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Use crypto/subtle.XORBytes #294

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29 changes: 0 additions & 29 deletions utils/xor/xor_amd64.go

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56 changes: 0 additions & 56 deletions utils/xor/xor_amd64.s

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31 changes: 0 additions & 31 deletions utils/xor/xor_arm64.go

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69 changes: 0 additions & 69 deletions utils/xor/xor_arm64.s

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70 changes: 6 additions & 64 deletions utils/xor/xor_generic.go
Original file line number Diff line number Diff line change
@@ -1,78 +1,20 @@
// SPDX-FileCopyrightText: 2013 The Go Authors. All rights reserved.
// SPDX-License-Identifier: BSD-3-Clause
// SPDX-FileCopyrightText: 2022 The Pion community <https://pion.ly>
// SPDX-FileCopyrightText: 2024 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

//go:build (!amd64 && !ppc64 && !ppc64le && !arm64 && !arm) || gccgo
// +build !amd64,!ppc64,!ppc64le,!arm64,!arm gccgo
//go:build go1.20 && !arm && !gccgo

// Package xor provides utility functions used by other Pion
// packages. Generic arch.
// Package xor provides the XorBytes function.
package xor

import (
"runtime"
"unsafe"
"crypto/subtle"
)

const (
wordSize = int(unsafe.Sizeof(uintptr(0))) // nolint:gosec
supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x" // nolint:gochecknoglobals
)

func isAligned(a *byte) bool {
return uintptr(unsafe.Pointer(a))%uintptr(wordSize) == 0
}

// XorBytes xors the bytes in a and b. The destination should have enough
// space, otherwise xorBytes will panic. Returns the number of bytes xor'd.
// XorBytes calls [crypto/suble.XORBytes].
//
//revive:disable-next-line
func XorBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
if n == 0 {
return 0
}

switch {
case supportsUnaligned:
fastXORBytes(dst, a, b, n)
case isAligned(&dst[0]) && isAligned(&a[0]) && isAligned(&b[0]):
fastXORBytes(dst, a, b, n)
default:
safeXORBytes(dst, a, b, n)
}
return n
}

// fastXORBytes xors in bulk. It only works on architectures that
// support unaligned read/writes.
// n needs to be smaller or equal than the length of a and b.
func fastXORBytes(dst, a, b []byte, n int) {
// Assert dst has enough space
_ = dst[n-1]

w := n / wordSize
if w > 0 {
dw := *(*[]uintptr)(unsafe.Pointer(&dst)) // nolint:gosec
aw := *(*[]uintptr)(unsafe.Pointer(&a)) // nolint:gosec
bw := *(*[]uintptr)(unsafe.Pointer(&b)) // nolint:gosec
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]
}
}

// n needs to be smaller or equal than the length of a and b.
func safeXORBytes(dst, a, b []byte, n int) {
for i := 0; i < n; i++ {
dst[i] = a[i] ^ b[i]
}
return subtle.XORBytes(dst, a, b)
}
77 changes: 77 additions & 0 deletions utils/xor/xor_old.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,77 @@
// SPDX-FileCopyrightText: 2013 The Go Authors. All rights reserved.
// SPDX-License-Identifier: BSD-3-Clause
// SPDX-FileCopyrightText: 2022 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

//go:build (!go1.20 && !arm) || gccgo

// Package xor provides the XorBytes function.
// This version is only used on Go up to version 1.19.
package xor

import (
"runtime"
"unsafe"
)

const (
wordSize = int(unsafe.Sizeof(uintptr(0))) // nolint:gosec
supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64" || runtime.GOARCH == "arm64" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x" // nolint:gochecknoglobals
)

func isAligned(a *byte) bool {
return uintptr(unsafe.Pointer(a))%uintptr(wordSize) == 0
}

// XorBytes xors the bytes in a and b. The destination should have enough
// space, otherwise xorBytes will panic. Returns the number of bytes xor'd.
//
//revive:disable-next-line
func XorBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
if n == 0 {
return 0
}

switch {
case supportsUnaligned:
fastXORBytes(dst, a, b, n)
case isAligned(&dst[0]) && isAligned(&a[0]) && isAligned(&b[0]):
fastXORBytes(dst, a, b, n)
default:
safeXORBytes(dst, a, b, n)
}
return n
}

// fastXORBytes xors in bulk. It only works on architectures that
// support unaligned read/writes.
// n needs to be smaller or equal than the length of a and b.
func fastXORBytes(dst, a, b []byte, n int) {
// Assert dst has enough space
_ = dst[n-1]

w := n / wordSize
if w > 0 {
dw := *(*[]uintptr)(unsafe.Pointer(&dst)) // nolint:gosec
aw := *(*[]uintptr)(unsafe.Pointer(&a)) // nolint:gosec
bw := *(*[]uintptr)(unsafe.Pointer(&b)) // nolint:gosec
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]
}
}

// n needs to be smaller or equal than the length of a and b.
func safeXORBytes(dst, a, b []byte, n int) {
for i := 0; i < n; i++ {
dst[i] = a[i] ^ b[i]
}
}
29 changes: 0 additions & 29 deletions utils/xor/xor_ppc64x.go

This file was deleted.

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