lib/compress/zstd_fast.c - third_party/zstd - Git at Google

 /*
  * 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.
  */

 #include "zstd_compress_internal.h"
 #include "zstd_fast.h"


 void ZSTD_fillHashTable(ZSTD_matchState_t* ms,
                         ZSTD_compressionParameters const* cParams,
                         void const* end, ZSTD_dictTableLoadMethod_e dtlm)
 {
     U32* const hashTable = ms->hashTable;
     U32  const hBits = cParams->hashLog;
     U32  const mls = cParams->searchLength;
     const BYTE* const base = ms->window.base;
     const BYTE* ip = base + ms->nextToUpdate;
     const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
     const U32 fastHashFillStep = 3;

     /* Always insert every fastHashFillStep position into the hash table.
      * Insert the other positions if their hash entry is empty.
      */
     for (; ip + fastHashFillStep - 1 <= iend; ip += fastHashFillStep) {
         U32 const current = (U32)(ip - base);
         U32 i;
         for (i = 0; i < fastHashFillStep; ++i) {
             size_t const hash = ZSTD_hashPtr(ip + i, hBits, mls);
             if (i == 0 || hashTable[hash] == 0)
                 hashTable[hash] = current + i;
             /* Only load extra positions for ZSTD_dtlm_full */
             if (dtlm == ZSTD_dtlm_fast)
                 break;
         }
     }
 }

 FORCE_INLINE_TEMPLATE
 size_t ZSTD_compressBlock_fast_generic(
         ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         void const* src, size_t srcSize,
         U32 const hlog, U32 stepSize, U32 const mls,
         ZSTD_dictMode_e const dictMode)
 {
     U32* const hashTable = ms->hashTable;
     const BYTE* const base = ms->window.base;
     const BYTE* const istart = (const BYTE*)src;
     const BYTE* ip = istart;
     const BYTE* anchor = istart;
     const U32   prefixStartIndex = ms->window.dictLimit;
     const BYTE* const prefixStart = base + prefixStartIndex;
     const BYTE* const iend = istart + srcSize;
     const BYTE* const ilimit = iend - HASH_READ_SIZE;
     U32 offset_1=rep[0], offset_2=rep[1];
     U32 offsetSaved = 0;

     const ZSTD_matchState_t* const dms = ms->dictMatchState;
     const U32* const dictHashTable = dictMode == ZSTD_dictMatchState ?
                                      dms->hashTable : NULL;
     const U32 dictStartIndex       = dictMode == ZSTD_dictMatchState ?
                                      dms->window.dictLimit : 0;
     const BYTE* const dictBase     = dictMode == ZSTD_dictMatchState ?
                                      dms->window.base : NULL;
     const BYTE* const dictStart    = dictMode == ZSTD_dictMatchState ?
                                      dictBase + dictStartIndex : NULL;
     const BYTE* const dictEnd      = dictMode == ZSTD_dictMatchState ?
                                      dms->window.nextSrc : NULL;
     const U32 dictIndexDelta       = dictMode == ZSTD_dictMatchState ?
                                      prefixStartIndex - (U32)(dictEnd - dictBase) :
                                      0;
     const U32 dictAndPrefixLength  = (U32)(ip - prefixStart + dictEnd - dictStart);

     assert(dictMode == ZSTD_noDict || dictMode == ZSTD_dictMatchState);

     /* otherwise, we would get index underflow when translating a dict index
      * into a local index */
     assert(dictMode != ZSTD_dictMatchState
         || prefixStartIndex >= (U32)(dictEnd - dictBase));

     /* init */
     stepSize += !stepSize;  /* support stepSize of 0 */
     ip += (dictAndPrefixLength == 0);
     if (dictMode == ZSTD_noDict) {
         U32 const maxRep = (U32)(ip - prefixStart);
         if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
         if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
     }
     if (dictMode == ZSTD_dictMatchState) {
         /* dictMatchState repCode checks don't currently handle repCode == 0
          * disabling. */
         assert(offset_1 <= dictAndPrefixLength);
         assert(offset_2 <= dictAndPrefixLength);
     }

