mirror of
https://github.com/mudler/luet.git
synced 2025-06-27 07:50:18 +00:00
4adc0dc9b9
Instead of using gox on one side and an action to release, we can merge them together with goreleaser which will build for extra targets (arm, mips if needed in the future) and it also takes care of creating checksums, a source archive, and a changelog and creating a release with all the artifacts. All binaries should respect the old naming convention, so any scripts out there should still work. Signed-off-by: Itxaka <igarcia@suse.com>
911 lines
24 KiB
Go
911 lines
24 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package flate
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import (
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"encoding/binary"
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"io"
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)
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const (
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// The largest offset code.
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offsetCodeCount = 30
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// The special code used to mark the end of a block.
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endBlockMarker = 256
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// The first length code.
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lengthCodesStart = 257
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// The number of codegen codes.
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codegenCodeCount = 19
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badCode = 255
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// bufferFlushSize indicates the buffer size
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// after which bytes are flushed to the writer.
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// Should preferably be a multiple of 6, since
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// we accumulate 6 bytes between writes to the buffer.
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bufferFlushSize = 240
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// bufferSize is the actual output byte buffer size.
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// It must have additional headroom for a flush
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// which can contain up to 8 bytes.
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bufferSize = bufferFlushSize + 8
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)
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// The number of extra bits needed by length code X - LENGTH_CODES_START.
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var lengthExtraBits = [32]int8{
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/* 257 */ 0, 0, 0,
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/* 260 */ 0, 0, 0, 0, 0, 1, 1, 1, 1, 2,
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/* 270 */ 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
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/* 280 */ 4, 5, 5, 5, 5, 0,
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}
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// The length indicated by length code X - LENGTH_CODES_START.
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var lengthBase = [32]uint8{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
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12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
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64, 80, 96, 112, 128, 160, 192, 224, 255,
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}
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// offset code word extra bits.
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var offsetExtraBits = [64]int8{
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0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
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4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
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9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
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/* extended window */
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14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
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}
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var offsetBase = [64]uint32{
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/* normal deflate */
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0x000000, 0x000001, 0x000002, 0x000003, 0x000004,
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0x000006, 0x000008, 0x00000c, 0x000010, 0x000018,
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0x000020, 0x000030, 0x000040, 0x000060, 0x000080,
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0x0000c0, 0x000100, 0x000180, 0x000200, 0x000300,
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0x000400, 0x000600, 0x000800, 0x000c00, 0x001000,
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0x001800, 0x002000, 0x003000, 0x004000, 0x006000,
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/* extended window */
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0x008000, 0x00c000, 0x010000, 0x018000, 0x020000,
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0x030000, 0x040000, 0x060000, 0x080000, 0x0c0000,
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0x100000, 0x180000, 0x200000, 0x300000,
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}
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// The odd order in which the codegen code sizes are written.
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var codegenOrder = []uint32{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
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type huffmanBitWriter struct {
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// writer is the underlying writer.
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// Do not use it directly; use the write method, which ensures
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// that Write errors are sticky.
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writer io.Writer
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// Data waiting to be written is bytes[0:nbytes]
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// and then the low nbits of bits.
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bits uint64
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nbits uint16
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nbytes uint8
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literalEncoding *huffmanEncoder
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offsetEncoding *huffmanEncoder
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codegenEncoding *huffmanEncoder
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err error
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lastHeader int
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// Set between 0 (reused block can be up to 2x the size)
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logNewTablePenalty uint
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lastHuffMan bool
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bytes [256]byte
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literalFreq [lengthCodesStart + 32]uint16
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offsetFreq [32]uint16
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codegenFreq [codegenCodeCount]uint16
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// codegen must have an extra space for the final symbol.
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codegen [literalCount + offsetCodeCount + 1]uint8
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}
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// Huffman reuse.
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//
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// The huffmanBitWriter supports reusing huffman tables and thereby combining block sections.
