip , const BYTE * iLimit , size_t * offsetPtr ) ;
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searchMax_f searchMax = searchMethod = = search_binaryTree ? ZSTD_BtFindBestMatch_extDict_selectMLS : ZSTD_HcFindBestMatch_extDict_selectMLS ;
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U32 offset_1 = rep [ 0 ] , offset_2 = rep [ 1 ] ;
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/* init */
ip + = ( ip = = prefixStart ) ;
/* Match Loop */
while ( ip < ilimit ) {
size_t matchLength = 0 ;
size_t offset = 0 ;
const BYTE * start = ip + 1 ;
U32 current = ( U32 ) ( ip - base ) ;
/* check repCode */
{ const U32 repIndex = ( U32 ) ( current + 1 - offset_1 ) ;
const BYTE * const repBase = repIndex < dictLimit ? dictBase : base ;
const BYTE * const repMatch = repBase + repIndex ;
if ( ( ( U32 ) ( ( dictLimit - 1 ) - repIndex ) > = 3 ) & ( repIndex > lowestIndex ) ) /* intentional overflow */
if ( MEM_read32 ( ip + 1 ) = = MEM_read32 ( repMatch ) ) {
/* repcode detected we should take it */
const BYTE * const repEnd = repIndex < dictLimit ? dictEnd : iend ;
matchLength = ZSTD_count_2segments ( ip + 1 + 4 , repMatch + 4 , iend , repEnd , prefixStart ) + 4 ;
if ( depth = = 0 ) goto _storeSequence ;
} }
/* first search (depth 0) */
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{ size_t offsetFound = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offsetFound ) ;
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if ( ml2 > matchLength )
matchLength = ml2 , start = ip , offset = offsetFound ;
}
if ( matchLength < 4 ) {
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ip + = ( ( ip - anchor ) > > kSearchStrength ) + 1 ; /* jump faster over incompressible sections */
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continue ;
}
/* let's try to find a better solution */
if ( depth > = 1 )
while ( ip < ilimit ) {
ip + + ;
current + + ;
/* check repCode */
if ( offset ) {
const U32 repIndex = ( U32 ) ( current - offset_1 ) ;
const BYTE * const repBase = repIndex < dictLimit ? dictBase : base ;
const BYTE * const repMatch = repBase + repIndex ;
if ( ( ( U32 ) ( ( dictLimit - 1 ) - repIndex ) > = 3 ) & ( repIndex > lowestIndex ) ) /* intentional overflow */
if ( MEM_read32 ( ip ) = = MEM_read32 ( repMatch ) ) {
/* repcode detected */
const BYTE * const repEnd = repIndex < dictLimit ? dictEnd : iend ;
size_t const repLength = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repEnd , prefixStart ) + 4 ;
int const gain2 = ( int ) ( repLength * 3 ) ;
int const gain1 = ( int ) ( matchLength * 3 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
if ( ( repLength > = 4 ) & & ( gain2 > gain1 ) )
matchLength = repLength , offset = 0 , start = ip ;
} }
/* search match, depth 1 */
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{ size_t offset2 = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offset2 ) ;
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int const gain2 = ( int ) ( ml2 * 4 - ZSTD_highbit32 ( ( U32 ) offset2 + 1 ) ) ; /* raw approx */
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 4 ) ;
if ( ( ml2 > = 4 ) & & ( gain2 > gain1 ) ) {
matchLength = ml2 , offset = offset2 , start = ip ;
continue ; /* search a better one */
} }
/* let's find an even better one */
if ( ( depth = = 2 ) & & ( ip < ilimit ) ) {
ip + + ;
current + + ;
/* check repCode */
if ( offset ) {
const U32 repIndex = ( U32 ) ( current - offset_1 ) ;
const BYTE * const repBase = repIndex < dictLimit ? dictBase : base ;
const BYTE * const repMatch = repBase + repIndex ;
if ( ( ( U32 ) ( ( dictLimit - 1 ) - repIndex ) > = 3 ) & ( repIndex > lowestIndex ) ) /* intentional overflow */
if ( MEM_read32 ( ip ) = = MEM_read32 ( repMatch ) ) {
/* repcode detected */
const BYTE * const repEnd = repIndex < dictLimit ? dictEnd : iend ;
size_t const repLength = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repEnd , prefixStart ) + 4 ;
int const gain2 = ( int ) ( repLength * 4 ) ;
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 1 ) ;
if ( ( repLength > = 4 ) & & ( gain2 > gain1 ) )
matchLength = repLength , offset = 0 , start = ip ;
} }
