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Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go')
-rw-r--r--vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go701
1 files changed, 0 insertions, 701 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go b/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go
deleted file mode 100644
index f9b2a699..00000000
--- a/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go
+++ /dev/null
@@ -1,701 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package flate
-
-import (
- "io"
-)
-
-const (
- // The largest offset code.
- offsetCodeCount = 30
-
- // The special code used to mark the end of a block.
- endBlockMarker = 256
-
- // The first length code.
- lengthCodesStart = 257
-
- // The number of codegen codes.
- codegenCodeCount = 19
- badCode = 255
-
- // bufferFlushSize indicates the buffer size
- // after which bytes are flushed to the writer.
- // Should preferably be a multiple of 6, since
- // we accumulate 6 bytes between writes to the buffer.
- bufferFlushSize = 240
-
- // bufferSize is the actual output byte buffer size.
- // It must have additional headroom for a flush
- // which can contain up to 8 bytes.
- bufferSize = bufferFlushSize + 8
-)
-
-// The number of extra bits needed by length code X - LENGTH_CODES_START.
-var lengthExtraBits = []int8{
- /* 257 */ 0, 0, 0,
- /* 260 */ 0, 0, 0, 0, 0, 1, 1, 1, 1, 2,
- /* 270 */ 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
- /* 280 */ 4, 5, 5, 5, 5, 0,
-}
-
-// The length indicated by length code X - LENGTH_CODES_START.
-var lengthBase = []uint32{
- 0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
- 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
- 64, 80, 96, 112, 128, 160, 192, 224, 255,
-}
-
-// offset code word extra bits.
-var offsetExtraBits = []int8{
- 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
- 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
- 9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
- /* extended window */
- 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
-}
-
-var offsetBase = []uint32{
- /* normal deflate */
- 0x000000, 0x000001, 0x000002, 0x000003, 0x000004,
- 0x000006, 0x000008, 0x00000c, 0x000010, 0x000018,
- 0x000020, 0x000030, 0x000040, 0x000060, 0x000080,
- 0x0000c0, 0x000100, 0x000180, 0x000200, 0x000300,
- 0x000400, 0x000600, 0x000800, 0x000c00, 0x001000,
- 0x001800, 0x002000, 0x003000, 0x004000, 0x006000,
-
- /* extended window */
- 0x008000, 0x00c000, 0x010000, 0x018000, 0x020000,
- 0x030000, 0x040000, 0x060000, 0x080000, 0x0c0000,
- 0x100000, 0x180000, 0x200000, 0x300000,
-}
-
-// The odd order in which the codegen code sizes are written.
-var codegenOrder = []uint32{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
-
-type huffmanBitWriter struct {
- // writer is the underlying writer.
- // Do not use it directly; use the write method, which ensures
- // that Write errors are sticky.
- writer io.Writer
-
- // Data waiting to be written is bytes[0:nbytes]
- // and then the low nbits of bits.
- bits uint64
- nbits uint
- bytes [bufferSize]byte
- codegenFreq [codegenCodeCount]int32
- nbytes int
- literalFreq []int32
- offsetFreq []int32
- codegen []uint8
- literalEncoding *huffmanEncoder
- offsetEncoding *huffmanEncoder
- codegenEncoding *huffmanEncoder
- err error
-}
-
-func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
- return &huffmanBitWriter{
- writer: w,
- literalFreq: make([]int32, maxNumLit),
- offsetFreq: make([]int32, offsetCodeCount),
- codegen: make([]uint8, maxNumLit+offsetCodeCount+1),
- literalEncoding: newHuffmanEncoder(maxNumLit),
- codegenEncoding: newHuffmanEncoder(codegenCodeCount),
- offsetEncoding: newHuffmanEncoder(offsetCodeCount),
- }
-}
-
-func (w *huffmanBitWriter) reset(writer io.Writer) {
- w.writer = writer
- w.bits, w.nbits, w.nbytes, w.err = 0, 0, 0, nil
- w.bytes = [bufferSize]byte{}
