tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1#ident "$Id: mktables.c,v 1.2 2002/12/12 22:41:27 hpa Exp $"
2/* ----------------------------------------------------------------------- *
3 *
4 * Copyright 2002 H. Peter Anvin - All Rights Reserved
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9 * Bostom MA 02111-1307, USA; either version 2 of the License, or
10 * (at your option) any later version; incorporated herein by reference.
11 *
12 * ----------------------------------------------------------------------- */
13
14/*
15 * mktables.c
16 *
17 * Make RAID-6 tables. This is a host user space program to be run at
18 * compile time.
19 */
20
21#include <stdio.h>
22#include <string.h>
23#include <inttypes.h>
24#include <stdlib.h>
25#include <time.h>
26
27static uint8_t gfmul(uint8_t a, uint8_t b)
28{
29 uint8_t v = 0;
30
31 while ( b ) {
32 if ( b & 1 ) v ^= a;
33 a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);
34 b >>= 1;
35 }
36 return v;
37}
38
39static uint8_t gfpow(uint8_t a, int b)
40{
41 uint8_t v = 1;
42
43 b %= 255;
44 if ( b < 0 )
45 b += 255;
46
47 while ( b ) {
48 if ( b & 1 ) v = gfmul(v,a);
49 a = gfmul(a,a);
50 b >>= 1;
51 }
52 return v;
53}
54
55int main(int argc, char *argv[])
56{
57 int i, j, k;
58 uint8_t v;
59 uint8_t exptbl[256], invtbl[256];
60
61 printf("#include \"raid6.h\"\n");
62
63 /* Compute multiplication table */
64 printf("\nconst u8 __attribute__((aligned(256)))\n"
65 "raid6_gfmul[256][256] =\n"
66 "{\n");
67 for ( i = 0 ; i < 256 ; i++ ) {
68 printf("\t{\n");
69 for ( j = 0 ; j < 256 ; j += 8 ) {
70 printf("\t\t");
71 for ( k = 0 ; k < 8 ; k++ ) {
72 printf("0x%02x, ", gfmul(i,j+k));
73 }
74 printf("\n");
75 }
76 printf("\t},\n");
77 }
78 printf("};\n");
79
80 /* Compute power-of-2 table (exponent) */
81 v = 1;
82 printf("\nconst u8 __attribute__((aligned(256)))\n"
83 "raid6_gfexp[256] =\n"
84 "{\n");
85 for ( i = 0 ; i < 256 ; i += 8 ) {
86 printf("\t");
87 for ( j = 0 ; j < 8 ; j++ ) {
88 exptbl[i+j] = v;
89 printf("0x%02x, ", v);
90 v = gfmul(v,2);
91 if ( v == 1 ) v = 0; /* For entry 255, not a real entry */
92 }
93 printf("\n");
94 }
95 printf("};\n");
96
97 /* Compute inverse table x^-1 == x^254 */
98 printf("\nconst u8 __attribute__((aligned(256)))\n"
99 "raid6_gfinv[256] =\n"
100 "{\n");
101 for ( i = 0 ; i < 256 ; i += 8 ) {
102 printf("\t");
103 for ( j = 0 ; j < 8 ; j++ ) {
104 invtbl[i+j] = v = gfpow(i+j,254);
105 printf("0x%02x, ", v);
106 }
107 printf("\n");
108 }
109 printf("};\n");
110
111 /* Compute inv(2^x + 1) (exponent-xor-inverse) table */
112 printf("\nconst u8 __attribute__((aligned(256)))\n"
113 "raid6_gfexi[256] =\n"
114 "{\n");
115 for ( i = 0 ; i < 256 ; i += 8 ) {
116 printf("\t");
117 for ( j = 0 ; j < 8 ; j++ ) {
118 printf("0x%02x, ", invtbl[exptbl[i+j]^1]);
119 }
120 printf("\n");
121 }
122 printf("};\n\n");
123
124 return 0;
125}