[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/klauspost/compress/zstd/blockenc.go b/vendor/github.com/klauspost/compress/zstd/blockenc.go
new file mode 100644
index 0000000..e1be092
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/blockenc.go
@@ -0,0 +1,871 @@
+// 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"
+ "math"
+ "math/bits"
+
+ "github.com/klauspost/compress/huff0"
+)
+
+type blockEnc struct {
+ size int
+ literals []byte
+ sequences []seq
+ coders seqCoders
+ litEnc *huff0.Scratch
+ dictLitEnc *huff0.Scratch
+ wr bitWriter
+
+ extraLits int
+ output []byte
+ recentOffsets [3]uint32
+ prevRecentOffsets [3]uint32
+
+ last bool
+ lowMem bool
+}
+
+// init should be used once the block has been created.
+// If called more than once, the effect is the same as calling reset.
+func (b *blockEnc) init() {
+ if b.lowMem {
+ // 1K literals
+ if cap(b.literals) < 1<<10 {
+ b.literals = make([]byte, 0, 1<<10)
+ }
+ const defSeqs = 20
+ if cap(b.sequences) < defSeqs {
+ b.sequences = make([]seq, 0, defSeqs)
+ }
+ // 1K
+ if cap(b.output) < 1<<10 {
+ b.output = make([]byte, 0, 1<<10)
+ }
+ } else {
+ if cap(b.literals) < maxCompressedBlockSize {
+ b.literals = make([]byte, 0, maxCompressedBlockSize)
+ }
+ const defSeqs = 200
+ if cap(b.sequences) < defSeqs {
+ b.sequences = make([]seq, 0, defSeqs)
+ }
+ if cap(b.output) < maxCompressedBlockSize {
+ b.output = make([]byte, 0, maxCompressedBlockSize)
+ }
+ }
+
+ if b.coders.mlEnc == nil {
+ b.coders.mlEnc = &fseEncoder{}
+ b.coders.mlPrev = &fseEncoder{}
+ b.coders.ofEnc = &fseEncoder{}
+ b.coders.ofPrev = &fseEncoder{}
+ b.coders.llEnc = &fseEncoder{}
+ b.coders.llPrev = &fseEncoder{}
+ }
+ b.litEnc = &huff0.Scratch{WantLogLess: 4}
+ b.reset(nil)
+}
+
+// initNewEncode can be used to reset offsets and encoders to the initial state.
+func (b *blockEnc) initNewEncode() {
+ b.recentOffsets = [3]uint32{1, 4, 8}
+ b.litEnc.Reuse = huff0.ReusePolicyNone
+ b.coders.setPrev(nil, nil, nil)
+}
+
+// reset will reset the block for a new encode, but in the same stream,
+// meaning that state will be carried over, but the block content is reset.
+// If a previous block is provided, the recent offsets are carried over.
+func (b *blockEnc) reset(prev *blockEnc) {
+ b.extraLits = 0
+ b.literals = b.literals[:0]
+ b.size = 0
+ b.sequences = b.sequences[:0]
+ b.output = b.output[:0]
+ b.last = false
+ if prev != nil {
+ b.recentOffsets = prev.prevRecentOffsets
+ }
+ b.dictLitEnc = nil
+}
+
+// reset will reset the block for a new encode, but in the same stream,
+// meaning that state will be carried over, but the block content is reset.
+// If a previous block is provided, the recent offsets are carried over.
+func (b *blockEnc) swapEncoders(prev *blockEnc) {
+ b.coders.swap(&prev.coders)
+ b.litEnc, prev.litEnc = prev.litEnc, b.litEnc
+}
+
+// blockHeader contains the information for a block header.
+type blockHeader uint32
+
+// setLast sets the 'last' indicator on a block.
+func (h *blockHeader) setLast(b bool) {
+ if b {
+ *h = *h | 1
+ } else {
+ const mask = (1 << 24) - 2
+ *h = *h & mask
+ }
+}
+
+// setSize will store the compressed size of a block.
+func (h *blockHeader) setSize(v uint32) {
+ const mask = 7
+ *h = (*h)&mask | blockHeader(v<<3)
+}
+
+// setType sets the block type.
+func (h *blockHeader) setType(t blockType) {
+ const mask = 1 | (((1 << 24) - 1) ^ 7)
+ *h = (*h & mask) | blockHeader(t<<1)
+}
+
+// appendTo will append the block header to a slice.