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//
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// This is controlled by several variables:
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//
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// If lastHeader is non-zero the Huffman table can be reused.
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// This also indicates that a Huffman table has been generated that can output all
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// possible symbols.
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// It also indicates that an EOB has not yet been emitted, so if a new tabel is generated
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// an EOB with the previous table must be written.
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//
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// If lastHuffMan is set, a table for outputting literals has been generated and offsets are invalid.
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//
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// An incoming block estimates the output size of a new table using a 'fresh' by calculating the
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// optimal size and adding a penalty in 'logNewTablePenalty'.
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// A Huffman table is not optimal, which is why we add a penalty, and generating a new table
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// is slower both for compression and decompression.
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func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
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return &huffmanBitWriter{
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writer: w,
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literalEncoding: newHuffmanEncoder(literalCount),
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codegenEncoding: newHuffmanEncoder(codegenCodeCount),
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offsetEncoding: newHuffmanEncoder(offsetCodeCount),
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}
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}
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func (w *huffmanBitWriter) reset(writer io.Writer) {
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w.writer = writer
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w.bits, w.nbits, w.nbytes, w.err = 0, 0, 0, nil
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w.lastHeader = 0
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w.lastHuffMan = false
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}
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func (w *huffmanBitWriter) canReuse(t *tokens) (offsets, lits bool) {
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offsets, lits = true, true
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a := t.offHist[:offsetCodeCount]
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b := w.offsetFreq[:len(a)]
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for i := range a {
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if b[i] == 0 && a[i] != 0 {
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offsets = false
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break
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}
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}
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a = t.extraHist[:literalCount-256]
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b = w.literalFreq[256:literalCount]
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b = b[:len(a)]
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for i := range a {
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if b[i] == 0 && a[i] != 0 {
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lits = false
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break
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}
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}
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if lits {
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a = t.litHist[:]
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b = w.literalFreq[:len(a)]
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for i := range a {
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if b[i] == 0 && a[i] != 0 {
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lits = false
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break
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}
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}
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}
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return
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}
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func (w *huffmanBitWriter) flush() {
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if w.err != nil {
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w.nbits = 0
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return
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}
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if w.lastHeader > 0 {
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// We owe an EOB
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w.writeCode(w.literalEncoding.codes[endBlockMarker])
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w.lastHeader = 0
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}
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n := w.nbytes
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for w.nbits != 0 {
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w.bytes[n] = byte(w.bits)
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w.bits >>= 8
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if w.nbits > 8 { // Avoid underflow
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w.nbits -= 8
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} else {
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w.nbits = 0
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}
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n++
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}
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w.bits = 0
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w.write(w.bytes[:n])
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w.nbytes = 0
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}
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func (w *huffmanBitWriter) write(b []byte) {
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if w.err != nil {
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return
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}
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_, w.err = w.writer.Write(b)
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}
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func (w *huffmanBitWriter) writeBits(b int32, nb uint16) {
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w.bits |= uint64(b) << w.nbits
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w.nbits += nb
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if w.nbits >= 48 {
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w.writeOutBits()
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}
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}
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func (w *huffmanBitWriter) writeBytes(bytes []byte) {
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if w.err != nil {
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return
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}
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n := w.nbytes
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if w.nbits&7 != 0 {
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w.err = InternalError("writeBytes with unfinished bits")
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return
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}
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for w.nbits != 0 {
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w.bytes[n] = byte(w.bits)
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w.bits >>= 8
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w.nbits -= 8
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n++
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}
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if n != 0 {
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w.write(w.bytes[:n])
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}
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w.nbytes = 0
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w.write(bytes)
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}
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// RFC 1951 3.2.7 specifies a special run-length encoding for specifying
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// the literal and offset lengths arrays (which are concatenated into a single
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// array). This method generates that run-length encoding.
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//
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// The result is written into the codegen array, and the frequencies
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// of each code is written into the codegenFreq array.
