forked from xi/go-tinyqr
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathgf.go
94 lines (83 loc) · 3.03 KB
/
gf.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
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
package qrcode
import "log"
type gfElement uint8
const (
gfZero = gfElement(0)
gfOne = gfElement(1)
)
var (
gfExpTable = [256]gfElement{
1, 2, 4, 8, 16, 32, 64, 128, 29, 58,
116, 232, 205, 135, 19, 38, 76, 152, 45, 90,
180, 117, 234, 201, 143, 3, 6, 12, 24, 48,
96, 192, 157, 39, 78, 156, 37, 74, 148, 53,
106, 212, 181, 119, 238, 193, 159, 35, 70, 140,
5, 10, 20, 40, 80, 160, 93, 186, 105, 210,
185, 111, 222, 161, 95, 190, 97, 194, 153, 47,
94, 188, 101, 202, 137, 15, 30, 60, 120, 240,
253, 231, 211, 187, 107, 214, 177, 127, 254, 225,
223, 163, 91, 182, 113, 226, 217, 175, 67, 134,
17, 34, 68, 136, 13, 26, 52, 104, 208, 189,
103, 206, 129, 31, 62, 124, 248, 237, 199, 147,
59, 118, 236, 197, 151, 51, 102, 204, 133, 23,
46, 92, 184, 109, 218, 169, 79, 158, 33, 66,
132, 21, 42, 84, 168, 77, 154, 41, 82, 164,
85, 170, 73, 146, 57, 114, 228, 213, 183, 115,
230, 209, 191, 99, 198, 145, 63, 126, 252, 229,
215, 179, 123, 246, 241, 255, 227, 219, 171, 75,
150, 49, 98, 196, 149, 55, 110, 220, 165, 87,
174, 65, 130, 25, 50, 100, 200, 141, 7, 14,
28, 56, 112, 224, 221, 167, 83, 166, 81, 162,
89, 178, 121, 242, 249, 239, 195, 155, 43, 86,
172, 69, 138, 9, 18, 36, 72, 144, 61, 122,
244, 245, 247, 243, 251, 235, 203, 139, 11, 22,
44, 88, 176, 125, 250, 233, 207, 131, 27, 54,
108, 216, 173, 71, 142, 1}
gfLogTable = [256]int{
-1, 0, 1, 25, 2, 50, 26, 198, 3, 223,
51, 238, 27, 104, 199, 75, 4, 100, 224, 14,
52, 141, 239, 129, 28, 193, 105, 248, 200, 8,
76, 113, 5, 138, 101, 47, 225, 36, 15, 33,
53, 147, 142, 218, 240, 18, 130, 69, 29, 181,
194, 125, 106, 39, 249, 185, 201, 154, 9, 120,
77, 228, 114, 166, 6, 191, 139, 98, 102, 221,
48, 253, 226, 152, 37, 179, 16, 145, 34, 136,
54, 208, 148, 206, 143, 150, 219, 189, 241, 210,
19, 92, 131, 56, 70, 64, 30, 66, 182, 163,
195, 72, 126, 110, 107, 58, 40, 84, 250, 133,
186, 61, 202, 94, 155, 159, 10, 21, 121, 43,
78, 212, 229, 172, 115, 243, 167, 87, 7, 112,
192, 247, 140, 128, 99, 13, 103, 74, 222, 237,
49, 197, 254, 24, 227, 165, 153, 119, 38, 184,
180, 124, 17, 68, 146, 217, 35, 32, 137, 46,
55, 63, 209, 91, 149, 188, 207, 205, 144, 135,
151, 178, 220, 252, 190, 97, 242, 86, 211, 171,
20, 42, 93, 158, 132, 60, 57, 83, 71, 109,
65, 162, 31, 45, 67, 216, 183, 123, 164, 118,
196, 23, 73, 236, 127, 12, 111, 246, 108, 161,
59, 82, 41, 157, 85, 170, 251, 96, 134, 177,
187, 204, 62, 90, 203, 89, 95, 176, 156, 169,
160, 81, 11, 245, 22, 235, 122, 117, 44, 215,
79, 174, 213, 233, 230, 231, 173, 232, 116, 214,
244, 234, 168, 80, 88, 175}
)
func gfInverse(a gfElement) gfElement {
if a == gfZero {
log.Panicln("No multiplicative inverse of 0")
}
return gfExpTable[255 - gfLogTable[a]]
}
func gfMultiply(a, b gfElement) gfElement {
if a == gfZero || b == gfZero {
return gfZero
}
return gfExpTable[(gfLogTable[a] + gfLogTable[b]) % 255]
}
func gfDivide(a, b gfElement) gfElement {
if a == gfZero {
return gfZero
} else if b == gfZero {
log.Panicln("Divide by zero")
}
return gfMultiply(a, gfInverse(b))
}