diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/zstd/enc_best.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/zstd/enc_best.go | 64 |
1 files changed, 36 insertions, 28 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_best.go b/vendor/github.com/klauspost/compress/zstd/enc_best.go index 96028ecd..830f5ba7 100644 --- a/vendor/github.com/klauspost/compress/zstd/enc_best.go +++ b/vendor/github.com/klauspost/compress/zstd/enc_best.go @@ -32,6 +32,7 @@ type match struct { length int32 rep int32 est int32 + _ [12]byte // Aligned size to cache line: 4+4+4+4+4 bytes + 12 bytes padding = 32 bytes } const highScore = 25000 @@ -84,14 +85,10 @@ func (e *bestFastEncoder) 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] = prevEntry{} - } - for i := range e.longTable[:] { - e.longTable[i] = prevEntry{} - } + e.table = [bestShortTableSize]prevEntry{} + e.longTable = [bestLongTableSize]prevEntry{} e.cur = e.maxMatchOff break } @@ -192,8 +189,8 @@ encodeLoop: panic("offset0 was 0") } - bestOf := func(a, b match) match { - if a.est+(a.s-b.s)*bitsPerByte>>10 < b.est+(b.s-a.s)*bitsPerByte>>10 { + bestOf := func(a, b *match) *match { + if a.est-b.est+(a.s-b.s)*bitsPerByte>>10 < 0 { return a } return b @@ -219,22 +216,26 @@ encodeLoop: return m } - best := bestOf(matchAt(candidateL.offset-e.cur, s, uint32(cv), -1), matchAt(candidateL.prev-e.cur, s, uint32(cv), -1)) - best = bestOf(best, matchAt(candidateS.offset-e.cur, s, uint32(cv), -1)) - best = bestOf(best, matchAt(candidateS.prev-e.cur, s, uint32(cv), -1)) + m1 := matchAt(candidateL.offset-e.cur, s, uint32(cv), -1) + m2 := matchAt(candidateL.prev-e.cur, s, uint32(cv), -1) + m3 := matchAt(candidateS.offset-e.cur, s, uint32(cv), -1) + m4 := matchAt(candidateS.prev-e.cur, s, uint32(cv), -1) + best := bestOf(bestOf(&m1, &m2), bestOf(&m3, &m4)) if canRepeat && best.length < goodEnough { cv32 := uint32(cv >> 8) spp := s + 1 - best = bestOf(best, matchAt(spp-offset1, spp, cv32, 1)) - best = bestOf(best, matchAt(spp-offset2, spp, cv32, 2)) - best = bestOf(best, matchAt(spp-offset3, spp, cv32, 3)) + m1 := matchAt(spp-offset1, spp, cv32, 1) + m2 := matchAt(spp-offset2, spp, cv32, 2) + m3 := matchAt(spp-offset3, spp, cv32, 3) + best = bestOf(bestOf(best, &m1), bestOf(&m2, &m3)) if best.length > 0 { cv32 = uint32(cv >> 24) spp += 2 - best = bestOf(best, matchAt(spp-offset1, spp, cv32, 1)) - best = bestOf(best, matchAt(spp-offset2, spp, cv32, 2)) - best = bestOf(best, matchAt(spp-offset3, spp, cv32, 3)) + m1 := matchAt(spp-offset1, spp, cv32, 1) + m2 := matchAt(spp-offset2, spp, cv32, 2) + m3 := matchAt(spp-offset3, spp, cv32, 3) + best = bestOf(bestOf(best, &m1), bestOf(&m2, &m3)) } } // Load next and check... @@ -261,26 +262,33 @@ encodeLoop: candidateL2 := e.longTable[hashLen(cv2, bestLongTableBits, bestLongLen)] // Short at s+1 - best = bestOf(best, matchAt(candidateS.offset-e.cur, s, uint32(cv), -1)) + m1 := matchAt(candidateS.offset-e.cur, s, uint32(cv), -1) // Long at s+1, s+2 - best = bestOf(best, matchAt(candidateL.offset-e.cur, s, uint32(cv), -1)) - best = bestOf(best, matchAt(candidateL.prev-e.cur, s, uint32(cv), -1)) - best = bestOf(best, matchAt(candidateL2.offset-e.cur, s+1, uint32(cv2), -1)) - best = bestOf(best, matchAt(candidateL2.prev-e.cur, s+1, uint32(cv2), -1)) + m2 := matchAt(candidateL.offset-e.cur, s, uint32(cv), -1) + m3 := matchAt(candidateL.prev-e.cur, s, uint32(cv), -1) + m4 := matchAt(candidateL2.offset-e.cur, s+1, uint32(cv2), -1) + m5 := matchAt(candidateL2.prev-e.cur, s+1, uint32(cv2), -1) + best = bestOf(bestOf(bestOf(best, &m1), &m2), bestOf(bestOf(&m3, &m4), &m5)) if false { // Short at s+3. // Too often worse... - best = bestOf(best, matchAt(e.table[hashLen(cv2>>8, bestShortTableBits, bestShortLen)].offset-e.cur, s+2, uint32(cv2>>8), -1)) + m := matchAt(e.table[hashLen(cv2>>8, bestShortTableBits, bestShortLen)].offset-e.cur, s+2, uint32(cv2>>8), -1) + best = bestOf(best, &m) } // See if we can find a better match by checking where the current best ends. // Use that offset to see if we can find a better full match. if sAt := best.s + best.length; sAt < sLimit { nextHashL := hashLen(load6432(src, sAt), bestLongTableBits, bestLongLen) candidateEnd := e.longTable[nextHashL] - if pos := candidateEnd.offset - e.cur - best.length; pos >= 0 { - bestEnd := bestOf(best, matchAt(pos, best.s, load3232(src, best.s), -1)) - if pos := candidateEnd.prev - e.cur - best.length; pos >= 0 { - bestEnd = bestOf(bestEnd, matchAt(pos, best.s, load3232(src, best.s), -1)) + // Start check at a fixed offset to allow for a few mismatches. + // For this compression level 2 yields the best results. + const skipBeginning = 2 + if pos := candidateEnd.offset - e.cur - best.length + skipBeginning; pos >= 0 { + m := matchAt(pos, best.s+skipBeginning, load3232(src, best.s+skipBeginning), -1) + bestEnd := bestOf(best, &m) + if pos := candidateEnd.prev - e.cur - best.length + skipBeginning; pos >= 0 { + m := matchAt(pos, best.s+skipBeginning, load3232(src, best.s+skipBeginning), -1) + bestEnd = bestOf(bestEnd, &m) } best = bestEnd } |