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-rw-r--r--vendor/github.com/klauspost/compress/zstd/enc_dfast.go1124
1 files changed, 1124 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_dfast.go b/vendor/github.com/klauspost/compress/zstd/enc_dfast.go
new file mode 100644
index 00000000..d6b31042
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/enc_dfast.go
@@ -0,0 +1,1124 @@
+// 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 (
+ dFastLongTableBits = 17 // Bits used in the long match table
+ dFastLongTableSize = 1 << dFastLongTableBits // Size of the table
+ dFastLongTableMask = dFastLongTableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
+ dFastLongLen = 8 // Bytes used for table hash
+
+ dLongTableShardCnt = 1 << (dFastLongTableBits - dictShardBits) // Number of shards in the table
+ dLongTableShardSize = dFastLongTableSize / tableShardCnt // Size of an individual shard
+
+ dFastShortTableBits = tableBits // Bits used in the short match table
+ dFastShortTableSize = 1 << dFastShortTableBits // Size of the table
+ dFastShortTableMask = dFastShortTableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
+ dFastShortLen = 5 // Bytes used for table hash
+
+)
+
+type doubleFastEncoder struct {
+ fastEncoder
+ longTable [dFastLongTableSize]tableEntry
+}
+
+type doubleFastEncoderDict struct {
+ fastEncoderDict
+ longTable [dFastLongTableSize]tableEntry
+ dictLongTable []tableEntry
+ longTableShardDirty [dLongTableShardCnt]bool
+}
+
+// Encode mimmics functionality in zstd_dfast.c
+func (e *doubleFastEncoder) 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] = tableEntry{}
+ }
+ 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
+ if v < minOff {
+ v = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ }
+ e.longTable[i].offset = v
+ }
+ 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 = 8
+
+ // 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
+
+ for {
+ if debugAsserts && canRepeat && offset1 == 0 {
+ panic("offset0 was 0")
+ }
+
+ nextHashS := hashLen(cv, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL := e.longTable[nextHashL]
+ candidateS := e.table[nextHashS]
+
+ const repOff = 1
+ repIndex := s - offset1 + repOff
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.table[nextHashS] = entry
+
+ 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)
+ s += lenght + repOff
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ }
+ // Find the offsets of our two matches.
+ coffsetL := s - (candidateL.offset - e.cur)
+ coffsetS := s - (candidateS.offset - e.cur)
+
+ // Check if we have a long match.
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ 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 short match.
+ if coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
+ // found a regular match
+ // See if we can find a long match at s+1
+ const checkAt = 1
+ cv := load6432(src, s+checkAt)
+ nextHashL = hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL = e.longTable[nextHashL]
+ coffsetL = s - (candidateL.offset - e.cur) + checkAt
+
+ // We can store it, since we have at least a 4 byte match.
+ e.longTable[nextHashL] = tableEntry{offset: s + checkAt + e.cur, val: uint32(cv)}
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ s += checkAt
+ if debugMatches {
+ println("long match (after short)")
+ }
+ break
+ }
+
+ t = candidateS.offset - e.cur
+ 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)
+ }
+
+ // A 4-byte match has been found. Update recent offsets.
+ // We'll later see if more than 4 bytes.
+ 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 4-byte match as long as possible.
+ l := e.matchlen(s+4, t+4, src) + 4
+
+ // 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) and start+2 (short)
+ index0 := s - l + 1
+ // Index match end-2 (long) and end-1 (short)
+ index1 := s - 2
+
+ cv0 := load6432(src, index0)
+ cv1 := load6432(src, index1)
+ te0 := tableEntry{offset: index0 + e.cur, val: uint32(cv0)}
+ te1 := tableEntry{offset: index1 + e.cur, val: uint32(cv1)}
+ e.longTable[hashLen(cv0, dFastLongTableBits, dFastLongLen)] = te0
+ e.longTable[hashLen(cv1, dFastLongTableBits, dFastLongLen)] = te1
+ cv0 >>= 8
+ cv1 >>= 8
+ te0.offset++
+ te1.offset++
+ te0.val = uint32(cv0)
+ te1.val = uint32(cv1)
+ e.table[hashLen(cv0, dFastShortTableBits, dFastShortLen)] = te0
+ e.table[hashLen(cv1, dFastShortTableBits, dFastShortLen)] = te1
+
+ 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, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+
+ // 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)
+
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.table[nextHashS] = entry
+ 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 *doubleFastEncoder) EncodeNoHist(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.
