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Merged
Cyan4973 merged 7 commits into from
Jun 15, 2019
Merged

Improves compression ratio for small windowLog #1624

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bc601bd
first implementation of small window size for btopt
Cyan4973 May 31, 2019
58adb10
extended exact window size to greedy/lazy modes
Cyan4973 May 31, 2019
a30feba
Made fast strategy compatible with new offset validation strategy
Cyan4973 May 31, 2019
d605f48
make double_fast compatible with new index invalidation strategy
Cyan4973 May 31, 2019
a968099
minor code cleaning for new index invalidation strategy
Cyan4973 May 31, 2019
fce4df3
fixed wrong assert in double_fast
Cyan4973 Jun 1, 2019
80d6cce
removed UINT32_MAX
Cyan4973 Jun 1, 2019
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10 changes: 5 additions & 5 deletions lib/compress/zstd_compress.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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,
&params, 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;
Expand Down
24 changes: 23 additions & 1 deletion lib/compress/zstd_compress_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
};

Expand Down Expand Up @@ -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.
Expand Down
63 changes: 38 additions & 25 deletions lib/compress/zstd_double_fast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
}
} }
}


Expand All @@ -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;
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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;
}

Expand All @@ -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;
}

Expand All @@ -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 */
Expand All @@ -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;
Expand All @@ -221,9 +227,7 @@ size_t ZSTD_compressBlock_doubleFast_generic(
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) {
Expand All @@ -242,7 +246,7 @@ size_t ZSTD_compressBlock_doubleFast_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);

_match_stored:
/* match found */
Expand Down Expand Up @@ -278,8 +282,7 @@ size_t ZSTD_compressBlock_doubleFast_generic(
continue;
}
break;
}
}
} }

if (dictMode == ZSTD_noDict) {
while ( (ip <= ilimit)
Expand All @@ -294,14 +297,15 @@ size_t ZSTD_compressBlock_doubleFast_generic(
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);
}


Expand Down Expand Up @@ -360,17 +364,26 @@ 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;
U32 offset_1=rep[0], offset_2=rep[1];

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);
Expand All @@ -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;
Expand All @@ -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);
Expand All @@ -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;
Expand Down Expand Up @@ -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);
}


Expand Down
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