mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-16 18:29:18 +08:00
56 lines
1.1 KiB
Go
56 lines
1.1 KiB
Go
|
/*
|
||
|
* Delta decoder
|
||
|
*
|
||
|
* Author: Lasse Collin <lasse.collin@tukaani.org>
|
||
|
*
|
||
|
* Translation to Go: Michael Cross <https://github.com/xi2>
|
||
|
*
|
||
|
* This file has been put into the public domain.
|
||
|
* You can do whatever you want with this file.
|
||
|
*/
|
||
|
|
||
|
package xz
|
||
|
|
||
|
type xzDecDelta struct {
|
||
|
delta [256]byte
|
||
|
pos byte
|
||
|
distance int // in range [1, 256]
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Decode raw stream which has a delta filter as the first filter.
|
||
|
*/
|
||
|
func xzDecDeltaRun(s *xzDecDelta, b *xzBuf, chain func(*xzBuf) xzRet) xzRet {
|
||
|
outStart := b.outPos
|
||
|
ret := chain(b)
|
||
|
for i := outStart; i < b.outPos; i++ {
|
||
|
tmp := b.out[i] + s.delta[byte(s.distance+int(s.pos))]
|
||
|
s.delta[s.pos] = tmp
|
||
|
b.out[i] = tmp
|
||
|
s.pos--
|
||
|
}
|
||
|
return ret
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Allocate memory for a delta decoder. xzDecDeltaReset must be used
|
||
|
* before calling xzDecDeltaRun.
|
||
|
*/
|
||
|
func xzDecDeltaCreate() *xzDecDelta {
|
||
|
return new(xzDecDelta)
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Returns xzOK if the given distance is valid. Otherwise
|
||
|
* xzOptionsError is returned.
|
||
|
*/
|
||
|
func xzDecDeltaReset(s *xzDecDelta, distance int) xzRet {
|
||
|
if distance < 1 || distance > 256 {
|
||
|
return xzOptionsError
|
||
|
}
|
||
|
s.delta = [256]byte{}
|
||
|
s.pos = 0
|
||
|
s.distance = distance
|
||
|
return xzOK
|
||
|
}
|