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-rw-r--r--vendor/github.com/klauspost/compress/zstd/seqdec.go503
1 files changed, 503 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/seqdec.go b/vendor/github.com/klauspost/compress/zstd/seqdec.go
new file mode 100644
index 000000000..d7fe6d82d
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/seqdec.go
@@ -0,0 +1,503 @@
+// 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 (
+ "errors"
+ "fmt"
+ "io"
+)
+
+type seq struct {
+ litLen uint32
+ matchLen uint32
+ offset uint32
+
+ // Codes are stored here for the encoder
+ // so they only have to be looked up once.
+ llCode, mlCode, ofCode uint8
+}
+
+type seqVals struct {
+ ll, ml, mo int
+}
+
+func (s seq) String() string {
+ if s.offset <= 3 {
+ if s.offset == 0 {
+ return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset: INVALID (0)")
+ }
+ return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset:", s.offset, " (repeat)")
+ }
+ return fmt.Sprint("litLen:", s.litLen, ", matchLen:", s.matchLen+zstdMinMatch, ", offset:", s.offset-3, " (new)")
+}
+
+type seqCompMode uint8
+
+const (
+ compModePredefined seqCompMode = iota
+ compModeRLE
+ compModeFSE
+ compModeRepeat
+)
+
+type sequenceDec struct {
+ // decoder keeps track of the current state and updates it from the bitstream.
+ fse *fseDecoder
+ state fseState
+ repeat bool
+}
+
+// init the state of the decoder with input from stream.
+func (s *sequenceDec) init(br *bitReader) error {
+ if s.fse == nil {
+ return errors.New("sequence decoder not defined")
+ }
+ s.state.init(br, s.fse.actualTableLog, s.fse.dt[:1<<s.fse.actualTableLog])
+ return nil
+}
+
+// sequenceDecs contains all 3 sequence decoders and their state.
+type sequenceDecs struct {
+ litLengths sequenceDec
+ offsets sequenceDec
+ matchLengths sequenceDec
+ prevOffset [3]int
+ dict []byte
+ literals []byte
+ out []byte
+ nSeqs int
+ br *bitReader
+ seqSize int
+ windowSize int
+ maxBits uint8
+ maxSyncLen uint64
+}
+
+// initialize all 3 decoders from the stream input.
+func (s *sequenceDecs) initialize(br *bitReader, hist *history, out []byte) error {
+ if err := s.litLengths.init(br); err != nil {
+ return errors.New("litLengths:" + err.Error())
+ }
+ if err := s.offsets.init(br); err != nil {
+ return errors.New("offsets:" + err.Error())
+ }
+ if err := s.matchLengths.init(br); err != nil {
+ return errors.New("matchLengths:" + err.Error())
+ }
+ s.br = br
+ s.prevOffset = hist.recentOffsets
+ s.maxBits = s.litLengths.fse.maxBits + s.offsets.fse.maxBits + s.matchLengths.fse.maxBits
+ s.windowSize = hist.windowSize
+ s.out = out
+ s.dict = nil
+ if hist.dict != nil {
+ s.dict = hist.dict.content
+ }
+ return nil
+}
+
+func (s *sequenceDecs) freeDecoders() {
+ if f := s.litLengths.fse; f != nil && !f.preDefined {
+ fseDecoderPool.Put(f)
+ s.litLengths.fse = nil
+ }
+ if f := s.offsets.fse; f != nil && !f.preDefined {
+ fseDecoderPool.Put(f)
+ s.offsets.fse = nil
+ }
+ if f := s.matchLengths.fse; f != nil && !f.preDefined {
+ fseDecoderPool.Put(f)
+ s.matchLengths.fse = nil
+ }
+}
+
+// execute will execute the decoded sequence with the provided history.
+// The sequence must be evaluated before being sent.
+func (s *sequenceDecs) execute(seqs []seqVals, hist []byte) error {
+ if len(s.dict) == 0 {
+ return s.executeSimple(seqs, hist)
+ }
+
+ // Ensure we have enough output size...
+ if len(s.out)+s.seqSize > cap(s.out) {
+ addBytes := s.seqSize + len(s.out)
+ s.out = append(s.out, make([]byte, addBytes)...)