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// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
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// information. Code badCode is an end marker
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//
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// numLiterals The number of literals in literalEncoding
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// numOffsets The number of offsets in offsetEncoding
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// litenc, offenc The literal and offset encoder to use
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func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int, litEnc, offEnc *huffmanEncoder) {
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for i := range w.codegenFreq {
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w.codegenFreq[i] = 0
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}
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// Note that we are using codegen both as a temporary variable for holding
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// a copy of the frequencies, and as the place where we put the result.
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// This is fine because the output is always shorter than the input used
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// so far.
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codegen := w.codegen[:] // cache
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// Copy the concatenated code sizes to codegen. Put a marker at the end.
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cgnl := codegen[:numLiterals]
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for i := range cgnl {
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cgnl[i] = uint8(litEnc.codes[i].len)
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}
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cgnl = codegen[numLiterals : numLiterals+numOffsets]
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for i := range cgnl {
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cgnl[i] = uint8(offEnc.codes[i].len)
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}
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codegen[numLiterals+numOffsets] = badCode
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size := codegen[0]
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count := 1
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outIndex := 0
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for inIndex := 1; size != badCode; inIndex++ {
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// INVARIANT: We have seen "count" copies of size that have not yet
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// had output generated for them.
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nextSize := codegen[inIndex]
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if nextSize == size {
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count++
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continue
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}
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// We need to generate codegen indicating "count" of size.
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if size != 0 {
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codegen[outIndex] = size
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outIndex++
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w.codegenFreq[size]++
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count--
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for count >= 3 {
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n := 6
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if n > count {
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n = count
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}
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codegen[outIndex] = 16
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outIndex++
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codegen[outIndex] = uint8(n - 3)
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outIndex++
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w.codegenFreq[16]++
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count -= n
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}
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} else {
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for count >= 11 {
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n := 138
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if n > count {
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n = count
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}
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codegen[outIndex] = 18
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outIndex++
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codegen[outIndex] = uint8(n - 11)
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outIndex++
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w.codegenFreq[18]++
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count -= n
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}
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if count >= 3 {
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// count >= 3 && count <= 10
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codegen[outIndex] = 17
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outIndex++
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codegen[outIndex] = uint8(count - 3)
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outIndex++
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w.codegenFreq[17]++
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count = 0
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}
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}
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count--
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for ; count >= 0; count-- {
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codegen[outIndex] = size
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outIndex++
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w.codegenFreq[size]++
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}
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// Set up invariant for next time through the loop.
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size = nextSize
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count = 1
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}
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// Marker indicating the end of the codegen.
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codegen[outIndex] = badCode
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}
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func (w *huffmanBitWriter) codegens() int {
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numCodegens := len(w.codegenFreq)
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for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
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numCodegens--
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}
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return numCodegens
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}
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func (w *huffmanBitWriter) headerSize() (size, numCodegens int) {
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numCodegens = len(w.codegenFreq)
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for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
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numCodegens--
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}
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return 3 + 5 + 5 + 4 + (3 * numCodegens) +
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w.codegenEncoding.bitLength(w.codegenFreq[:]) +
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int(w.codegenFreq[16])*2 +
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int(w.codegenFreq[17])*3 +
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int(w.codegenFreq[18])*7, numCodegens
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}
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// dynamicSize returns the size of dynamically encoded data in bits.
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func (w *huffmanBitWriter) dynamicReuseSize(litEnc, offEnc *huffmanEncoder) (size int) {
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size = litEnc.bitLength(w.literalFreq[:]) +
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offEnc.bitLength(w.offsetFreq[:])
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return size
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}
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// dynamicSize returns the size of dynamically encoded data in bits.
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func (w *huffmanBitWriter) dynamicSize(litEnc, offEnc *huffmanEncoder, extraBits int) (size, numCodegens int) {
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header, numCodegens := w.headerSize()
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size = header +
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litEnc.bitLength(w.literalFreq[:]) +
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offEnc.bitLength(w.offsetFreq[:]) +
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extraBits
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return size, numCodegens
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}
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// extraBitSize will return the number of bits that will be written
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// as "extra" bits on matches.