+ if e.cur >= bufferReset {
+ for i := range e.table[:] {
+ e.table[i] = tableEntry{}
+ }
+ for i := range e.longTable[:] {
+ e.longTable[i] = tableEntry{}
+ }
+ e.cur = e.maxMatchOff
+ }
+
+ s := int32(0)
+ 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
+ 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 = 8
+
+ // 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
+ for {
+
+ nextHashS := hashLen(cv, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL := e.longTable[nextHashL]
+ candidateS := e.table[nextHashS]
+
+ const repOff = 1
+ repIndex := s - offset1 + repOff
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.table[nextHashS] = entry
+
+ if len(blk.sequences) > 2 {
+ if load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
+ // Consider history as well.
+ var seq seq
+ //length := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
+ length := 4 + int32(matchLen(src[s+4+repOff:], src[repIndex+4:]))
+
+ seq.matchLen = uint32(length - 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] {
+ 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)
+ s += length + repOff
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, length)
+
+ }
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ }
+ // Find the offsets of our two matches.
+ coffsetL := s - (candidateL.offset - e.cur)
+ coffsetS := s - (candidateS.offset - e.cur)
+
+ // Check if we have a long match.
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d). cur: %d", s, t, e.cur))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugMatches {
+ println("long match")
+ }
+ break
+ }
+
+ // Check if we have a short match.
+ if coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
+ // found a regular match
+ // See if we can find a long match at s+1
+ const checkAt = 1
+ cv := load6432(src, s+checkAt)
+ nextHashL = hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL = e.longTable[nextHashL]
+ coffsetL = s - (candidateL.offset - e.cur) + checkAt
+
+ // We can store it, since we have at least a 4 byte match.
+ e.longTable[nextHashL] = tableEntry{offset: s + checkAt + e.cur, val: uint32(cv)}
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ s += checkAt
+ if debugMatches {
+ println("long match (after short)")
+ }
+ break
+ }
+
+ t = candidateS.offset - e.cur
+ 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)
+ }
+
+ // A 4-byte match has been found. Update recent offsets.
+ // We'll later see if more than 4 bytes.
+ offset2 = offset1
+ offset1 = s - t
+
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+
+ // Extend the 4-byte match as long as possible.
+ //l := e.matchlen(s+4, t+4, src) + 4
+ l := int32(matchLen(src[s+4:], src[t+4:])) + 4
+
+ // Extend backwards
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for t > tMin && s > nextEmit && src[t-1] == src[s-1] {
+ 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) and start+2 (short)
+ index0 := s - l + 1
+ // Index match end-2 (long) and end-1 (short)
+ index1 := s - 2
+
+ cv0 := load6432(src, index0)
+ cv1 := load6432(src, index1)
+ te0 := tableEntry{offset: index0 + e.cur, val: uint32(cv0)}
+ te1 := tableEntry{offset: index1 + e.cur, val: uint32(cv1)}
+ e.longTable[hashLen(cv0, dFastLongTableBits, dFastLongLen)] = te0
+ e.longTable[hashLen(cv1, dFastLongTableBits, dFastLongLen)] = te1
+ cv0 >>= 8
+ cv1 >>= 8
+ te0.offset++
+ te1.offset++
+ te0.val = uint32(cv0)
+ te1.val = uint32(cv1)
+ e.table[hashLen(cv0, dFastShortTableBits, dFastShortLen)] = te0
+ e.table[hashLen(cv1, dFastShortTableBits, dFastShortLen)] = te1
+
+ cv = load6432(src, s)
+
+ if len(blk.sequences) <= 2 {
+ 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(cv1>>8, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+
+ // 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)
+ l := 4 + int32(matchLen(src[s+4:], src[o2+4:]))
+
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.table[nextHashS] = entry
+ 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)
+ }
+ if debugEncoder {
+ println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
+ }
+
+ // We do not store history, so we must offset e.cur to avoid false matches for next user.