-}
-
-func (w *huffmanBitWriter) flush() {
- if w.err != nil {
- w.nbits = 0
- return
- }
- n := w.nbytes
- for w.nbits != 0 {
- w.bytes[n] = byte(w.bits)
- w.bits >>= 8
- if w.nbits > 8 { // Avoid underflow
- w.nbits -= 8
- } else {
- w.nbits = 0
- }
- n++
- }
- w.bits = 0
- w.write(w.bytes[:n])
- w.nbytes = 0
-}
-
-func (w *huffmanBitWriter) write(b []byte) {
- if w.err != nil {
- return
- }
- _, w.err = w.writer.Write(b)
-}
-
-func (w *huffmanBitWriter) writeBits(b int32, nb uint) {
- if w.err != nil {
- return
- }
- w.bits |= uint64(b) << w.nbits
- w.nbits += nb
- if w.nbits >= 48 {
- bits := w.bits
- w.bits >>= 48
- w.nbits -= 48
- n := w.nbytes
- bytes := w.bytes[n : n+6]
- bytes[0] = byte(bits)
- bytes[1] = byte(bits >> 8)
- bytes[2] = byte(bits >> 16)
- bytes[3] = byte(bits >> 24)
- bytes[4] = byte(bits >> 32)
- bytes[5] = byte(bits >> 40)
- n += 6
- if n >= bufferFlushSize {
- w.write(w.bytes[:n])
- n = 0
- }
- w.nbytes = n
- }
-}
-
-func (w *huffmanBitWriter) writeBytes(bytes []byte) {
- if w.err != nil {
- return
- }
- n := w.nbytes
- if w.nbits&7 != 0 {
- w.err = InternalError("writeBytes with unfinished bits")
- return
- }
- for w.nbits != 0 {
- w.bytes[n] = byte(w.bits)
- w.bits >>= 8
- w.nbits -= 8
- n++
- }
- if n != 0 {
- w.write(w.bytes[:n])
- }
- w.nbytes = 0
- w.write(bytes)
-}
-
-// RFC 1951 3.2.7 specifies a special run-length encoding for specifying
-// the literal and offset lengths arrays (which are concatenated into a single
-// array). This method generates that run-length encoding.
-//
-// The result is written into the codegen array, and the frequencies
-// of each code is written into the codegenFreq array.
-// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
-// information. Code badCode is an end marker
-//
-// numLiterals The number of literals in literalEncoding
-// numOffsets The number of offsets in offsetEncoding
-// litenc, offenc The literal and offset encoder to use
-func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int, litEnc, offEnc *huffmanEncoder) {
- for i := range w.codegenFreq {
- w.codegenFreq[i] = 0
- }
- // Note that we are using codegen both as a temporary variable for holding
- // a copy of the frequencies, and as the place where we put the result.
- // This is fine because the output is always shorter than the input used
- // so far.
- codegen := w.codegen // cache
- // Copy the concatenated code sizes to codegen. Put a marker at the end.
- cgnl := codegen[:numLiterals]
- for i := range cgnl {
- cgnl[i] = uint8(litEnc.codes[i].len)
- }
-
- cgnl = codegen[numLiterals : numLiterals+numOffsets]
- for i := range cgnl {
- cgnl[i] = uint8(offEnc.codes[i].len)
- }
- codegen[numLiterals+numOffsets] = badCode
-
- size := codegen[0]
- count := 1
- outIndex := 0
- for inIndex := 1; size != badCode; inIndex++ {
- // INVARIANT: We have seen "count" copies of size that have not yet
- // had output generated for them.
- nextSize := codegen[inIndex]
- if nextSize == size {
- count++
- continue
- }
- // We need to generate codegen indicating "count" of size.
- if size != 0 {
- codegen[outIndex] = size
- outIndex++
- w.codegenFreq[size]++
- count--
- for count >= 3 {
- n := 6
- if n > count {
- n = count
- }
- codegen[outIndex] = 16
- outIndex++
- codegen[outIndex] = uint8(n - 3)
- outIndex++
- w.codegenFreq[16]++
- count -= n
- }
- } else {
- for count >= 11 {
- n := 138
- if n > count {
- n = count
- }
- codegen[outIndex] = 18
- outIndex++
- codegen[outIndex] = uint8(n - 11)
- outIndex++
- w.codegenFreq[18]++
- count -= n
- }
- if count >= 3 {
- // count >= 3 && count <= 10
- codegen[outIndex] = 17
- outIndex++
- codegen[outIndex] = uint8(count - 3)
- outIndex++
- w.codegenFreq[17]++
- count = 0
- }
- }
- count--
- for ; count >= 0; count-- {
- codegen[outIndex] = size
- outIndex++
- w.codegenFreq[size]++
- }
- // Set up invariant for next time through the loop.
