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-rw-r--r--vendor/github.com/klauspost/compress/zstd/enc_better.go1237
1 files changed, 1237 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_better.go b/vendor/github.com/klauspost/compress/zstd/enc_better.go
new file mode 100644
index 00000000..602c05ee
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/enc_better.go
@@ -0,0 +1,1237 @@
+// Copyright 2019+ Klaus Post. All rights reserved.
+// License information can be found in the LICENSE file.
+// Based on work by Yann Collet, released under BSD License.
+
+package zstd
+
+import "fmt"
+
+const (
+ betterLongTableBits = 19 // Bits used in the long match table
+ betterLongTableSize = 1 << betterLongTableBits // Size of the table
+ betterLongLen = 8 // Bytes used for table hash
+
+ // Note: Increasing the short table bits or making the hash shorter
+ // can actually lead to compression degradation since it will 'steal' more from the
+ // long match table and match offsets are quite big.
+ // This greatly depends on the type of input.
+ betterShortTableBits = 13 // Bits used in the short match table
+ betterShortTableSize = 1 << betterShortTableBits // Size of the table
+ betterShortLen = 5 // Bytes used for table hash
+
+ betterLongTableShardCnt = 1 << (betterLongTableBits - dictShardBits) // Number of shards in the table
+ betterLongTableShardSize = betterLongTableSize / betterLongTableShardCnt // Size of an individual shard
+
+ betterShortTableShardCnt = 1 << (betterShortTableBits - dictShardBits) // Number of shards in the table
+ betterShortTableShardSize = betterShortTableSize / betterShortTableShardCnt // Size of an individual shard
+)
+
+type prevEntry struct {
+ offset int32
+ prev int32
+}
+
+// betterFastEncoder uses 2 tables, one for short matches (5 bytes) and one for long matches.
+// The long match table contains the previous entry with the same hash,
+// effectively making it a "chain" of length 2.
+// When we find a long match we choose between the two values and select the longest.
+// When we find a short match, after checking the long, we check if we can find a long at n+1
+// and that it is longer (lazy matching).
+type betterFastEncoder struct {
+ fastBase
+ table [betterShortTableSize]tableEntry
+ longTable [betterLongTableSize]prevEntry
+}
+
+type betterFastEncoderDict struct {
+ betterFastEncoder
+ dictTable []tableEntry
+ dictLongTable []prevEntry
+ shortTableShardDirty [betterShortTableShardCnt]bool
+ longTableShardDirty [betterLongTableShardCnt]bool
+ allDirty bool
+}
+
+// Encode improves compression...
+func (e *betterFastEncoder) Encode(blk *blockEnc, src []byte) {
+ const (
+ // Input margin is the number of bytes we read (8)
+ // and the maximum we will read ahead (2)
+ inputMargin = 8 + 2
+ minNonLiteralBlockSize = 16
+ )
+
+ // Protect against e.cur wraparound.
+ for e.cur >= bufferReset {
+ if len(e.hist) == 0 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntry{}
+ }
+ for i := range e.longTable[:] {
+ e.longTable[i] = prevEntry{}
+ }
+ e.cur = e.maxMatchOff
+ break
+ }
+ // Shift down everything in the table that isn't already too far away.
+ minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
+ for i := range e.table[:] {
+ v := e.table[i].offset
+ if v < minOff {
+ v = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ }
+ e.table[i].offset = v
+ }
+ for i := range e.longTable[:] {
+ v := e.longTable[i].offset
+ v2 := e.longTable[i].prev
+ if v < minOff {
+ v = 0
+ v2 = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ if v2 < minOff {
+ v2 = 0
+ } else {
+ v2 = v2 - e.cur + e.maxMatchOff
+ }
+ }
+ e.longTable[i] = prevEntry{
+ offset: v,
+ prev: v2,
+ }
+ }
+ e.cur = e.maxMatchOff
+ break
+ }
+
+ s := e.addBlock(src)
+ blk.size = len(src)
+ if len(src) < minNonLiteralBlockSize {
+ blk.extraLits = len(src)
+ blk.literals = blk.literals[:len(src)]
+ copy(blk.literals, src)
+ return
+ }
+
+ // Override src
+ src = e.hist
+ sLimit := int32(len(src)) - inputMargin
+ // stepSize is the number of bytes to skip on every main loop iteration.
+ // It should be >= 1.