+func (h blockHeader) appendTo(b []byte) []byte {
+ return append(b, uint8(h), uint8(h>>8), uint8(h>>16))
+}
+
+// String returns a string representation of the block.
+func (h blockHeader) String() string {
+ return fmt.Sprintf("Type: %d, Size: %d, Last:%t", (h>>1)&3, h>>3, h&1 == 1)
+}
+
+// literalsHeader contains literals header information.
+type literalsHeader uint64
+
+// setType can be used to set the type of literal block.
+func (h *literalsHeader) setType(t literalsBlockType) {
+ const mask = math.MaxUint64 - 3
+ *h = (*h & mask) | literalsHeader(t)
+}
+
+// setSize can be used to set a single size, for uncompressed and RLE content.
+func (h *literalsHeader) setSize(regenLen int) {
+ inBits := bits.Len32(uint32(regenLen))
+ // Only retain 2 bits
+ const mask = 3
+ lh := uint64(*h & mask)
+ switch {
+ case inBits < 5:
+ lh |= (uint64(regenLen) << 3) | (1 << 60)
+ if debug {
+ got := int(lh>>3) & 0xff
+ if got != regenLen {
+ panic(fmt.Sprint("litRegenSize = ", regenLen, "(want) != ", got, "(got)"))
+ }
+ }
+ case inBits < 12:
+ lh |= (1 << 2) | (uint64(regenLen) << 4) | (2 << 60)
+ case inBits < 20:
+ lh |= (3 << 2) | (uint64(regenLen) << 4) | (3 << 60)
+ default:
+ panic(fmt.Errorf("internal error: block too big (%d)", regenLen))
+ }
+ *h = literalsHeader(lh)
+}
+
+// setSizes will set the size of a compressed literals section and the input length.
+func (h *literalsHeader) setSizes(compLen, inLen int, single bool) {
+ compBits, inBits := bits.Len32(uint32(compLen)), bits.Len32(uint32(inLen))
+ // Only retain 2 bits
+ const mask = 3
+ lh := uint64(*h & mask)
+ switch {
+ case compBits <= 10 && inBits <= 10:
+ if !single {
+ lh |= 1 << 2
+ }
+ lh |= (uint64(inLen) << 4) | (uint64(compLen) << (10 + 4)) | (3 << 60)
+ if debug {
+ const mmask = (1 << 24) - 1
+ n := (lh >> 4) & mmask
+ if int(n&1023) != inLen {
+ panic(fmt.Sprint("regensize:", int(n&1023), "!=", inLen, inBits))
+ }
+ if int(n>>10) != compLen {
+ panic(fmt.Sprint("compsize:", int(n>>10), "!=", compLen, compBits))
+ }
+ }
+ case compBits <= 14 && inBits <= 14:
+ lh |= (2 << 2) | (uint64(inLen) << 4) | (uint64(compLen) << (14 + 4)) | (4 << 60)
+ if single {
+ panic("single stream used with more than 10 bits length.")
+ }
+ case compBits <= 18 && inBits <= 18:
+ lh |= (3 << 2) | (uint64(inLen) << 4) | (uint64(compLen) << (18 + 4)) | (5 << 60)
+ if single {
+ panic("single stream used with more than 10 bits length.")
+ }
+ default:
+ panic("internal error: block too big")
+ }
+ *h = literalsHeader(lh)
+}
+
+// appendTo will append the literals header to a byte slice.
+func (h literalsHeader) appendTo(b []byte) []byte {
+ size := uint8(h >> 60)
+ switch size {
+ case 1:
+ b = append(b, uint8(h))
+ case 2:
+ b = append(b, uint8(h), uint8(h>>8))
+ case 3:
+ b = append(b, uint8(h), uint8(h>>8), uint8(h>>16))
+ case 4:
+ b = append(b, uint8(h), uint8(h>>8), uint8(h>>16), uint8(h>>24))
+ case 5:
+ b = append(b, uint8(h), uint8(h>>8), uint8(h>>16), uint8(h>>24), uint8(h>>32))
+ default:
+ panic(fmt.Errorf("internal error: literalsHeader has invalid size (%d)", size))
+ }
+ return b
+}
+
+// size returns the output size with currently set values.