     /* Main Search Loop */
     while (ip < ilimit) {   /* < instead of <=, because repcode check at (ip+1) */
         size_t mLength;
         size_t const h = ZSTD_hashPtr(ip, hlog, mls);
         U32 const current = (U32)(ip-base);
         U32 const matchIndex = hashTable[h];
         const BYTE* match = base + matchIndex;
         const U32 repIndex = current + 1 - offset_1;
         const BYTE* repMatch = (dictMode == ZSTD_dictMatchState
                             && repIndex < prefixStartIndex) ?
                                dictBase + (repIndex - dictIndexDelta) :
                                base + repIndex;
         hashTable[h] = current;   /* update hash table */

         if ( (dictMode == ZSTD_dictMatchState)
           && ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
           && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
             const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
             mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
             ip++;
             ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
         } else if ( dictMode == ZSTD_noDict
                  && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
             mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
             ip++;
             ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
         } else if ( (matchIndex <= prefixStartIndex)
                  || (MEM_read32(match) != MEM_read32(ip)) ) {
             if (dictMode == ZSTD_dictMatchState) {
                 U32 const dictMatchIndex = dictHashTable[h];
                 const BYTE* dictMatch = dictBase + dictMatchIndex;
                 if (dictMatchIndex <= dictStartIndex ||
                     MEM_read32(dictMatch) != MEM_read32(ip)) {
                     assert(stepSize >= 1);
                     ip += ((ip-anchor) >> kSearchStrength) + stepSize;
                     continue;
                 } else {
                     /* found a dict match */
                     U32 const offset = (U32)(current-dictMatchIndex-dictIndexDelta);
                     mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4;
                     while (((ip>anchor) & (dictMatch>dictStart))
                          && (ip[-1] == dictMatch[-1])) {
                         ip--; dictMatch--; mLength++;
                     } /* catch up */
                     offset_2 = offset_1;
                     offset_1 = offset;
                     ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
                 }
             } else {
                 assert(stepSize >= 1);
                 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
                 continue;
             }
         } else {
             /* found a regular match */
             U32 const offset = (U32)(ip-match);
             mLength = ZSTD_count(ip+4, match+4, iend) + 4;
             while (((ip>anchor) & (match>prefixStart))
                  && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
             offset_2 = offset_1;
             offset_1 = offset;
             ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
         }

         /* match found */
         ip += mLength;
         anchor = ip;

         if (ip <= ilimit) {
             /* Fill Table */
             hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2;  /* here because current+2 could be > iend-8 */
             hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);

             /* check immediate repcode */
             if (dictMode == ZSTD_dictMatchState) {
                 while (ip <= ilimit) {
                     U32 const current2 = (U32)(ip-base);
                     U32 const repIndex2 = current2 - offset_2;
                     const BYTE* repMatch2 = repIndex2 < prefixStartIndex ?
                             dictBase - dictIndexDelta + repIndex2 :
                             base + repIndex2;
                     if ( ((U32)((prefixStartIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
                        && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
                         const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
                         size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
                         U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset;   /* swap offset_2 <=> offset_1 */
                         ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
                         hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
                         ip += repLength2;
                         anchor = ip;
                         continue;
                     }
                     break;
                 }
             }

             if (dictMode == ZSTD_noDict) {
                 while ( (ip <= ilimit)
                      && ( (offset_2>0)
                         & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
                     /* store sequence */
                     size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
                     U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff;  /* swap offset_2 <=> offset_1 */
                     hashTable[ZSTD_hashPtr(ip, hlog, mls)] = (U32)(ip-base);
                     ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH);
                     ip += rLength;
                     anchor = ip;
                     continue;   /* faster when present ... (?) */
     }   }   }   }

     /* save reps for next block */
     rep[0] = offset_1 ? offset_1 : offsetSaved;
     rep[1] = offset_2 ? offset_2 : offsetSaved;

