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package rardecode
import (
"io"
)
const audioSize = 257
type decoder20 struct {
br *rarBitReader
size int64 // unpacked bytes left to be decompressed
hdrRead bool // block header has been read
isAudio bool // current block is Audio
codeLength [audioSize * 4]byte
lz *lz20Decoder
audio *audio20Decoder
}
func (d *decoder20) version() int { return decode20Ver }
// init intializes the decoder for decoding a new file.
func (d *decoder20) init(r byteReader, reset bool, size int64, ver int) {
if d.br == nil {
d.br = newRarBitReader(r)
} else {
d.br.reset(r)
}
d.size = size
if reset {
d.hdrRead = false
d.isAudio = false
if d.audio != nil {
d.audio.reset()
}
clear(d.codeLength[:])
}
}
func readCodeLengthTable20(br *rarBitReader, table []byte) error {
var bitlength [19]byte
for i := 0; i < len(bitlength); i++ {
n, err := br.readBits(4)
if err != nil {
return err
}
bitlength[i] = byte(n)
}
var bl huffmanDecoder
bl.init(bitlength[:])
for i := 0; i < len(table); {
l, err := bl.readSym(br)
if err != nil {
return err
}
if l < 16 {
table[i] = (table[i] + byte(l)) & 0xf
i++
continue
}
if l == 16 {
if i == 0 {
return ErrInvalidLengthTable
}
var n int
n, err = br.readBits(2)
if err != nil {
return err
}
n += 3
n = min(i+n, len(table))
v := table[i-1]
for i < n {
table[i] = v
i++
}
continue
}
var n int
if l == 17 {
n, err = br.readBits(3)
if err != nil {
return err
}
n += 3
} else {
n, err = br.readBits(7)
if err != nil {
return err
}
n += 11
}
n = min(i+n, len(table))
clear(table[i:n])
i = n
}
return nil
}
func (d *decoder20) readBlockHeader() error {
n, err := d.br.readBits(1)
if err != nil {
return err
}
d.isAudio = n > 0
n, err = d.br.readBits(1)
if err != nil {
return err
}
if n == 0 {
clear(d.codeLength[:])
}
if d.isAudio {
if d.audio == nil {
d.audio = new(audio20Decoder)
}
err = d.audio.init(d.br, d.codeLength[:])
} else {
if d.lz == nil {
d.lz = new(lz20Decoder)
}
err = d.lz.init(d.br, d.codeLength[:])
}
d.hdrRead = true
return err
}
func (d *decoder20) fill(dr *decodeReader) error {
for d.size > 0 && dr.notFull() {
if !d.hdrRead {
if err := d.readBlockHeader(); err != nil {
return err
}
}
var n int64
var err error
if d.isAudio {
n, err = d.audio.fill(dr, d.size)
} else {
n, err = d.lz.fill(dr, d.size)
}
d.size -= n
switch err {
case nil:
continue
case errEndOfBlock:
d.hdrRead = false
continue
case io.EOF:
err = ErrDecoderOutOfData
}
return err
}
if d.size == 0 {
return io.EOF
}
return nil
}
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