+ const stepSize = 1
+
+ const kSearchStrength = 9
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := s
+ cv := load6432(src, s)
+
+ // Relative offsets
+ offset1 := int32(blk.recentOffsets[0])
+ offset2 := int32(blk.recentOffsets[1])
+
+ addLiterals := func(s *seq, until int32) {
+ if until == nextEmit {
+ return
+ }
+ blk.literals = append(blk.literals, src[nextEmit:until]...)
+ s.litLen = uint32(until - nextEmit)
+ }
+ if debugEncoder {
+ println("recent offsets:", blk.recentOffsets)
+ }
+
+encodeLoop:
+ for {
+ var t int32
+ // We allow the encoder to optionally turn off repeat offsets across blocks
+ canRepeat := len(blk.sequences) > 2
+ var matched int32
+
+ for {
+ if debugAsserts && canRepeat && offset1 == 0 {
+ panic("offset0 was 0")
+ }
+
+ nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
+ nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
+ candidateL := e.longTable[nextHashL]
+ candidateS := e.table[nextHashS]
+
+ const repOff = 1
+ repIndex := s - offset1 + repOff
+ off := s + e.cur
+ e.longTable[nextHashL] = prevEntry{offset: off, prev: candidateL.offset}
+ e.table[nextHashS] = tableEntry{offset: off, val: uint32(cv)}
+
+ if canRepeat {
+ if repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
+ // Consider history as well.
+ var seq seq
+ lenght := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
+
+ seq.matchLen = uint32(lenght - zstdMinMatch)
+
+ // We might be able to match backwards.
+ // Extend as long as we can.
+ start := s + repOff
+ // We end the search early, so we don't risk 0 literals
+ // and have to do special offset treatment.
+ startLimit := nextEmit + 1
+
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
+ repIndex--
+ start--
+ seq.matchLen++
+ }
+ addLiterals(&seq, start)
+
+ // rep 0
+ seq.offset = 1
+ if debugSequences {
+ println("repeat sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ // Index match start+1 (long) -> s - 1
+ index0 := s + repOff
+ s += lenght + repOff
+
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+ // Index skipped...
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ index0 += 2
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ const repOff2 = 1
+
+ // We deviate from the reference encoder and also check offset 2.
+ // Still slower and not much better, so disabled.
+ // repIndex = s - offset2 + repOff2
+ if false && repIndex >= 0 && load6432(src, repIndex) == load6432(src, s+repOff) {
+ // Consider history as well.
+ var seq seq
+ lenght := 8 + e.matchlen(s+8+repOff2, repIndex+8, src)
+
+ seq.matchLen = uint32(lenght - zstdMinMatch)
+
+ // We might be able to match backwards.
+ // Extend as long as we can.
+ start := s + repOff2
+ // We end the search early, so we don't risk 0 literals
+ // and have to do special offset treatment.
+ startLimit := nextEmit + 1
+
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
+ repIndex--
+ start--
+ seq.matchLen++
+ }
+ addLiterals(&seq, start)
+
+ // rep 2
+ seq.offset = 2
+ if debugSequences {
+ println("repeat sequence 2", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ index0 := s + repOff2
+ s += lenght + repOff2
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+
+ // Index skipped...
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ index0 += 2
+ }
+ cv = load6432(src, s)
+ // Swap offsets
+ offset1, offset2 = offset2, offset1
+ continue
+ }
+ }
+ // Find the offsets of our two matches.
+ coffsetL := candidateL.offset - e.cur
+ coffsetLP := candidateL.prev - e.cur
+
+ // Check if we have a long match.
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matched = e.matchlen(s+8, coffsetL+8, src) + 8
+ t = coffsetL
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+
+ if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
+ // Found a long match, at least 8 bytes.
+ prevMatch := e.matchlen(s+8, coffsetLP+8, src) + 8
+ if prevMatch > matched {
+ matched = prevMatch
+ t = coffsetLP
+ }
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+ }
+ break
+ }
+
+ // Check if we have a long match on prev.
+ if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
+ // Found a long match, at least 8 bytes.
+ matched = e.matchlen(s+8, coffsetLP+8, src) + 8
+ t = coffsetLP
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+ break
+ }
+
+ coffsetS := candidateS.offset - e.cur
+
+ // Check if we have a short match.
