hash\
hash/adler32\
hash/crc32\
+ hash/crc64\
http\
image\
image/jpeg\
func update(crc uint32, tab *Table, p []byte) uint32 {
crc = ^crc
- for i := 0; i < len(p); i++ {
- crc = tab[byte(crc)^p[i]] ^ (crc >> 8)
+ for _, v := range p {
+ crc = tab[byte(crc)^v] ^ (crc >> 8)
}
return ^crc
}
+// Update returns the result of adding the bytes in p to the crc.
+func Update(crc uint32, tab *Table, p []byte) uint32 {
+ return update(crc, tab, p)
+}
+
func (d *digest) Write(p []byte) (n int, err os.Error) {
d.crc = update(d.crc, d.tab, p)
return len(p), nil
"testing"
)
-type _Crc32Test struct {
+type test struct {
out uint32
in string
}
-var golden = []_Crc32Test{
- _Crc32Test{0x0, ""},
- _Crc32Test{0xe8b7be43, "a"},
- _Crc32Test{0x9e83486d, "ab"},
- _Crc32Test{0x352441c2, "abc"},
- _Crc32Test{0xed82cd11, "abcd"},
- _Crc32Test{0x8587d865, "abcde"},
- _Crc32Test{0x4b8e39ef, "abcdef"},
- _Crc32Test{0x312a6aa6, "abcdefg"},
- _Crc32Test{0xaeef2a50, "abcdefgh"},
- _Crc32Test{0x8da988af, "abcdefghi"},
- _Crc32Test{0x3981703a, "abcdefghij"},
- _Crc32Test{0x6b9cdfe7, "Discard medicine more than two years old."},
- _Crc32Test{0xc90ef73f, "He who has a shady past knows that nice guys finish last."},
- _Crc32Test{0xb902341f, "I wouldn't marry him with a ten foot pole."},
- _Crc32Test{0x42080e8, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
- _Crc32Test{0x154c6d11, "The days of the digital watch are numbered. -Tom Stoppard"},
- _Crc32Test{0x4c418325, "Nepal premier won't resign."},
- _Crc32Test{0x33955150, "For every action there is an equal and opposite government program."},
- _Crc32Test{0x26216a4b, "His money is twice tainted: 'taint yours and 'taint mine."},
- _Crc32Test{0x1abbe45e, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
- _Crc32Test{0xc89a94f7, "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
- _Crc32Test{0xab3abe14, "size: a.out: bad magic"},
- _Crc32Test{0xbab102b6, "The major problem is with sendmail. -Mark Horton"},
- _Crc32Test{0x999149d7, "Give me a rock, paper and scissors and I will move the world. CCFestoon"},
- _Crc32Test{0x6d52a33c, "If the enemy is within range, then so are you."},
- _Crc32Test{0x90631e8d, "It's well we cannot hear the screams/That we create in others' dreams."},
- _Crc32Test{0x78309130, "You remind me of a TV show, but that's all right: I watch it anyway."},
- _Crc32Test{0x7d0a377f, "C is as portable as Stonehedge!!"},
- _Crc32Test{0x8c79fd79, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
- _Crc32Test{0xa20b7167, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction. Lewis-Randall Rule"},
- _Crc32Test{0x8e0bb443, "How can you write a big system without C++? -Paul Glick"},
+var golden = []test{
+ test{0x0, ""},
+ test{0xe8b7be43, "a"},
+ test{0x9e83486d, "ab"},
+ test{0x352441c2, "abc"},
+ test{0xed82cd11, "abcd"},
+ test{0x8587d865, "abcde"},
+ test{0x4b8e39ef, "abcdef"},
+ test{0x312a6aa6, "abcdefg"},
+ test{0xaeef2a50, "abcdefgh"},
+ test{0x8da988af, "abcdefghi"},
+ test{0x3981703a, "abcdefghij"},
+ test{0x6b9cdfe7, "Discard medicine more than two years old."},
+ test{0xc90ef73f, "He who has a shady past knows that nice guys finish last."},
+ test{0xb902341f, "I wouldn't marry him with a ten foot pole."},
+ test{0x42080e8, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+ test{0x154c6d11, "The days of the digital watch are numbered. -Tom Stoppard"},
+ test{0x4c418325, "Nepal premier won't resign."},
+ test{0x33955150, "For every action there is an equal and opposite government program."},