     /* Return the last literals size */
     return iend - anchor;
 }


 size_t ZSTD_compressBlock_fast(
         ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
 {
     U32 const hlog = cParams->hashLog;
     U32 const mls = cParams->searchLength;
     U32 const stepSize = cParams->targetLength;
     assert(ms->dictMatchState == NULL);
     switch(mls)
     {
     default: /* includes case 3 */
     case 4 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4, ZSTD_noDict);
     case 5 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5, ZSTD_noDict);
     case 6 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6, ZSTD_noDict);
     case 7 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7, ZSTD_noDict);
     }
 }

 size_t ZSTD_compressBlock_fast_dictMatchState(
         ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
 {
     U32 const hlog = cParams->hashLog;
     U32 const mls = cParams->searchLength;
     U32 const stepSize = cParams->targetLength;
     assert(ms->dictMatchState != NULL);
     switch(mls)
     {
     default: /* includes case 3 */
     case 4 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4, ZSTD_dictMatchState);
     case 5 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5, ZSTD_dictMatchState);
     case 6 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6, ZSTD_dictMatchState);
     case 7 :
         return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7, ZSTD_dictMatchState);
     }
 }


 static size_t ZSTD_compressBlock_fast_extDict_generic(
         ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         void const* src, size_t srcSize,
         U32 const hlog, U32 stepSize, U32 const mls)
 {
     U32* hashTable = ms->hashTable;
     const BYTE* const base = ms->window.base;
     const BYTE* const dictBase = ms->window.dictBase;
     const BYTE* const istart = (const BYTE*)src;
     const BYTE* ip = istart;
     const BYTE* anchor = istart;
     const U32   dictStartIndex = ms->window.lowLimit;
     const BYTE* const dictStart = dictBase + dictStartIndex;
     const U32   prefixStartIndex = ms->window.dictLimit;
     const BYTE* const prefixStart = base + prefixStartIndex;
     const BYTE* const dictEnd = dictBase + prefixStartIndex;
     const BYTE* const iend = istart + srcSize;
     const BYTE* const ilimit = iend - 8;
     U32 offset_1=rep[0], offset_2=rep[1];

     stepSize += !stepSize;   /* support stepSize == 0 */

     /* Search Loop */
     while (ip < ilimit) {  /* < instead of <=, because (ip+1) */
         const size_t h = ZSTD_hashPtr(ip, hlog, mls);
         const U32    matchIndex = hashTable[h];
         const BYTE* const matchBase = matchIndex < prefixStartIndex ? dictBase : base;
         const BYTE*  match = matchBase + matchIndex;
         const U32    current = (U32)(ip-base);
         const U32    repIndex = current + 1 - offset_1;
         const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base;
         const BYTE* const repMatch = repBase + repIndex;
         size_t mLength;
         hashTable[h] = current;   /* update hash table */
         assert(offset_1 <= current +1);   /* check repIndex */

         if ( (((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > dictStartIndex))
            && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
             const BYTE* repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
             mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
             ip++;
             ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
         } else {
             if ( (matchIndex < dictStartIndex) ||
                  (MEM_read32(match) != MEM_read32(ip)) ) {
                 assert(stepSize >= 1);
                 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
                 continue;
             }
             {   const BYTE* matchEnd = matchIndex < prefixStartIndex ? dictEnd : iend;
                 const BYTE* lowMatchPtr = matchIndex < prefixStartIndex ? dictStart : prefixStart;
                 U32 offset;
                 mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4;
                 while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; }   /* catch up */
                 offset = current - matchIndex;
                 offset_2 = offset_1;
                 offset_1 = offset;
                 ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
         }   }

         /* found a match : store it */
         ip += mLength;
         anchor = ip;

         if (ip <= ilimit) {
             /* Fill Table */
             hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2;
             hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
             /* check immediate repcode */
             while (ip <= ilimit) {
                 U32 const current2 = (U32)(ip-base);
                 U32 const repIndex2 = current2 - offset_2;
                 const BYTE* repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2;
                 if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (repIndex2 > dictStartIndex))  /* intentional overflow */
                    && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
                     const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
                     size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
                     U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset;   /* swap offset_2 <=> offset_1 */
                     ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
                     hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
                     ip += repLength2;
                     anchor = ip;
                     continue;
                 }
                 break;
     }   }   }

     /* save reps for next block */
     rep[0] = offset_1;
     rep[1] = offset_2;