+ if s-coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
+ // found a regular match
+ matched = e.matchlen(s+4, coffsetS+4, src) + 4
+
+ // See if we can find a long match at s+1
+ const checkAt = 1
+ cv := load6432(src, s+checkAt)
+ nextHashL = hashLen(cv, betterLongTableBits, betterLongLen)
+ candidateL = e.longTable[nextHashL]
+ coffsetL = candidateL.offset - e.cur
+
+ // We can store it, since we have at least a 4 byte match.
+ e.longTable[nextHashL] = prevEntry{offset: s + checkAt + e.cur, prev: candidateL.offset}
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
+ if matchedNext > matched {
+ t = coffsetL
+ s += checkAt
+ matched = matchedNext
+ if debugMatches {
+ println("long match (after short)")
+ }
+ break
+ }
+ }
+
+ // Check prev long...
+ coffsetL = candidateL.prev - e.cur
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
+ if matchedNext > matched {
+ t = coffsetL
+ s += checkAt
+ matched = matchedNext
+ if debugMatches {
+ println("prev long match (after short)")
+ }
+ break
+ }
+ }
+ t = coffsetS
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugAsserts && t < 0 {
+ panic("t<0")
+ }
+ if debugMatches {
+ println("short match")
+ }
+ break
+ }
+
+ // No match found, move forward in input.
+ s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
+ if s >= sLimit {
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ }
+
+ // Try to find a better match by searching for a long match at the end of the current best match
+ if s+matched < sLimit {
+ nextHashL := hashLen(load6432(src, s+matched), betterLongTableBits, betterLongLen)
+ cv := load3232(src, s)
+ candidateL := e.longTable[nextHashL]
+ coffsetL := candidateL.offset - e.cur - matched
+ if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
+ // Found a long match, at least 4 bytes.
+ matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
+ if matchedNext > matched {
+ t = coffsetL
+ matched = matchedNext
+ if debugMatches {
+ println("long match at end-of-match")
+ }
+ }
+ }
+
+ // Check prev long...
+ if true {
+ coffsetL = candidateL.prev - e.cur - matched
+ if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
+ // Found a long match, at least 4 bytes.
+ matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
+ if matchedNext > matched {
+ t = coffsetL
+ matched = matchedNext
+ if debugMatches {
+ println("prev long match at end-of-match")
+ }
+ }
+ }
+ }
+ }
+ // A match has been found. Update recent offsets.
+ offset2 = offset1
+ offset1 = s - t
+
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+
+ if debugAsserts && canRepeat && int(offset1) > len(src) {
+ panic("invalid offset")
+ }
+
+ // Extend the n-byte match as long as possible.
+ l := matched
+
+ // Extend backwards
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
+ s--
+ t--
+ l++
+ }
+
+ // Write our sequence
+ var seq seq
+ seq.litLen = uint32(s - nextEmit)
+ seq.matchLen = uint32(l - zstdMinMatch)
+ if seq.litLen > 0 {
+ blk.literals = append(blk.literals, src[nextEmit:s]...)
+ }
+ seq.offset = uint32(s-t) + 3
+ s += l
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+ nextEmit = s
+ if s >= sLimit {
+ break encodeLoop
+ }
+
+ // Index match start+1 (long) -> s - 1
+ index0 := s - l + 1
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ index0 += 2
+ }
+
+ cv = load6432(src, s)
+ if !canRepeat {
+ continue
+ }
+
+ // Check offset 2
+ for {
+ o2 := s - offset2
+ if load3232(src, o2) != uint32(cv) {
+ // Do regular search
+ break
+ }
+
+ // Store this, since we have it.
+ nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
+ nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
+
+ // We have at least 4 byte match.
+ // No need to check backwards. We come straight from a match
+ l := 4 + e.matchlen(s+4, o2+4, src)
+
+ e.longTable[nextHashL] = prevEntry{offset: s + e.cur, prev: e.longTable[nextHashL].offset}
+ e.table[nextHashS] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+ seq.matchLen = uint32(l) - zstdMinMatch
+ seq.litLen = 0
+
+ // Since litlen is always 0, this is offset 1.
+ seq.offset = 1
+ s += l
+ nextEmit = s
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ // Swap offset 1 and 2.
+ offset1, offset2 = offset2, offset1
+ if s >= sLimit {
+ // Finished
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ }
+ }
+
+ if int(nextEmit) < len(src) {
+ blk.literals = append(blk.literals, src[nextEmit:]...)
