gotosocial/vendor/mellium.im/sasl/xor_unaligned.go
Tobi Smethurst 98263a7de6
Grand test fixup (#138)
* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig
2021-08-12 21:03:24 +02:00

52 lines
1.2 KiB
Go

// 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.
// This file was split out from Go's crypto/cipher/xor.go
// +build 386 amd64 ppc64 ppc64le s390x appengine
package sasl
import (
"unsafe"
)
const wordSize = int(unsafe.Sizeof(uintptr(0)))
// xorBytes xors in bulk. It only works on architectures that support unaligned
// read/writes.
func xorBytes(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
}
// xorWords XORs multiples of 4 or 8 bytes (depending on architecture.) The
// arguments are assumed to be of equal length.
func xorWords(dst, a, b []byte) {
dw := *(*[]uintptr)(unsafe.Pointer(&dst))
aw := *(*[]uintptr)(unsafe.Pointer(&a))
bw := *(*[]uintptr)(unsafe.Pointer(&b))
n := len(b) / wordSize
for i := 0; i < n; i++ {
dw[i] = aw[i] ^ bw[i]
}
}