     /* Return the last literals size */
     return iend - anchor;
 }


 size_t ZSTD_compressBlock_fast_extDict(
         ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
 {
     U32 const hlog = cParams->hashLog;
     U32 const mls = cParams->searchLength;
     U32 const stepSize = cParams->targetLength;
     switch(mls)
     {
     default: /* includes case 3 */
     case 4 :
         return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4);
     case 5 :
         return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5);
     case 6 :
         return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6);
     case 7 :
         return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7);
     }
 }
	/*
	* 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.
	*/

	#include "zstd_compress_internal.h"
	#include "zstd_fast.h"


	void ZSTD_fillHashTable(ZSTD_matchState_t* ms,
	ZSTD_compressionParameters const* cParams,
	void const* end, ZSTD_dictTableLoadMethod_e dtlm)
	{
	U32* const hashTable = ms->hashTable;
	U32 const hBits = cParams->hashLog;
	U32 const mls = cParams->searchLength;
	const BYTE* const base = ms->window.base;
	const BYTE* ip = base + ms->nextToUpdate;
	const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
	const U32 fastHashFillStep = 3;

	/* Always insert every fastHashFillStep position into the hash table.
	* Insert the other positions if their hash entry is empty.
	*/
	for (; ip + fastHashFillStep - 1 <= iend; ip += fastHashFillStep) {
	U32 const current = (U32)(ip - base);
	U32 i;
	for (i = 0; i < fastHashFillStep; ++i) {
	size_t const hash = ZSTD_hashPtr(ip + i, hBits, mls);
	if (i == 0 \|\| hashTable[hash] == 0)
	hashTable[hash] = current + i;
	/* Only load extra positions for ZSTD_dtlm_full */
	if (dtlm == ZSTD_dtlm_fast)
	break;
	}
	}
	}

	FORCE_INLINE_TEMPLATE
	size_t ZSTD_compressBlock_fast_generic(
	ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
	void const* src, size_t srcSize,
	U32 const hlog, U32 stepSize, U32 const mls,
	ZSTD_dictMode_e const dictMode)
	{
	U32* const hashTable = ms->hashTable;
	const BYTE* const base = ms->window.base;
	const BYTE* const istart = (const BYTE*)src;
	const BYTE* ip = istart;
	const BYTE* anchor = istart;
	const U32 prefixStartIndex = ms->window.dictLimit;
	const BYTE* const prefixStart = base + prefixStartIndex;
	const BYTE* const iend = istart + srcSize;
	const BYTE* const ilimit = iend - HASH_READ_SIZE;
	U32 offset_1=rep[0], offset_2=rep[1];
	U32 offsetSaved = 0;

	const ZSTD_matchState_t* const dms = ms->dictMatchState;
	const U32* const dictHashTable = dictMode == ZSTD_dictMatchState ?
	dms->hashTable : NULL;
	const U32 dictStartIndex = dictMode == ZSTD_dictMatchState ?
	dms->window.dictLimit : 0;
	const BYTE* const dictBase = dictMode == ZSTD_dictMatchState ?
	dms->window.base : NULL;
	const BYTE* const dictStart = dictMode == ZSTD_dictMatchState ?
	dictBase + dictStartIndex : NULL;
	const BYTE* const dictEnd = dictMode == ZSTD_dictMatchState ?
	dms->window.nextSrc : NULL;
	const U32 dictIndexDelta = dictMode == ZSTD_dictMatchState ?
	prefixStartIndex - (U32)(dictEnd - dictBase) :
	0;
	const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart);

	assert(dictMode == ZSTD_noDict \|\| dictMode == ZSTD_dictMatchState);

	/* otherwise, we would get index underflow when translating a dict index
	* into a local index */
	assert(dictMode != ZSTD_dictMatchState
	\|\| prefixStartIndex >= (U32)(dictEnd - dictBase));

	/* init */
	stepSize += !stepSize; /* support stepSize of 0 */
	ip += (dictAndPrefixLength == 0);
	if (dictMode == ZSTD_noDict) {
	U32 const maxRep = (U32)(ip - prefixStart);
	if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
	if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
	}
	if (dictMode == ZSTD_dictMatchState) {
	/* dictMatchState repCode checks don't currently handle repCode == 0
	* disabling. */
	assert(offset_1 <= dictAndPrefixLength);
	assert(offset_2 <= dictAndPrefixLength);
	}