+ blk.extraLits = len(src) - int(nextEmit)
+ }
+ blk.recentOffsets[0] = uint32(offset1)
+ blk.recentOffsets[1] = uint32(offset2)
+ if debugEncoder {
+ println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
+ }
+}
+
+// EncodeNoHist will encode a block with no history and no following blocks.
+// Most notable difference is that src will not be copied for history and
+// we do not need to check for max match length.
+func (e *betterFastEncoder) EncodeNoHist(blk *blockEnc, src []byte) {
+ e.ensureHist(len(src))
+ e.Encode(blk, src)
+}
+
+// Encode improves compression...
+func (e *betterFastEncoderDict) Encode(blk *blockEnc, src []byte) {
+ const (
+ // Input margin is the number of bytes we read (8)
+ // and the maximum we will read ahead (2)
+ inputMargin = 8 + 2
+ minNonLiteralBlockSize = 16
+ )
+
+ // Protect against e.cur wraparound.
+ for e.cur >= bufferReset {
+ if len(e.hist) == 0 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntry{}
+ }
+ for i := range e.longTable[:] {
+ e.longTable[i] = prevEntry{}
+ }
+ e.cur = e.maxMatchOff
+ e.allDirty = true
+ break
+ }
+ // Shift down everything in the table that isn't already too far away.
+ minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
+ for i := range e.table[:] {
+ v := e.table[i].offset
+ if v < minOff {
+ v = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ }
+ e.table[i].offset = v
+ }
+ for i := range e.longTable[:] {
+ v := e.longTable[i].offset
+ v2 := e.longTable[i].prev
+ if v < minOff {
+ v = 0
+ v2 = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ if v2 < minOff {
+ v2 = 0
+ } else {
+ v2 = v2 - e.cur + e.maxMatchOff
+ }
+ }
+ e.longTable[i] = prevEntry{
+ offset: v,
+ prev: v2,
+ }
+ }
+ e.allDirty = true
+ e.cur = e.maxMatchOff
+ break
+ }
+
+ s := e.addBlock(src)
+ blk.size = len(src)
+ if len(src) < minNonLiteralBlockSize {
+ blk.extraLits = len(src)
+ blk.literals = blk.literals[:len(src)]
+ copy(blk.literals, src)
+ return
+ }
+
+ // Override src
+ src = e.hist
+ sLimit := int32(len(src)) - inputMargin
+ // stepSize is the number of bytes to skip on every main loop iteration.
+ // It should be >= 1.
+ const stepSize = 1
+
+ const kSearchStrength = 9
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := s
+ cv := load6432(src, s)
+
+ // Relative offsets
+ offset1 := int32(blk.recentOffsets[0])
+ offset2 := int32(blk.recentOffsets[1])
+
+ addLiterals := func(s *seq, until int32) {
+ if until == nextEmit {
+ return
+ }
+ blk.literals = append(blk.literals, src[nextEmit:until]...)
+ s.litLen = uint32(until - nextEmit)
+ }
+ if debugEncoder {
+ println("recent offsets:", blk.recentOffsets)
+ }
+
+encodeLoop:
+ for {
+ var t int32
+ // We allow the encoder to optionally turn off repeat offsets across blocks
+ canRepeat := len(blk.sequences) > 2
+ var matched int32
+
+ for {
+ if debugAsserts && canRepeat && offset1 == 0 {
+ panic("offset0 was 0")
+ }
+
+ nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
+ nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
+ candidateL := e.longTable[nextHashL]
+ candidateS := e.table[nextHashS]
+
+ const repOff = 1
+ repIndex := s - offset1 + repOff
+ off := s + e.cur
+ e.longTable[nextHashL] = prevEntry{offset: off, prev: candidateL.offset}
+ e.markLongShardDirty(nextHashL)
+ e.table[nextHashS] = tableEntry{offset: off, val: uint32(cv)}
+ e.markShortShardDirty(nextHashS)
+
+ if canRepeat {
+ if repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
+ // Consider history as well.
+ var seq seq
+ lenght := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
+
+ seq.matchLen = uint32(lenght - zstdMinMatch)
+
+ // We might be able to match backwards.
+ // Extend as long as we can.
+ start := s + repOff
+ // We end the search early, so we don't risk 0 literals
+ // and have to do special offset treatment.
+ startLimit := nextEmit + 1
+
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
+ repIndex--
+ start--
+ seq.matchLen++
+ }
+ addLiterals(&seq, start)
+
+ // rep 0
+ seq.offset = 1
+ if debugSequences {
+ println("repeat sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ // Index match start+1 (long) -> s - 1
+ index0 := s + repOff
+ s += lenght + repOff
+
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+ // Index skipped...
