// 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) }