| 1 | // Code generated by go generate gen_inflate.go. DO NOT EDIT.
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| 2 |
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| 3 | package flate
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| 4 |
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| 5 | import (
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| 6 | "bufio"
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| 7 | "bytes"
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| 8 | "fmt"
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| 9 | "math/bits"
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| 10 | "strings"
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| 11 | )
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| 12 |
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| 13 | // Decode a single Huffman block from f.
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| 14 | // hl and hd are the Huffman states for the lit/length values
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| 15 | // and the distance values, respectively. If hd == nil, using the
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| 16 | // fixed distance encoding associated with fixed Huffman blocks.
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| 17 | func (f *decompressor) huffmanBytesBuffer() {
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| 18 | const (
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| 19 | stateInit = iota // Zero value must be stateInit
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| 20 | stateDict
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| 21 | )
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| 22 | fr := f.r.(*bytes.Buffer)
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| 23 |
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| 24 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
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| 25 | // but is smart enough to keep local variables in registers, so use nb and b,
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| 26 | // inline call to moreBits and reassign b,nb back to f on return.
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| 27 | fnb, fb := f.nb, f.b
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| 28 |
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| 29 | switch f.stepState {
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| 30 | case stateInit:
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| 31 | goto readLiteral
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| 32 | case stateDict:
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| 33 | goto copyHistory
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| 34 | }
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| 35 |
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| 36 | readLiteral:
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| 37 | // Read literal and/or (length, distance) according to RFC section 3.2.3.
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| 38 | {
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| 39 | var v int
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| 40 | {
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| 41 | // Inlined v, err := f.huffSym(f.hl)
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| 42 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
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| 43 | // with single element, huffSym must error on these two edge cases. In both
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| 44 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
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| 45 | // satisfy the n == 0 check below.
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| 46 | n := uint(f.hl.maxRead)
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| 47 | for {
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| 48 | for fnb < n {
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| 49 | c, err := fr.ReadByte()
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| 50 | if err != nil {
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| 51 | f.b, f.nb = fb, fnb
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| 52 | f.err = noEOF(err)
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| 53 | return
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| 54 | }
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| 55 | f.roffset++
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| 56 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 57 | fnb += 8
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| 58 | }
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| 59 | chunk := f.hl.chunks[fb&(huffmanNumChunks-1)]
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| 60 | n = uint(chunk & huffmanCountMask)
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| 61 | if n > huffmanChunkBits {
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| 62 | chunk = f.hl.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hl.linkMask]
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| 63 | n = uint(chunk & huffmanCountMask)
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| 64 | }
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| 65 | if n <= fnb {
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| 66 | if n == 0 {
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| 67 | f.b, f.nb = fb, fnb
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| 68 | if debugDecode {
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| 69 | fmt.Println("huffsym: n==0")
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| 70 | }
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| 71 | f.err = CorruptInputError(f.roffset)
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| 72 | return
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| 73 | }
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| 74 | fb = fb >> (n & regSizeMaskUint32)
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| 75 | fnb = fnb - n
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| 76 | v = int(chunk >> huffmanValueShift)
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| 77 | break
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| 78 | }
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| 79 | }
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| 80 | }
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| 81 |
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| 82 | var length int
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| 83 | switch {
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| 84 | case v < 256:
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| 85 | f.dict.writeByte(byte(v))
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| 86 | if f.dict.availWrite() == 0 {
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| 87 | f.toRead = f.dict.readFlush()
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| 88 | f.step = (*decompressor).huffmanBytesBuffer
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| 89 | f.stepState = stateInit
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| 90 | f.b, f.nb = fb, fnb
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| 91 | return
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| 92 | }
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| 93 | goto readLiteral
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| 94 | case v == 256:
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| 95 | f.b, f.nb = fb, fnb
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| 96 | f.finishBlock()
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| 97 | return
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| 98 | // otherwise, reference to older data
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| 99 | case v < 265:
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| 100 | length = v - (257 - 3)
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| 101 | case v < maxNumLit:
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| 102 | val := decCodeToLen[(v - 257)]
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| 103 | length = int(val.length) + 3
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| 104 | n := uint(val.extra)
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| 105 | for fnb < n {
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| 106 | c, err := fr.ReadByte()
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| 107 | if err != nil {
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| 108 | f.b, f.nb = fb, fnb
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| 109 | if debugDecode {
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| 110 | fmt.Println("morebits n>0:", err)
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| 111 | }
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| 112 | f.err = err
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| 113 | return
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| 114 | }
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| 115 | f.roffset++
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| 116 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 117 | fnb += 8
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| 118 | }
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| 119 | length += int(fb & bitMask32[n])
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| 120 | fb >>= n & regSizeMaskUint32
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| 121 | fnb -= n
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| 122 | default:
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| 123 | if debugDecode {
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| 124 | fmt.Println(v, ">= maxNumLit")
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| 125 | }
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| 126 | f.err = CorruptInputError(f.roffset)
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| 127 | f.b, f.nb = fb, fnb
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| 128 | return
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| 129 | }
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| 130 |
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| 131 | var dist uint32
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| 132 | if f.hd == nil {
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| 133 | for fnb < 5 {
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| 134 | c, err := fr.ReadByte()
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| 135 | if err != nil {
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| 136 | f.b, f.nb = fb, fnb
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| 137 | if debugDecode {
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| 138 | fmt.Println("morebits f.nb<5:", err)
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| 139 | }
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| 140 | f.err = err
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| 141 | return
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| 142 | }
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| 143 | f.roffset++
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| 144 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 145 | fnb += 8
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| 146 | }
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| 147 | dist = uint32(bits.Reverse8(uint8(fb & 0x1F << 3)))
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| 148 | fb >>= 5
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| 149 | fnb -= 5
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| 150 | } else {
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| 151 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
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| 152 | // with single element, huffSym must error on these two edge cases. In both
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| 153 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
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| 154 | // satisfy the n == 0 check below.
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| 155 | n := uint(f.hd.maxRead)
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| 156 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
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| 157 | // but is smart enough to keep local variables in registers, so use nb and b,
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| 158 | // inline call to moreBits and reassign b,nb back to f on return.
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| 159 | for {
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| 160 | for fnb < n {
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| 161 | c, err := fr.ReadByte()
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| 162 | if err != nil {
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| 163 | f.b, f.nb = fb, fnb
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| 164 | f.err = noEOF(err)
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| 165 | return
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| 166 | }
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| 167 | f.roffset++
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| 168 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 169 | fnb += 8
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| 170 | }
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| 171 | chunk := f.hd.chunks[fb&(huffmanNumChunks-1)]
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| 172 | n = uint(chunk & huffmanCountMask)
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| 173 | if n > huffmanChunkBits {
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| 174 | chunk = f.hd.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hd.linkMask]
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| 175 | n = uint(chunk & huffmanCountMask)
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| 176 | }
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| 177 | if n <= fnb {
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| 178 | if n == 0 {
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| 179 | f.b, f.nb = fb, fnb
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| 180 | if debugDecode {
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| 181 | fmt.Println("huffsym: n==0")
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| 182 | }
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| 183 | f.err = CorruptInputError(f.roffset)
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| 184 | return
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| 185 | }
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| 186 | fb = fb >> (n & regSizeMaskUint32)
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| 187 | fnb = fnb - n
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| 188 | dist = uint32(chunk >> huffmanValueShift)
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| 189 | break
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| 190 | }
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| 191 | }
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| 192 | }
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| 193 |
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| 194 | switch {
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| 195 | case dist < 4:
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| 196 | dist++
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| 197 | case dist < maxNumDist:
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| 198 | nb := uint(dist-2) >> 1
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| 199 | // have 1 bit in bottom of dist, need nb more.
