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crypto/md5: fix for big-endian processors

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R=golang-dev, minux.ma, agl
CC=golang-dev
https://golang.org/cl/7305059
This commit is contained in:
Ian Lance Taylor 2013-02-07 13:31:53 -08:00
parent 514f10b9ab
commit 2b44c33b4a
1 changed files with 12 additions and 2 deletions
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14
src/pkg/crypto/md5/md5block.go
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@ -5,6 +5,16 @@ import (
"unsafe"
)
const x86 = runtime.GOARCH == "amd64" || runtime.GOARCH == "386"
var littleEndian bool
func init() {
x := uint32(0x04030201)
y := [4]byte{0x1, 0x2, 0x3, 0x4}
littleEndian = *(*[4]byte)(unsafe.Pointer(&x)) == y
}
func block(dig *digest, p []byte) {
a := dig.s[0]
b := dig.s[1]
@ -16,13 +26,13 @@ func block(dig *digest, p []byte) {
aa, bb, cc, dd := a, b, c, d
// This is a constant condition - it is not evaluated on each iteration.
if runtime.GOARCH == "amd64" || runtime.GOARCH == "386" {
if x86 {
// MD5 was designed so that x86 processors can just iterate
// over the block data directly as uint32s, and we generate
// less code and run 1.3x faster if we take advantage of that.
// My apologies.
X = (*[16]uint32)(unsafe.Pointer(&p[0]))
} else if uintptr(unsafe.Pointer(&p[0]))&(unsafe.Alignof(uint32(0))-1) == 0 {
} else if littleEndian && uintptr(unsafe.Pointer(&p[0]))&(unsafe.Alignof(uint32(0))-1) == 0 {
X = (*[16]uint32)(unsafe.Pointer(&p[0]))
} else {
X = &xbuf