- size = nextSize
- count = 1
- }
- // Marker indicating the end of the codegen.
- codegen[outIndex] = badCode
-}
-
-// dynamicSize returns the size of dynamically encoded data in bits.
-func (w *huffmanBitWriter) dynamicSize(litEnc, offEnc *huffmanEncoder, extraBits int) (size, numCodegens int) {
- numCodegens = len(w.codegenFreq)
- for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
- numCodegens--
- }
- header := 3 + 5 + 5 + 4 + (3 * numCodegens) +
- w.codegenEncoding.bitLength(w.codegenFreq[:]) +
- int(w.codegenFreq[16])*2 +
- int(w.codegenFreq[17])*3 +
- int(w.codegenFreq[18])*7
- size = header +
- litEnc.bitLength(w.literalFreq) +
- offEnc.bitLength(w.offsetFreq) +
- extraBits
-
- return size, numCodegens
-}
-
-// fixedSize returns the size of dynamically encoded data in bits.
-func (w *huffmanBitWriter) fixedSize(extraBits int) int {
- return 3 +
- fixedLiteralEncoding.bitLength(w.literalFreq) +
- fixedOffsetEncoding.bitLength(w.offsetFreq) +
- extraBits
-}
-
-// storedSize calculates the stored size, including header.
-// The function returns the size in bits and whether the block
-// fits inside a single block.
-func (w *huffmanBitWriter) storedSize(in []byte) (int, bool) {
- if in == nil {
- return 0, false
- }
- if len(in) <= maxStoreBlockSize {
- return (len(in) + 5) * 8, true
- }
- return 0, false
-}
-
-func (w *huffmanBitWriter) writeCode(c hcode) {
- if w.err != nil {
- return
- }
- w.bits |= uint64(c.code) << w.nbits
- w.nbits += uint(c.len)
- if w.nbits >= 48 {
- bits := w.bits
- w.bits >>= 48
- w.nbits -= 48
- n := w.nbytes
- bytes := w.bytes[n : n+6]
- bytes[0] = byte(bits)
- bytes[1] = byte(bits >> 8)
- bytes[2] = byte(bits >> 16)
- bytes[3] = byte(bits >> 24)
- bytes[4] = byte(bits >> 32)
- bytes[5] = byte(bits >> 40)
- n += 6
- if n >= bufferFlushSize {
- w.write(w.bytes[:n])
- n = 0
- }
- w.nbytes = n
- }
-}
-
-// Write the header of a dynamic Huffman block to the output stream.
-//
-// numLiterals The number of literals specified in codegen
-// numOffsets The number of offsets specified in codegen
-// numCodegens The number of codegens used in codegen
-func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, numCodegens int, isEof bool) {
- if w.err != nil {
- return
- }
- var firstBits int32 = 4
- if isEof {
- firstBits = 5
- }
- w.writeBits(firstBits, 3)
- w.writeBits(int32(numLiterals-257), 5)
- w.writeBits(int32(numOffsets-1), 5)
- w.writeBits(int32(numCodegens-4), 4)
-
- for i := 0; i < numCodegens; i++ {
- value := uint(w.codegenEncoding.codes[codegenOrder[i]].len)
- w.writeBits(int32(value), 3)
- }
-
- i := 0
- for {
- var codeWord int = int(w.codegen[i])
- i++
- if codeWord == badCode {
- break
- }
- w.writeCode(w.codegenEncoding.codes[uint32(codeWord)])
-
- switch codeWord {
- case 16:
- w.writeBits(int32(w.codegen[i]), 2)
- i++
- break
- case 17:
- w.writeBits(int32(w.codegen[i]), 3)
- i++
- break
- case 18:
- w.writeBits(int32(w.codegen[i]), 7)
- i++
- break
- }
- }
-}
-
-func (w *huffmanBitWriter) writeStoredHeader(length int, isEof bool) {
- if w.err != nil {
- return
- }
- 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
- }
- // 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 []token, eof bool, input []byte) {
- if w.err != nil {
- return
- }
-
- tokens = append(tokens, endBlockMarker)
- numLiterals, numOffsets := w.indexTokens(tokens)
-
- var extraBits int
- storedSize, storable := w.storedSize(input)
- if storable {
- // We only bother calculating the costs of the extra bits required by
- // the length of offset fields (which will be the same for both fixed
- // and dynamic encoding), if we need to compare those two encodings
- // against stored encoding.