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| 200 | extra := (dist & 1) << (nb & regSizeMaskUint32)
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| 201 | for fnb < nb {
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| 202 | c, err := fr.ReadByte()
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| 203 | if err != nil {
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| 204 | f.b, f.nb = fb, fnb
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| 205 | if debugDecode {
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| 206 | fmt.Println("morebits f.nb<nb:", err)
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| 207 | }
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| 208 | f.err = err
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| 209 | return
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| 210 | }
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| 211 | f.roffset++
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| 212 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 213 | fnb += 8
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| 214 | }
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| 215 | extra |= fb & bitMask32[nb]
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| 216 | fb >>= nb & regSizeMaskUint32
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| 217 | fnb -= nb
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| 218 | dist = 1<<((nb+1)®SizeMaskUint32) + 1 + extra
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| 219 | // slower: dist = bitMask32[nb+1] + 2 + extra
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| 220 | default:
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| 221 | f.b, f.nb = fb, fnb
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| 222 | if debugDecode {
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| 223 | fmt.Println("dist too big:", dist, maxNumDist)
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| 224 | }
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| 225 | f.err = CorruptInputError(f.roffset)
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| 226 | return
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| 227 | }
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| 228 |
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| 229 | // No check on length; encoding can be prescient.
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| 230 | if dist > uint32(f.dict.histSize()) {
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| 231 | f.b, f.nb = fb, fnb
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| 232 | if debugDecode {
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| 233 | fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
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| 234 | }
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| 235 | f.err = CorruptInputError(f.roffset)
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| 236 | return
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| 237 | }
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| 238 |
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| 239 | f.copyLen, f.copyDist = length, int(dist)
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| 240 | goto copyHistory
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| 241 | }
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| 242 |
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| 243 | copyHistory:
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| 244 | // Perform a backwards copy according to RFC section 3.2.3.
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| 245 | {
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| 246 | cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
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| 247 | if cnt == 0 {
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| 248 | cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
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| 249 | }
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| 250 | f.copyLen -= cnt
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| 251 |
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| 252 | if f.dict.availWrite() == 0 || f.copyLen > 0 {
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| 253 | f.toRead = f.dict.readFlush()
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| 254 | f.step = (*decompressor).huffmanBytesBuffer // We need to continue this work
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| 255 | f.stepState = stateDict
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| 256 | f.b, f.nb = fb, fnb
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| 257 | return
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| 258 | }
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| 259 | goto readLiteral
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| 260 | }
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| 261 | // Not reached
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| 262 | }
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| 263 |
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| 264 | // Decode a single Huffman block from f.
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| 265 | // hl and hd are the Huffman states for the lit/length values
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| 266 | // and the distance values, respectively. If hd == nil, using the
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| 267 | // fixed distance encoding associated with fixed Huffman blocks.
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| 268 | func (f *decompressor) huffmanBytesReader() {
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| 269 | const (
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| 270 | stateInit = iota // Zero value must be stateInit
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| 271 | stateDict
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| 272 | )
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| 273 | fr := f.r.(*bytes.Reader)
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| 274 |
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| 275 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
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| 276 | // but is smart enough to keep local variables in registers, so use nb and b,
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| 277 | // inline call to moreBits and reassign b,nb back to f on return.
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| 278 | fnb, fb := f.nb, f.b
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| 279 |
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| 280 | switch f.stepState {
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| 281 | case stateInit:
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| 282 | goto readLiteral
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| 283 | case stateDict:
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| 284 | goto copyHistory
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| 285 | }
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| 286 |
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| 287 | readLiteral:
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| 288 | // Read literal and/or (length, distance) according to RFC section 3.2.3.
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| 289 | {
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| 290 | var v int
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| 291 | {
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| 292 | // Inlined v, err := f.huffSym(f.hl)
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| 293 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
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| 294 | // with single element, huffSym must error on these two edge cases. In both
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| 295 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
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| 296 | // satisfy the n == 0 check below.
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| 297 | n := uint(f.hl.maxRead)
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| 298 | for {
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| 299 | for fnb < n {
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| 300 | c, err := fr.ReadByte()
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| 301 | if err != nil {
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| 302 | f.b, f.nb = fb, fnb
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| 303 | f.err = noEOF(err)
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| 304 | return
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| 305 | }
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| 306 | f.roffset++
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| 307 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 308 | fnb += 8
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| 309 | }
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| 310 | chunk := f.hl.chunks[fb&(huffmanNumChunks-1)]
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| 311 | n = uint(chunk & huffmanCountMask)
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| 312 | if n > huffmanChunkBits {
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| 313 | chunk = f.hl.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hl.linkMask]
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| 314 | n = uint(chunk & huffmanCountMask)
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| 315 | }
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| 316 | if n <= fnb {
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| 317 | if n == 0 {
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| 318 | f.b, f.nb = fb, fnb
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| 319 | if debugDecode {
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| 320 | fmt.Println("huffsym: n==0")
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| 321 | }
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| 322 | f.err = CorruptInputError(f.roffset)
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| 323 | return
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| 324 | }
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| 325 | fb = fb >> (n & regSizeMaskUint32)
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| 326 | fnb = fnb - n
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| 327 | v = int(chunk >> huffmanValueShift)
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| 328 | break
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| 329 | }
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| 330 | }
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| 331 | }
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| 332 |
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| 333 | var length int
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| 334 | switch {
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| 335 | case v < 256:
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| 336 | f.dict.writeByte(byte(v))
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| 337 | if f.dict.availWrite() == 0 {
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| 338 | f.toRead = f.dict.readFlush()
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| 339 | f.step = (*decompressor).huffmanBytesReader
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| 340 | f.stepState = stateInit
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| 341 | f.b, f.nb = fb, fnb
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| 342 | return
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| 343 | }
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| 344 | goto readLiteral
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| 345 | case v == 256:
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| 346 | f.b, f.nb = fb, fnb
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| 347 | f.finishBlock()
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| 348 | return
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| 349 | // otherwise, reference to older data
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| 350 | case v < 265:
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| 351 | length = v - (257 - 3)
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| 352 | case v < maxNumLit:
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| 353 | val := decCodeToLen[(v - 257)]
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| 354 | length = int(val.length) + 3
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| 355 | n := uint(val.extra)
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| 356 | for fnb < n {
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| 357 | c, err := fr.ReadByte()
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| 358 | if err != nil {
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| 359 | f.b, f.nb = fb, fnb
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| 360 | if debugDecode {
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| 361 | fmt.Println("morebits n>0:", err)
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| 362 | }
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| 363 | f.err = err
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| 364 | return
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| 365 | }
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| 366 | f.roffset++
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| 367 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 368 | fnb += 8
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| 369 | }
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| 370 | length += int(fb & bitMask32[n])
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| 371 | fb >>= n & regSizeMaskUint32
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| 372 | fnb -= n
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| 373 | default:
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| 374 | if debugDecode {
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| 375 | fmt.Println(v, ">= maxNumLit")
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| 376 | }
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| 377 | f.err = CorruptInputError(f.roffset)
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| 378 | f.b, f.nb = fb, fnb
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| 379 | return
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| 380 | }
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| 381 |
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| 382 | var dist uint32
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| 383 | if f.hd == nil {
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| 384 | for fnb < 5 {
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| 385 | c, err := fr.ReadByte()
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| 386 | if err != nil {
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| 387 | f.b, f.nb = fb, fnb
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| 388 | if debugDecode {
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| 389 | fmt.Println("morebits f.nb<5:", err)
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| 390 | }
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| 391 | f.err = err
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| 392 | return
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| 393 | }
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| 394 | f.roffset++
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| 395 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
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| 396 | fnb += 8
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| 397 | }
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| 398 | dist = uint32(bits.Reverse8(uint8(fb & 0x1F << 3)))
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| 399 | fb >>= 5
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| 400 | fnb -= 5
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| 401 | } else {
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| 402 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 403 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 404 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 405 | // satisfy the n == 0 check below.