+func (h literalsHeader) size() int {
+ return int(h >> 60)
+}
+
+func (h literalsHeader) String() string {
+ return fmt.Sprintf("Type: %d, SizeFormat: %d, Size: 0x%d, Bytes:%d", literalsBlockType(h&3), (h>>2)&3, h&((1<<60)-1)>>4, h>>60)
+}
+
+// pushOffsets will push the recent offsets to the backup store.
+func (b *blockEnc) pushOffsets() {
+ b.prevRecentOffsets = b.recentOffsets
+}
+
+// pushOffsets will push the recent offsets to the backup store.
+func (b *blockEnc) popOffsets() {
+ b.recentOffsets = b.prevRecentOffsets
+}
+
+// matchOffset will adjust recent offsets and return the adjusted one,
+// if it matches a previous offset.
+func (b *blockEnc) matchOffset(offset, lits uint32) uint32 {
+ // Check if offset is one of the recent offsets.
+ // Adjusts the output offset accordingly.
+ // Gives a tiny bit of compression, typically around 1%.
+ if true {
+ if lits > 0 {
+ switch offset {
+ case b.recentOffsets[0]:
+ offset = 1
+ case b.recentOffsets[1]:
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset = 2
+ case b.recentOffsets[2]:
+ b.recentOffsets[2] = b.recentOffsets[1]
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset = 3
+ default:
+ b.recentOffsets[2] = b.recentOffsets[1]
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset += 3
+ }
+ } else {
+ switch offset {
+ case b.recentOffsets[1]:
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset = 1
+ case b.recentOffsets[2]:
+ b.recentOffsets[2] = b.recentOffsets[1]
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset = 2
+ case b.recentOffsets[0] - 1:
+ b.recentOffsets[2] = b.recentOffsets[1]
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset = 3
+ default:
+ b.recentOffsets[2] = b.recentOffsets[1]
+ b.recentOffsets[1] = b.recentOffsets[0]
+ b.recentOffsets[0] = offset
+ offset += 3
+ }
+ }
+ } else {
+ offset += 3
+ }
+ return offset
+}
+
+// encodeRaw can be used to set the output to a raw representation of supplied bytes.
+func (b *blockEnc) encodeRaw(a []byte) {
+ var bh blockHeader
+ bh.setLast(b.last)
+ bh.setSize(uint32(len(a)))
+ bh.setType(blockTypeRaw)
+ b.output = bh.appendTo(b.output[:0])
+ b.output = append(b.output, a...)
+ if debug {
+ println("Adding RAW block, length", len(a), "last:", b.last)
+ }
+}
+
+// encodeRaw can be used to set the output to a raw representation of supplied bytes.
+func (b *blockEnc) encodeRawTo(dst, src []byte) []byte {
+ var bh blockHeader
+ bh.setLast(b.last)
+ bh.setSize(uint32(len(src)))
+ bh.setType(blockTypeRaw)
+ dst = bh.appendTo(dst)
+ dst = append(dst, src...)
+ if debug {
+ println("Adding RAW block, length", len(src), "last:", b.last)
+ }
+ return dst
+}
+
+// encodeLits can be used if the block is only litLen.
+func (b *blockEnc) encodeLits(lits []byte, raw bool) error {
+ var bh blockHeader
+ bh.setLast(b.last)
+ bh.setSize(uint32(len(lits)))
+
+ // Don't compress extremely small blocks
+ if len(lits) < 8 || (len(lits) < 32 && b.dictLitEnc == nil) || raw {
+ if debug {
+ println("Adding RAW block, length", len(lits), "last:", b.last)
+ }
+ bh.setType(blockTypeRaw)
+ b.output = bh.appendTo(b.output)
+ b.output = append(b.output, lits...)
+ return nil
+ }
+
+ var (
+ out []byte
+ reUsed, single bool
+ err error
+ )
+ if b.dictLitEnc != nil {
+ b.litEnc.TransferCTable(b.dictLitEnc)
+ b.litEnc.Reuse = huff0.ReusePolicyAllow
+ b.dictLitEnc = nil
+ }
+ if len(lits) >= 1024 {
+ // Use 4 Streams.
+ out, reUsed, err = huff0.Compress4X(lits, b.litEnc)
+ } else if len(lits) > 32 {
+ // Use 1 stream
+ single = true
+ out, reUsed, err = huff0.Compress1X(lits, b.litEnc)
+ } else {
+ err = huff0.ErrIncompressible
+ }
+
+ switch err {
+ case huff0.ErrIncompressible:
+ if debug {
+ println("Adding RAW block, length", len(lits), "last:", b.last)
+ }
+ bh.setType(blockTypeRaw)
+ b.output = bh.appendTo(b.output)
+ b.output = append(b.output, lits...)
