1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
// Copyright (c) 2025 Minio Inc. All rights reserved.
// Use of this source code is governed by a license that can be
// found in the LICENSE file.
// Package crc64nvme implements the 64-bit cyclic redundancy check with NVME polynomial.
package crc64nvme
import (
"encoding/binary"
"errors"
"hash"
"sync"
"unsafe"
)
const (
// The size of a CRC-64 checksum in bytes.
Size = 8
// The NVME polynoimial (reversed, as used by Go)
NVME = 0x9a6c9329ac4bc9b5
)
var (
// precalculated table.
nvmeTable = makeTable(NVME)
)
// table is a 256-word table representing the polynomial for efficient processing.
type table [256]uint64
var (
slicing8TablesBuildOnce sync.Once
slicing8TableNVME *[8]table
)
func buildSlicing8TablesOnce() {
slicing8TablesBuildOnce.Do(buildSlicing8Tables)
}
func buildSlicing8Tables() {
slicing8TableNVME = makeSlicingBy8Table(makeTable(NVME))
}
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
}
func makeSlicingBy8Table(t *table) *[8]table {
var helperTable [8]table
helperTable[0] = *t
for i := 0; i < 256; i++ {
crc := t[i]
for j := 1; j < 8; j++ {
crc = t[crc&0xff] ^ (crc >> 8)
helperTable[j][i] = crc
}
}
return &helperTable
}
// digest represents the partial evaluation of a checksum.
type digest struct {
crc uint64
}
// New creates a new hash.Hash64 computing the CRC-64 checksum using the
// NVME polynomial. Its Sum method will lay the
// value out in big-endian byte order. The returned Hash64 also
// implements [encoding.BinaryMarshaler] and [encoding.BinaryUnmarshaler] to
// marshal and unmarshal the internal state of the hash.
func New() hash.Hash64 { return &digest{0} }
func (d *digest) Size() int { return Size }
func (d *digest) BlockSize() int { return 1 }
func (d *digest) Reset() { d.crc = 0 }
const (
magic = "crc\x02"
marshaledSize = len(magic) + 8 + 8
)
func (d *digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, marshaledSize)
b = append(b, magic...)
b = binary.BigEndian.AppendUint64(b, tableSum)
b = binary.BigEndian.AppendUint64(b, d.crc)
return b, nil
}
func (d *digest) UnmarshalBinary(b []byte) error {
if len(b) < len(magic) || string(b[:len(magic)]) != magic {
return errors.New("hash/crc64: invalid hash state identifier")
}
if len(b) != marshaledSize {
return errors.New("hash/crc64: invalid hash state size")
}
if tableSum != binary.BigEndian.Uint64(b[4:]) {
return errors.New("hash/crc64: tables do not match")
}
d.crc = binary.BigEndian.Uint64(b[12:])
return nil
}
func update(crc uint64, p []byte) uint64 {
if hasAsm && len(p) > 127 {
ptr := unsafe.Pointer(&p[0])
if align := (uintptr(ptr)+15)&^0xf - uintptr(ptr); align > 0 {
// Align to 16-byte boundary.
crc = update(crc, p[:align])
p = p[align:]
}
runs := len(p) / 128
if hasAsm512 && runs >= 8 {
// Use 512-bit wide instructions for >= 1KB.
crc = updateAsm512(crc, p[:128*runs])
} else if runs > 0 {
crc = updateAsm(crc, p[:128*runs])
}
return update(crc, p[128*runs:])
}
buildSlicing8TablesOnce()
crc = ^crc
// table comparison is somewhat expensive, so avoid it for small sizes
if len(p) >= 64 {
var helperTable = slicing8TableNVME
// Update using slicing-by-8
for len(p) > 8 {
crc ^= binary.LittleEndian.Uint64(p)
crc = helperTable[7][crc&0xff] ^
helperTable[6][(crc>>8)&0xff] ^
helperTable[5][(crc>>16)&0xff] ^
helperTable[4][(crc>>24)&0xff] ^
helperTable[3][(crc>>32)&0xff] ^
helperTable[2][(crc>>40)&0xff] ^
helperTable[1][(crc>>48)&0xff] ^
helperTable[0][crc>>56]
p = p[8:]
}
}
// For reminders or small sizes
for _, v := range p {
crc = nvmeTable[byte(crc)^v] ^ (crc >> 8)
}
return ^crc
}
// Update returns the result of adding the bytes in p to the crc.
func Update(crc uint64, p []byte) uint64 {
return update(crc, p)
}
func (d *digest) Write(p []byte) (n int, err error) {
d.crc = update(d.crc, p)
return len(p), nil
}
func (d *digest) Sum64() uint64 { return d.crc }
func (d *digest) Sum(in []byte) []byte {
s := d.Sum64()
return append(in, byte(s>>56), byte(s>>48), byte(s>>40), byte(s>>32), byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
}
// Checksum returns the CRC-64 checksum of data
// using the NVME polynomial.
func Checksum(data []byte) uint64 { return update(0, data) }
// ISO tablesum of NVME poly
const tableSum = 0x8ddd9ee4402c7163
|
