mirror of https://gogs.blitter.com/RLabs/xs
117 lines
2.9 KiB
Go
117 lines
2.9 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.
|
||
|
|
|
||
|
|
package xor
|
||
|
|
|
||
|
|
import (
|
||
|
|
"runtime"
|
||
|
|
"unsafe"
|
||
|
|
)
|
||
|
|
|
||
|
|
const wordSize = int(unsafe.Sizeof(uintptr(0)))
|
||
|
|
const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x"
|
||
|
|
|
||
|
|
// xor the bytes in a and b. The destination is assumed to have enough space.
|
||
|
|
func bytesNoSIMD(dst, a, b []byte, size int) {
|
||
|
|
if supportsUnaligned {
|
||
|
|
fastXORBytes(dst, a, b, size)
|
||
|
|
} else {
|
||
|
|
// TODO(hanwen): if (dst, a, b) have common alignment
|
||
|
|
// we could still try fastXORBytes. It is not clear
|
||
|
|
// how often this happens, and it's only worth it if
|
||
|
|
// the block encryption itself is hardware
|
||
|
|
// accelerated.
|
||
|
|
safeXORBytes(dst, a, b, size)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// split slice for cache-friendly
|
||
|
|
const unitSize = 16 * 1024
|
||
|
|
|
||
|
|
func matrixNoSIMD(dst []byte, src [][]byte) {
|
||
|
|
size := len(src[0])
|
||
|
|
start := 0
|
||
|
|
do := unitSize
|
||
|
|
for start < size {
|
||
|
|
end := start + do
|
||
|
|
if end <= size {
|
||
|
|
partNoSIMD(start, end, dst, src)
|
||
|
|
start = start + do
|
||
|
|
} else {
|
||
|
|
partNoSIMD(start, size, dst, src)
|
||
|
|
start = size
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// split vect will improve performance with big data by reducing cache pollution
|
||
|
|
func partNoSIMD(start, end int, dst []byte, src [][]byte) {
|
||
|
|
bytesNoSIMD(dst[start:end], src[0][start:end], src[1][start:end], end-start)
|
||
|
|
for i := 2; i < len(src); i++ {
|
||
|
|
bytesNoSIMD(dst[start:end], dst[start:end], src[i][start:end], end-start)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// fastXORBytes xor in bulk. It only works on architectures that
|
||
|
|
// support unaligned read/writes.
|
||
|
|
func fastXORBytes(dst, a, b []byte, n int) {
|
||
|
|
w := n / wordSize
|
||
|
|
if w > 0 {
|
||
|
|
wordBytes := w * wordSize
|
||
|
|
fastXORWords(dst[:wordBytes], a[:wordBytes], b[:wordBytes])
|
||
|
|
}
|
||
|
|
for i := n - n%wordSize; i < n; i++ {
|
||
|
|
dst[i] = a[i] ^ b[i]
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func safeXORBytes(dst, a, b []byte, n int) {
|
||
|
|
ex := n % 8
|
||
|
|
for i := 0; i < ex; i++ {
|
||
|
|
dst[i] = a[i] ^ b[i]
|
||
|
|
}
|
||
|
|
|
||
|
|
for i := ex; i < n; i += 8 {
|
||
|
|
_dst := dst[i : i+8]
|
||
|
|
_a := a[i : i+8]
|
||
|
|
_b := b[i : i+8]
|
||
|
|
_dst[0] = _a[0] ^ _b[0]
|
||
|
|
_dst[1] = _a[1] ^ _b[1]
|
||
|
|
_dst[2] = _a[2] ^ _b[2]
|
||
|
|
_dst[3] = _a[3] ^ _b[3]
|
||
|
|
|
||
|
|
_dst[4] = _a[4] ^ _b[4]
|
||
|
|
_dst[5] = _a[5] ^ _b[5]
|
||
|
|
_dst[6] = _a[6] ^ _b[6]
|
||
|
|
_dst[7] = _a[7] ^ _b[7]
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// fastXORWords XORs multiples of 4 or 8 bytes (depending on architecture.)
|
||
|
|
// The arguments are assumed to be of equal length.
|
||
|
|
func fastXORWords(dst, a, b []byte) {
|
||
|
|
dw := *(*[]uintptr)(unsafe.Pointer(&dst))
|
||
|
|
aw := *(*[]uintptr)(unsafe.Pointer(&a))
|
||
|
|
bw := *(*[]uintptr)(unsafe.Pointer(&b))
|
||
|
|
n := len(b) / wordSize
|
||
|
|
ex := n % 8
|
||
|
|
for i := 0; i < ex; i++ {
|
||
|
|
dw[i] = aw[i] ^ bw[i]
|
||
|
|
}
|
||
|
|
|
||
|
|
for i := ex; i < n; i += 8 {
|
||
|
|
_dw := dw[i : i+8]
|
||
|
|
_aw := aw[i : i+8]
|
||
|
|
_bw := bw[i : i+8]
|
||
|
|
_dw[0] = _aw[0] ^ _bw[0]
|
||
|
|
_dw[1] = _aw[1] ^ _bw[1]
|
||
|
|
_dw[2] = _aw[2] ^ _bw[2]
|
||
|
|
_dw[3] = _aw[3] ^ _bw[3]
|
||
|
|
_dw[4] = _aw[4] ^ _bw[4]
|
||
|
|
_dw[5] = _aw[5] ^ _bw[5]
|
||
|
|
_dw[6] = _aw[6] ^ _bw[6]
|
||
|
|
_dw[7] = _aw[7] ^ _bw[7]
|
||
|
|
}
|
||
|
|
}
|