forked from gitea/gitea
133 lines
2.1 KiB
Go
133 lines
2.1 KiB
Go
package rardecode
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import "io"
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type ppm29Decoder struct {
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m model // ppm model
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esc byte // escape character
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br io.ByteReader
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}
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func (d *ppm29Decoder) init(br *rarBitReader) error {
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maxOrder, err := br.readBits(7)
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if err != nil {
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return err
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}
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reset := maxOrder&0x20 > 0
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// Should have flushed all unread bits from bitReader by now,
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// use underlying ByteReader
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d.br = br.r
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var maxMB int
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if reset {
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c, err := d.br.ReadByte()
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if err != nil {
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return err
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}
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maxMB = int(c) + 1
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}
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if maxOrder&0x40 > 0 {
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d.esc, err = d.br.ReadByte()
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if err != nil {
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return err
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}
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}
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maxOrder = (maxOrder & 0x1f) + 1
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if maxOrder > 16 {
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maxOrder = 16 + (maxOrder-16)*3
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}
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return d.m.init(d.br, reset, maxOrder, maxMB)
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}
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func (d *ppm29Decoder) reset() {
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d.esc = 2
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}
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func (d *ppm29Decoder) readFilterData() ([]byte, error) {
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c, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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n := int(c&7) + 1
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if n == 7 {
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b, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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n += int(b)
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} else if n == 8 {
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b, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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n = int(b) << 8
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b, err = d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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n |= int(b)
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}
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n++
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buf := make([]byte, n)
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buf[0] = byte(c)
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for i := 1; i < n; i++ {
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buf[i], err = d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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}
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return buf, nil
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}
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func (d *ppm29Decoder) decode(w *window) ([]byte, error) {
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c, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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if c != d.esc {
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w.writeByte(c)
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return nil, nil
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}
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c, err = d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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switch c {
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case 0:
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return nil, endOfBlock
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case 2:
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return nil, endOfBlockAndFile
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case 3:
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return d.readFilterData()
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case 4:
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offset := 0
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for i := 0; i < 3; i++ {
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c, err = d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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offset = offset<<8 | int(c)
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}
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len, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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w.copyBytes(int(len)+32, offset+2)
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case 5:
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len, err := d.m.ReadByte()
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if err != nil {
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return nil, err
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}
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w.copyBytes(int(len)+4, 1)
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default:
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w.writeByte(d.esc)
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}
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return nil, nil
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}
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