- for lengthCode := lengthCodesStart + 8; lengthCode < numLiterals; lengthCode++ {
- // First eight length codes have extra size = 0.
- extraBits += int(w.literalFreq[lengthCode]) * int(lengthExtraBits[lengthCode-lengthCodesStart])
- }
- for offsetCode := 4; offsetCode < numOffsets; offsetCode++ {
- // First four offset codes have extra size = 0.
- extraBits += int(w.offsetFreq[offsetCode]) * int(offsetExtraBits[offsetCode])
- }
- }
-
- // 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, 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 []token, eof bool, input []byte) {
- if w.err != nil {
- return
- }
-
- tokens = append(tokens, endBlockMarker)
- numLiterals, numOffsets := w.indexTokens(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)
- size, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, 0)
-
- // 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)
- return
- }
-
- // Write Huffman table.
- w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
-
- // Write the tokens.
- w.writeTokens(tokens, 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(tokens []token) (numLiterals, numOffsets int) {
- for i := range w.literalFreq {
- w.literalFreq[i] = 0
- }
- for i := range w.offsetFreq {
- w.offsetFreq[i] = 0
- }
-
- for _, t := range tokens {
- if t < matchType {
- w.literalFreq[t.literal()]++
- continue
- }
- length := t.length()
- offset := t.offset()
- w.literalFreq[lengthCodesStart+lengthCode(length)]++
- w.offsetFreq[offsetCode(offset)]++
- }
-
- // 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
- }
- w.literalEncoding.generate(w.literalFreq, 15)
- w.offsetEncoding.generate(w.offsetFreq, 15)
- return
-}
-
-// 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
- }
- for _, t := range tokens {
- if t < matchType {
- w.writeCode(leCodes[t.literal()])
- continue
- }
- // Write the length
- length := t.length()
- lengthCode := lengthCode(length)
- w.writeCode(leCodes[lengthCode+lengthCodesStart])
- extraLengthBits := uint(lengthExtraBits[lengthCode])
- if extraLengthBits > 0 {
- extraLength := int32(length - lengthBase[lengthCode])
- w.writeBits(extraLength, extraLengthBits)
- }
- // Write the offset
- offset := t.offset()
- offsetCode := offsetCode(offset)
- w.writeCode(oeCodes[offsetCode])
- extraOffsetBits := uint(offsetExtraBits[offsetCode])
- if extraOffsetBits > 0 {
- extraOffset := int32(offset - offsetBase[offsetCode])
- w.writeBits(extraOffset, extraOffsetBits)
- }
- }
-}
-
-// 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, 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) {
- if w.err != nil {
- return
- }
-
- // Clear histogram
- for i := range w.literalFreq {
- w.literalFreq[i] = 0
- }
-
- // Add everything as literals
- histogram(input, w.literalFreq)
-
- w.literalFreq[endBlockMarker] = 1
-
- const numLiterals = endBlockMarker + 1
- const numOffsets = 1
-
- w.literalEncoding.generate(w.literalFreq, 15)
-
- // Figure out smallest code.
- // Always use dynamic Huffman or Store
- var numCodegens int
-
- // 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)
- size, numCodegens := w.dynamicSize(w.literalEncoding, huffOffset, 0)
-
- // 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)
- return
- }
-
- // Huffman.
- w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
- encoding := w.literalEncoding.codes[:257]
- n := w.nbytes
- for _, t := range input {
- // Bitwriting inlined, ~30% speedup
- c := encoding[t]
- w.bits |= uint64(c.code) << w.nbits
- w.nbits += uint(c.len)
- if w.nbits < 48 {
- continue
- }
- // Store 6 bytes
- bits := w.bits
- w.bits >>= 48
- w.nbits -= 48
- bytes := w.bytes[n : n+6]
- bytes[0] = byte(bits)
- bytes[1] = byte(bits >> 8)
- bytes[2] = byte(bits >> 16)
- bytes[3] = byte(bits >> 24)
- bytes[4] = byte(bits >> 32)
- bytes[5] = byte(bits >> 40)
- n += 6
- if n < bufferFlushSize {
- continue
- }
- w.write(w.bytes[:n])
- if w.err != nil {
- return // Return early in the event of write failures
- }
- n = 0
- }
- w.nbytes = n
- w.writeCode(encoding[endBlockMarker])
-}
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