mirror of
https://github.com/go-gitea/gitea
synced 2024-12-26 02:24:27 +00:00
50 lines
1.4 KiB
Go
50 lines
1.4 KiB
Go
|
// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
|
||
|
|
// Use of this source code is governed by a BSD-style
|
||
|
|
// license that can be found in the LICENSE file.
|
||
|
|
|
||
|
|
package lzma
|
||
|
|
|
||
|
|
import "fmt"
|
||
|
|
|
||
|
|
// directCodec allows the encoding and decoding of values with a fixed number
|
||
|
|
// of bits. The number of bits must be in the range [1,32].
|
||
|
|
type directCodec byte
|
||
|
|
|
||
|
|
// makeDirectCodec creates a directCodec. The function panics if the number of
|
||
|
|
// bits is not in the range [1,32].
|
||
|
|
func makeDirectCodec(bits int) directCodec {
|
||
|
|
if !(1 <= bits && bits <= 32) {
|
||
|
|
panic(fmt.Errorf("bits=%d out of range", bits))
|
||
|
|
}
|
||
|
|
return directCodec(bits)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Bits returns the number of bits supported by this codec.
|
||
|
|
func (dc directCodec) Bits() int {
|
||
|
|
return int(dc)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Encode uses the range encoder to encode a value with the fixed number of
|
||
|
|
// bits. The most-significant bit is encoded first.
|
||
|
|
func (dc directCodec) Encode(e *rangeEncoder, v uint32) error {
|
||
|
|
for i := int(dc) - 1; i >= 0; i-- {
|
||
|
|
if err := e.DirectEncodeBit(v >> uint(i)); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Decode uses the range decoder to decode a value with the given number of
|
||
|
|
// given bits. The most-significant bit is decoded first.
|
||
|
|
func (dc directCodec) Decode(d *rangeDecoder) (v uint32, err error) {
|
||
|
|
for i := int(dc) - 1; i >= 0; i-- {
|
||
|
|
x, err := d.DirectDecodeBit()
|
||
|
|
if err != nil {
|
||
|
|
return 0, err
|
||
|
|
}
|
||
|
|
v = (v << 1) | x
|
||
|
|
}
|
||
|
|
return v, nil
|
||
|
|
}
|