	/* Main Search Loop */
	while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
	size_t mLength;
	size_t const h = ZSTD_hashPtr(ip, hlog, mls);
	U32 const current = (U32)(ip-base);
	U32 const matchIndex = hashTable[h];
	const BYTE* match = base + matchIndex;
	const U32 repIndex = current + 1 - offset_1;
	const BYTE* repMatch = (dictMode == ZSTD_dictMatchState
	&& repIndex < prefixStartIndex) ?
	dictBase + (repIndex - dictIndexDelta) :
	base + repIndex;
	hashTable[h] = current; /* update hash table */

	if ( (dictMode == ZSTD_dictMatchState)
	&& ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
	&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
	const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
	mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
	ip++;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
	} else if ( dictMode == ZSTD_noDict
	&& ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
	mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
	ip++;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
	} else if ( (matchIndex <= prefixStartIndex)
	\|\| (MEM_read32(match) != MEM_read32(ip)) ) {
	if (dictMode == ZSTD_dictMatchState) {
	U32 const dictMatchIndex = dictHashTable[h];
	const BYTE* dictMatch = dictBase + dictMatchIndex;
	if (dictMatchIndex <= dictStartIndex \|\|
	MEM_read32(dictMatch) != MEM_read32(ip)) {
	assert(stepSize >= 1);
	ip += ((ip-anchor) >> kSearchStrength) + stepSize;
	continue;
	} else {
	/* found a dict match */
	U32 const offset = (U32)(current-dictMatchIndex-dictIndexDelta);
	mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4;
	while (((ip>anchor) & (dictMatch>dictStart))
	&& (ip[-1] == dictMatch[-1])) {
	ip--; dictMatch--; mLength++;
	} /* catch up */
	offset_2 = offset_1;
	offset_1 = offset;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
	}
	} else {
	assert(stepSize >= 1);
	ip += ((ip-anchor) >> kSearchStrength) + stepSize;
	continue;
	}
	} else {
	/* found a regular match */
	U32 const offset = (U32)(ip-match);
	mLength = ZSTD_count(ip+4, match+4, iend) + 4;
	while (((ip>anchor) & (match>prefixStart))
	&& (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
	offset_2 = offset_1;
	offset_1 = offset;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
	}

	/* match found */
	ip += mLength;
	anchor = ip;

	if (ip <= ilimit) {
	/* Fill Table */
	hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2; /* here because current+2 could be > iend-8 */
	hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);

	/* check immediate repcode */
	if (dictMode == ZSTD_dictMatchState) {
	while (ip <= ilimit) {
	U32 const current2 = (U32)(ip-base);
	U32 const repIndex2 = current2 - offset_2;
	const BYTE* repMatch2 = repIndex2 < prefixStartIndex ?
	dictBase - dictIndexDelta + repIndex2 :
	base + repIndex2;
	if ( ((U32)((prefixStartIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
	&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
	const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
	size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
	U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
	ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
	hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
	ip += repLength2;
	anchor = ip;
	continue;
	}
	break;
	}
	}

	if (dictMode == ZSTD_noDict) {
	while ( (ip <= ilimit)
	&& ( (offset_2>0)
	& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
	/* store sequence */
	size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
	U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; /* swap offset_2 <=> offset_1 */
	hashTable[ZSTD_hashPtr(ip, hlog, mls)] = (U32)(ip-base);
	ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH);
	ip += rLength;
	anchor = ip;
	continue; /* faster when present ... (?) */
	} } } }

	/* save reps for next block */
	rep[0] = offset_1 ? offset_1 : offsetSaved;
	rep[1] = offset_2 ? offset_2 : offsetSaved;