|
|---|
| 406 | n := uint(f.hd.maxRead)
|
|---|
| 407 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 408 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 409 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 410 | for {
|
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| 411 | for fnb < n {
|
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| 412 | c, err := fr.ReadByte()
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| 413 | if err != nil {
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| 414 | f.b, f.nb = fb, fnb
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| 415 | f.err = noEOF(err)
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| 416 | return
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| 417 | }
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| 418 | f.roffset++
|
|---|
| 419 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 420 | fnb += 8
|
|---|
| 421 | }
|
|---|
| 422 | chunk := f.hd.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 423 | n = uint(chunk & huffmanCountMask)
|
|---|
| 424 | if n > huffmanChunkBits {
|
|---|
| 425 | chunk = f.hd.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hd.linkMask]
|
|---|
| 426 | n = uint(chunk & huffmanCountMask)
|
|---|
| 427 | }
|
|---|
| 428 | if n <= fnb {
|
|---|
| 429 | if n == 0 {
|
|---|
| 430 | f.b, f.nb = fb, fnb
|
|---|
| 431 | if debugDecode {
|
|---|
| 432 | fmt.Println("huffsym: n==0")
|
|---|
| 433 | }
|
|---|
| 434 | f.err = CorruptInputError(f.roffset)
|
|---|
| 435 | return
|
|---|
| 436 | }
|
|---|
| 437 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 438 | fnb = fnb - n
|
|---|
| 439 | dist = uint32(chunk >> huffmanValueShift)
|
|---|
| 440 | break
|
|---|
| 441 | }
|
|---|
| 442 | }
|
|---|
| 443 | }
|
|---|
| 444 |
|
|---|
| 445 | switch {
|
|---|
| 446 | case dist < 4:
|
|---|
| 447 | dist++
|
|---|
| 448 | case dist < maxNumDist:
|
|---|
| 449 | nb := uint(dist-2) >> 1
|
|---|
| 450 | // have 1 bit in bottom of dist, need nb more.
|
|---|
| 451 | extra := (dist & 1) << (nb & regSizeMaskUint32)
|
|---|
| 452 | for fnb < nb {
|
|---|
| 453 | c, err := fr.ReadByte()
|
|---|
| 454 | if err != nil {
|
|---|
| 455 | f.b, f.nb = fb, fnb
|
|---|
| 456 | if debugDecode {
|
|---|
| 457 | fmt.Println("morebits f.nb<nb:", err)
|
|---|
| 458 | }
|
|---|
| 459 | f.err = err
|
|---|
| 460 | return
|
|---|
| 461 | }
|
|---|
| 462 | f.roffset++
|
|---|
| 463 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 464 | fnb += 8
|
|---|
| 465 | }
|
|---|
| 466 | extra |= fb & bitMask32[nb]
|
|---|
| 467 | fb >>= nb & regSizeMaskUint32
|
|---|
| 468 | fnb -= nb
|
|---|
| 469 | dist = 1<<((nb+1)®SizeMaskUint32) + 1 + extra
|
|---|
| 470 | // slower: dist = bitMask32[nb+1] + 2 + extra
|
|---|
| 471 | default:
|
|---|
| 472 | f.b, f.nb = fb, fnb
|
|---|
| 473 | if debugDecode {
|
|---|
| 474 | fmt.Println("dist too big:", dist, maxNumDist)
|
|---|
| 475 | }
|
|---|
| 476 | f.err = CorruptInputError(f.roffset)
|
|---|
| 477 | return
|
|---|
| 478 | }
|
|---|
| 479 |
|
|---|
| 480 | // No check on length; encoding can be prescient.
|
|---|
| 481 | if dist > uint32(f.dict.histSize()) {
|
|---|
| 482 | f.b, f.nb = fb, fnb
|
|---|
| 483 | if debugDecode {
|
|---|
| 484 | fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
|
|---|
| 485 | }
|
|---|
| 486 | f.err = CorruptInputError(f.roffset)
|
|---|
| 487 | return
|
|---|
| 488 | }
|
|---|
| 489 |
|
|---|
| 490 | f.copyLen, f.copyDist = length, int(dist)
|
|---|
| 491 | goto copyHistory
|
|---|
| 492 | }
|
|---|
| 493 |
|
|---|
| 494 | copyHistory:
|
|---|
| 495 | // Perform a backwards copy according to RFC section 3.2.3.
|
|---|
| 496 | {
|
|---|
| 497 | cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
|
|---|
| 498 | if cnt == 0 {
|
|---|
| 499 | cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
|
|---|
| 500 | }
|
|---|
| 501 | f.copyLen -= cnt
|
|---|
| 502 |
|
|---|
| 503 | if f.dict.availWrite() == 0 || f.copyLen > 0 {
|
|---|
| 504 | f.toRead = f.dict.readFlush()
|
|---|
| 505 | f.step = (*decompressor).huffmanBytesReader // We need to continue this work
|
|---|
| 506 | f.stepState = stateDict
|
|---|
| 507 | f.b, f.nb = fb, fnb
|
|---|
| 508 | return
|
|---|
| 509 | }
|
|---|
| 510 | goto readLiteral
|
|---|
| 511 | }
|
|---|
| 512 | // Not reached
|
|---|
| 513 | }
|
|---|
| 514 |
|
|---|
| 515 | // Decode a single Huffman block from f.
|
|---|
| 516 | // hl and hd are the Huffman states for the lit/length values
|
|---|
| 517 | // and the distance values, respectively. If hd == nil, using the
|
|---|
| 518 | // fixed distance encoding associated with fixed Huffman blocks.
|
|---|
| 519 | func (f *decompressor) huffmanBufioReader() {
|
|---|
| 520 | const (
|
|---|
| 521 | stateInit = iota // Zero value must be stateInit
|
|---|
| 522 | stateDict
|
|---|
| 523 | )
|
|---|
| 524 | fr := f.r.(*bufio.Reader)
|
|---|
| 525 |
|
|---|
| 526 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 527 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 528 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 529 | fnb, fb := f.nb, f.b
|
|---|
| 530 |
|
|---|
| 531 | switch f.stepState {
|
|---|
| 532 | case stateInit:
|
|---|
| 533 | goto readLiteral
|
|---|
| 534 | case stateDict:
|
|---|
| 535 | goto copyHistory
|
|---|
| 536 | }
|
|---|
| 537 |
|
|---|
| 538 | readLiteral:
|
|---|
| 539 | // Read literal and/or (length, distance) according to RFC section 3.2.3.
