commit
72a3fbc0e4
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@ -51,10 +51,12 @@ size_t ZSTD_compressBlock_fast_generic(
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U32* const hashTable = ms->hashTable;
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U32 const hlog = cParams->hashLog;
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/* support stepSize of 0 */
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U32 const stepSize = cParams->targetLength + !(cParams->targetLength);
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size_t const stepSize = cParams->targetLength + !(cParams->targetLength) + 1;
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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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/* We check ip0 (ip + 0) and ip1 (ip + 1) each loop */
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const BYTE* ip0 = istart;
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const BYTE* ip1;
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const BYTE* anchor = istart;
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const U32 prefixStartIndex = ms->window.dictLimit;
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const BYTE* const prefixStart = base + prefixStartIndex;
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@ -64,62 +66,96 @@ size_t ZSTD_compressBlock_fast_generic(
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U32 offsetSaved = 0;
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/* init */
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ip += (ip == prefixStart);
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ip0 += (ip0 == prefixStart);
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ip1 = ip0 + 1;
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{
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U32 const maxRep = (U32)(ip - prefixStart);
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U32 const maxRep = (U32)(ip0 - prefixStart);
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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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while (ip1 < ilimit) { /* < instead of <=, because check at ip0+2 */
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size_t mLength;
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size_t const h = ZSTD_hashPtr(ip, hlog, mls);
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U32 const current = (U32)(ip-base);
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U32 const matchIndex = hashTable[h];
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const BYTE* match = base + matchIndex;
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hashTable[h] = current; /* update hash table */
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BYTE const* ip2 = ip0 + 2;
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size_t const h0 = ZSTD_hashPtr(ip0, hlog, mls);
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U32 const val0 = MEM_read32(ip0);
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size_t const h1 = ZSTD_hashPtr(ip1, hlog, mls);
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U32 const val1 = MEM_read32(ip1);
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U32 const current0 = (U32)(ip0-base);
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U32 const current1 = (U32)(ip1-base);
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U32 const matchIndex0 = hashTable[h0];
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U32 const matchIndex1 = hashTable[h1];
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BYTE const* repMatch = ip2-offset_1;
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const BYTE* match0 = base + matchIndex0;
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const BYTE* match1 = base + matchIndex1;
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U32 offcode;
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hashTable[h0] = current0; /* update hash table */
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hashTable[h1] = current1; /* update hash table */
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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, ip-anchor, anchor, 0, mLength-MINMATCH);
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} else if ((matchIndex <= prefixStartIndex) || MEM_read32(match) != MEM_read32(ip)) {
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assert(stepSize >= 1);
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ip += ((ip-anchor) >> kSearchStrength) + stepSize;
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continue;
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} else {
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/* found a regular match */
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U32 const offset = (U32)(ip-match);
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mLength = ZSTD_count(ip+4, match+4, iend) + 4;
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while (((ip>anchor) & (match>prefixStart))
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&& (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
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offset_2 = offset_1;
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offset_1 = offset;
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ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
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assert(ip0 + 1 == ip1);
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if ((offset_1 > 0) & (MEM_read32(repMatch) == MEM_read32(ip2))) {
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mLength = ip2[-1] == repMatch[-1] ? 1 : 0;
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ip0 = ip2 - mLength;
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match0 = repMatch - mLength;
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offcode = 0;
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goto _match;
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}
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if ((matchIndex0 > prefixStartIndex) && MEM_read32(match0) == val0) {
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/* found a regular match */
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goto _offset;
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}
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if ((matchIndex1 > prefixStartIndex) && MEM_read32(match1) == val1) {
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/* found a regular match after one literal */
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ip0 = ip1;
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match0 = match1;
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goto _offset;
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}
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{
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size_t const step = ((ip0-anchor) >> (kSearchStrength - 1)) + stepSize;
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assert(step >= 2);
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ip0 += step;
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ip1 += step;
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continue;
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}
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_offset: /* Requires: ip0, match0 */
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/* Compute the offset code */
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offset_2 = offset_1;
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offset_1 = (U32)(ip0-match0);
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offcode = offset_1 + ZSTD_REP_MOVE;
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mLength = 0;
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/* Count the backwards match length */
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while (((ip0>anchor) & (match0>prefixStart))
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&& (ip0[-1] == match0[-1])) { ip0--; match0--; mLength++; } /* catch up */
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_match: /* Requires: ip0, match0, offcode */
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/* Count the forward length */
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mLength += ZSTD_count(ip0+mLength+4, match0+mLength+4, iend) + 4;
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ZSTD_storeSeq(seqStore, ip0-anchor, anchor, offcode, mLength-MINMATCH);
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/* match found */
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ip += mLength;
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anchor = ip;
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ip0 += mLength;
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anchor = ip0;
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ip1 = ip0 + 1;
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if (ip <= ilimit) {
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if (ip0 <= ilimit) {
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/* Fill Table */
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assert(base+current+2 > istart); /* check base overflow */
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hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2; /* here because current+2 could be > iend-8 */
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hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
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assert(base+current0+2 > istart); /* check base overflow */
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hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */
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hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);
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while ( (ip <= ilimit)
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while ( (ip0 <= ilimit)
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&& ( (offset_2>0)
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& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
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& (MEM_read32(ip0) == MEM_read32(ip0 - 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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size_t const rLength = ZSTD_count(ip0+4, ip0+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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hashTable[ZSTD_hashPtr(ip, hlog, mls)] = (U32)(ip-base);
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hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);
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ip0 += rLength;
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ip1 = ip0 + 1;
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ZSTD_storeSeq(seqStore, 0, anchor, 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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anchor = ip0;
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continue; /* faster when present (confirmed on gcc-8) ... (?) */
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}
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}
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}
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