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
24static 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
38static 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
56int 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