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684b7a999f
* Dump: Use mholt/archive/v3 to support tar including many compressions Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Dump: Allow dump output to stdout Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Dump: Fixed bug present since #6677 where SessionConfig.Provider is never "file" Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Dump: never pack RepoRootPath, LFS.ContentPath and LogRootPath when they are below AppDataPath Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Dump: also dump LFS (fixes #10058) Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Dump: never dump CustomPath if CustomPath is a subdir of or equal to AppDataPath (fixes #10365) Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * Use log.Info instead of fmt.Fprintf Signed-off-by: Philipp Homann <homann.philipp@googlemail.com> * import ordering * make fmt Co-authored-by: zeripath <art27@cantab.net> Co-authored-by: techknowlogick <techknowlogick@gitea.io> Co-authored-by: Matti R <matti@mdranta.net>
248 lines
5.5 KiB
Go
248 lines
5.5 KiB
Go
// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package lzma
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import (
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"errors"
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"io"
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)
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// rangeEncoder implements range encoding of single bits. The low value can
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// overflow therefore we need uint64. The cache value is used to handle
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// overflows.
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type rangeEncoder struct {
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lbw *LimitedByteWriter
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nrange uint32
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low uint64
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cacheLen int64
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cache byte
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}
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// maxInt64 provides the maximal value of the int64 type
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const maxInt64 = 1<<63 - 1
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// newRangeEncoder creates a new range encoder.
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func newRangeEncoder(bw io.ByteWriter) (re *rangeEncoder, err error) {
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lbw, ok := bw.(*LimitedByteWriter)
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if !ok {
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lbw = &LimitedByteWriter{BW: bw, N: maxInt64}
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}
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return &rangeEncoder{
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lbw: lbw,
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nrange: 0xffffffff,
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cacheLen: 1}, nil
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}
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// Available returns the number of bytes that still can be written. The
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// method takes the bytes that will be currently written by Close into
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// account.
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func (e *rangeEncoder) Available() int64 {
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return e.lbw.N - (e.cacheLen + 4)
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}
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// writeByte writes a single byte to the underlying writer. An error is
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// returned if the limit is reached. The written byte will be counted if
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// the underlying writer doesn't return an error.
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func (e *rangeEncoder) writeByte(c byte) error {
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if e.Available() < 1 {
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return ErrLimit
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}
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return e.lbw.WriteByte(c)
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}
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// DirectEncodeBit encodes the least-significant bit of b with probability 1/2.
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func (e *rangeEncoder) DirectEncodeBit(b uint32) error {
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e.nrange >>= 1
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e.low += uint64(e.nrange) & (0 - (uint64(b) & 1))
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// normalize
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const top = 1 << 24
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if e.nrange >= top {
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return nil
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}
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e.nrange <<= 8
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return e.shiftLow()
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}
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// EncodeBit encodes the least significant bit of b. The p value will be
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// updated by the function depending on the bit encoded.
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func (e *rangeEncoder) EncodeBit(b uint32, p *prob) error {
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bound := p.bound(e.nrange)
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if b&1 == 0 {
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e.nrange = bound
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p.inc()
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} else {
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e.low += uint64(bound)
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e.nrange -= bound
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p.dec()
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}
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// normalize
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const top = 1 << 24
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if e.nrange >= top {
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return nil
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}
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e.nrange <<= 8
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return e.shiftLow()
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}
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// Close writes a complete copy of the low value.
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func (e *rangeEncoder) Close() error {
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for i := 0; i < 5; i++ {
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if err := e.shiftLow(); err != nil {
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return err
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}
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}
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return nil
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}
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// shiftLow shifts the low value for 8 bit. The shifted byte is written into
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// the byte writer. The cache value is used to handle overflows.
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func (e *rangeEncoder) shiftLow() error {
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if uint32(e.low) < 0xff000000 || (e.low>>32) != 0 {
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tmp := e.cache
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for {
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err := e.writeByte(tmp + byte(e.low>>32))
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if err != nil {
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return err
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}
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tmp = 0xff
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e.cacheLen--
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if e.cacheLen <= 0 {
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if e.cacheLen < 0 {
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panic("negative cacheLen")
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}
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break
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}
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}
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e.cache = byte(uint32(e.low) >> 24)
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}
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e.cacheLen++
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e.low = uint64(uint32(e.low) << 8)
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return nil
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}
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// rangeDecoder decodes single bits of the range encoding stream.
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type rangeDecoder struct {
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br io.ByteReader
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nrange uint32
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code uint32
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}
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// init initializes the range decoder, by reading from the byte reader.
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func (d *rangeDecoder) init() error {
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d.nrange = 0xffffffff
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d.code = 0
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b, 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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if b != 0 {
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return errors.New("newRangeDecoder: first byte not zero")
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}
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for i := 0; i < 4; i++ {
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if err = d.updateCode(); err != nil {
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return err
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}
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}
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if d.code >= d.nrange {
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return errors.New("newRangeDecoder: d.code >= d.nrange")
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}
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return nil
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}
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// newRangeDecoder initializes a range decoder. It reads five bytes from the
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// reader and therefore may return an error.
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func newRangeDecoder(br io.ByteReader) (d *rangeDecoder, err error) {
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d = &rangeDecoder{br: br, nrange: 0xffffffff}
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b, err := d.br.ReadByte()
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if err != nil {
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return nil, err
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}
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if b != 0 {
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return nil, errors.New("newRangeDecoder: first byte not zero")
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}
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for i := 0; i < 4; i++ {
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if err = d.updateCode(); err != nil {
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return nil, err
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}
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}
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if d.code >= d.nrange {
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return nil, errors.New("newRangeDecoder: d.code >= d.nrange")
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}
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return d, nil
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}
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// possiblyAtEnd checks whether the decoder may be at the end of the stream.
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func (d *rangeDecoder) possiblyAtEnd() bool {
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return d.code == 0
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}
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// DirectDecodeBit decodes a bit with probability 1/2. The return value b will
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// contain the bit at the least-significant position. All other bits will be
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// zero.
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func (d *rangeDecoder) DirectDecodeBit() (b uint32, err error) {
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d.nrange >>= 1
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d.code -= d.nrange
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t := 0 - (d.code >> 31)
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d.code += d.nrange & t
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b = (t + 1) & 1
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// d.code will stay less then d.nrange
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// normalize
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// assume d.code < d.nrange
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const top = 1 << 24
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if d.nrange >= top {
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return b, nil
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}
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d.nrange <<= 8
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// d.code < d.nrange will be maintained
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return b, d.updateCode()
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}
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// decodeBit decodes a single bit. The bit will be returned at the
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// least-significant position. All other bits will be zero. The probability
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// value will be updated.
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func (d *rangeDecoder) DecodeBit(p *prob) (b uint32, err error) {
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bound := p.bound(d.nrange)
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if d.code < bound {
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d.nrange = bound
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p.inc()
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b = 0
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} else {
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d.code -= bound
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d.nrange -= bound
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p.dec()
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b = 1
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}
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// normalize
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// assume d.code < d.nrange
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const top = 1 << 24
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if d.nrange >= top {
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return b, nil
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}
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d.nrange <<= 8
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// d.code < d.nrange will be maintained
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return b, d.updateCode()
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}
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// updateCode reads a new byte into the code.
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func (d *rangeDecoder) updateCode() error {
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b, 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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d.code = (d.code << 8) | uint32(b)
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return nil
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}
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