+ s.out = s.out[:len(s.out)-addBytes]
+ }
+
+ if debugDecoder {
+ printf("Execute %d seqs with hist %d, dict %d, literals: %d into %d bytes\n", len(seqs), len(hist), len(s.dict), len(s.literals), s.seqSize)
+ }
+
+ var t = len(s.out)
+ out := s.out[:t+s.seqSize]
+
+ for _, seq := range seqs {
+ // Add literals
+ copy(out[t:], s.literals[:seq.ll])
+ t += seq.ll
+ s.literals = s.literals[seq.ll:]
+
+ // Copy from dictionary...
+ if seq.mo > t+len(hist) || seq.mo > s.windowSize {
+ if len(s.dict) == 0 {
+ return fmt.Errorf("match offset (%d) bigger than current history (%d)", seq.mo, t+len(hist))
+ }
+
+ // we may be in dictionary.
+ dictO := len(s.dict) - (seq.mo - (t + len(hist)))
+ if dictO < 0 || dictO >= len(s.dict) {
+ return fmt.Errorf("match offset (%d) bigger than current history+dict (%d)", seq.mo, t+len(hist)+len(s.dict))
+ }
+ end := dictO + seq.ml
+ if end > len(s.dict) {
+ n := len(s.dict) - dictO
+ copy(out[t:], s.dict[dictO:])
+ t += n
+ seq.ml -= n
+ } else {
+ copy(out[t:], s.dict[dictO:end])
+ t += end - dictO
+ continue
+ }
+ }
+
+ // Copy from history.
+ if v := seq.mo - t; v > 0 {
+ // v is the start position in history from end.
+ start := len(hist) - v
+ if seq.ml > v {
+ // Some goes into current block.
+ // Copy remainder of history
+ copy(out[t:], hist[start:])
+ t += v
+ seq.ml -= v
+ } else {
+ copy(out[t:], hist[start:start+seq.ml])
+ t += seq.ml
+ continue
+ }
+ }
+ // We must be in current buffer now
+ if seq.ml > 0 {
+ start := t - seq.mo
+ if seq.ml <= t-start {
+ // No overlap
+ copy(out[t:], out[start:start+seq.ml])
+ t += seq.ml
+ continue
+ } else {
+ // Overlapping copy
+ // Extend destination slice and copy one byte at the time.
+ src := out[start : start+seq.ml]
+ dst := out[t:]
+ dst = dst[:len(src)]
+ t += len(src)
+ // Destination is the space we just added.
+ for i := range src {
+ dst[i] = src[i]
+ }
+ }
+ }
+ }
+
+ // Add final literals
+ copy(out[t:], s.literals)
+ if debugDecoder {
+ t += len(s.literals)
+ if t != len(out) {
+ panic(fmt.Errorf("length mismatch, want %d, got %d, ss: %d", len(out), t, s.seqSize))
+ }
+ }
+ s.out = out
+
+ return nil
+}
+
+// decode sequences from the stream with the provided history.
+func (s *sequenceDecs) decodeSync(hist []byte) error {
+ supported, err := s.decodeSyncSimple(hist)
+ if supported {
+ return err
+ }
+
+ br := s.br
+ seqs := s.nSeqs
+ startSize := len(s.out)
+ // Grab full sizes tables, to avoid bounds checks.
+ llTable, mlTable, ofTable := s.litLengths.fse.dt[:maxTablesize], s.matchLengths.fse.dt[:maxTablesize], s.offsets.fse.dt[:maxTablesize]
+ llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
+ out := s.out
+ maxBlockSize := maxCompressedBlockSize
+ if s.windowSize < maxBlockSize {
+ maxBlockSize = s.windowSize
+ }
+
+ if debugDecoder {
+ println("decodeSync: decoding", seqs, "sequences", br.remain(), "bits remain on stream")
+ }
+ for i := seqs - 1; i >= 0; i-- {
+ if br.overread() {
+ printf("reading sequence %d, exceeded available data. Overread by %d\n", seqs-i, -br.remain())
+ return io.ErrUnexpectedEOF
+ }
+ var ll, mo, ml int
+ if len(br.in) > 4+((maxOffsetBits+16+16)>>3) {
+ // inlined function:
+ // ll, mo, ml = s.nextFast(br, llState, mlState, ofState)
+
+ // Final will not read from stream.