+ if e.cur < bufferReset {
+ e.cur += int32(len(src))
+ }
+}
+
+// Encode will encode the content, with a dictionary if initialized for it.
+func (e *doubleFastEncoderDict) 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] = tableEntry{}
+ }
+ e.markAllShardsDirty()
+ 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
+ if v < minOff {
+ v = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ }
+ e.longTable[i].offset = v
+ }
+ e.markAllShardsDirty()
+ 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 = 8
+
+ // 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
+
+ for {
+ if debugAsserts && canRepeat && offset1 == 0 {
+ panic("offset0 was 0")
+ }
+
+ nextHashS := hashLen(cv, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL := e.longTable[nextHashL]
+ candidateS := e.table[nextHashS]
+
+ const repOff = 1
+ repIndex := s - offset1 + repOff
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.markLongShardDirty(nextHashL)
+ e.table[nextHashS] = entry
+ e.markShardDirty(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)
+ s += lenght + repOff
+ nextEmit = s
+ if s >= sLimit {
+ if debugEncoder {
+ println("repeat ended", s, lenght)
+
+ }
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ }
+ // Find the offsets of our two matches.
+ coffsetL := s - (candidateL.offset - e.cur)
+ coffsetS := s - (candidateS.offset - e.cur)
+
+ // Check if we have a long match.
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ 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 short match.
+ if coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
+ // found a regular match
+ // See if we can find a long match at s+1
+ const checkAt = 1
+ cv := load6432(src, s+checkAt)
+ nextHashL = hashLen(cv, dFastLongTableBits, dFastLongLen)
+ candidateL = e.longTable[nextHashL]
+ coffsetL = s - (candidateL.offset - e.cur) + checkAt
+
+ // We can store it, since we have at least a 4 byte match.
+ e.longTable[nextHashL] = tableEntry{offset: s + checkAt + e.cur, val: uint32(cv)}
+ e.markLongShardDirty(nextHashL)
+ if coffsetL < e.maxMatchOff && uint32(cv) == candidateL.val {
+ // Found a long match, likely at least 8 bytes.
+ // Reference encoder checks all 8 bytes, we only check 4,
+ // but the likelihood of both the first 4 bytes and the hash matching should be enough.
+ t = candidateL.offset - e.cur
+ s += checkAt
+ if debugMatches {
+ println("long match (after short)")
+ }
+ break
+ }
+
+ t = candidateS.offset - e.cur
+ 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)
+ }
+
+ // A 4-byte match has been found. Update recent offsets.
+ // We'll later see if more than 4 bytes.
+ 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 4-byte match as long as possible.