+ test{0x26216a4b, "His money is twice tainted: 'taint yours and 'taint mine."},
+ test{0x1abbe45e, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+ test{0xc89a94f7, "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+ test{0xab3abe14, "size: a.out: bad magic"},
+ test{0xbab102b6, "The major problem is with sendmail. -Mark Horton"},
+ test{0x999149d7, "Give me a rock, paper and scissors and I will move the world. CCFestoon"},
+ test{0x6d52a33c, "If the enemy is within range, then so are you."},
+ test{0x90631e8d, "It's well we cannot hear the screams/That we create in others' dreams."},
+ test{0x78309130, "You remind me of a TV show, but that's all right: I watch it anyway."},
+ test{0x7d0a377f, "C is as portable as Stonehedge!!"},
+ test{0x8c79fd79, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+ test{0xa20b7167, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction. Lewis-Randall Rule"},
+ test{0x8e0bb443, "How can you write a big system without C++? -Paul Glick"},
}
func TestGolden(t *testing.T) {
--- /dev/null
+# Copyright 2009 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.
+
+include ../../../Make.$(GOARCH)
+
+TARG=hash/crc64
+GOFILES=\
+ crc64.go\
+
+include ../../../Make.pkg
--- /dev/null
+// Copyright 2009 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.
+
+// This package implements the 64-bit cyclic redundancy check, or CRC-64, checksum.
+// See http://en.wikipedia.org/wiki/Cyclic_redundancy_check for information.
+package crc64
+
+import (
+ "hash"
+ "os"
+)
+
+// The size of a CRC-64 checksum in bytes.
+const Size = 8
+
+// Predefined polynomials.
+const (
+ // The ISO polynomial, defined in ISO 3309 and used in HDLC.
+ ISO = 0xD800000000000000
+
+ // The ECMA polynomial, defined in ECMA 182.
+ ECMA = 0xC96C5795D7870F42
+)
+
+// Table is a 256-word table representing the polynomial for efficient processing.
+type Table [256]uint64
+
+// MakeTable returns the Table constructed from the specified polynomial.
+func MakeTable(poly uint64) *Table {
+ t := new(Table)
+ for i := 0; i < 256; i++ {
+ crc := uint64(i)
+ for j := 0; j < 8; j++ {
+ if crc&1 == 1 {
+ crc = (crc >> 1) ^ poly
+ } else {
+ crc >>= 1
+ }
+ }
+ t[i] = crc
+ }
+ return t
+}
+
+// digest represents the partial evaluation of a checksum.
+type digest struct {
+ crc uint64
+ tab *Table
+}
+
+// New creates a new hash.Hash64 computing the CRC-64 checksum
+// using the polynomial represented by the Table.
+func New(tab *Table) hash.Hash64 { return &digest{0, tab} }
+
+func (d *digest) Size() int { return Size }
+
+func (d *digest) Reset() { d.crc = 0 }
+
+func update(crc uint64, tab *Table, p []byte) uint64 {
+ crc = ^crc
+ for _, v := range p {
+ crc = tab[byte(crc)^v] ^ (crc >> 8)
+ }
+ return ^crc
+}
+
+// Update returns the result of adding the bytes in p to the crc.
+func Update(crc uint64, tab *Table, p []byte) uint64 {
+ return update(crc, tab, p)
+}
+
+func (d *digest) Write(p []byte) (n int, err os.Error) {
+ d.crc = update(d.crc, d.tab, p)
+ return len(p), nil
+}
+
+func (d *digest) Sum64() uint64 { return d.crc }
+
+func (d *digest) Sum() []byte {
+ p := make([]byte, 8)
+ s := d.Sum64()
+ p[0] = byte(s >> 54)
+ p[1] = byte(s >> 48)
+ p[2] = byte(s >> 40)
+ p[3] = byte(s >> 32)
+ p[4] = byte(s >> 24)
+ p[5] = byte(s >> 16)
+ p[6] = byte(s >> 8)
+ p[7] = byte(s)
+ return p
+}
+
+// Checksum returns the CRC-64 checksum of data
+// using the polynomial represented by the Table.
