Extract Single-Segment Variant of ZSTD_dfast
W. Felix Handte
parent
52598d54e9
commit
258c0623e1
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@ -47,6 +47,160 @@ void ZSTD_fillDoubleHashTable(ZSTD_matchState_t* ms,
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}
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FORCE_INLINE_TEMPLATE
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size_t ZSTD_compressBlock_doubleFast_singleSegment_generic(
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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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U32 const mls /* template */)
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{
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ZSTD_compressionParameters const* cParams = &ms->cParams;
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U32* const hashLong = ms->hashTable;
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const U32 hBitsL = cParams->hashLog;
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U32* const hashSmall = ms->chainTable;
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const U32 hBitsS = cParams->chainLog;
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const BYTE* const base = ms->window.base;
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const BYTE* const istart = (const BYTE*)src;
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const BYTE* ip = istart;
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const BYTE* anchor = istart;
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const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
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/* presumes that, if there is a dictionary, it must be using Attach mode */
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const U32 prefixLowestIndex = ZSTD_getLowestPrefixIndex(ms, endIndex, cParams->windowLog);
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const BYTE* const prefixLowest = base + prefixLowestIndex;
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const BYTE* const iend = istart + srcSize;
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const BYTE* const ilimit = iend - HASH_READ_SIZE;
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U32 offset_1=rep[0], offset_2=rep[1];
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U32 offsetSaved = 0;
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DEBUGLOG(5, "ZSTD_compressBlock_doubleFast_singleSegment_generic");
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/* init */
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ip += ((ip - prefixLowest) == 0);
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{
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U32 const curr = (U32)(ip - base);
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U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, cParams->windowLog);
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U32 const maxRep = curr - windowLow;
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if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
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if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
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}
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/* Main Search Loop */
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while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
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size_t mLength;
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U32 offset;
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size_t const h2 = ZSTD_hashPtr(ip, hBitsL, 8);
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size_t const h = ZSTD_hashPtr(ip, hBitsS, mls);
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U32 const curr = (U32)(ip-base);
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U32 const matchIndexL = hashLong[h2];
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U32 matchIndexS = hashSmall[h];
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const BYTE* matchLong = base + matchIndexL;
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const BYTE* match = base + matchIndexS;
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hashLong[h2] = hashSmall[h] = curr; /* update hash tables */
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/* check noDict repcode */
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if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) {
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mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
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ip++;
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ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH);
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goto _match_stored;
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}
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if (matchIndexL > prefixLowestIndex) {
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/* check prefix long match */
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if (MEM_read64(matchLong) == MEM_read64(ip)) {
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mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;
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offset = (U32)(ip-matchLong);
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while (((ip>anchor) & (matchLong>prefixLowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
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goto _match_found;
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}
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}
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if (matchIndexS > prefixLowestIndex) {
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/* check prefix short match */
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if (MEM_read32(match) == MEM_read32(ip)) {
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goto _search_next_long;
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}
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}
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ip += ((ip-anchor) >> kSearchStrength) + 1;
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#if defined(__aarch64__)
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PREFETCH_L1(ip+256);
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#endif
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continue;
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_search_next_long:
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{ size_t const hl3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
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U32 const matchIndexL3 = hashLong[hl3];
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const BYTE* matchL3 = base + matchIndexL3;
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hashLong[hl3] = curr + 1;
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/* check prefix long +1 match */
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if (matchIndexL3 > prefixLowestIndex) {
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if (MEM_read64(matchL3) == MEM_read64(ip+1)) {
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mLength = ZSTD_count(ip+9, matchL3+8, iend) + 8;
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ip++;
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offset = (U32)(ip-matchL3);
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while (((ip>anchor) & (matchL3>prefixLowest)) && (ip[-1] == matchL3[-1])) { ip--; matchL3--; mLength++; } /* catch up */
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goto _match_found;
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}
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}
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}
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/* if no long +1 match, explore the short match we found */
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{
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mLength = ZSTD_count(ip+4, match+4, iend) + 4;
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offset = (U32)(ip - match);
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while (((ip>anchor) & (match>prefixLowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
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}
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/* fall-through */
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_match_found:
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offset_2 = offset_1;
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offset_1 = offset;
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ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
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_match_stored:
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/* match found */
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ip += mLength;
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anchor = ip;
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if (ip <= ilimit) {
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/* Complementary insertion */
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/* done after iLimit test, as candidates could be > iend-8 */
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{ U32 const indexToInsert = curr+2;
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hashLong[ZSTD_hashPtr(base+indexToInsert, hBitsL, 8)] = indexToInsert;
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hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] = (U32)(ip-2-base);
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hashSmall[ZSTD_hashPtr(base+indexToInsert, hBitsS, mls)] = indexToInsert;
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hashSmall[ZSTD_hashPtr(ip-1, hBitsS, mls)] = (U32)(ip-1-base);
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}
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/* check immediate repcode */
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while ( (ip <= ilimit)
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&& ( (offset_2>0)
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& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
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/* store sequence */
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size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
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U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; /* swap offset_2 <=> offset_1 */
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hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip-base);
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hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip-base);
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ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, rLength-MINMATCH);
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ip += rLength;
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anchor = ip;
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continue; /* faster when present ... (?) */
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} }
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} /* while (ip < ilimit) */
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/* save reps for next block */
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rep[0] = offset_1 ? offset_1 : offsetSaved;
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rep[1] = offset_2 ? offset_2 : offsetSaved;
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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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FORCE_INLINE_TEMPLATE
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size_t ZSTD_compressBlock_doubleFast_generic(
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ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
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@ -323,13 +477,13 @@ size_t ZSTD_compressBlock_doubleFast(
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{
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default: /* includes case 3 */
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case 4 :
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return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 4, ZSTD_noDict);
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return ZSTD_compressBlock_doubleFast_singleSegment_generic(ms, seqStore, rep, src, srcSize, 4);
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case 5 :
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return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 5, ZSTD_noDict);
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return ZSTD_compressBlock_doubleFast_singleSegment_generic(ms, seqStore, rep, src, srcSize, 5);
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case 6 :
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return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 6, ZSTD_noDict);
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return ZSTD_compressBlock_doubleFast_singleSegment_generic(ms, seqStore, rep, src, srcSize, 6);
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case 7 :
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return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 7, ZSTD_noDict);
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return ZSTD_compressBlock_doubleFast_singleSegment_generic(ms, seqStore, rep, src, srcSize, 7);
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}
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}
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