+ l := e.matchlen(s+4, t+4, src) + 4
+
+ // 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) and start+2 (short)
+ index0 := s - l + 1
+ // Index match end-2 (long) and end-1 (short)
+ index1 := s - 2
+
+ cv0 := load6432(src, index0)
+ cv1 := load6432(src, index1)
+ te0 := tableEntry{offset: index0 + e.cur, val: uint32(cv0)}
+ te1 := tableEntry{offset: index1 + e.cur, val: uint32(cv1)}
+ longHash1 := hashLen(cv0, dFastLongTableBits, dFastLongLen)
+ longHash2 := hashLen(cv0, dFastLongTableBits, dFastLongLen)
+ e.longTable[longHash1] = te0
+ e.longTable[longHash2] = te1
+ e.markLongShardDirty(longHash1)
+ e.markLongShardDirty(longHash2)
+ cv0 >>= 8
+ cv1 >>= 8
+ te0.offset++
+ te1.offset++
+ te0.val = uint32(cv0)
+ te1.val = uint32(cv1)
+ hashVal1 := hashLen(cv0, dFastShortTableBits, dFastShortLen)
+ hashVal2 := hashLen(cv1, dFastShortTableBits, dFastShortLen)
+ e.table[hashVal1] = te0
+ e.markShardDirty(hashVal1)
+ e.table[hashVal2] = te1
+ e.markShardDirty(hashVal2)
+
+ 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, dFastShortTableBits, dFastShortLen)
+ nextHashL := hashLen(cv, dFastLongTableBits, dFastLongLen)
+
+ // 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)
+
+ entry := tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.longTable[nextHashL] = entry
+ e.markLongShardDirty(nextHashL)
+ e.table[nextHashS] = entry
+ e.markShardDirty(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)
+ }
+ // If we encoded more than 64K mark all dirty.
+ if len(src) > 64<<10 {
+ e.markAllShardsDirty()
+ }
+}
+
+// ResetDict will reset and set a dictionary if not nil
+func (e *doubleFastEncoder) Reset(d *dict, singleBlock bool) {
+ e.fastEncoder.Reset(d, singleBlock)
+ if d != nil {
+ panic("doubleFastEncoder: Reset with dict not supported")
+ }
+}
+
+// ResetDict will reset and set a dictionary if not nil
+func (e *doubleFastEncoderDict) Reset(d *dict, singleBlock bool) {
+ allDirty := e.allDirty
+ e.fastEncoderDict.Reset(d, singleBlock)
+ if d == nil {
+ return
+ }
+
+ // 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([]tableEntry, len(e.longTable))
+ }
+ if len(d.content) >= 8 {
+ cv := load6432(d.content, 0)
+ e.dictLongTable[hashLen(cv, dFastLongTableBits, dFastLongLen)] = tableEntry{
+ val: uint32(cv),
+ offset: e.maxMatchOff,
+ }
+ end := int32(len(d.content)) - 8 + e.maxMatchOff
+ for i := e.maxMatchOff + 1; i < end; i++ {
+ cv = cv>>8 | (uint64(d.content[i-e.maxMatchOff+7]) << 56)
+ e.dictLongTable[hashLen(cv, dFastLongTableBits, dFastLongLen)] = tableEntry{
+ val: uint32(cv),
+ offset: i,
+ }
+ }
+ }
+ e.lastDictID = d.id
+ e.allDirty = true
+ }
+ // Reset table to initial state
+ e.cur = e.maxMatchOff
+
+ dirtyShardCnt := 0
+ if !allDirty {
+ for i := range e.longTableShardDirty {
+ if e.longTableShardDirty[i] {
+ dirtyShardCnt++
+ }
+ }
+ }
+
+ if allDirty || dirtyShardCnt > dLongTableShardCnt/2 {
+ copy(e.longTable[:], e.dictLongTable)
+ for i := range e.longTableShardDirty {
+ e.longTableShardDirty[i] = false
+ }
+ return
+ }
+ for i := range e.longTableShardDirty {
+ if !e.longTableShardDirty[i] {
+ continue
+ }
+
+ copy(e.longTable[i*dLongTableShardSize:(i+1)*dLongTableShardSize], e.dictLongTable[i*dLongTableShardSize:(i+1)*dLongTableShardSize])
+ e.longTableShardDirty[i] = false
+ }
+}
+
+func (e *doubleFastEncoderDict) markLongShardDirty(entryNum uint32) {
+ e.longTableShardDirty[entryNum/dLongTableShardSize] = true
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 08:46:52 +0000