|
|---|
| 540 | {
|
|---|
| 541 | var v int
|
|---|
| 542 | {
|
|---|
| 543 | // Inlined v, err := f.huffSym(f.hl)
|
|---|
| 544 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 545 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 546 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 547 | // satisfy the n == 0 check below.
|
|---|
| 548 | n := uint(f.hl.maxRead)
|
|---|
| 549 | for {
|
|---|
| 550 | for fnb < n {
|
|---|
| 551 | c, err := fr.ReadByte()
|
|---|
| 552 | if err != nil {
|
|---|
| 553 | f.b, f.nb = fb, fnb
|
|---|
| 554 | f.err = noEOF(err)
|
|---|
| 555 | return
|
|---|
| 556 | }
|
|---|
| 557 | f.roffset++
|
|---|
| 558 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 559 | fnb += 8
|
|---|
| 560 | }
|
|---|
| 561 | chunk := f.hl.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 562 | n = uint(chunk & huffmanCountMask)
|
|---|
| 563 | if n > huffmanChunkBits {
|
|---|
| 564 | chunk = f.hl.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hl.linkMask]
|
|---|
| 565 | n = uint(chunk & huffmanCountMask)
|
|---|
| 566 | }
|
|---|
| 567 | if n <= fnb {
|
|---|
| 568 | if n == 0 {
|
|---|
| 569 | f.b, f.nb = fb, fnb
|
|---|
| 570 | if debugDecode {
|
|---|
| 571 | fmt.Println("huffsym: n==0")
|
|---|
| 572 | }
|
|---|
| 573 | f.err = CorruptInputError(f.roffset)
|
|---|
| 574 | return
|
|---|
| 575 | }
|
|---|
| 576 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 577 | fnb = fnb - n
|
|---|
| 578 | v = int(chunk >> huffmanValueShift)
|
|---|
| 579 | break
|
|---|
| 580 | }
|
|---|
| 581 | }
|
|---|
| 582 | }
|
|---|
| 583 |
|
|---|
| 584 | var length int
|
|---|
| 585 | switch {
|
|---|
| 586 | case v < 256:
|
|---|
| 587 | f.dict.writeByte(byte(v))
|
|---|
| 588 | if f.dict.availWrite() == 0 {
|
|---|
| 589 | f.toRead = f.dict.readFlush()
|
|---|
| 590 | f.step = (*decompressor).huffmanBufioReader
|
|---|
| 591 | f.stepState = stateInit
|
|---|
| 592 | f.b, f.nb = fb, fnb
|
|---|
| 593 | return
|
|---|
| 594 | }
|
|---|
| 595 | goto readLiteral
|
|---|
| 596 | case v == 256:
|
|---|
| 597 | f.b, f.nb = fb, fnb
|
|---|
| 598 | f.finishBlock()
|
|---|
| 599 | return
|
|---|
| 600 | // otherwise, reference to older data
|
|---|
| 601 | case v < 265:
|
|---|
| 602 | length = v - (257 - 3)
|
|---|
| 603 | case v < maxNumLit:
|
|---|
| 604 | val := decCodeToLen[(v - 257)]
|
|---|
| 605 | length = int(val.length) + 3
|
|---|
| 606 | n := uint(val.extra)
|
|---|
| 607 | for fnb < n {
|
|---|
| 608 | c, err := fr.ReadByte()
|
|---|
| 609 | if err != nil {
|
|---|
| 610 | f.b, f.nb = fb, fnb
|
|---|
| 611 | if debugDecode {
|
|---|
| 612 | fmt.Println("morebits n>0:", err)
|
|---|
| 613 | }
|
|---|
| 614 | f.err = err
|
|---|
| 615 | return
|
|---|
| 616 | }
|
|---|
| 617 | f.roffset++
|
|---|
| 618 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 619 | fnb += 8
|
|---|
| 620 | }
|
|---|
| 621 | length += int(fb & bitMask32[n])
|
|---|
| 622 | fb >>= n & regSizeMaskUint32
|
|---|
| 623 | fnb -= n
|
|---|
| 624 | default:
|
|---|
| 625 | if debugDecode {
|
|---|
| 626 | fmt.Println(v, ">= maxNumLit")
|
|---|
| 627 | }
|
|---|
| 628 | f.err = CorruptInputError(f.roffset)
|
|---|
| 629 | f.b, f.nb = fb, fnb
|
|---|
| 630 | return
|
|---|
| 631 | }
|
|---|
| 632 |
|
|---|
| 633 | var dist uint32
|
|---|
| 634 | if f.hd == nil {
|
|---|
| 635 | for fnb < 5 {
|
|---|
| 636 | c, err := fr.ReadByte()
|
|---|
| 637 | if err != nil {
|
|---|
| 638 | f.b, f.nb = fb, fnb
|
|---|
| 639 | if debugDecode {
|
|---|
| 640 | fmt.Println("morebits f.nb<5:", err)
|
|---|
| 641 | }
|
|---|
| 642 | f.err = err
|
|---|
| 643 | return
|
|---|
| 644 | }
|
|---|
| 645 | f.roffset++
|
|---|
| 646 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 647 | fnb += 8
|
|---|
| 648 | }
|
|---|
| 649 | dist = uint32(bits.Reverse8(uint8(fb & 0x1F << 3)))
|
|---|
| 650 | fb >>= 5
|
|---|
| 651 | fnb -= 5
|
|---|
| 652 | } else {
|
|---|
| 653 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 654 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 655 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 656 | // satisfy the n == 0 check below.
|
|---|
| 657 | n := uint(f.hd.maxRead)
|
|---|
| 658 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 659 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 660 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 661 | for {
|
|---|
| 662 | for fnb < n {
|
|---|
| 663 | c, err := fr.ReadByte()
|
|---|
| 664 | if err != nil {
|
|---|
| 665 | f.b, f.nb = fb, fnb
|
|---|
| 666 | f.err = noEOF(err)
|
|---|
| 667 | return
|
|---|
| 668 | }
|
|---|
| 669 | f.roffset++
|
|---|
| 670 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 671 | fnb += 8
|
|---|
| 672 | }
|
|---|
| 673 | chunk := f.hd.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 674 | n = uint(chunk & huffmanCountMask)
|
|---|
| 675 | if n > huffmanChunkBits {
|
|---|
| 676 | chunk = f.hd.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hd.linkMask]
|
|---|
| 677 | n = uint(chunk & huffmanCountMask)
|
|---|
| 678 | }
|
|---|
| 679 | if n <= fnb {
|
|---|
| 680 | if n == 0 {
|
|---|
| 681 | f.b, f.nb = fb, fnb
|
|---|
| 682 | if debugDecode {
|
|---|
| 683 | fmt.Println("huffsym: n==0")
|
|---|
| 684 | }
|
|---|
| 685 | f.err = CorruptInputError(f.roffset)
|
|---|
| 686 | return
|
|---|
| 687 | }
|
|---|
| 688 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 689 | fnb = fnb - n
|
|---|
| 690 | dist = uint32(chunk >> huffmanValueShift)
|
|---|
| 691 | break
|
|---|
| 692 | }
|
|---|
| 693 | }
|
|---|
| 694 | }
|
|---|
| 695 |
|
|---|
| 696 | switch {
|
|---|
| 697 | case dist < 4:
|
|---|
| 698 | dist++
|
|---|
| 699 | case dist < maxNumDist:
|
|---|
| 700 | nb := uint(dist-2) >> 1
|
|---|
| 701 | // have 1 bit in bottom of dist, need nb more.
