forked from hardcoresushi/DroidFS
56 lines
2.0 KiB
Go
56 lines
2.0 KiB
Go
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
|
|
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// +build amd64 arm64 ppc64 ppc64le s390x mips64 mips64le
|
|
|
|
// This code assumes that it's safe to perform unaligned word-sized loads. This is safe on:
|
|
// - arm64 per http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0024a/ch05s01s02.html
|
|
// - Section "5.5.8 Alignment Interrupt" of PowerPC Operating Environment Architecture Book III Version 2.02
|
|
// (the first PowerPC ISA version to include 64-bit), available from
|
|
// http://www.ibm.com/developerworks/systems/library/es-archguide-v2.html does not permit fixed-point loads
|
|
// or stores to generate exceptions on unaligned access
|
|
// - IBM mainframe's have allowed unaligned accesses since the System/370 arrived in 1970
|
|
// - On mips unaligned accesses are fixed up by the kernel per https://www.linux-mips.org/wiki/Alignment
|
|
// so performance might be quite bad but it will work.
|
|
|
|
package cmac
|
|
|
|
import (
|
|
"log"
|
|
"unsafe"
|
|
)
|
|
|
|
// XOR the blockSize bytes starting at a and b, writing the result over dst.
|
|
func xorBlock(
|
|
dstPtr unsafe.Pointer,
|
|
aPtr unsafe.Pointer,
|
|
bPtr unsafe.Pointer) {
|
|
// Check assumptions. (These are compile-time constants, so this should
|
|
// compile out.)
|
|
const wordSize = unsafe.Sizeof(uintptr(0))
|
|
if blockSize != 2*wordSize {
|
|
log.Panicf("%d %d", blockSize, wordSize)
|
|
}
|
|
|
|
// Convert.
|
|
a := (*[2]uintptr)(aPtr)
|
|
b := (*[2]uintptr)(bPtr)
|
|
dst := (*[2]uintptr)(dstPtr)
|
|
|
|
// Compute.
|
|
dst[0] = a[0] ^ b[0]
|
|
dst[1] = a[1] ^ b[1]
|
|
}
|