/usr/share/gocode/src/github.com/templexxx/xor/nosimd.go is in golang-github-templexxx-xor-dev 0.1.2-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | // 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]
}
}
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