872 lines
22 KiB
Go
872 lines
22 KiB
Go
// 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]))
|
|
}
|