diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index b4feaef8..77b8b9b7 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -1387,7 +1387,7 @@ ZSTD_reset_matchState(ZSTD_matchState_t* ms, note : `params` are assumed fully validated at this stage */ static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc, ZSTD_CCtx_params params, - U64 pledgedSrcSize, + U64 const pledgedSrcSize, ZSTD_compResetPolicy_e const crp, ZSTD_buffered_policy_e const zbuff) { @@ -2868,7 +2868,8 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx, ms->dictMatchState = NULL; } - ZSTD_window_enforceMaxDist(&ms->window, ip + blockSize, maxDist, &ms->loadedDictEnd, &ms->dictMatchState); + ZSTD_checkDictValidity(&ms->window, ip + blockSize, maxDist, &ms->loadedDictEnd, &ms->dictMatchState); + /* Ensure hash/chain table insertion resumes no sooner than lowlimit */ if (ms->nextToUpdate < ms->window.lowLimit) ms->nextToUpdate = ms->window.lowLimit; @@ -3296,12 +3297,11 @@ static size_t ZSTD_compressBegin_internal(ZSTD_CCtx* cctx, FORWARD_IF_ERROR( ZSTD_resetCCtx_internal(cctx, params, pledgedSrcSize, ZSTDcrp_continue, zbuff) ); - { - size_t const dictID = ZSTD_compress_insertDictionary( + { size_t const dictID = ZSTD_compress_insertDictionary( cctx->blockState.prevCBlock, &cctx->blockState.matchState, ¶ms, dict, dictSize, dictContentType, dtlm, cctx->entropyWorkspace); FORWARD_IF_ERROR(dictID); - assert(dictID <= (size_t)(U32)-1); + assert(dictID <= UINT_MAX); cctx->dictID = (U32)dictID; } return 0; diff --git a/lib/compress/zstd_compress_internal.h b/lib/compress/zstd_compress_internal.h index ee9d9e31..55304fa3 100644 --- a/lib/compress/zstd_compress_internal.h +++ b/lib/compress/zstd_compress_internal.h @@ -141,7 +141,7 @@ struct ZSTD_matchState_t { U32* hashTable3; U32* chainTable; optState_t opt; /* optimal parser state */ - const ZSTD_matchState_t * dictMatchState; + const ZSTD_matchState_t* dictMatchState; ZSTD_compressionParameters cParams; }; @@ -731,6 +731,28 @@ ZSTD_window_enforceMaxDist(ZSTD_window_t* window, } } +/* Similar to ZSTD_window_enforceMaxDist(), + * but only invalidates dictionary + * when input progresses beyond window size. */ +MEM_STATIC void +ZSTD_checkDictValidity(ZSTD_window_t* window, + const void* blockEnd, + U32 maxDist, + U32* loadedDictEndPtr, + const ZSTD_matchState_t** dictMatchStatePtr) +{ + U32 const blockEndIdx = (U32)((BYTE const*)blockEnd - window->base); + U32 const loadedDictEnd = (loadedDictEndPtr != NULL) ? *loadedDictEndPtr : 0; + DEBUGLOG(5, "ZSTD_checkDictValidity: blockEndIdx=%u, maxDist=%u, loadedDictEnd=%u", + (unsigned)blockEndIdx, (unsigned)maxDist, (unsigned)loadedDictEnd); + + if (loadedDictEnd && (blockEndIdx > maxDist + loadedDictEnd)) { + /* On reaching window size, dictionaries are invalidated */ + if (loadedDictEndPtr) *loadedDictEndPtr = 0; + if (dictMatchStatePtr) *dictMatchStatePtr = NULL; + } +} + /** * ZSTD_window_update(): * Updates the window by appending [src, src + srcSize) to the window. diff --git a/lib/compress/zstd_double_fast.c b/lib/compress/zstd_double_fast.c index 47faf6d6..f156da9d 100644 --- a/lib/compress/zstd_double_fast.c +++ b/lib/compress/zstd_double_fast.c @@ -43,8 +43,7 @@ void ZSTD_fillDoubleHashTable(ZSTD_matchState_t* ms, /* Only load extra positions for ZSTD_dtlm_full */ if (dtlm == ZSTD_dtlm_fast) break; - } - } + } } } @@ -63,7 +62,10 @@ size_t ZSTD_compressBlock_doubleFast_generic( const BYTE* const istart = (const BYTE*)src; const BYTE* ip = istart; const BYTE* anchor = istart; - const U32 prefixLowestIndex = ms->window.dictLimit; + const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); + const U32 lowestValid = ms->window.dictLimit; + const U32 maxDistance = 1U << cParams->windowLog; + const U32 prefixLowestIndex = (endIndex - lowestValid > maxDistance) ? endIndex - maxDistance : lowestValid; const BYTE* const prefixLowest = base + prefixLowestIndex; const BYTE* const iend = istart + srcSize; const BYTE* const ilimit = iend - HASH_READ_SIZE; @@ -95,8 +97,15 @@ size_t ZSTD_compressBlock_doubleFast_generic( dictCParams->chainLog : hBitsS; const U32 dictAndPrefixLength = (U32)(ip - prefixLowest + dictEnd - dictStart); + DEBUGLOG(5, "ZSTD_compressBlock_doubleFast_generic"); + assert(dictMode == ZSTD_noDict || dictMode == ZSTD_dictMatchState); + /* if a dictionary is attached, it must be within window range */ + if (dictMode == ZSTD_dictMatchState) { + assert(lowestValid + maxDistance >= endIndex); + } + /* init */ ip += (dictAndPrefixLength == 0); if (dictMode == ZSTD_noDict) { @@ -138,7 +147,7 @@ size_t ZSTD_compressBlock_doubleFast_generic( const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; ip++; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH); goto _match_stored; } @@ -147,7 +156,7 @@ size_t ZSTD_compressBlock_doubleFast_generic( && ((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); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH); goto _match_stored; } @@ -170,8 +179,7 @@ size_t ZSTD_compressBlock_doubleFast_generic( offset = (U32)(current - dictMatchIndexL - dictIndexDelta); while (((ip>anchor) & (dictMatchL>dictStart)) && (ip[-1] == dictMatchL[-1])) { ip--; dictMatchL--; mLength++; } /* catch up */ goto _match_found; - } - } + } } if (matchIndexS > prefixLowestIndex) { /* check prefix short match */ @@ -186,16 +194,14 @@ size_t ZSTD_compressBlock_doubleFast_generic( if (match > dictStart && MEM_read32(match) == MEM_read32(ip)) { goto _search_next_long; - } - } + } } ip += ((ip-anchor) >> kSearchStrength) + 1; continue; _search_next_long: - { - size_t const hl3 = ZSTD_hashPtr(ip+1, hBitsL, 8); + { size_t const hl3 = ZSTD_hashPtr(ip+1, hBitsL, 8); size_t const dictHLNext = ZSTD_hashPtr(ip+1, dictHBitsL, 8); U32 const matchIndexL3 = hashLong[hl3]; const BYTE* matchL3 = base + matchIndexL3; @@ -221,9 +227,7 @@ _search_next_long: offset = (U32)(current + 1 - dictMatchIndexL3 - dictIndexDelta); while (((ip>anchor) & (dictMatchL3>dictStart)) && (ip[-1] == dictMatchL3[-1])) { ip--; dictMatchL3--; mLength++; } /* catch up */ goto _match_found; - } - } - } + } } } /* if no long +1 match, explore the short match we found */ if (dictMode == ZSTD_dictMatchState && matchIndexS < prefixLowestIndex) { @@ -242,7 +246,7 @@ _match_found: offset_2 = offset_1; offset_1 = offset; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); _match_stored: /* match found */ @@ -278,8 +282,7 @@ _match_stored: continue; } break; - } - } + } } if (dictMode == ZSTD_noDict) { while ( (ip <= ilimit) @@ -294,14 +297,15 @@ _match_stored: ip += rLength; anchor = ip; continue; /* faster when present ... (?) */ - } } } } + } } } + } /* while (ip < ilimit) */ /* 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; + return (size_t)(iend - anchor); } @@ -360,10 +364,15 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( const BYTE* anchor = istart; const BYTE* const iend = istart + srcSize; const BYTE* const ilimit = iend - 8; - const U32 prefixStartIndex = ms->window.dictLimit; const BYTE* const base = ms->window.base; + const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); + const U32 maxDistance = 1U << cParams->windowLog; + const U32 lowestValid = ms->window.lowLimit; + const U32 lowLimit = (endIndex - lowestValid > maxDistance) ? endIndex - maxDistance : lowestValid; + const U32 dictStartIndex = lowLimit; + const U32 dictLimit = ms->window.dictLimit; + const U32 prefixStartIndex = (dictLimit > lowLimit) ? dictLimit : lowLimit; const BYTE* const prefixStart = base + prefixStartIndex; - const U32 dictStartIndex = ms->window.lowLimit; const BYTE* const dictBase = ms->window.dictBase; const BYTE* const dictStart = dictBase + dictStartIndex; const BYTE* const dictEnd = dictBase + prefixStartIndex; @@ -371,6 +380,10 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( DEBUGLOG(5, "ZSTD_compressBlock_doubleFast_extDict_generic (srcSize=%zu)", srcSize); + /* if extDict is invalidated due to maxDistance, switch to "regular" variant */ + if (prefixStartIndex == dictStartIndex) + return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, mls, ZSTD_noDict); + /* Search Loop */ while (ip < ilimit) { /* < instead of <=, because (ip+1) */ const size_t hSmall = ZSTD_hashPtr(ip, hBitsS, mls); @@ -396,7 +409,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( 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); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH); } else { if ((matchLongIndex > dictStartIndex) && (MEM_read64(matchLong) == MEM_read64(ip))) { const BYTE* const matchEnd = matchLongIndex < prefixStartIndex ? dictEnd : iend; @@ -407,7 +420,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( while (((ip>anchor) & (matchLong>lowMatchPtr)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */ offset_2 = offset_1; offset_1 = offset; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); } else if ((matchIndex > dictStartIndex) && (MEM_read32(match) == MEM_read32(ip))) { size_t const h3 = ZSTD_hashPtr(ip+1, hBitsL, 8); @@ -432,7 +445,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( } offset_2 = offset_1; offset_1 = offset; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); } else { ip += ((ip-anchor) >> kSearchStrength) + 1; @@ -475,7 +488,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic( rep[1] = offset_2; /* Return the last literals size */ - return iend - anchor; + return (size_t)(iend - anchor); } diff --git a/lib/compress/zstd_fast.c b/lib/compress/zstd_fast.c index ed997b44..a05b8a47 100644 --- a/lib/compress/zstd_fast.c +++ b/lib/compress/zstd_fast.c @@ -13,7 +13,8 @@ void ZSTD_fillHashTable(ZSTD_matchState_t* ms, - void const* end, ZSTD_dictTableLoadMethod_e dtlm) + const void* const end, + ZSTD_dictTableLoadMethod_e dtlm) { const ZSTD_compressionParameters* const cParams = &ms->cParams; U32* const hashTable = ms->hashTable; @@ -41,6 +42,7 @@ void ZSTD_fillHashTable(ZSTD_matchState_t* ms, } } } } } + FORCE_INLINE_TEMPLATE size_t ZSTD_compressBlock_fast_generic( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], @@ -58,7 +60,10 @@ size_t ZSTD_compressBlock_fast_generic( const BYTE* ip0 = istart; const BYTE* ip1; const BYTE* anchor = istart; - const U32 prefixStartIndex = ms->window.dictLimit; + const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); + const U32 maxDistance = 1U << cParams->windowLog; + const U32 validStartIndex = ms->window.dictLimit; + const U32 prefixStartIndex = (endIndex - validStartIndex > maxDistance) ? endIndex - maxDistance : validStartIndex; const BYTE* const prefixStart = base + prefixStartIndex; const BYTE* const iend = istart + srcSize; const BYTE* const ilimit = iend - HASH_READ_SIZE; @@ -165,7 +170,7 @@ _match: /* Requires: ip0, match0, offcode */ rep[1] = offset_2 ? offset_2 : offsetSaved; /* Return the last literals size */ - return iend - anchor; + return (size_t)(iend - anchor); } @@ -222,8 +227,15 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic( const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart); const U32 dictHLog = dictCParams->hashLog; - /* otherwise, we would get index underflow when translating a dict index - * into a local index */ + /* if a dictionary is still attached, it necessarily means that + * it is within window size. So we just check it. */ + const U32 maxDistance = 1U << cParams->windowLog; + const U32 endIndex = (U32)((size_t)(ip - base) + srcSize); + assert(endIndex - prefixStartIndex <= maxDistance); + (void)maxDistance; (void)endIndex; /* these variables are not used when assert() is disabled */ + + /* ensure there will be no no underflow + * when translating a dict index into a local index */ assert(prefixStartIndex >= (U32)(dictEnd - dictBase)); /* init */ @@ -251,7 +263,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic( 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); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH); } else if ( (matchIndex <= prefixStartIndex) ) { size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls); U32 const dictMatchIndex = dictHashTable[dictHash]; @@ -271,7 +283,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic( } /* catch up */ offset_2 = offset_1; offset_1 = offset; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); } } else if (MEM_read32(match) != MEM_read32(ip)) { /* it's not a match, and we're not going to check the dictionary */ @@ -286,7 +298,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic( && (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); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); } /* match found */ @@ -327,7 +339,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic( rep[1] = offset_2 ? offset_2 : offsetSaved; /* Return the last literals size */ - return iend - anchor; + return (size_t)(iend - anchor); } size_t ZSTD_compressBlock_fast_dictMatchState( @@ -366,15 +378,24 @@ static size_t ZSTD_compressBlock_fast_extDict_generic( const BYTE* const istart = (const BYTE*)src; const BYTE* ip = istart; const BYTE* anchor = istart; - const U32 dictStartIndex = ms->window.lowLimit; + const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); + const U32 maxDistance = 1U << cParams->windowLog; + const U32 validLow = ms->window.lowLimit; + const