+ var llB, mlB, moB uint8
+ ll, llB = llState.final()
+ ml, mlB = mlState.final()
+ mo, moB = ofState.final()
+
+ // extra bits are stored in reverse order.
+ br.fillFast()
+ mo += br.getBits(moB)
+ if s.maxBits > 32 {
+ br.fillFast()
+ }
+ ml += br.getBits(mlB)
+ ll += br.getBits(llB)
+
+ if moB > 1 {
+ s.prevOffset[2] = s.prevOffset[1]
+ s.prevOffset[1] = s.prevOffset[0]
+ s.prevOffset[0] = mo
+ } else {
+ // mo = s.adjustOffset(mo, ll, moB)
+ // Inlined for rather big speedup
+ if ll == 0 {
+ // There is an exception though, when current sequence's literals_length = 0.
+ // In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
+ // an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
+ mo++
+ }
+
+ if mo == 0 {
+ mo = s.prevOffset[0]
+ } else {
+ var temp int
+ if mo == 3 {
+ temp = s.prevOffset[0] - 1
+ } else {
+ temp = s.prevOffset[mo]
+ }
+
+ if temp == 0 {
+ // 0 is not valid; input is corrupted; force offset to 1
+ println("WARNING: temp was 0")
+ temp = 1
+ }
+
+ if mo != 1 {
+ s.prevOffset[2] = s.prevOffset[1]
+ }
+ s.prevOffset[1] = s.prevOffset[0]
+ s.prevOffset[0] = temp
+ mo = temp
+ }
+ }
+ br.fillFast()
+ } else {
+ ll, mo, ml = s.next(br, llState, mlState, ofState)
+ br.fill()
+ }
+
+ if debugSequences {
+ println("Seq", seqs-i-1, "Litlen:", ll, "mo:", mo, "(abs) ml:", ml)
+ }
+
+ if ll > len(s.literals) {
+ return fmt.Errorf("unexpected literal count, want %d bytes, but only %d is available", ll, len(s.literals))
+ }
+ size := ll + ml + len(out)
+ if size-startSize > maxBlockSize {
+ return fmt.Errorf("output bigger than max block size (%d)", maxBlockSize)
+ }
+ if size > cap(out) {
+ // Not enough size, which can happen under high volume block streaming conditions
+ // but could be if destination slice is too small for sync operations.
+ // over-allocating here can create a large amount of GC pressure so we try to keep
+ // it as contained as possible
+ used := len(out) - startSize
+ addBytes := 256 + ll + ml + used>>2
+ // Clamp to max block size.
+ if used+addBytes > maxBlockSize {
+ addBytes = maxBlockSize - used
+ }
+ out = append(out, make([]byte, addBytes)...)
+ out = out[:len(out)-addBytes]
+ }
+ if ml > maxMatchLen {
+ return fmt.Errorf("match len (%d) bigger than max allowed length", ml)
+ }
+
+ // Add literals
+ out = append(out, s.literals[:ll]...)
+ s.literals = s.literals[ll:]
+
+ if mo == 0 && ml > 0 {
+ return fmt.Errorf("zero matchoff and matchlen (%d) > 0", ml)
+ }
+
+ if mo > len(out)+len(hist) || mo > s.windowSize {
+ if len(s.dict) == 0 {
+ return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(out)+len(hist)-startSize)
+ }
+
+ // we may be in dictionary.
+ dictO := len(s.dict) - (mo - (len(out) + len(hist)))
+ if dictO < 0 || dictO >= len(s.dict) {
+ return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(out)+len(hist)-startSize)
+ }
+ end := dictO + ml
+ if end > len(s.dict) {
+ out = append(out, s.dict[dictO:]...)
+ ml -= len(s.dict) - dictO
+ } else {
+ out = append(out, s.dict[dictO:end]...)
+ mo = 0
+ ml = 0
+ }
+ }
+
+ // Copy from history.
+ // TODO: Blocks without history could be made to ignore this completely.
+ if v := mo - len(out); v > 0 {
+ // v is the start position in history from end.
+ start := len(hist) - v
+ if ml > v {
+ // Some goes into current block.