+ return nil
+ case huff0.ErrUseRLE:
+ if debug {
+ println("Adding RLE block, length", len(lits))
+ }
+ bh.setType(blockTypeRLE)
+ b.output = bh.appendTo(b.output)
+ b.output = append(b.output, lits[0])
+ return nil
+ case nil:
+ default:
+ return err
+ }
+ // Compressed...
+ // Now, allow reuse
+ b.litEnc.Reuse = huff0.ReusePolicyAllow
+ bh.setType(blockTypeCompressed)
+ var lh literalsHeader
+ if reUsed {
+ if debug {
+ println("Reused tree, compressed to", len(out))
+ }
+ lh.setType(literalsBlockTreeless)
+ } else {
+ if debug {
+ println("New tree, compressed to", len(out), "tree size:", len(b.litEnc.OutTable))
+ }
+ lh.setType(literalsBlockCompressed)
+ }
+ // Set sizes
+ lh.setSizes(len(out), len(lits), single)
+ bh.setSize(uint32(len(out) + lh.size() + 1))
+
+ // Write block headers.
+ b.output = bh.appendTo(b.output)
+ b.output = lh.appendTo(b.output)
+ // Add compressed data.
+ b.output = append(b.output, out...)
+ // No sequences.
+ b.output = append(b.output, 0)
+ return nil
+}
+
+// fuzzFseEncoder can be used to fuzz the FSE encoder.
+func fuzzFseEncoder(data []byte) int {
+ if len(data) > maxSequences || len(data) < 2 {
+ return 0
+ }
+ enc := fseEncoder{}
+ hist := enc.Histogram()[:256]
+ maxSym := uint8(0)
+ for i, v := range data {
+ v = v & 63
+ data[i] = v
+ hist[v]++
+ if v > maxSym {
+ maxSym = v
+ }
+ }
+ if maxSym == 0 {
+ // All 0
+ return 0
+ }
+ maxCount := func(a []uint32) int {
+ var max uint32
+ for _, v := range a {
+ if v > max {
+ max = v
+ }
+ }
+ return int(max)
+ }
+ cnt := maxCount(hist[:maxSym])
+ if cnt == len(data) {
+ // RLE
+ return 0
+ }
+ enc.HistogramFinished(maxSym, cnt)
+ err := enc.normalizeCount(len(data))
+ if err != nil {
+ return 0
+ }
+ _, err = enc.writeCount(nil)
+ if err != nil {
+ panic(err)
+ }
+ return 1
+}
+
+// encode will encode the block and append the output in b.output.
+// Previous offset codes must be pushed if more blocks are expected.
+func (b *blockEnc) encode(org []byte, raw, rawAllLits bool) error {
+ if len(b.sequences) == 0 {
+ return b.encodeLits(b.literals, rawAllLits)
+ }
+ // We want some difference to at least account for the headers.
+ saved := b.size - len(b.literals) - (b.size >> 5)
+ if saved < 16 {
+ if org == nil {
+ return errIncompressible
+ }
+ b.popOffsets()
+ return b.encodeLits(org, rawAllLits)
+ }
+
+ var bh blockHeader
+ var lh literalsHeader
+ bh.setLast(b.last)
+ bh.setType(blockTypeCompressed)
+ // Store offset of the block header. Needed when we know the size.
+ bhOffset := len(b.output)
+ b.output = bh.appendTo(b.output)
+
+ var (
+ out []byte
+ reUsed, single bool
+ err error
+ )
+ if b.dictLitEnc != nil {
+ b.litEnc.TransferCTable(b.dictLitEnc)
+ b.litEnc.Reuse = huff0.ReusePolicyAllow
+ b.dictLitEnc = nil
+ }
+ if len(b.literals) >= 1024 && !raw {
+ // Use 4 Streams.
+ out, reUsed, err = huff0.Compress4X(b.literals, b.litEnc)
+ } else if len(b.literals) > 32 && !raw {
+ // Use 1 stream
+ single = true
+ out, reUsed, err = huff0.Compress1X(b.literals, b.litEnc)
+ } else {
+ err = huff0.ErrIncompressible
+ }
+
+ switch err {
+ case huff0.ErrIncompressible:
+ lh.setType(literalsBlockRaw)
+ lh.setSize(len(b.literals))
+ b.output = lh.appendTo(b.output)
+ b.output = append(b.output, b.literals...)