U32 lowLimit = (endIndex - validLow > maxDistance) ? endIndex - maxDistance : validLow; + const U32 dictStartIndex = lowLimit; const BYTE* const dictStart = dictBase + dictStartIndex; - const U32 prefixStartIndex = ms->window.dictLimit; + const U32 dictLimit = ms->window.dictLimit; + const U32 prefixStartIndex = dictLimit < lowLimit ? lowLimit : 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]; + /* switch to "regular" variant if extDict is invalidated due to maxDistance */ + if (prefixStartIndex == dictStartIndex) + return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, mls); + /* Search Loop */ while (ip < ilimit) { /* < instead of <=, because (ip+1) */ const size_t h = ZSTD_hashPtr(ip, hlog, mls); @@ -394,7 +415,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic( 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); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH); } else { if ( (matchIndex < dictStartIndex) || (MEM_read32(match) != MEM_read32(ip)) ) { @@ -410,7 +431,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic( offset = current - matchIndex; offset_2 = offset_1; offset_1 = offset; - ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); + ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); } } /* found a match : store it */ @@ -445,7 +466,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic( rep[1] = offset_2; /* Return the last literals size */ - return iend - anchor; + return (size_t)(iend - anchor); } diff --git a/lib/compress/zstd_lazy.c b/lib/compress/zstd_lazy.c index aa932b51..94d906c0 100644 --- a/lib/compress/zstd_lazy.c +++ b/lib/compress/zstd_lazy.c @@ -83,7 +83,10 @@ ZSTD_insertDUBT1(ZSTD_matchState_t* ms, U32* largerPtr = smallerPtr + 1; 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) */ U32 dummy32; /* to be nullified at the end */ - U32 const windowLow = ms->window.lowLimit; + U32 const windowValid = ms->window.lowLimit; + U32 const maxDistance = 1U << cParams->windowLog; + U32 const windowLow = (current - windowValid > maxDistance) ? current - maxDistance : windowValid; + DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)", current, dictLimit, windowLow); @@ -239,7 +242,9 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms, const BYTE* const base = ms->window.base; U32 const current = (U32)(ip-base); - U32 const windowLow = ms->window.lowLimit; + U32 const maxDistance = 1U << cParams->windowLog; + U32 const windowValid = ms->window.lowLimit; + U32 const windowLow = (current - windowValid > maxDistance) ? current - maxDistance : windowValid; U32* const bt = ms->chainTable; U32 const btLog = cParams->chainLog - 1; @@ -490,8 +495,10 @@ size_t ZSTD_HcFindBestMatch_generic ( const U32 dictLimit = ms->window.dictLimit; const BYTE* const prefixStart = base + dictLimit; const BYTE* const dictEnd = dictBase + dictLimit; - const U32 lowLimit = ms->window.lowLimit; const U32 current = (U32)(ip-base); + const U32 maxDistance = 1U << cParams->windowLog; + const U32 lowValid = ms->window.lowLimit; + const U32 lowLimit = (current - lowValid > maxDistance) ? current - maxDistance : lowValid; const U32 minChain = current > chainSize ? current - chainSize : 0; U32 nbAttempts = 1U << cParams->searchLog; size_t ml=4-1; diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c index cf46e750..39858a82 100644 --- a/lib/compress/zstd_opt.c +++ b/lib/compress/zstd_opt.c @@ -547,6 +547,7 @@ U32 ZSTD_insertBtAndGetAllMatches ( { const ZSTD_compressionParameters* const cParams = &ms->cParams; U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); + U32 const maxDistance = 1U << cParams->windowLog; const BYTE* const base = ms->window.base; U32 const current = (U32)(ip-base); U32 const hashLog = cParams->hashLog; @@ -562,8 +563,9 @@ U32 ZSTD_insertBtAndGetAllMatches ( U32 const dictLimit = ms->window.dictLimit; const BYTE* const dictEnd = dictBase + dictLimit; const BYTE* const prefixStart = base + dictLimit; - U32 const btLow = btMask >= current ? 0 : current - btMask; - U32 const windowLow = ms->window.lowLimit; + U32 const btLow = (btMask >= current) ? 0 : current - btMask; + U32 const windowValid = ms->window.lowLimit; + U32 const windowLow = ((current - windowValid) > maxDistance) ? current - maxDistance : windowValid; U32 const matchLow = windowLow ? windowLow : 1; U32* smallerPtr = bt + 2*(current&btMask); U32* largerPtr = bt + 2*(current&btMask) + 1;