+ // Copy remainder of history
+ out = append(out, hist[start:]...)
+ ml -= v
+ } else {
+ out = append(out, hist[start:start+ml]...)
+ ml = 0
+ }
+ }
+ // We must be in current buffer now
+ if ml > 0 {
+ start := len(out) - mo
+ if ml <= len(out)-start {
+ // No overlap
+ out = append(out, out[start:start+ml]...)
+ } else {
+ // Overlapping copy
+ // Extend destination slice and copy one byte at the time.
+ out = out[:len(out)+ml]
+ src := out[start : start+ml]
+ // Destination is the space we just added.
+ dst := out[len(out)-ml:]
+ dst = dst[:len(src)]
+ for i := range src {
+ dst[i] = src[i]
+ }
+ }
+ }
+ if i == 0 {
+ // This is the last sequence, so we shouldn't update state.
+ break
+ }
+
+ // Manually inlined, ~ 5-20% faster
+ // Update all 3 states at once. Approx 20% faster.
+ nBits := llState.nbBits() + mlState.nbBits() + ofState.nbBits()
+ if nBits == 0 {
+ llState = llTable[llState.newState()&maxTableMask]
+ mlState = mlTable[mlState.newState()&maxTableMask]
+ ofState = ofTable[ofState.newState()&maxTableMask]
+ } else {
+ bits := br.get32BitsFast(nBits)
+
+ lowBits := uint16(bits >> ((ofState.nbBits() + mlState.nbBits()) & 31))
+ llState = llTable[(llState.newState()+lowBits)&maxTableMask]
+
+ lowBits = uint16(bits >> (ofState.nbBits() & 31))
+ lowBits &= bitMask[mlState.nbBits()&15]
+ mlState = mlTable[(mlState.newState()+lowBits)&maxTableMask]
+
+ lowBits = uint16(bits) & bitMask[ofState.nbBits()&15]
+ ofState = ofTable[(ofState.newState()+lowBits)&maxTableMask]
+ }
+ }
+
+ if size := len(s.literals) + len(out) - startSize; size > maxBlockSize {
+ return fmt.Errorf("output bigger than max block size (%d)", maxBlockSize)
+ }
+
+ // Add final literals
+ s.out = append(out, s.literals...)
+ return br.close()
+}
+
+var bitMask [16]uint16
+
+func init() {
+ for i := range bitMask[:] {
+ bitMask[i] = uint16((1 << uint(i)) - 1)
+ }
+}
+
+func (s *sequenceDecs) next(br *bitReader, llState, mlState, ofState decSymbol) (ll, mo, ml int) {
+ // Final will not read from stream.
+ ll, llB := llState.final()
+ ml, mlB := mlState.final()
+ mo, moB := ofState.final()
+
+ // extra bits are stored in reverse order.
+ br.fill()
+ mo += br.getBits(moB)
+ if s.maxBits > 32 {
+ br.fill()
+ }
+ // matchlength+literal length, max 32 bits
+ ml += br.getBits(mlB)
+ ll += br.getBits(llB)
+ mo = s.adjustOffset(mo, ll, moB)
+ return
+}
+
+func (s *sequenceDecs) adjustOffset(offset, litLen int, offsetB uint8) int {
+ if offsetB > 1 {
+ s.prevOffset[2] = s.prevOffset[1]
+ s.prevOffset[1] = s.prevOffset[0]
+ s.prevOffset[0] = offset
+ return offset
+ }
+
+ if litLen == 0 {
+ // There is an exception though, when current sequence's literals_length = 0.
+ // In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
+ // an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
+ offset++
+ }
+
+ if offset == 0 {
+ return s.prevOffset[0]
+ }
+ var temp int
+ if offset == 3 {
+ temp = s.prevOffset[0] - 1
+ } else {
+ temp = s.prevOffset[offset]
+ }
+
+ if temp == 0 {
+ // 0 is not valid; input is corrupted; force offset to 1
+ println("temp was 0")
+ temp = 1
+ }
+
+ if offset != 1 {
+ s.prevOffset[2] = s.prevOffset[1]
+ }
+ s.prevOffset[1] = s.prevOffset[0]
+ s.prevOffset[0] = temp
+ return temp
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-07-15 14:20:27 +0000