+ if debug {
+ println("Adding literals RAW, length", len(b.literals))
+ }
+ case huff0.ErrUseRLE:
+ lh.setType(literalsBlockRLE)
+ lh.setSize(len(b.literals))
+ b.output = lh.appendTo(b.output)
+ b.output = append(b.output, b.literals[0])
+ if debug {
+ println("Adding literals RLE")
+ }
+ case nil:
+ // Compressed litLen...
+ if reUsed {
+ if debug {
+ println("reused tree")
+ }
+ lh.setType(literalsBlockTreeless)
+ } else {
+ if debug {
+ println("new tree, size:", len(b.litEnc.OutTable))
+ }
+ lh.setType(literalsBlockCompressed)
+ if debug {
+ _, _, err := huff0.ReadTable(out, nil)
+ if err != nil {
+ panic(err)
+ }
+ }
+ }
+ lh.setSizes(len(out), len(b.literals), single)
+ if debug {
+ printf("Compressed %d literals to %d bytes", len(b.literals), len(out))
+ println("Adding literal header:", lh)
+ }
+ b.output = lh.appendTo(b.output)
+ b.output = append(b.output, out...)
+ b.litEnc.Reuse = huff0.ReusePolicyAllow
+ if debug {
+ println("Adding literals compressed")
+ }
+ default:
+ if debug {
+ println("Adding literals ERROR:", err)
+ }
+ return err
+ }
+ // Sequence compression
+
+ // Write the number of sequences
+ switch {
+ case len(b.sequences) < 128:
+ b.output = append(b.output, uint8(len(b.sequences)))
+ case len(b.sequences) < 0x7f00: // TODO: this could be wrong
+ n := len(b.sequences)
+ b.output = append(b.output, 128+uint8(n>>8), uint8(n))
+ default:
+ n := len(b.sequences) - 0x7f00
+ b.output = append(b.output, 255, uint8(n), uint8(n>>8))
+ }
+ if debug {
+ println("Encoding", len(b.sequences), "sequences")
+ }
+ b.genCodes()
+ llEnc := b.coders.llEnc
+ ofEnc := b.coders.ofEnc
+ mlEnc := b.coders.mlEnc
+ err = llEnc.normalizeCount(len(b.sequences))
+ if err != nil {
+ return err
+ }
+ err = ofEnc.normalizeCount(len(b.sequences))
+ if err != nil {
+ return err
+ }
+ err = mlEnc.normalizeCount(len(b.sequences))
+ if err != nil {
+ return err
+ }
+
+ // Choose the best compression mode for each type.
+ // Will evaluate the new vs predefined and previous.
+ chooseComp := func(cur, prev, preDef *fseEncoder) (*fseEncoder, seqCompMode) {
+ // See if predefined/previous is better
+ hist := cur.count[:cur.symbolLen]
+ nSize := cur.approxSize(hist) + cur.maxHeaderSize()
+ predefSize := preDef.approxSize(hist)
+ prevSize := prev.approxSize(hist)
+
+ // Add a small penalty for new encoders.
+ // Don't bother with extremely small (<2 byte gains).