/* search match, depth 2 */
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{ size_t offset2 = 999999999 ;
size_t const ml2 = searchMax ( ms , ip , iend , & offset2 ) ;
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int const gain2 = ( int ) ( ml2 * 4 - ZSTD_highbit32 ( ( U32 ) offset2 + 1 ) ) ; /* raw approx */
int const gain1 = ( int ) ( matchLength * 4 - ZSTD_highbit32 ( ( U32 ) offset + 1 ) + 7 ) ;
if ( ( ml2 > = 4 ) & & ( gain2 > gain1 ) ) {
matchLength = ml2 , offset = offset2 , start = ip ;
continue ;
} } }
break ; /* nothing found : store previous solution */
}
/* catch up */
if ( offset ) {
U32 const matchIndex = ( U32 ) ( ( start - base ) - ( offset - ZSTD_REP_MOVE ) ) ;
const BYTE * match = ( matchIndex < dictLimit ) ? dictBase + matchIndex : base + matchIndex ;
const BYTE * const mStart = ( matchIndex < dictLimit ) ? dictStart : prefixStart ;
while ( ( start > anchor ) & & ( match > mStart ) & & ( start [ - 1 ] = = match [ - 1 ] ) ) { start - - ; match - - ; matchLength + + ; } /* catch up */
offset_2 = offset_1 ; offset_1 = ( U32 ) ( offset - ZSTD_REP_MOVE ) ;
}
/* store sequence */
_storeSequence :
{ size_t const litLength = start - anchor ;
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ZSTD_storeSeq ( seqStore , litLength , anchor , iend , ( U32 ) offset , matchLength - MINMATCH ) ;
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anchor = ip = start + matchLength ;
}
/* check immediate repcode */
while ( ip < = ilimit ) {
const U32 repIndex = ( U32 ) ( ( ip - base ) - offset_2 ) ;
const BYTE * const repBase = repIndex < dictLimit ? dictBase : base ;
const BYTE * const repMatch = repBase + repIndex ;
if ( ( ( U32 ) ( ( dictLimit - 1 ) - repIndex ) > = 3 ) & ( repIndex > lowestIndex ) ) /* intentional overflow */
if ( MEM_read32 ( ip ) = = MEM_read32 ( repMatch ) ) {
/* repcode detected we should take it */
const BYTE * const repEnd = repIndex < dictLimit ? dictEnd : iend ;
matchLength = ZSTD_count_2segments ( ip + 4 , repMatch + 4 , iend , repEnd , prefixStart ) + 4 ;
offset = offset_2 ; offset_2 = offset_1 ; offset_1 = ( U32 ) offset ; /* swap offset history */
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ZSTD_storeSeq ( seqStore , 0 , anchor , iend , 0 , matchLength - MINMATCH ) ;
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ip + = matchLength ;
anchor = ip ;
continue ; /* faster when present ... (?) */
}
break ;
} }
/* Save reps for next block */
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rep [ 0 ] = offset_1 ;
rep [ 1 ] = offset_2 ;
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/* Return the last literals size */
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return ( size_t ) ( iend - anchor ) ;
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}
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size_t ZSTD_compressBlock_greedy_extDict (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_extDict_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 0 ) ;
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}
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size_t ZSTD_compressBlock_lazy_extDict (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_extDict_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 1 ) ;
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}
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size_t ZSTD_compressBlock_lazy2_extDict (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_extDict_generic ( ms , seqStore , rep , src , srcSize , search_hashChain , 2 ) ;
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}
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size_t ZSTD_compressBlock_btlazy2_extDict (
ZSTD_matchState_t * ms , seqStore_t * seqStore , U32 rep [ ZSTD_REP_NUM ] ,
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void const * src , size_t srcSize )
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{
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return ZSTD_compressBlock_lazy_extDict_generic ( ms , seqStore , rep , src , srcSize , search_binaryTree , 2 ) ;
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}