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func (w *huffmanBitWriter) extraBitSize() int {
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total := 0
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for i, n := range w.literalFreq[257:literalCount] {
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total += int(n) * int(lengthExtraBits[i&31])
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}
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for i, n := range w.offsetFreq[:offsetCodeCount] {
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total += int(n) * int(offsetExtraBits[i&31])
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}
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return total
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}
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// fixedSize returns the size of dynamically encoded data in bits.
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func (w *huffmanBitWriter) fixedSize(extraBits int) int {
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return 3 +
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fixedLiteralEncoding.bitLength(w.literalFreq[:]) +
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fixedOffsetEncoding.bitLength(w.offsetFreq[:]) +
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extraBits
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}
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// storedSize calculates the stored size, including header.
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// The function returns the size in bits and whether the block
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// fits inside a single block.
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func (w *huffmanBitWriter) storedSize(in []byte) (int, bool) {
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if in == nil {
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return 0, false
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}
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if len(in) <= maxStoreBlockSize {
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return (len(in) + 5) * 8, true
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}
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return 0, false
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}
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func (w *huffmanBitWriter) writeCode(c hcode) {
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// The function does not get inlined if we "& 63" the shift.
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w.bits |= uint64(c.code) << w.nbits
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w.nbits += c.len
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if w.nbits >= 48 {
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w.writeOutBits()
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}
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}
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// writeOutBits will write bits to the buffer.
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func (w *huffmanBitWriter) writeOutBits() {
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bits := w.bits
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w.bits >>= 48
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w.nbits -= 48
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n := w.nbytes
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// We over-write, but faster...
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binary.LittleEndian.PutUint64(w.bytes[n:], bits)
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n += 6
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if n >= bufferFlushSize {
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if w.err != nil {
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n = 0
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return
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}
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w.write(w.bytes[:n])
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n = 0
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}
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w.nbytes = n
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}
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// Write the header of a dynamic Huffman block to the output stream.
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//
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// numLiterals The number of literals specified in codegen
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// numOffsets The number of offsets specified in codegen
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// numCodegens The number of codegens used in codegen
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func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, numCodegens int, isEof bool) {
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if w.err != nil {
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return
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}
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var firstBits int32 = 4
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if isEof {
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firstBits = 5
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}
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w.writeBits(firstBits, 3)
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w.writeBits(int32(numLiterals-257), 5)
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w.writeBits(int32(numOffsets-1), 5)
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w.writeBits(int32(numCodegens-4), 4)
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for i := 0; i < numCodegens; i++ {
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value := uint(w.codegenEncoding.codes[codegenOrder[i]].len)
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w.writeBits(int32(value), 3)
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}
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i := 0
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for {
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var codeWord = uint32(w.codegen[i])
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i++
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if codeWord == badCode {
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break
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}
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w.writeCode(w.codegenEncoding.codes[codeWord])
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switch codeWord {
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case 16:
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w.writeBits(int32(w.codegen[i]), 2)
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i++
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case 17:
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w.writeBits(int32(w.codegen[i]), 3)
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i++
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case 18:
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w.writeBits(int32(w.codegen[i]), 7)
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i++
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}
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}
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}
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// writeStoredHeader will write a stored header.
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// If the stored block is only used for EOF,
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// it is replaced with a fixed huffman block.
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func (w *huffmanBitWriter) writeStoredHeader(length int, isEof bool) {
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if w.err != nil {
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return
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}
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if w.lastHeader > 0 {
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// We owe an EOB
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w.writeCode(w.literalEncoding.codes[endBlockMarker])
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w.lastHeader = 0
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}
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// To write EOF, use a fixed encoding block. 10 bits instead of 5 bytes.
