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1 | /* -*- linux-c -*- ------------------------------------------------------- * |
2 | * |
3 | * Copyright 2002-2007 H. Peter Anvin - All Rights Reserved |
4 | * |
5 | * This file is part of the Linux kernel, and is made available under |
6 | * the terms of the GNU General Public License version 2 or (at your |
7 | * option) any later version; incorporated herein by reference. |
8 | * |
9 | * ----------------------------------------------------------------------- */ |
10 | |
11 | /* |
12 | * mktables.c |
13 | * |
14 | * Make RAID-6 tables. This is a host user space program to be run at |
15 | * compile time. |
16 | */ |
17 | |
18 | #include <stdio.h> |
19 | #include <string.h> |
20 | #include <inttypes.h> |
21 | #include <stdlib.h> |
22 | #include <time.h> |
23 | |
24 | static uint8_t gfmul(uint8_t a, uint8_t b) |
25 | { |
26 | uint8_t v = 0; |
27 | |
28 | while (b) { |
29 | if (b & 1) |
30 | v ^= a; |
31 | a = (a << 1) ^ (a & 0x80 ? 0x1d : 0); |
32 | b >>= 1; |
33 | } |
34 | |
35 | return v; |
36 | } |
37 | |
38 | static uint8_t gfpow(uint8_t a, int b) |
39 | { |
40 | uint8_t v = 1; |
41 | |
42 | b %= 255; |
43 | if (b < 0) |
44 | b += 255; |
45 | |
46 | while (b) { |
47 | if (b & 1) |
48 | v = gfmul(v, a); |
49 | a = gfmul(a, a); |
50 | b >>= 1; |
51 | } |
52 | |
53 | return v; |
54 | } |
55 | |
56 | int main(int argc, char *argv[]) |
57 | { |
58 | int i, j, k; |
59 | uint8_t v; |
60 | uint8_t exptbl[256], invtbl[256]; |
61 | |
62 | printf("#include <linux/raid/pq.h>\n"); |
63 | |
64 | /* Compute multiplication table */ |
65 | printf("\nconst u8 __attribute__((aligned(256)))\n" |
66 | "raid6_gfmul[256][256] =\n" |
67 | "{\n"); |
68 | for (i = 0; i < 256; i++) { |
69 | printf("\t{\n"); |
70 | for (j = 0; j < 256; j += 8) { |
71 | printf("\t\t"); |
72 | for (k = 0; k < 8; k++) |
73 | printf("0x%02x,%c", gfmul(i, j + k), |
74 | (k == 7) ? '\n' : ' '); |
75 | } |
76 | printf("\t},\n"); |
77 | } |
78 | printf("};\n"); |
79 | printf("#ifdef __KERNEL__\n"); |
80 | printf("EXPORT_SYMBOL(raid6_gfmul);\n"); |
81 | printf("#endif\n"); |
82 | |
83 | /* Compute power-of-2 table (exponent) */ |
84 | v = 1; |
85 | printf("\nconst u8 __attribute__((aligned(256)))\n" |
86 | "raid6_gfexp[256] =\n" "{\n"); |
87 | for (i = 0; i < 256; i += 8) { |
88 | printf("\t"); |
89 | for (j = 0; j < 8; j++) { |
90 | exptbl[i + j] = v; |
91 | printf("0x%02x,%c", v, (j == 7) ? '\n' : ' '); |
92 | v = gfmul(v, 2); |
93 | if (v == 1) |
94 | v = 0; /* For entry 255, not a real entry */ |
95 | } |
96 | } |
97 | printf("};\n"); |
98 | printf("#ifdef __KERNEL__\n"); |
99 | printf("EXPORT_SYMBOL(raid6_gfexp);\n"); |
100 | printf("#endif\n"); |
101 | |
102 | /* Compute inverse table x^-1 == x^254 */ |
103 | printf("\nconst u8 __attribute__((aligned(256)))\n" |
104 | "raid6_gfinv[256] =\n" "{\n"); |
105 | for (i = 0; i < 256; i += 8) { |
106 | printf("\t"); |
107 | for (j = 0; j < 8; j++) { |
108 | invtbl[i + j] = v = gfpow(i + j, 254); |
109 | printf("0x%02x,%c", v, (j == 7) ? '\n' : ' '); |
110 | } |
111 | } |
112 | printf("};\n"); |
113 | printf("#ifdef __KERNEL__\n"); |
114 | printf("EXPORT_SYMBOL(raid6_gfinv);\n"); |
115 | printf("#endif\n"); |
116 | |
117 | /* Compute inv(2^x + 1) (exponent-xor-inverse) table */ |
118 | printf("\nconst u8 __attribute__((aligned(256)))\n" |
119 | "raid6_gfexi[256] =\n" "{\n"); |
120 | for (i = 0; i < 256; i += 8) { |
121 | printf("\t"); |
122 | for (j = 0; j < 8; j++) |
123 | printf("0x%02x,%c", invtbl[exptbl[i + j] ^ 1], |
124 | (j == 7) ? '\n' : ' '); |
125 | } |
126 | printf("};\n"); |
127 | printf("#ifdef __KERNEL__\n"); |
128 | printf("EXPORT_SYMBOL(raid6_gfexi);\n"); |
129 | printf("#endif\n"); |
130 | |
131 | return 0; |
132 | } |
133 |
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