+func Checksum(data []byte, tab *Table) uint64 { return update(0, tab, data) }
--- /dev/null
+// Copyright 2009 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 crc64
+
+import (
+ "io"
+ "testing"
+)
+
+type test struct {
+ out uint64
+ in string
+}
+
+var golden = []test{
+ test{0x0, ""},
+ test{0x3420000000000000, "a"},
+ test{0x36c4200000000000, "ab"},
+ test{0x3776c42000000000, "abc"},
+ test{0x336776c420000000, "abcd"},
+ test{0x32d36776c4200000, "abcde"},
+ test{0x3002d36776c42000, "abcdef"},
+ test{0x31b002d36776c420, "abcdefg"},
+ test{0xe21b002d36776c4, "abcdefgh"},
+ test{0x8b6e21b002d36776, "abcdefghi"},
+ test{0x7f5b6e21b002d367, "abcdefghij"},
+ test{0x8ec0e7c835bf9cdf, "Discard medicine more than two years old."},
+ test{0xc7db1759e2be5ab4, "He who has a shady past knows that nice guys finish last."},
+ test{0xfbf9d9603a6fa020, "I wouldn't marry him with a ten foot pole."},
+ test{0xeafc4211a6daa0ef, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+ test{0x3e05b21c7a4dc4da, "The days of the digital watch are numbered. -Tom Stoppard"},
+ test{0x5255866ad6ef28a6, "Nepal premier won't resign."},
+ test{0x8a79895be1e9c361, "For every action there is an equal and opposite government program."},
+ test{0x8878963a649d4916, "His money is twice tainted: 'taint yours and 'taint mine."},
+ test{0xa7b9d53ea87eb82f, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+ test{0xdb6805c0966a2f9c, "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+ test{0xf3553c65dacdadd2, "size: a.out: bad magic"},
+ test{0x9d5e034087a676b9, "The major problem is with sendmail. -Mark Horton"},
+ test{0xa6db2d7f8da96417, "Give me a rock, paper and scissors and I will move the world. CCFestoon"},
+ test{0x325e00cd2fe819f9, "If the enemy is within range, then so are you."},
+ test{0x88c6600ce58ae4c6, "It's well we cannot hear the screams/That we create in others' dreams."},
+ test{0x28c4a3f3b769e078, "You remind me of a TV show, but that's all right: I watch it anyway."},
+ test{0xa698a34c9d9f1dca, "C is as portable as Stonehedge!!"},
+ test{0xf6c1e2a8c26c5cfc, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+ test{0xd402559dfe9b70c, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction. Lewis-Randall Rule"},
+ test{0xdb6efff26aa94946, "How can you write a big system without C++? -Paul Glick"},
+}
+
+var tab = MakeTable(ISO)
+
+func TestGolden(t *testing.T) {
+ for i := 0; i < len(golden); i++ {
+ g := golden[i]
+ c := New(tab)
+ io.WriteString(c, g.in)
+ s := c.Sum64()
+ if s != g.out {
+ t.Errorf("crc64(%s) = 0x%x want 0x%x", g.in, s, g.out)
+ t.FailNow()
+ }
+ }
+}
+
+func BenchmarkCrc64KB(b *testing.B) {
+ b.StopTimer()
+ data := make([]uint8, 1024)
+ for i := 0; i < 1024; i++ {
+ data[i] = uint8(i)
+ }
+ c := New(tab)
+ b.StartTimer()
+
+ for i := 0; i < b.N; i++ {
+ c.Write(data)
+ }
+}
Hash
Sum32() uint32
}
+
+// Hash64 is the common interface implemented by all 64-bit hash functions.
+type Hash64 interface {
+ Hash
+ Sum64() uint64
+}