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if length == 0 && isEof {
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w.writeFixedHeader(isEof)
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// EOB: 7 bits, value: 0
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w.writeBits(0, 7)
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w.flush()
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return
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}
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var flag int32
|
|
if isEof {
|
|
flag = 1
|
|
}
|
|
w.writeBits(flag, 3)
|
|
w.flush()
|
|
w.writeBits(int32(length), 16)
|
|
w.writeBits(int32(^uint16(length)), 16)
|
|
}
|
|
|
|
func (w *huffmanBitWriter) writeFixedHeader(isEof bool) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
if w.lastHeader > 0 {
|
|
// We owe an EOB
|
|
w.writeCode(w.literalEncoding.codes[endBlockMarker])
|
|
w.lastHeader = 0
|
|
}
|
|
|
|
// Indicate that we are a fixed Huffman block
|
|
var value int32 = 2
|
|
if isEof {
|
|
value = 3
|
|
}
|
|
w.writeBits(value, 3)
|
|
}
|
|
|
|
// writeBlock will write a block of tokens with the smallest encoding.
|
|
// The original input can be supplied, and if the huffman encoded data
|
|
// is larger than the original bytes, the data will be written as a
|
|
// stored block.
|
|
// If the input is nil, the tokens will always be Huffman encoded.
|
|
func (w *huffmanBitWriter) writeBlock(tokens *tokens, eof bool, input []byte) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
|
|
tokens.AddEOB()
|
|
if w.lastHeader > 0 {
|
|
// We owe an EOB
|
|
w.writeCode(w.literalEncoding.codes[endBlockMarker])
|
|
w.lastHeader = 0
|
|
}
|
|
numLiterals, numOffsets := w.indexTokens(tokens, false)
|
|
w.generate(tokens)
|
|
var extraBits int
|
|
storedSize, storable := w.storedSize(input)
|
|
if storable {
|
|
extraBits = w.extraBitSize()
|
|
}
|
|
|
|
// Figure out smallest code.
|
|
// Fixed Huffman baseline.
|
|
var literalEncoding = fixedLiteralEncoding
|
|
var offsetEncoding = fixedOffsetEncoding
|
|
var size = w.fixedSize(extraBits)
|
|
|
|
// Dynamic Huffman?
|
|
var numCodegens int
|
|
|
|
// Generate codegen and codegenFrequencies, which indicates how to encode
|
|
// the literalEncoding and the offsetEncoding.
|
|
w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
|
|
w.codegenEncoding.generate(w.codegenFreq[:], 7)
|
|
dynamicSize, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, extraBits)
|
|
|
|
if dynamicSize < size {
|
|
size = dynamicSize
|
|
literalEncoding = w.literalEncoding
|
|
offsetEncoding = w.offsetEncoding
|
|
}
|
|
|
|
// Stored bytes?
|
|
if storable && storedSize < size {
|
|
w.writeStoredHeader(len(input), eof)
|
|
w.writeBytes(input)
|
|
return
|
|
}
|
|
|
|
// Huffman.
|
|
if literalEncoding == fixedLiteralEncoding {
|
|
w.writeFixedHeader(eof)
|
|
} else {
|
|
w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
|
|
}
|
|
|
|
// Write the tokens.
|
|
w.writeTokens(tokens.Slice(), literalEncoding.codes, offsetEncoding.codes)
|
|
}
|
|
|
|
// writeBlockDynamic encodes a block using a dynamic Huffman table.
|
|
// This should be used if the symbols used have a disproportionate
|
|
// histogram distribution.
|
|
// If input is supplied and the compression savings are below 1/16th of the
|
|
// input size the block is stored.
|
|
func (w *huffmanBitWriter) writeBlockDynamic(tokens *tokens, eof bool, input []byte, sync bool) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
|
|
sync = sync || eof
|
|
if sync {
|
|
tokens.AddEOB()
|
|
}
|
|
|
|
// We cannot reuse pure huffman table, and must mark as EOF.
