blob: 34365eb26102fa9cd8461df21a326c89f04b1946 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package stun
import (
"runtime"
"unsafe"
)
// #nosec
const wordSize = int(unsafe.Sizeof(uintptr(0)))
var supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64"
// fastXORBytes xors in bulk. It only works on architectures that
// support unaligned read/writes.
//
// #nosec
func fastXORBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
w := n / wordSize
if w > 0 {
dw := *(*[]uintptr)(unsafe.Pointer(&dst))
aw := *(*[]uintptr)(unsafe.Pointer(&a))
bw := *(*[]uintptr)(unsafe.Pointer(&b))
for i := 0; i < w; i++ {
dw[i] = aw[i] ^ bw[i]
}
}
for i := n - n%wordSize; i < n; i++ {
dst[i] = a[i] ^ b[i]
}
return n
}
func safeXORBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
for i := 0; i < n; i++ {
dst[i] = a[i] ^ b[i]
}
return n
}
// xorBytes xors the bytes in a and b. The destination is assumed to have enough
// space. Returns the number of bytes xor'd.
func xorBytes(dst, a, b []byte) int {
if supportsUnaligned {
return fastXORBytes(dst, a, b)
}
return safeXORBytes(dst, a, b)
}
|
