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