Golang程序
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332行
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6.57 KB
// Copyright 2012 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.
// +build ignore
// This program generates md5block.go
// Invoke as
//
// go run gen.go [-full] -output md5block.go
//
// The -full flag causes the generated code to do a full
// (16x) unrolling instead of a 4x unrolling.
package main
import (
"bytes"
"flag"
"go/format"
"io/ioutil"
"log"
"strings"
"text/template"
)
var filename = flag.String("output", "md5block.go", "output file name")
func main() {
flag.Parse()
var buf bytes.Buffer
t := template.Must(template.New("main").Funcs(funcs).Parse(program))
if err := t.Execute(&buf, data); err != nil {
log.Fatal(err)
}
data, err := format.Source(buf.Bytes())
if err != nil {
log.Fatal(err)
}
err = ioutil.WriteFile(*filename, data, 0644)
if err != nil {
log.Fatal(err)
}
}
type Data struct {
a, b, c, d string
Shift1 []int
Shift2 []int
Shift3 []int
Shift4 []int
Table1 []uint32
Table2 []uint32
Table3 []uint32
Table4 []uint32
Full bool
}
var funcs = template.FuncMap{
"dup": dup,
"relabel": relabel,
"rotate": rotate,
}
func dup(count int, x []int) []int {
var out []int
for i := 0; i < count; i++ {
out = append(out, x...)
}
return out
}
func relabel(s string) string {
return strings.NewReplacer("a", data.a, "b", data.b, "c", data.c, "d", data.d).Replace(s)
}
func rotate() string {
data.a, data.b, data.c, data.d = data.d, data.a, data.b, data.c
return "" // no output
}
func init() {
flag.BoolVar(&data.Full, "full", false, "complete unrolling")
}
var data = Data{
a: "a",
b: "b",
c: "c",
d: "d",
Shift1: []int{7, 12, 17, 22},
Shift2: []int{5, 9, 14, 20},
Shift3: []int{4, 11, 16, 23},
Shift4: []int{6, 10, 15, 21},
// table[i] = int((1<<32) * abs(sin(i+1 radians))).
Table1: []uint32{
// round 1
0xd76aa478,
0xe8c7b756,
0x242070db,
0xc1bdceee,
0xf57c0faf,
0x4787c62a,
0xa8304613,
0xfd469501,
0x698098d8,
0x8b44f7af,
0xffff5bb1,
0x895cd7be,
0x6b901122,
0xfd987193,
0xa679438e,
0x49b40821,
},
Table2: []uint32{
// round 2
0xf61e2562,
0xc040b340,
0x265e5a51,
0xe9b6c7aa,
0xd62f105d,
0x2441453,
0xd8a1e681,
0xe7d3fbc8,
0x21e1cde6,
0xc33707d6,
0xf4d50d87,
0x455a14ed,
0xa9e3e905,
0xfcefa3f8,
0x676f02d9,
0x8d2a4c8a,
},
Table3: []uint32{
// round3
0xfffa3942,
0x8771f681,
0x6d9d6122,
0xfde5380c,
0xa4beea44,
0x4bdecfa9,
0xf6bb4b60,
0xbebfbc70,
0x289b7ec6,
0xeaa127fa,
0xd4ef3085,
0x4881d05,
0xd9d4d039,
0xe6db99e5,
0x1fa27cf8,
0xc4ac5665,
},
Table4: []uint32{
// round 4
0xf4292244,
0x432aff97,
0xab9423a7,
0xfc93a039,
0x655b59c3,
0x8f0ccc92,
0xffeff47d,
0x85845dd1,
0x6fa87e4f,
0xfe2ce6e0,
0xa3014314,
0x4e0811a1,
0xf7537e82,
0xbd3af235,
0x2ad7d2bb,
0xeb86d391,
},
}
var program = `// 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.
// DO NOT EDIT.
// Generate with: go run gen.go{{if .Full}} -full{{end}} -output md5block.go
package md5
import (
"unsafe"
"runtime"
)
{{if not .Full}}
var t1 = [...]uint32{
{{range .Table1}}{{printf "\t%#x,\n" .}}{{end}}
}
var t2 = [...]uint32{
{{range .Table2}}{{printf "\t%#x,\n" .}}{{end}}
}
var t3 = [...]uint32{
{{range .Table3}}{{printf "\t%#x,\n" .}}{{end}}
}
var t4 = [...]uint32{
{{range .Table4}}{{printf "\t%#x,\n" .}}{{end}}
}
{{end}}
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 blockGeneric(dig *digest, p []byte) {
a := dig.s[0]
b := dig.s[1]
c := dig.s[2]
d := dig.s[3]
var X *[16]uint32
var xbuf [16]uint32
for len(p) >= chunk {
aa, bb, cc, dd := a, b, c, d
// This is a constant condition - it is not evaluated on each iteration.
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 littleEndian && uintptr(unsafe.Pointer(&p[0]))&(unsafe.Alignof(uint32(0))-1) == 0 {
X = (*[16]uint32)(unsafe.Pointer(&p[0]))
} else {
X = &xbuf
j := 0
for i := 0; i < 16; i++ {
X[i&15] = uint32(p[j]) | uint32(p[j+1])<<8 | uint32(p[j+2])<<16 | uint32(p[j+3])<<24
j += 4
}
}
{{if .Full}}
// Round 1.
{{range $i, $s := dup 4 .Shift1}}
{{index $.Table1 $i | printf "a += (((c^d)&b)^d) + X[%d] + %d" $i | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
{{rotate}}
{{end}}
// Round 2.
{{range $i, $s := dup 4 .Shift2}}
{{index $.Table2 $i | printf "a += (((b^c)&d)^c) + X[(1+5*%d)&15] + %d" $i | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
{{rotate}}
{{end}}
// Round 3.
{{range $i, $s := dup 4 .Shift3}}
{{index $.Table3 $i | printf "a += (b^c^d) + X[(5+3*%d)&15] + %d" $i | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
{{rotate}}
{{end}}
// Round 4.
{{range $i, $s := dup 4 .Shift4}}
{{index $.Table4 $i | printf "a += (c^(b|^d)) + X[(7*%d)&15] + %d" $i | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
{{rotate}}
{{end}}
{{else}}
// Round 1.
for i := uint(0); i < 16; {
{{range $s := .Shift1}}
{{printf "a += (((c^d)&b)^d) + X[i&15] + t1[i&15]" | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
i++
{{rotate}}
{{end}}
}
// Round 2.
for i := uint(0); i < 16; {
{{range $s := .Shift2}}
{{printf "a += (((b^c)&d)^c) + X[(1+5*i)&15] + t2[i&15]" | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
i++
{{rotate}}
{{end}}
}
// Round 3.
for i := uint(0); i < 16; {
{{range $s := .Shift3}}
{{printf "a += (b^c^d) + X[(5+3*i)&15] + t3[i&15]" | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
i++
{{rotate}}
{{end}}
}
// Round 4.
for i := uint(0); i < 16; {
{{range $s := .Shift4}}
{{printf "a += (c^(b|^d)) + X[(7*i)&15] + t4[i&15]" | relabel}}
{{printf "a = a<<%d | a>>(32-%d) + b" $s $s | relabel}}
i++
{{rotate}}
{{end}}
}
{{end}}
a += aa
b += bb
c += cc
d += dd
p = p[chunk:]
}
dig.s[0] = a
dig.s[1] = b
dig.s[2] = c
dig.s[3] = d
}
`