|
|---|
| 702 | extra := (dist & 1) << (nb & regSizeMaskUint32)
|
|---|
| 703 | for fnb < nb {
|
|---|
| 704 | c, err := fr.ReadByte()
|
|---|
| 705 | if err != nil {
|
|---|
| 706 | f.b, f.nb = fb, fnb
|
|---|
| 707 | if debugDecode {
|
|---|
| 708 | fmt.Println("morebits f.nb<nb:", err)
|
|---|
| 709 | }
|
|---|
| 710 | f.err = err
|
|---|
| 711 | return
|
|---|
| 712 | }
|
|---|
| 713 | f.roffset++
|
|---|
| 714 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 715 | fnb += 8
|
|---|
| 716 | }
|
|---|
| 717 | extra |= fb & bitMask32[nb]
|
|---|
| 718 | fb >>= nb & regSizeMaskUint32
|
|---|
| 719 | fnb -= nb
|
|---|
| 720 | dist = 1<<((nb+1)®SizeMaskUint32) + 1 + extra
|
|---|
| 721 | // slower: dist = bitMask32[nb+1] + 2 + extra
|
|---|
| 722 | default:
|
|---|
| 723 | f.b, f.nb = fb, fnb
|
|---|
| 724 | if debugDecode {
|
|---|
| 725 | fmt.Println("dist too big:", dist, maxNumDist)
|
|---|
| 726 | }
|
|---|
| 727 | f.err = CorruptInputError(f.roffset)
|
|---|
| 728 | return
|
|---|
| 729 | }
|
|---|
| 730 |
|
|---|
| 731 | // No check on length; encoding can be prescient.
|
|---|
| 732 | if dist > uint32(f.dict.histSize()) {
|
|---|
| 733 | f.b, f.nb = fb, fnb
|
|---|
| 734 | if debugDecode {
|
|---|
| 735 | fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
|
|---|
| 736 | }
|
|---|
| 737 | f.err = CorruptInputError(f.roffset)
|
|---|
| 738 | return
|
|---|
| 739 | }
|
|---|
| 740 |
|
|---|
| 741 | f.copyLen, f.copyDist = length, int(dist)
|
|---|
| 742 | goto copyHistory
|
|---|
| 743 | }
|
|---|
| 744 |
|
|---|
| 745 | copyHistory:
|
|---|
| 746 | // Perform a backwards copy according to RFC section 3.2.3.
|
|---|
| 747 | {
|
|---|
| 748 | cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
|
|---|
| 749 | if cnt == 0 {
|
|---|
| 750 | cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
|
|---|
| 751 | }
|
|---|
| 752 | f.copyLen -= cnt
|
|---|
| 753 |
|
|---|
| 754 | if f.dict.availWrite() == 0 || f.copyLen > 0 {
|
|---|
| 755 | f.toRead = f.dict.readFlush()
|
|---|
| 756 | f.step = (*decompressor).huffmanBufioReader // We need to continue this work
|
|---|
| 757 | f.stepState = stateDict
|
|---|
| 758 | f.b, f.nb = fb, fnb
|
|---|
| 759 | return
|
|---|
| 760 | }
|
|---|
| 761 | goto readLiteral
|
|---|
| 762 | }
|
|---|
| 763 | // Not reached
|
|---|
| 764 | }
|
|---|
| 765 |
|
|---|
| 766 | // Decode a single Huffman block from f.
|
|---|
| 767 | // hl and hd are the Huffman states for the lit/length values
|
|---|
| 768 | // and the distance values, respectively. If hd == nil, using the
|
|---|
| 769 | // fixed distance encoding associated with fixed Huffman blocks.
|
|---|
| 770 | func (f *decompressor) huffmanStringsReader() {
|
|---|
| 771 | const (
|
|---|
| 772 | stateInit = iota // Zero value must be stateInit
|
|---|
| 773 | stateDict
|
|---|
| 774 | )
|
|---|
| 775 | fr := f.r.(*strings.Reader)
|
|---|
| 776 |
|
|---|
| 777 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 778 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 779 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 780 | fnb, fb := f.nb, f.b
|
|---|
| 781 |
|
|---|
| 782 | switch f.stepState {
|
|---|
| 783 | case stateInit:
|
|---|
| 784 | goto readLiteral
|
|---|
| 785 | case stateDict:
|
|---|
| 786 | goto copyHistory
|
|---|
| 787 | }
|
|---|
| 788 |
|
|---|
| 789 | readLiteral:
|
|---|
| 790 | // Read literal and/or (length, distance) according to RFC section 3.2.3.
|
|---|
| 791 | {
|
|---|
| 792 | var v int
|
|---|
| 793 | {
|
|---|
| 794 | // Inlined v, err := f.huffSym(f.hl)
|
|---|
| 795 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 796 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 797 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 798 | // satisfy the n == 0 check below.
|
|---|
| 799 | n := uint(f.hl.maxRead)
|
|---|
| 800 | for {
|
|---|
| 801 | for fnb < n {
|
|---|
| 802 | c, err := fr.ReadByte()
|
|---|
| 803 | if err != nil {
|
|---|
| 804 | f.b, f.nb = fb, fnb
|
|---|
| 805 | f.err = noEOF(err)
|
|---|
| 806 | return
|
|---|
| 807 | }
|
|---|
| 808 | f.roffset++
|
|---|
| 809 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 810 | fnb += 8
|
|---|
| 811 | }
|
|---|
| 812 | chunk := f.hl.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 813 | n = uint(chunk & huffmanCountMask)
|
|---|
| 814 | if n > huffmanChunkBits {
|
|---|
| 815 | chunk = f.hl.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hl.linkMask]
|
|---|
| 816 | n = uint(chunk & huffmanCountMask)
|
|---|
| 817 | }
|
|---|
| 818 | if n <= fnb {
|
|---|
| 819 | if n == 0 {
|
|---|
| 820 | f.b, f.nb = fb, fnb
|
|---|
| 821 | if debugDecode {
|
|---|
| 822 | fmt.Println("huffsym: n==0")
|
|---|
| 823 | }
|
|---|
| 824 | f.err = CorruptInputError(f.roffset)
|
|---|
| 825 | return
|
|---|
| 826 | }
|
|---|
| 827 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 828 | fnb = fnb - n
|
|---|
| 829 | v = int(chunk >> huffmanValueShift)
|
|---|
| 830 | break
|
|---|
| 831 | }
|
|---|
| 832 | }
|
|---|
| 833 | }
|
|---|
| 834 |
|
|---|
| 835 | var length int
|
|---|
| 836 | switch {
|
|---|
| 837 | case v < 256:
|
|---|
| 838 | f.dict.writeByte(byte(v))
|
|---|
| 839 | if f.dict.availWrite() == 0 {
|
|---|
| 840 | f.toRead = f.dict.readFlush()
|
|---|
| 841 | f.step = (*decompressor).huffmanStringsReader
|
|---|
| 842 | f.stepState = stateInit
|
|---|
| 843 | f.b, f.nb = fb, fnb
|
|---|
| 844 | return
|
|---|
| 845 | }
|
