diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/zstd/enc_better.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/zstd/enc_better.go | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_better.go b/vendor/github.com/klauspost/compress/zstd/enc_better.go index c769f694..8582f31a 100644 --- a/vendor/github.com/klauspost/compress/zstd/enc_better.go +++ b/vendor/github.com/klauspost/compress/zstd/enc_better.go @@ -62,14 +62,10 @@ func (e *betterFastEncoder) Encode(blk *blockEnc, src []byte) { ) // Protect against e.cur wraparound. - for e.cur >= bufferReset { + for e.cur >= e.bufferReset-int32(len(e.hist)) { if len(e.hist) == 0 { - for i := range e.table[:] { - e.table[i] = tableEntry{} - } - for i := range e.longTable[:] { - e.longTable[i] = prevEntry{} - } + e.table = [betterShortTableSize]tableEntry{} + e.longTable = [betterLongTableSize]prevEntry{} e.cur = e.maxMatchOff break } @@ -416,15 +412,23 @@ encodeLoop: // Try to find a better match by searching for a long match at the end of the current best match if s+matched < sLimit { + // Allow some bytes at the beginning to mismatch. + // Sweet spot is around 3 bytes, but depends on input. + // The skipped bytes are tested in Extend backwards, + // and still picked up as part of the match if they do. + const skipBeginning = 3 + nextHashL := hashLen(load6432(src, s+matched), betterLongTableBits, betterLongLen) - cv := load3232(src, s) + s2 := s + skipBeginning + cv := load3232(src, s2) candidateL := e.longTable[nextHashL] - coffsetL := candidateL.offset - e.cur - matched - if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) { + coffsetL := candidateL.offset - e.cur - matched + skipBeginning + if coffsetL >= 0 && coffsetL < s2 && s2-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) { // Found a long match, at least 4 bytes. - matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4 + matchedNext := e.matchlen(s2+4, coffsetL+4, src) + 4 if matchedNext > matched { t = coffsetL + s = s2 matched = matchedNext if debugMatches { println("long match at end-of-match") @@ -434,12 +438,13 @@ encodeLoop: // Check prev long... if true { - coffsetL = candidateL.prev - e.cur - matched - if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) { + coffsetL = candidateL.prev - e.cur - matched + skipBeginning + if coffsetL >= 0 && coffsetL < s2 && s2-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) { // Found a long match, at least 4 bytes. - matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4 + matchedNext := e.matchlen(s2+4, coffsetL+4, src) + 4 if matchedNext > matched { t = coffsetL + s = s2 matched = matchedNext if debugMatches { println("prev long match at end-of-match") @@ -578,7 +583,7 @@ func (e *betterFastEncoderDict) Encode(blk *blockEnc, src []byte) { ) // Protect against e.cur wraparound. - for e.cur >= bufferReset { + for e.cur >= e.bufferReset-int32(len(e.hist)) { if len(e.hist) == 0 { for i := range e.table[:] { e.table[i] = tableEntry{} |