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.markLongShardDirty(h0)
+ h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
+ e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ e.markShortShardDirty(h1)
+ index0 += 2
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ const repOff2 = 1
+
+ // We deviate from the reference encoder and also check offset 2.
+ // Still slower and not much better, so disabled.
+ // repIndex = s - offset2 + repOff2
+ if false && repIndex >= 0 && load6432(src, repIndex) == load6432(src, s+repOff) {
+ // Consider history as well.
+ var seq seq
+ lenght := 8 + e.matchlen(s+8+repOff2, repIndex+8, src)
+
+ seq.matchLen = uint32(lenght - zstdMinMatch)
+
+ // We might be able to match backwards.
+ // Extend as long as we can.
+ start := s + repOff2
+ // We end the search early, so we don't risk 0 literals
+ // and have to do special offset treatment.
+ startLimit := nextEmit + 1
+
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
+ repIndex--
+ start--
+ seq.matchLen++
+ }
+ addLiterals(&seq, start)
+
+ // rep 2
+ seq.offset = 2
+ if debugSequences {
+ println("repeat sequence 2", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ index0 := s + repOff2
+ s += lenght + repOff2
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+
+ // Index skipped...
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.markLongShardDirty(h0)
+ h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
+ e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ e.markShortShardDirty(h1)
+ index0 += 2
+ }
+ cv = load6432(src, s)
+ // Swap offsets
+ offset1, offset2 = offset2, offset1
+ continue
+ }
+ }
+ // Find the offsets of our two matches.
+ coffsetL := candidateL.offset - e.cur
+ coffsetLP := candidateL.prev - e.cur
+
+ // Check if we have a long match.
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matched = e.matchlen(s+8, coffsetL+8, src) + 8
+ t = coffsetL
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+
+ if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
+ // Found a long match, at least 8 bytes.
+ prevMatch := e.matchlen(s+8, coffsetLP+8, src) + 8
+ if prevMatch > matched {
+ matched = prevMatch
+ t = coffsetLP
+ }
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+ }
+ break
+ }
+
+ // Check if we have a long match on prev.
+ if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
+ // Found a long match, at least 8 bytes.
+ matched = e.matchlen(s+8, coffsetLP+8, src) + 8
+ t = coffsetLP
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+ break
+ }
+
+ coffsetS := candidateS.offset - e.cur
+
+ // Check if we have a short match.
+ if s-coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
+ // found a regular match
+ matched = e.matchlen(s+4, coffsetS+4, src) + 4
+
+ // See if we can find a long match at s+1
+ const checkAt = 1
+ cv := load6432(src, s+checkAt)
+ nextHashL = hashLen(cv, betterLongTableBits, betterLongLen)
+ candidateL = e.longTable[nextHashL]
+ coffsetL = candidateL.offset - e.cur
+
+ // We can store it, since we have at least a 4 byte match.
+ e.longTable[nextHashL] = prevEntry{offset: s + checkAt + e.cur, prev: candidateL.offset}
+ e.markLongShardDirty(nextHashL)
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
+ if matchedNext > matched {
+ t = coffsetL
+ s += checkAt
+ matched = matchedNext
+ if debugMatches {
+ println("long match (after short)")
+ }
+ break
+ }
+ }
+
+ // Check prev long...
+ coffsetL = candidateL.prev - e.cur
+ if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
+ // Found a long match, at least 8 bytes.
+ matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
+ if matchedNext > matched {
+ t = coffsetL
+ s += checkAt
+ matched = matchedNext
+ if debugMatches {
+ println("prev long match (after short)")
+ }
+ break
+ }
+ }
+ t = coffsetS
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugAsserts && t < 0 {
+ panic("t<0")
+ }
+ if debugMatches {
+ println("short match")
+ }
+ break
+ }
+
+ // No match found, move forward in input.
+ s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
+ if s >= sLimit {
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ }
+ // Try to find a better match by searching for a long match at the end of the current best match
+ if s+matched < sLimit {
+ nextHashL := hashLen(load6432(src, s+matched), betterLongTableBits, betterLongLen)
+ cv := load3232(src, s)
+ candidateL := e.longTable[nextHashL]
+ coffsetL := candidateL.offset - e.cur - matched
+ if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
+ // Found a long match, at least 4 bytes.
+ matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
+ if matchedNext > matched {
+ t = coffsetL
+ matched = matchedNext
+ if debugMatches {
+ println("long match at end-of-match")
+ }
+ }
+ }
+
+ // Check prev long...
+ if true {
+ coffsetL = candidateL.prev - e.cur - matched
+ if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
+ // Found a long match, at least 4 bytes.
+ matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
+ if matchedNext > matched {
+ t = coffsetL
+ matched = matchedNext
+ if debugMatches {
+ println("prev long match at end-of-match")
+ }
+ }
+ }
+ }
+ }
+ // A match has been found. Update recent offsets.
+ offset2 = offset1
+ offset1 = s - t
+
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+
+ if debugAsserts && canRepeat && int(offset1) > len(src) {
+ panic("invalid offset")
+ }
+
+ // Extend the n-byte match as long as possible.
+ l := matched
+
+ // Extend backwards
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
+ s--
+ t--
+ l++
+ }
+
+ // Write our sequence
+ var seq seq
+ seq.litLen = uint32(s - nextEmit)
+ seq.matchLen = uint32(l - zstdMinMatch)
+ if seq.litLen > 0 {
+ blk.literals = append(blk.literals, src[nextEmit:s]...)
+ }
+ seq.offset = uint32(s-t) + 3
+ s += l
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+ nextEmit = s
+ if s >= sLimit {
+ break encodeLoop
+ }
+
+ // Index match start+1 (long) -> s - 1
+ index0 := s - l + 1
+ for index0 < s-1 {
+ cv0 := load6432(src, index0)
+ cv1 := cv0 >> 8
+ h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
+ off := index0 + e.cur
+ e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
+ e.markLongShardDirty(h0)
+ h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
+ e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
+ e.markShortShardDirty(h1)
+ index0 += 2
+ }
+
+ cv = load6432(src, s)
+ if !canRepeat {
+ continue
+ }
+
+ // Check offset 2
+ for {
+ o2 := s - offset2
+ if load3232(src, o2) != uint32(cv) {
+ // Do regular search
+ break
+ }
+
+ // Store this, since we have it.
+ nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
+ nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
+
+ // We have at least 4 byte match.
+ // No need to check backwards. We come straight from a match
+ l := 4 + e.matchlen(s+4, o2+4, src)
+
+ e.longTable[nextHashL] = prevEntry{offset: s + e.cur, prev: e.longTable[nextHashL].offset}
+ e.markLongShardDirty(nextHashL)
+ e.table[nextHashS] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.markShortShardDirty(nextHashS)
+ seq.matchLen = uint32(l) - zstdMinMatch
+ seq.litLen = 0
+
+ // Since litlen is always 0, this is offset 1.
+ seq.offset = 1
+ s += l
+ nextEmit = s
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ // Swap offset 1 and 2.
+ offset1, offset2 = offset2, offset1
+ if s >= sLimit {
+ // Finished
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ }
+ }
+
+ if int(nextEmit) < len(src) {
+ blk.literals = append(blk.literals, src[nextEmit:]...)
+ blk.extraLits = len(src) - int(nextEmit)
+ }
+ blk.recentOffsets[0] = uint32(offset1)
+ blk.recentOffsets[1] = uint32(offset2)
+ if debugEncoder {
+ println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
+ }
+}
+
+// ResetDict will reset and set a dictionary if not nil
+func (e *betterFastEncoder) Reset(d *dict, singleBlock bool) {
+ e.resetBase(d, singleBlock)
+ if d != nil {
+ panic("betterFastEncoder: Reset with dict")
+ }
+}
+
+// ResetDict will reset and set a dictionary if not nil
+func (e *betterFastEncoderDict) Reset(d *dict, singleBlock bool) {
+ e.resetBase(d, singleBlock)
