-
Notifications
You must be signed in to change notification settings - Fork 4.6k
/
byteorder_big_endian.go
74 lines (64 loc) · 1.64 KB
/
byteorder_big_endian.go
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
package utils
import (
"bytes"
"io"
)
// BigEndian is the big-endian implementation of ByteOrder.
var BigEndian ByteOrder = bigEndian{}
type bigEndian struct{}
var _ ByteOrder = &bigEndian{}
// ReadUintN reads N bytes
func (bigEndian) ReadUintN(b io.ByteReader, length uint8) (uint64, error) {
var res uint64
for i := uint8(0); i < length; i++ {
bt, err := b.ReadByte()
if err != nil {
return 0, err
}
res ^= uint64(bt) << ((length - 1 - i) * 8)
}
return res, nil
}
// ReadUint32 reads a uint32
func (bigEndian) ReadUint32(b io.ByteReader) (uint32, error) {
var b1, b2, b3, b4 uint8
var err error
if b4, err = b.ReadByte(); err != nil {
return 0, err
}
if b3, err = b.ReadByte(); err != nil {
return 0, err
}
if b2, err = b.ReadByte(); err != nil {
return 0, err
}
if b1, err = b.ReadByte(); err != nil {
return 0, err
}
return uint32(b1) + uint32(b2)<<8 + uint32(b3)<<16 + uint32(b4)<<24, nil
}
// ReadUint16 reads a uint16
func (bigEndian) ReadUint16(b io.ByteReader) (uint16, error) {
var b1, b2 uint8
var err error
if b2, err = b.ReadByte(); err != nil {
return 0, err
}
if b1, err = b.ReadByte(); err != nil {
return 0, err
}
return uint16(b1) + uint16(b2)<<8, nil
}
func (bigEndian) WriteUintN(b *bytes.Buffer, length uint8, i uint64) {
for j := length; j > 0; j-- {
b.WriteByte(uint8(i >> (8 * (j - 1))))
}
}
// WriteUint32 writes a uint32
func (bigEndian) WriteUint32(b *bytes.Buffer, i uint32) {
b.Write([]byte{uint8(i >> 24), uint8(i >> 16), uint8(i >> 8), uint8(i)})
}
// WriteUint16 writes a uint16
func (bigEndian) WriteUint16(b *bytes.Buffer, i uint16) {
b.Write([]byte{uint8(i >> 8), uint8(i)})
}