+ nSize = nSize + (nSize+2*8*16)>>4
+ switch {
+ case predefSize <= prevSize && predefSize <= nSize || forcePreDef:
+ if debug {
+ println("Using predefined", predefSize>>3, "<=", nSize>>3)
+ }
+ return preDef, compModePredefined
+ case prevSize <= nSize:
+ if debug {
+ println("Using previous", prevSize>>3, "<=", nSize>>3)
+ }
+ return prev, compModeRepeat
+ default:
+ if debug {
+ println("Using new, predef", predefSize>>3, ". previous:", prevSize>>3, ">", nSize>>3, "header max:", cur.maxHeaderSize()>>3, "bytes")
+ println("tl:", cur.actualTableLog, "symbolLen:", cur.symbolLen, "norm:", cur.norm[:cur.symbolLen], "hist", cur.count[:cur.symbolLen])
+ }
+ return cur, compModeFSE
+ }
+ }
+
+ // Write compression mode
+ var mode uint8
+ if llEnc.useRLE {
+ mode |= uint8(compModeRLE) << 6
+ llEnc.setRLE(b.sequences[0].llCode)
+ if debug {
+ println("llEnc.useRLE")
+ }
+ } else {
+ var m seqCompMode
+ llEnc, m = chooseComp(llEnc, b.coders.llPrev, &fsePredefEnc[tableLiteralLengths])
+ mode |= uint8(m) << 6
+ }
+ if ofEnc.useRLE {
+ mode |= uint8(compModeRLE) << 4
+ ofEnc.setRLE(b.sequences[0].ofCode)
+ if debug {
+ println("ofEnc.useRLE")
+ }
+ } else {
+ var m seqCompMode
+ ofEnc, m = chooseComp(ofEnc, b.coders.ofPrev, &fsePredefEnc[tableOffsets])
+ mode |= uint8(m) << 4
+ }
+
+ if mlEnc.useRLE {
+ mode |= uint8(compModeRLE) << 2
+ mlEnc.setRLE(b.sequences[0].mlCode)
+ if debug {
+ println("mlEnc.useRLE, code: ", b.sequences[0].mlCode, "value", b.sequences[0].matchLen)
+ }
+ } else {
+ var m seqCompMode
+ mlEnc, m = chooseComp(mlEnc, b.coders.mlPrev, &fsePredefEnc[tableMatchLengths])
+ mode |= uint8(m) << 2
+ }
+ b.output = append(b.output, mode)
+ if debug {
+ printf("Compression modes: 0b%b", mode)
+ }
+ b.output, err = llEnc.writeCount(b.output)
+ if err != nil {
+ return err
+ }
+ start := len(b.output)
+ b.output, err = ofEnc.writeCount(b.output)
+ if err != nil {
+ return err
+ }
+ if false {
+ println("block:", b.output[start:], "tablelog", ofEnc.actualTableLog, "maxcount:", ofEnc.maxCount)
+ fmt.Printf("selected TableLog: %d, Symbol length: %d\n", ofEnc.actualTableLog, ofEnc.symbolLen)
+ for i, v := range ofEnc.norm[:ofEnc.symbolLen] {
+ fmt.Printf("%3d: %5d -> %4d \n", i, ofEnc.count[i], v)
+ }
+ }
+ b.output, err = mlEnc.writeCount(b.output)
+ if err != nil {
+ return err
+ }
+
+ // Maybe in block?
+ wr := &b.wr
+ wr.reset(b.output)
+
+ var ll, of, ml cState
+
+ // Current sequence
+ seq := len(b.sequences) - 1
+ s := b.sequences[seq]
+ llEnc.setBits(llBitsTable[:])
+ mlEnc.setBits(mlBitsTable[:])
+ ofEnc.setBits(nil)
+
+ llTT, ofTT, mlTT := llEnc.ct.symbolTT[:256], ofEnc.ct.symbolTT[:256], mlEnc.ct.symbolTT[:256]
+
+ // We have 3 bounds checks here (and in the loop).
+ // Since we are iterating backwards it is kinda hard to avoid.
+ llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
+ ll.init(wr, &llEnc.ct, llB)
+ of.init(wr, &ofEnc.ct, ofB)
+ wr.flush32()
+ ml.init(wr, &mlEnc.ct, mlB)
+
+ // Each of these lookups also generates a bounds check.
+ wr.addBits32NC(s.litLen, llB.outBits)
+ wr.addBits32NC(s.matchLen, mlB.outBits)
+ wr.flush32()
+ wr.addBits32NC(s.offset, ofB.outBits)
+ if debugSequences {
+ println("Encoded seq", seq, s, "codes:", s.llCode, s.mlCode, s.ofCode, "states:", ll.state, ml.state, of.state, "bits:", llB, mlB, ofB)
+ }
+ seq--
+ if llEnc.maxBits+mlEnc.maxBits+ofEnc.maxBits <= 32 {
+ // No need to flush (common)
+ for seq >= 0 {
+ s = b.sequences[seq]
+ wr.flush32()
+ llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
+ // tabelog max is 8 for all.