|
|
if (w.lastHuffMan || eof) && w.lastHeader > 0 {
|
|
// We will not try to reuse.
|
|
w.writeCode(w.literalEncoding.codes[endBlockMarker])
|
|
w.lastHeader = 0
|
|
w.lastHuffMan = false
|
|
}
|
|
if !sync {
|
|
tokens.Fill()
|
|
}
|
|
numLiterals, numOffsets := w.indexTokens(tokens, !sync)
|
|
|
|
var size int
|
|
// Check if we should reuse.
|
|
if w.lastHeader > 0 {
|
|
// Estimate size for using a new table.
|
|
// Use the previous header size as the best estimate.
|
|
newSize := w.lastHeader + tokens.EstimatedBits()
|
|
newSize += newSize >> w.logNewTablePenalty
|
|
|
|
// The estimated size is calculated as an optimal table.
|
|
// We add a penalty to make it more realistic and re-use a bit more.
|
|
reuseSize := w.dynamicReuseSize(w.literalEncoding, w.offsetEncoding) + w.extraBitSize()
|
|
|
|
// Check if a new table is better.
|
|
if newSize < reuseSize {
|
|
// Write the EOB we owe.
|
|
w.writeCode(w.literalEncoding.codes[endBlockMarker])
|
|
size = newSize
|
|
w.lastHeader = 0
|
|
} else {
|
|
size = reuseSize
|
|
}
|
|
// Check if we get a reasonable size decrease.
|
|
if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
|
|
w.writeStoredHeader(len(input), eof)
|
|
w.writeBytes(input)
|
|
w.lastHeader = 0
|
|
return
|
|
}
|
|
}
|
|
|
|
// We want a new block/table
|
|
if w.lastHeader == 0 {
|
|
w.generate(tokens)
|
|
// Generate codegen and codegenFrequencies, which indicates how to encode
|
|
// the literalEncoding and the offsetEncoding.
|
|
w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
|
|
w.codegenEncoding.generate(w.codegenFreq[:], 7)
|
|
var numCodegens int
|
|
size, numCodegens = w.dynamicSize(w.literalEncoding, w.offsetEncoding, w.extraBitSize())
|
|
// Store bytes, if we don't get a reasonable improvement.
|
|
if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
|
|
w.writeStoredHeader(len(input), eof)
|
|
w.writeBytes(input)
|
|
w.lastHeader = 0
|
|
return
|
|
}
|
|
|
|
// Write Huffman table.
|
|
w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
|
|
w.lastHeader, _ = w.headerSize()
|
|
w.lastHuffMan = false
|
|
}
|
|
|
|
if sync {
|
|
w.lastHeader = 0
|
|
}
|
|
// Write the tokens.
|
|
w.writeTokens(tokens.Slice(), w.literalEncoding.codes, w.offsetEncoding.codes)
|
|
}
|
|
|
|
// indexTokens indexes a slice of tokens, and updates
|
|
// literalFreq and offsetFreq, and generates literalEncoding
|
|
// and offsetEncoding.
|
|
// The number of literal and offset tokens is returned.
|
|
func (w *huffmanBitWriter) indexTokens(t *tokens, filled bool) (numLiterals, numOffsets int) {
|
|
copy(w.literalFreq[:], t.litHist[:])
|
|
copy(w.literalFreq[256:], t.extraHist[:])
|
|
copy(w.offsetFreq[:], t.offHist[:offsetCodeCount])
|
|
|
|
if t.n == 0 {
|
|
return
|
|
}
|
|
if filled {
|
|
return maxNumLit, maxNumDist
|
|
}
|
|
// get the number of literals
|
|
numLiterals = len(w.literalFreq)
|
|
for w.literalFreq[numLiterals-1] == 0 {
|
|
numLiterals--
|
|
}
|
|
// get the number of offsets
|
|
numOffsets = len(w.offsetFreq)
|
|
for numOffsets > 0 && w.offsetFreq[numOffsets-1] == 0 {
|
|
numOffsets--
|
|
}
|
|
if numOffsets == 0 {
|
|
// We haven't found a single match. If we want to go with the dynamic encoding,
|
|
// we should count at least one offset to be sure that the offset huffman tree could be encoded.
