Remove long range matcher immediate repcode check
The compression ratio gets about 0.01% worse on the files I tested, but the code is much simpler.dev
parent
af866b3a58
commit
7e2bf4ebad
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@ -514,14 +514,7 @@ size_t ZSTD_ldm_blockCompress(rawSeq const* sequences, size_t nbSeq,
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{
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ZSTD_blockCompressor const blockCompressor =
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ZSTD_selectBlockCompressor(cParams->strategy, extDict);
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int const doImmediateRepCheck = cParams->strategy < ZSTD_btopt;
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/* Prefix and extDict parameters */
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U32 const dictLimit = ms->dictLimit;
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U32 const lowestIndex = extDict ? ms->lowLimit : dictLimit;
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BYTE const* const base = ms->base;
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BYTE const* const dictBase = extDict ? ms->dictBase : NULL;
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BYTE const* const dictEnd = extDict ? dictBase + dictLimit : NULL;
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BYTE const* const lowPrefixPtr = base + dictLimit;
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/* Input bounds */
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BYTE const* const istart = (BYTE const*)src;
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BYTE const* const iend = istart + srcSize;
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@ -558,69 +551,6 @@ size_t ZSTD_ldm_blockCompress(rawSeq const* sequences, size_t nbSeq,
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sequence.matchLength - MINMATCH);
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ip += sequence.matchLength;
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}
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/* Check immediate repcode */
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if (doImmediateRepCheck) {
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rawSeq* nextSeq = (seq + 1 < *nbSeq) ? &sequences[seq + 1] : NULL;
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/* Allow repcodes up to the next predefined sequence */
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BYTE const* const repCheckEnd = nextSeq
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? ip + nextSeq->litLength
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: iend;
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BYTE const* const repCheckLimit = repCheckEnd - HASH_READ_SIZE;
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assert(repCheckEnd <= iend);
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if (extDict) {
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while (ip < repCheckLimit) {
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U32 const current = (U32)(ip-base);
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U32 const repIndex = current - rep[1];
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const BYTE* repMatch = repIndex < dictLimit ?
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dictBase + repIndex : base + repIndex;
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if ( (((U32)((dictLimit-1) - repIndex) >= 3) &
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(repIndex > lowestIndex)) /* intentional overflow */
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&& (MEM_read32(repMatch) == MEM_read32(ip)) ) {
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const BYTE* const repEnd = repIndex < dictLimit ?
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dictEnd : repCheckEnd;
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size_t const rLength = ZSTD_count_2segments(
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ip+4, repMatch+4, repCheckEnd, repEnd,
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lowPrefixPtr) + 4;
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/* Swap rep[1] <=> rep[0] */
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U32 const tmpOffset = rep[1];
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rep[1] = rep[0];
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rep[0] = tmpOffset;
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ZSTD_storeSeq(seqStore, 0, ip, 0, rLength-MINMATCH);
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ip += rLength;
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if (nextSeq) {
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assert(nextSeq->litLength >= rLength);
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nextSeq->litLength -= rLength;
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}
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continue;
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}
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break;
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}
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} else {
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while ( (ip < repCheckLimit)
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&& ( (rep[1] > 0) && (rep[1] <= (U32)(ip - lowPrefixPtr))
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&& (MEM_read32(ip) == MEM_read32(ip - rep[1])) )) {
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size_t const rLength = ZSTD_count(ip+4, ip+4-rep[1],
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repCheckEnd) + 4;
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/* Swap rep[1] <=> rep[0] */
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{
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U32 const tmpOff = rep[1];
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rep[1] = rep[0];
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rep[0] = tmpOff;
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}
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ZSTD_storeSeq(seqStore, 0, ip, 0, rLength-MINMATCH);
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ip += rLength;
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if (nextSeq) {
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assert(nextSeq->litLength >= rLength);
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nextSeq->litLength -= rLength;
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}
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}
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}
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}
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}
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ZSTD_ldm_limitTableUpdate(ms, ip);
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ZSTD_ldm_fillFastTables(ms, cParams, ip);
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