|---|
| 846 | goto readLiteral
|
|---|
| 847 | case v == 256:
|
|---|
| 848 | f.b, f.nb = fb, fnb
|
|---|
| 849 | f.finishBlock()
|
|---|
| 850 | return
|
|---|
| 851 | // otherwise, reference to older data
|
|---|
| 852 | case v < 265:
|
|---|
| 853 | length = v - (257 - 3)
|
|---|
| 854 | case v < maxNumLit:
|
|---|
| 855 | val := decCodeToLen[(v - 257)]
|
|---|
| 856 | length = int(val.length) + 3
|
|---|
| 857 | n := uint(val.extra)
|
|---|
| 858 | for fnb < n {
|
|---|
| 859 | c, err := fr.ReadByte()
|
|---|
| 860 | if err != nil {
|
|---|
| 861 | f.b, f.nb = fb, fnb
|
|---|
| 862 | if debugDecode {
|
|---|
| 863 | fmt.Println("morebits n>0:", err)
|
|---|
| 864 | }
|
|---|
| 865 | f.err = err
|
|---|
| 866 | return
|
|---|
| 867 | }
|
|---|
| 868 | f.roffset++
|
|---|
| 869 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 870 | fnb += 8
|
|---|
| 871 | }
|
|---|
| 872 | length += int(fb & bitMask32[n])
|
|---|
| 873 | fb >>= n & regSizeMaskUint32
|
|---|
| 874 | fnb -= n
|
|---|
| 875 | default:
|
|---|
| 876 | if debugDecode {
|
|---|
| 877 | fmt.Println(v, ">= maxNumLit")
|
|---|
| 878 | }
|
|---|
| 879 | f.err = CorruptInputError(f.roffset)
|
|---|
| 880 | f.b, f.nb = fb, fnb
|
|---|
| 881 | return
|
|---|
| 882 | }
|
|---|
| 883 |
|
|---|
| 884 | var dist uint32
|
|---|
| 885 | if f.hd == nil {
|
|---|
| 886 | for fnb < 5 {
|
|---|
| 887 | c, err := fr.ReadByte()
|
|---|
| 888 | if err != nil {
|
|---|
| 889 | f.b, f.nb = fb, fnb
|
|---|
| 890 | if debugDecode {
|
|---|
| 891 | fmt.Println("morebits f.nb<5:", err)
|
|---|
| 892 | }
|
|---|
| 893 | f.err = err
|
|---|
| 894 | return
|
|---|
| 895 | }
|
|---|
| 896 | f.roffset++
|
|---|
| 897 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 898 | fnb += 8
|
|---|
| 899 | }
|
|---|
| 900 | dist = uint32(bits.Reverse8(uint8(fb & 0x1F << 3)))
|
|---|
| 901 | fb >>= 5
|
|---|
| 902 | fnb -= 5
|
|---|
| 903 | } else {
|
|---|
| 904 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 905 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 906 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 907 | // satisfy the n == 0 check below.
|
|---|
| 908 | n := uint(f.hd.maxRead)
|
|---|
| 909 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 910 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 911 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 912 | for {
|
|---|
| 913 | for fnb < n {
|
|---|
| 914 | c, err := fr.ReadByte()
|
|---|
| 915 | if err != nil {
|
|---|
| 916 | f.b, f.nb = fb, fnb
|
|---|
| 917 | f.err = noEOF(err)
|
|---|
| 918 | return
|
|---|
| 919 | }
|
|---|
| 920 | f.roffset++
|
|---|
| 921 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 922 | fnb += 8
|
|---|
| 923 | }
|
|---|
| 924 | chunk := f.hd.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 925 | n = uint(chunk & huffmanCountMask)
|
|---|
| 926 | if n > huffmanChunkBits {
|
|---|
| 927 | chunk = f.hd.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hd.linkMask]
|
|---|
| 928 | n = uint(chunk & huffmanCountMask)
|
|---|
| 929 | }
|
|---|
| 930 | if n <= fnb {
|
|---|
| 931 | if n == 0 {
|
|---|
| 932 | f.b, f.nb = fb, fnb
|
|---|
| 933 | if debugDecode {
|
|---|
| 934 | fmt.Println("huffsym: n==0")
|
|---|
| 935 | }
|
|---|
| 936 | f.err = CorruptInputError(f.roffset)
|
|---|
| 937 | return
|
|---|
| 938 | }
|
|---|
| 939 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 940 | fnb = fnb - n
|
|---|
| 941 | dist = uint32(chunk >> huffmanValueShift)
|
|---|
| 942 | break
|
|---|
| 943 | }
|
|---|
| 944 | }
|
|---|
| 945 | }
|
|---|
| 946 |
|
|---|
| 947 | switch {
|
|---|
| 948 | case dist < 4:
|
|---|
| 949 | dist++
|
|---|
| 950 | case dist < maxNumDist:
|
|---|
| 951 | nb := uint(dist-2) >> 1
|
|---|
| 952 | // have 1 bit in bottom of dist, need nb more.
|
|---|
| 953 | extra := (dist & 1) << (nb & regSizeMaskUint32)
|
|---|
| 954 | for fnb < nb {
|
|---|
| 955 | c, err := fr.ReadByte()
|
|---|
| 956 | if err != nil {
|
|---|
| 957 | f.b, f.nb = fb, fnb
|
|---|
| 958 | if debugDecode {
|
|---|
| 959 | fmt.Println("morebits f.nb<nb:", err)
|
|---|
| 960 | }
|
|---|
| 961 | f.err = err
|
|---|
| 962 | return
|
|---|
| 963 | }
|
|---|
| 964 | f.roffset++
|
|---|
| 965 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 966 | fnb += 8
|
|---|
| 967 | }
|
|---|
| 968 | extra |= fb & bitMask32[nb]
|
|---|
| 969 | fb >>= nb & regSizeMaskUint32
|
|---|
| 970 | fnb -= nb
|
|---|
| 971 | dist = 1<<((nb+1)®SizeMaskUint32) + 1 + extra
|
|---|
| 972 | // slower: dist = bitMask32[nb+1] + 2 + extra
|
|---|
| 973 | default:
|
|---|
| 974 | f.b, f.nb = fb, fnb
|
|---|
| 975 | if debugDecode {
|
|---|
| 976 | fmt.Println("dist too big:", dist, maxNumDist)
|
|---|
| 977 | }
|
|---|
| 978 | f.err = CorruptInputError(f.roffset)
|
|---|
| 979 | return
|
|---|
| 980 | }
|
|---|
| 981 |
|
|---|
| 982 | // No check on length; encoding can be prescient.
|
|---|
| 983 | if dist > uint32(f.dict.histSize()) {
|
|---|
| 984 | f.b, f.nb = fb, fnb
|
|---|
| 985 | if debugDecode {
|
|---|
| 986 | fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
|
|---|
| 987 | }
|
|---|
| 988 | f.err = CorruptInputError(f.roffset)
|
|---|
| 989 | return
|
|---|
| 990 | }
|
|---|
| 991 |
|
|---|
| 992 | f.copyLen, f.copyDist = length, int(dist)
|
|---|
| 993 | goto copyHistory
|
|---|
| 994 | }
|
|---|
| 995 |
|
|---|
| 996 | copyHistory:
|
|---|
| 997 | // Perform a backwards copy according to RFC section 3.2.3.