+ of.encode(ofB)
+ ml.encode(mlB)
+ ll.encode(llB)
+ wr.flush32()
+
+ // We checked that all can stay within 32 bits
+ wr.addBits32NC(s.litLen, llB.outBits)
+ wr.addBits32NC(s.matchLen, mlB.outBits)
+ wr.addBits32NC(s.offset, ofB.outBits)
+
+ if debugSequences {
+ println("Encoded seq", seq, s)
+ }
+
+ seq--
+ }
+ } else {
+ for seq >= 0 {
+ s = b.sequences[seq]
+ wr.flush32()
+ llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
+ // tabelog max is below 8 for each.
+ of.encode(ofB)
+ ml.encode(mlB)
+ ll.encode(llB)
+ wr.flush32()
+
+ // ml+ll = max 32 bits total
+ wr.addBits32NC(s.litLen, llB.outBits)
+ wr.addBits32NC(s.matchLen, mlB.outBits)
+ wr.flush32()
+ wr.addBits32NC(s.offset, ofB.outBits)
+
+ if debugSequences {
+ println("Encoded seq", seq, s)
+ }
+
+ seq--
+ }
+ }
+ ml.flush(mlEnc.actualTableLog)
+ of.flush(ofEnc.actualTableLog)
+ ll.flush(llEnc.actualTableLog)
+ err = wr.close()
+ if err != nil {
+ return err
+ }
+ b.output = wr.out
+
+ if len(b.output)-3-bhOffset >= b.size {
+ // Maybe even add a bigger margin.
+ b.litEnc.Reuse = huff0.ReusePolicyNone
+ return errIncompressible
+ }
+
+ // Size is output minus block header.
+ bh.setSize(uint32(len(b.output)-bhOffset) - 3)
+ if debug {
+ println("Rewriting block header", bh)
+ }
+ _ = bh.appendTo(b.output[bhOffset:bhOffset])
+ b.coders.setPrev(llEnc, mlEnc, ofEnc)
+ return nil
+}
+
+var errIncompressible = errors.New("incompressible")
+
+func (b *blockEnc) genCodes() {
+ if len(b.sequences) == 0 {
+ // nothing to do
+ return
+ }
+
+ if len(b.sequences) > math.MaxUint16 {
+ panic("can only encode up to 64K sequences")
+ }
+ // No bounds checks after here:
+ llH := b.coders.llEnc.Histogram()[:256]
+ ofH := b.coders.ofEnc.Histogram()[:256]
+ mlH := b.coders.mlEnc.Histogram()[:256]
+ for i := range llH {
+ llH[i] = 0
+ }
+ for i := range ofH {
+ ofH[i] = 0
+ }
+ for i := range mlH {
+ mlH[i] = 0
+ }
+
+ var llMax, ofMax, mlMax uint8
+ for i, seq := range b.sequences {
+ v := llCode(seq.litLen)
+ seq.llCode = v
+ llH[v]++
+ if v > llMax {
+ llMax = v
+ }
+
+ v = ofCode(seq.offset)
+ seq.ofCode = v
+ ofH[v]++
+ if v > ofMax {
+ ofMax = v
+ }
+
+ v = mlCode(seq.matchLen)
+ seq.mlCode = v
+ mlH[v]++
+ if v > mlMax {
+ mlMax = v
+ if debugAsserts && mlMax > maxMatchLengthSymbol {
+ panic(fmt.Errorf("mlMax > maxMatchLengthSymbol (%d), matchlen: %d", mlMax, seq.matchLen))
+ }
+ }
+ b.sequences[i] = seq
+ }
+ maxCount := func(a []uint32) int {
+ var max uint32
+ for _, v := range a {
+ if v > max {
+ max = v
+ }
+ }
+ return int(max)
+ }
+ if debugAsserts && mlMax > maxMatchLengthSymbol {
+ panic(fmt.Errorf("mlMax > maxMatchLengthSymbol (%d)", mlMax))
+ }
+ if debugAsserts && ofMax > maxOffsetBits {
+ panic(fmt.Errorf("ofMax > maxOffsetBits (%d)", ofMax))
+ }
+ if debugAsserts && llMax > maxLiteralLengthSymbol {
+ panic(fmt.Errorf("llMax > maxLiteralLengthSymbol (%d)", llMax))
+ }
+
+ b.coders.mlEnc.HistogramFinished(mlMax, maxCount(mlH[:mlMax+1]))
+ b.coders.ofEnc.HistogramFinished(ofMax, maxCount(ofH[:ofMax+1]))
+ b.coders.llEnc.HistogramFinished(llMax, maxCount(llH[:llMax+1]))
+}