	/* Return the last literals size */
	return iend - anchor;
	}


	size_t ZSTD_compressBlock_fast(
	ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
	ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
	{
	U32 const hlog = cParams->hashLog;
	U32 const mls = cParams->searchLength;
	U32 const stepSize = cParams->targetLength;
	assert(ms->dictMatchState == NULL);
	switch(mls)
	{
	default: /* includes case 3 */
	case 4 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4, ZSTD_noDict);
	case 5 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5, ZSTD_noDict);
	case 6 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6, ZSTD_noDict);
	case 7 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7, ZSTD_noDict);
	}
	}

	size_t ZSTD_compressBlock_fast_dictMatchState(
	ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
	ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
	{
	U32 const hlog = cParams->hashLog;
	U32 const mls = cParams->searchLength;
	U32 const stepSize = cParams->targetLength;
	assert(ms->dictMatchState != NULL);
	switch(mls)
	{
	default: /* includes case 3 */
	case 4 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4, ZSTD_dictMatchState);
	case 5 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5, ZSTD_dictMatchState);
	case 6 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6, ZSTD_dictMatchState);
	case 7 :
	return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7, ZSTD_dictMatchState);
	}
	}


	static size_t ZSTD_compressBlock_fast_extDict_generic(
	ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
	void const* src, size_t srcSize,
	U32 const hlog, U32 stepSize, U32 const mls)
	{
	U32* hashTable = ms->hashTable;
	const BYTE* const base = ms->window.base;
	const BYTE* const dictBase = ms->window.dictBase;
	const BYTE* const istart = (const BYTE*)src;
	const BYTE* ip = istart;
	const BYTE* anchor = istart;
	const U32 dictStartIndex = ms->window.lowLimit;
	const BYTE* const dictStart = dictBase + dictStartIndex;
	const U32 prefixStartIndex = ms->window.dictLimit;
	const BYTE* const prefixStart = base + prefixStartIndex;
	const BYTE* const dictEnd = dictBase + prefixStartIndex;
	const BYTE* const iend = istart + srcSize;
	const BYTE* const ilimit = iend - 8;
	U32 offset_1=rep[0], offset_2=rep[1];

	stepSize += !stepSize; /* support stepSize == 0 */

	/* Search Loop */
	while (ip < ilimit) { /* < instead of <=, because (ip+1) */
	const size_t h = ZSTD_hashPtr(ip, hlog, mls);
	const U32 matchIndex = hashTable[h];
	const BYTE* const matchBase = matchIndex < prefixStartIndex ? dictBase : base;
	const BYTE* match = matchBase + matchIndex;
	const U32 current = (U32)(ip-base);
	const U32 repIndex = current + 1 - offset_1;
	const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base;
	const BYTE* const repMatch = repBase + repIndex;
	size_t mLength;
	hashTable[h] = current; /* update hash table */
	assert(offset_1 <= current +1); /* check repIndex */

	if ( (((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > dictStartIndex))
	&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
	const BYTE* repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
	mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
	ip++;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
	} else {
	if ( (matchIndex < dictStartIndex) \|\|
	(MEM_read32(match) != MEM_read32(ip)) ) {
	assert(stepSize >= 1);
	ip += ((ip-anchor) >> kSearchStrength) + stepSize;
	continue;
	}
	{ const BYTE* matchEnd = matchIndex < prefixStartIndex ? dictEnd : iend;
	const BYTE* lowMatchPtr = matchIndex < prefixStartIndex ? dictStart : prefixStart;
	U32 offset;
	mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4;
	while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
	offset = current - matchIndex;
	offset_2 = offset_1;
	offset_1 = offset;
	ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
	} }

	/* found a match : store it */
	ip += mLength;
	anchor = ip;

	if (ip <= ilimit) {
	/* Fill Table */
	hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2;
	hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
	/* check immediate repcode */
	while (ip <= ilimit) {
	U32 const current2 = (U32)(ip-base);
	U32 const repIndex2 = current2 - offset_2;
	const BYTE* repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2;
	if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (repIndex2 > dictStartIndex)) /* intentional overflow */
	&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
	const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
	size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
	U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
	ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
	hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
	ip += repLength2;
	anchor = ip;
	continue;
	}
	break;
	} } }

	/* save reps for next block */
	rep[0] = offset_1;
	rep[1] = offset_2;

	/* Return the last literals size */
	return iend - anchor;
	}


	size_t ZSTD_compressBlock_fast_extDict(
	ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
	ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
	{
	U32 const hlog = cParams->hashLog;
	U32 const mls = cParams->searchLength;
	U32 const stepSize = cParams->targetLength;
	switch(mls)
	{
	default: /* includes case 3 */
	case 4 :
	return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4);
	case 5 :
	return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5);
	case 6 :
	return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6);
	case 7 :
	return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7);
	}
	}