+ if d == nil {
+ return
+ }
+ // Init or copy dict table
+ if len(e.dictTable) != len(e.table) || d.id != e.lastDictID {
+ if len(e.dictTable) != len(e.table) {
+ e.dictTable = make([]tableEntry, len(e.table))
+ }
+ end := int32(len(d.content)) - 8 + e.maxMatchOff
+ for i := e.maxMatchOff; i < end; i += 4 {
+ const hashLog = betterShortTableBits
+
+ cv := load6432(d.content, i-e.maxMatchOff)
+ nextHash := hashLen(cv, hashLog, betterShortLen) // 0 -> 4
+ nextHash1 := hashLen(cv>>8, hashLog, betterShortLen) // 1 -> 5
+ nextHash2 := hashLen(cv>>16, hashLog, betterShortLen) // 2 -> 6
+ nextHash3 := hashLen(cv>>24, hashLog, betterShortLen) // 3 -> 7
+ e.dictTable[nextHash] = tableEntry{
+ val: uint32(cv),
+ offset: i,
+ }
+ e.dictTable[nextHash1] = tableEntry{
+ val: uint32(cv >> 8),
+ offset: i + 1,
+ }
+ e.dictTable[nextHash2] = tableEntry{
+ val: uint32(cv >> 16),
+ offset: i + 2,
+ }
+ e.dictTable[nextHash3] = tableEntry{
+ val: uint32(cv >> 24),
+ offset: i + 3,
+ }
+ }
+ e.lastDictID = d.id
+ e.allDirty = true
+ }
+
+ // Init or copy dict table
+ if len(e.dictLongTable) != len(e.longTable) || d.id != e.lastDictID {
+ if len(e.dictLongTable) != len(e.longTable) {
+ e.dictLongTable = make([]prevEntry, len(e.longTable))
+ }
+ if len(d.content) >= 8 {
+ cv := load6432(d.content, 0)
+ h := hashLen(cv, betterLongTableBits, betterLongLen)
+ e.dictLongTable[h] = prevEntry{
+ offset: e.maxMatchOff,
+ prev: e.dictLongTable[h].offset,
+ }
+
+ end := int32(len(d.content)) - 8 + e.maxMatchOff
+ off := 8 // First to read
+ for i := e.maxMatchOff + 1; i < end; i++ {
+ cv = cv>>8 | (uint64(d.content[off]) << 56)
+ h := hashLen(cv, betterLongTableBits, betterLongLen)
+ e.dictLongTable[h] = prevEntry{
+ offset: i,
+ prev: e.dictLongTable[h].offset,
+ }
+ off++
+ }
+ }
+ e.lastDictID = d.id
+ e.allDirty = true
+ }
+
+ // Reset table to initial state
+ {
+ dirtyShardCnt := 0
+ if !e.allDirty {
+ for i := range e.shortTableShardDirty {
+ if e.shortTableShardDirty[i] {
+ dirtyShardCnt++
+ }
+ }
+ }
+ const shardCnt = betterShortTableShardCnt
+ const shardSize = betterShortTableShardSize
+ if e.allDirty || dirtyShardCnt > shardCnt*4/6 {
+ copy(e.table[:], e.dictTable)
+ for i := range e.shortTableShardDirty {
+ e.shortTableShardDirty[i] = false
+ }
+ } else {
+ for i := range e.shortTableShardDirty {
+ if !e.shortTableShardDirty[i] {
+ continue
+ }
+
+ copy(e.table[i*shardSize:(i+1)*shardSize], e.dictTable[i*shardSize:(i+1)*shardSize])
+ e.shortTableShardDirty[i] = false
+ }
+ }
+ }
+ {
+ dirtyShardCnt := 0
+ if !e.allDirty {
+ for i := range e.shortTableShardDirty {
+ if e.shortTableShardDirty[i] {
+ dirtyShardCnt++
+ }
+ }
+ }
+ const shardCnt = betterLongTableShardCnt
+ const shardSize = betterLongTableShardSize
+ if e.allDirty || dirtyShardCnt > shardCnt*4/6 {
+ copy(e.longTable[:], e.dictLongTable)
+ for i := range e.longTableShardDirty {
+ e.longTableShardDirty[i] = false
+ }
+ } else {
+ for i := range e.longTableShardDirty {
+ if !e.longTableShardDirty[i] {
+ continue
+ }
+
+ copy(e.longTable[i*shardSize:(i+1)*shardSize], e.dictLongTable[i*shardSize:(i+1)*shardSize])
+ e.longTableShardDirty[i] = false
+ }
+ }
+ }
+ e.cur = e.maxMatchOff
+ e.allDirty = false
+}
+
+func (e *betterFastEncoderDict) markLongShardDirty(entryNum uint32) {
+ e.longTableShardDirty[entryNum/betterLongTableShardSize] = true
+}
+
+func (e *betterFastEncoderDict) markShortShardDirty(entryNum uint32) {
+ e.shortTableShardDirty[entryNum/betterShortTableShardSize] = true
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 05:56:20 +0000