|
|
w.offsetFreq[0] = 1
|
|
numOffsets = 1
|
|
}
|
|
return
|
|
}
|
|
|
|
func (w *huffmanBitWriter) generate(t *tokens) {
|
|
w.literalEncoding.generate(w.literalFreq[:literalCount], 15)
|
|
w.offsetEncoding.generate(w.offsetFreq[:offsetCodeCount], 15)
|
|
}
|
|
|
|
// writeTokens writes a slice of tokens to the output.
|
|
// codes for literal and offset encoding must be supplied.
|
|
func (w *huffmanBitWriter) writeTokens(tokens []token, leCodes, oeCodes []hcode) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
if len(tokens) == 0 {
|
|
return
|
|
}
|
|
|
|
// Only last token should be endBlockMarker.
|
|
var deferEOB bool
|
|
if tokens[len(tokens)-1] == endBlockMarker {
|
|
tokens = tokens[:len(tokens)-1]
|
|
deferEOB = true
|
|
}
|
|
|
|
// Create slices up to the next power of two to avoid bounds checks.
|
|
lits := leCodes[:256]
|
|
offs := oeCodes[:32]
|
|
lengths := leCodes[lengthCodesStart:]
|
|
lengths = lengths[:32]
|
|
for _, t := range tokens {
|
|
if t < matchType {
|
|
w.writeCode(lits[t.literal()])
|
|
continue
|
|
}
|
|
|
|
// Write the length
|
|
length := t.length()
|
|
lengthCode := lengthCode(length)
|
|
if false {
|
|
w.writeCode(lengths[lengthCode&31])
|
|
} else {
|
|
// inlined
|
|
c := lengths[lengthCode&31]
|
|
w.bits |= uint64(c.code) << w.nbits
|
|
w.nbits += c.len
|
|
if w.nbits >= 48 {
|
|
w.writeOutBits()
|
|
}
|
|
}
|
|
|
|
extraLengthBits := uint16(lengthExtraBits[lengthCode&31])
|
|
if extraLengthBits > 0 {
|
|
extraLength := int32(length - lengthBase[lengthCode&31])
|
|
w.writeBits(extraLength, extraLengthBits)
|
|
}
|
|
// Write the offset
|
|
offset := t.offset()
|
|
offsetCode := offsetCode(offset)
|
|
if false {
|
|
w.writeCode(offs[offsetCode&31])
|
|
} else {
|
|
// inlined
|
|
c := offs[offsetCode&31]
|
|
w.bits |= uint64(c.code) << w.nbits
|
|
w.nbits += c.len
|
|
if w.nbits >= 48 {
|
|
w.writeOutBits()
|
|
}
|
|
}
|
|
extraOffsetBits := uint16(offsetExtraBits[offsetCode&63])
|
|
if extraOffsetBits > 0 {
|
|
extraOffset := int32(offset - offsetBase[offsetCode&63])
|
|
w.writeBits(extraOffset, extraOffsetBits)
|
|
}
|
|
}
|
|
if deferEOB {
|
|
w.writeCode(leCodes[endBlockMarker])
|
|
}
|
|
}
|
|
|
|
// huffOffset is a static offset encoder used for huffman only encoding.
|
|
// It can be reused since we will not be encoding offset values.
|
|
var huffOffset *huffmanEncoder
|
|
|
|
func init() {
|
|
w := newHuffmanBitWriter(nil)
|
|
w.offsetFreq[0] = 1
|
|
huffOffset = newHuffmanEncoder(offsetCodeCount)
|
|
huffOffset.generate(w.offsetFreq[:offsetCodeCount], 15)
|
|
}
|
|
|
|
// writeBlockHuff encodes a block of bytes as either
|
|
// Huffman encoded literals or uncompressed bytes if the
|
|
// results only gains very little from compression.