|
|---|
| 998 | {
|
|---|
| 999 | cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
|
|---|
| 1000 | if cnt == 0 {
|
|---|
| 1001 | cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
|
|---|
| 1002 | }
|
|---|
| 1003 | f.copyLen -= cnt
|
|---|
| 1004 |
|
|---|
| 1005 | if f.dict.availWrite() == 0 || f.copyLen > 0 {
|
|---|
| 1006 | f.toRead = f.dict.readFlush()
|
|---|
| 1007 | f.step = (*decompressor).huffmanStringsReader // We need to continue this work
|
|---|
| 1008 | f.stepState = stateDict
|
|---|
| 1009 | f.b, f.nb = fb, fnb
|
|---|
| 1010 | return
|
|---|
| 1011 | }
|
|---|
| 1012 | goto readLiteral
|
|---|
| 1013 | }
|
|---|
| 1014 | // Not reached
|
|---|
| 1015 | }
|
|---|
| 1016 |
|
|---|
| 1017 | // Decode a single Huffman block from f.
|
|---|
| 1018 | // hl and hd are the Huffman states for the lit/length values
|
|---|
| 1019 | // and the distance values, respectively. If hd == nil, using the
|
|---|
| 1020 | // fixed distance encoding associated with fixed Huffman blocks.
|
|---|
| 1021 | func (f *decompressor) huffmanGenericReader() {
|
|---|
| 1022 | const (
|
|---|
| 1023 | stateInit = iota // Zero value must be stateInit
|
|---|
| 1024 | stateDict
|
|---|
| 1025 | )
|
|---|
| 1026 | fr := f.r.(Reader)
|
|---|
| 1027 |
|
|---|
| 1028 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 1029 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 1030 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 1031 | fnb, fb := f.nb, f.b
|
|---|
| 1032 |
|
|---|
| 1033 | switch f.stepState {
|
|---|
| 1034 | case stateInit:
|
|---|
| 1035 | goto readLiteral
|
|---|
| 1036 | case stateDict:
|
|---|
| 1037 | goto copyHistory
|
|---|
| 1038 | }
|
|---|
| 1039 |
|
|---|
| 1040 | readLiteral:
|
|---|
| 1041 | // Read literal and/or (length, distance) according to RFC section 3.2.3.
|
|---|
| 1042 | {
|
|---|
| 1043 | var v int
|
|---|
| 1044 | {
|
|---|
| 1045 | // Inlined v, err := f.huffSym(f.hl)
|
|---|
| 1046 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 1047 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 1048 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 1049 | // satisfy the n == 0 check below.
|
|---|
| 1050 | n := uint(f.hl.maxRead)
|
|---|
| 1051 | for {
|
|---|
| 1052 | for fnb < n {
|
|---|
| 1053 | c, err := fr.ReadByte()
|
|---|
| 1054 | if err != nil {
|
|---|
| 1055 | f.b, f.nb = fb, fnb
|
|---|
| 1056 | f.err = noEOF(err)
|
|---|
| 1057 | return
|
|---|
| 1058 | }
|
|---|
| 1059 | f.roffset++
|
|---|
| 1060 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 1061 | fnb += 8
|
|---|
| 1062 | }
|
|---|
| 1063 | chunk := f.hl.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 1064 | n = uint(chunk & huffmanCountMask)
|
|---|
| 1065 | if n > huffmanChunkBits {
|
|---|
| 1066 | chunk = f.hl.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hl.linkMask]
|
|---|
| 1067 | n = uint(chunk & huffmanCountMask)
|
|---|
| 1068 | }
|
|---|
| 1069 | if n <= fnb {
|
|---|
| 1070 | if n == 0 {
|
|---|
| 1071 | f.b, f.nb = fb, fnb
|
|---|
| 1072 | if debugDecode {
|
|---|
| 1073 | fmt.Println("huffsym: n==0")
|
|---|
| 1074 | }
|
|---|
| 1075 | f.err = CorruptInputError(f.roffset)
|
|---|
| 1076 | return
|
|---|
| 1077 | }
|
|---|
| 1078 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 1079 | fnb = fnb - n
|
|---|
| 1080 | v = int(chunk >> huffmanValueShift)
|
|---|
| 1081 | break
|
|---|
| 1082 | }
|
|---|
| 1083 | }
|
|---|
| 1084 | }
|
|---|
| 1085 |
|
|---|
| 1086 | var length int
|
|---|
| 1087 | switch {
|
|---|
| 1088 | case v < 256:
|
|---|
| 1089 | f.dict.writeByte(byte(v))
|
|---|
| 1090 | if f.dict.availWrite() == 0 {
|
|---|
| 1091 | f.toRead = f.dict.readFlush()
|
|---|
| 1092 | f.step = (*decompressor).huffmanGenericReader
|
|---|
| 1093 | f.stepState = stateInit
|
|---|
| 1094 | f.b, f.nb = fb, fnb
|
|---|
| 1095 | return
|
|---|
| 1096 | }
|
|---|
| 1097 | goto readLiteral
|
|---|
| 1098 | case v == 256:
|
|---|
| 1099 | f.b, f.nb = fb, fnb
|
|---|
| 1100 | f.finishBlock()
|
|---|
| 1101 | return
|
|---|
| 1102 | // otherwise, reference to older data
|
|---|
| 1103 | case v < 265:
|
|---|
| 1104 | length = v - (257 - 3)
|
|---|
| 1105 | case v < maxNumLit:
|
|---|
| 1106 | val := decCodeToLen[(v - 257)]
|
|---|
| 1107 | length = int(val.length) + 3
|
|---|
| 1108 | n := uint(val.extra)
|
|---|
| 1109 | for fnb < n {
|
|---|
| 1110 | c, err := fr.ReadByte()
|
|---|
| 1111 | if err != nil {
|
|---|
| 1112 | f.b, f.nb = fb, fnb
|
|---|
| 1113 | if debugDecode {
|
|---|
| 1114 | fmt.Println("morebits n>0:", err)
|
|---|
| 1115 | }
|
|---|
| 1116 | f.err = err
|
|---|
| 1117 | return
|
|---|
| 1118 | }
|
|---|
| 1119 | f.roffset++
|
|---|
| 1120 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 1121 | fnb += 8
|
|---|
| 1122 | }
|
|---|
| 1123 | length += int(fb & bitMask32[n])
|
|---|
| 1124 | fb >>= n & regSizeMaskUint32
|
|---|
| 1125 | fnb -= n
|
|---|
| 1126 | default:
|
|---|
| 1127 | if debugDecode {
|
|---|
| 1128 | fmt.Println(v, ">= maxNumLit")
|
|---|
| 1129 | }
|
|---|
| 1130 | f.err = CorruptInputError(f.roffset)
|
|---|
| 1131 | f.b, f.nb = fb, fnb
|
|---|
| 1132 | return
|
|---|
| 1133 | }
|
|---|
| 1134 |
|
|---|
| 1135 | var dist uint32
|
|---|
| 1136 | if f.hd == nil {
|
|---|
| 1137 | for fnb < 5 {
|
|---|
| 1138 | c, err := fr.ReadByte()
|
|---|
| 1139 | if err != nil {
|
|---|
| 1140 | f.b, f.nb = fb, fnb
|
|---|
| 1141 | if debugDecode {
|
|---|
| 1142 | fmt.Println("morebits f.nb<5:", err)
|
|---|
| 1143 | }
|
|---|
| 1144 | f.err = err
|
|---|
| 1145 | return
|
|---|
| 1146 | }
|
|---|
| 1147 | f.roffset++
|
|---|
| 1148 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 1149 | fnb += 8
|
|---|
| 1150 | }
|
|---|
| 1151 | dist = uint32(bits.Reverse8(uint8(fb & 0x1F << 3)))
|
|---|
| 1152 | fb >>= 5
|
|---|
| 1153 | fnb -= 5
|
|---|
| 1154 | } else {
|
|---|
| 1155 | // Since a huffmanDecoder can be empty or be composed of a degenerate tree
|
|---|
| 1156 | // with single element, huffSym must error on these two edge cases. In both
|
|---|
| 1157 | // cases, the chunks slice will be 0 for the invalid sequence, leading it
|
|---|
| 1158 | // satisfy the n == 0 check below.