|
|
func (w *huffmanBitWriter) writeBlockHuff(eof bool, input []byte, sync bool) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
|
|
// Clear histogram
|
|
for i := range w.literalFreq[:] {
|
|
w.literalFreq[i] = 0
|
|
}
|
|
if !w.lastHuffMan {
|
|
for i := range w.offsetFreq[:] {
|
|
w.offsetFreq[i] = 0
|
|
}
|
|
}
|
|
|
|
// Add everything as literals
|
|
// We have to estimate the header size.
|
|
// Assume header is around 70 bytes:
|
|
// https://stackoverflow.com/a/25454430
|
|
const guessHeaderSizeBits = 70 * 8
|
|
estBits := histogramSize(input, w.literalFreq[:], !eof && !sync)
|
|
estBits += w.lastHeader + len(input)/32
|
|
if w.lastHeader == 0 {
|
|
estBits += guessHeaderSizeBits
|
|
}
|
|
estBits += estBits >> w.logNewTablePenalty
|
|
|
|
// Store bytes, if we don't get a reasonable improvement.
|
|
ssize, storable := w.storedSize(input)
|
|
if storable && ssize < estBits {
|
|
w.writeStoredHeader(len(input), eof)
|
|
w.writeBytes(input)
|
|
return
|
|
}
|
|
|
|
reuseSize := 0
|
|
if w.lastHeader > 0 {
|
|
reuseSize = w.literalEncoding.bitLength(w.literalFreq[:256])
|
|
|
|
if estBits < reuseSize {
|
|
// We owe an EOB
|
|
w.writeCode(w.literalEncoding.codes[endBlockMarker])
|
|
w.lastHeader = 0
|
|
}
|
|
}
|
|
|
|
const numLiterals = endBlockMarker + 1
|
|
const numOffsets = 1
|
|
if w.lastHeader == 0 {
|
|
if !eof && !sync {
|
|
// Generate a slightly suboptimal tree that can be used for all.
|
|
fillHist(w.literalFreq[:numLiterals])
|
|
}
|
|
w.literalFreq[endBlockMarker] = 1
|
|
w.literalEncoding.generate(w.literalFreq[:numLiterals], 15)
|
|
|
|
// Generate codegen and codegenFrequencies, which indicates how to encode
|
|
// the literalEncoding and the offsetEncoding.
|
|
w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, huffOffset)
|
|
w.codegenEncoding.generate(w.codegenFreq[:], 7)
|
|
numCodegens := w.codegens()
|
|
|
|
// Huffman.
|
|
w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
|
|
w.lastHuffMan = true
|
|
w.lastHeader, _ = w.headerSize()
|
|
}
|
|
|
|
encoding := w.literalEncoding.codes[:257]
|
|
for _, t := range input {
|
|
// Bitwriting inlined, ~30% speedup
|
|
c := encoding[t]
|
|
w.bits |= uint64(c.code) << w.nbits
|
|
w.nbits += c.len
|
|
if w.nbits >= 48 {
|
|
bits := w.bits
|
|
w.bits >>= 48
|
|
w.nbits -= 48
|
|
n := w.nbytes
|
|
binary.LittleEndian.PutUint64(w.bytes[n:], bits)
|
|
n += 6
|
|
if n >= bufferFlushSize {
|
|
if w.err != nil {
|
|
n = 0
|
|
return
|
|
}
|
|
w.write(w.bytes[:n])
|
|
n = 0
|
|
}
|
|
w.nbytes = n
|
|
}
|
|
}
|
|
if eof || sync {
|
|
w.writeCode(encoding[endBlockMarker])
|
|
w.lastHeader = 0
|
|
w.lastHuffMan = false
|
|
}
|
|
}
|