|
|---|
| 1159 | n := uint(f.hd.maxRead)
|
|---|
| 1160 | // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
|
|---|
| 1161 | // but is smart enough to keep local variables in registers, so use nb and b,
|
|---|
| 1162 | // inline call to moreBits and reassign b,nb back to f on return.
|
|---|
| 1163 | for {
|
|---|
| 1164 | for fnb < n {
|
|---|
| 1165 | c, err := fr.ReadByte()
|
|---|
| 1166 | if err != nil {
|
|---|
| 1167 | f.b, f.nb = fb, fnb
|
|---|
| 1168 | f.err = noEOF(err)
|
|---|
| 1169 | return
|
|---|
| 1170 | }
|
|---|
| 1171 | f.roffset++
|
|---|
| 1172 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 1173 | fnb += 8
|
|---|
| 1174 | }
|
|---|
| 1175 | chunk := f.hd.chunks[fb&(huffmanNumChunks-1)]
|
|---|
| 1176 | n = uint(chunk & huffmanCountMask)
|
|---|
| 1177 | if n > huffmanChunkBits {
|
|---|
| 1178 | chunk = f.hd.links[chunk>>huffmanValueShift][(fb>>huffmanChunkBits)&f.hd.linkMask]
|
|---|
| 1179 | n = uint(chunk & huffmanCountMask)
|
|---|
| 1180 | }
|
|---|
| 1181 | if n <= fnb {
|
|---|
| 1182 | if n == 0 {
|
|---|
| 1183 | f.b, f.nb = fb, fnb
|
|---|
| 1184 | if debugDecode {
|
|---|
| 1185 | fmt.Println("huffsym: n==0")
|
|---|
| 1186 | }
|
|---|
| 1187 | f.err = CorruptInputError(f.roffset)
|
|---|
| 1188 | return
|
|---|
| 1189 | }
|
|---|
| 1190 | fb = fb >> (n & regSizeMaskUint32)
|
|---|
| 1191 | fnb = fnb - n
|
|---|
| 1192 | dist = uint32(chunk >> huffmanValueShift)
|
|---|
| 1193 | break
|
|---|
| 1194 | }
|
|---|
| 1195 | }
|
|---|
| 1196 | }
|
|---|
| 1197 |
|
|---|
| 1198 | switch {
|
|---|
| 1199 | case dist < 4:
|
|---|
| 1200 | dist++
|
|---|
| 1201 | case dist < maxNumDist:
|
|---|
| 1202 | nb := uint(dist-2) >> 1
|
|---|
| 1203 | // have 1 bit in bottom of dist, need nb more.
|
|---|
| 1204 | extra := (dist & 1) << (nb & regSizeMaskUint32)
|
|---|
| 1205 | for fnb < nb {
|
|---|
| 1206 | c, err := fr.ReadByte()
|
|---|
| 1207 | if err != nil {
|
|---|
| 1208 | f.b, f.nb = fb, fnb
|
|---|
| 1209 | if debugDecode {
|
|---|
| 1210 | fmt.Println("morebits f.nb<nb:", err)
|
|---|
| 1211 | }
|
|---|
| 1212 | f.err = err
|
|---|
| 1213 | return
|
|---|
| 1214 | }
|
|---|
| 1215 | f.roffset++
|
|---|
| 1216 | fb |= uint32(c) << (fnb & regSizeMaskUint32)
|
|---|
| 1217 | fnb += 8
|
|---|
| 1218 | }
|
|---|
| 1219 | extra |= fb & bitMask32[nb]
|
|---|
| 1220 | fb >>= nb & regSizeMaskUint32
|
|---|
| 1221 | fnb -= nb
|
|---|
| 1222 | dist = 1<<((nb+1)®SizeMaskUint32) + 1 + extra
|
|---|
| 1223 | // slower: dist = bitMask32[nb+1] + 2 + extra
|
|---|
| 1224 | default:
|
|---|
| 1225 | f.b, f.nb = fb, fnb
|
|---|
| 1226 | if debugDecode {
|
|---|
| 1227 | fmt.Println("dist too big:", dist, maxNumDist)
|
|---|
| 1228 | }
|
|---|
| 1229 | f.err = CorruptInputError(f.roffset)
|
|---|
| 1230 | return
|
|---|
| 1231 | }
|
|---|
| 1232 |
|
|---|
| 1233 | // No check on length; encoding can be prescient.
|
|---|
| 1234 | if dist > uint32(f.dict.histSize()) {
|
|---|
| 1235 | f.b, f.nb = fb, fnb
|
|---|
| 1236 | if debugDecode {
|
|---|
| 1237 | fmt.Println("dist > f.dict.histSize():", dist, f.dict.histSize())
|
|---|
| 1238 | }
|
|---|
| 1239 | f.err = CorruptInputError(f.roffset)
|
|---|
| 1240 | return
|
|---|
| 1241 | }
|
|---|
| 1242 |
|
|---|
| 1243 | f.copyLen, f.copyDist = length, int(dist)
|
|---|
| 1244 | goto copyHistory
|
|---|
| 1245 | }
|
|---|
| 1246 |
|
|---|
| 1247 | copyHistory:
|
|---|
| 1248 | // Perform a backwards copy according to RFC section 3.2.3.
|
|---|
| 1249 | {
|
|---|
| 1250 | cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
|
|---|
| 1251 | if cnt == 0 {
|
|---|
| 1252 | cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
|
|---|
| 1253 | }
|
|---|
| 1254 | f.copyLen -= cnt
|
|---|
| 1255 |
|
|---|
| 1256 | if f.dict.availWrite() == 0 || f.copyLen > 0 {
|
|---|
| 1257 | f.toRead = f.dict.readFlush()
|
|---|
| 1258 | f.step = (*decompressor).huffmanGenericReader // We need to continue this work
|
|---|
| 1259 | f.stepState = stateDict
|
|---|
| 1260 | f.b, f.nb = fb, fnb
|
|---|
| 1261 | return
|
|---|
| 1262 | }
|
|---|
| 1263 | goto readLiteral
|
|---|
| 1264 | }
|
|---|
| 1265 | // Not reached
|
|---|
| 1266 | }
|
|---|
| 1267 |
|
|---|
| 1268 | func (f *decompressor) huffmanBlockDecoder() func() {
|
|---|
| 1269 | switch f.r.(type) {
|
|---|
| 1270 | case *bytes.Buffer:
|
|---|
| 1271 | return f.huffmanBytesBuffer
|
|---|
| 1272 | case *bytes.Reader:
|
|---|
| 1273 | return f.huffmanBytesReader
|
|---|
| 1274 | case *bufio.Reader:
|
|---|
| 1275 | return f.huffmanBufioReader
|
|---|
| 1276 | case *strings.Reader:
|
|---|
| 1277 | return f.huffmanStringsReader
|
|---|
| 1278 | case Reader:
|
|---|
| 1279 | return f.huffmanGenericReader
|
|---|
| 1280 | default:
|
|---|
| 1281 | return f.huffmanGenericReader
|
|---|
| 1282 | }
|
|---|
| 1283 | }
|
|---|
