1// SPDX-License-Identifier: GPL-2.0-or-later
2/* -*- linux-c -*- ------------------------------------------------------- *
3 *
4 *   Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
5 *
6 * ----------------------------------------------------------------------- */
7
8/*
9 * mktables.c
10 *
11 * Make RAID-6 tables.  This is a host user space program to be run at
12 * compile time.
13 */
14
15#include <stdio.h>
16#include <string.h>
17#include <inttypes.h>
18#include <stdlib.h>
19#include <time.h>
20
21static uint8_t gfmul(uint8_t a, uint8_t b)
22{
23	uint8_t v = 0;
24
25	while (b) {
26		if (b & 1)
27			v ^= a;
28		a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);
29		b >>= 1;
30	}
31
32	return v;
33}
34
35static uint8_t gfpow(uint8_t a, int b)
36{
37	uint8_t v = 1;
38
39	b %= 255;
40	if (b < 0)
41		b += 255;
42
43	while (b) {
44		if (b & 1)
45			v = gfmul(v, a);
46		a = gfmul(a, a);
47		b >>= 1;
48	}
49
50	return v;
51}
52
53int main(int argc, char *argv[])
54{
55	int i, j, k;
56	uint8_t v;
57	uint8_t exptbl[256], invtbl[256];
58
59	printf("#ifdef __KERNEL__\n");
60	printf("#include <linux/export.h>\n");
61	printf("#endif\n");
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 vector multiplication table */
84	printf("\nconst u8  __attribute__((aligned(256)))\n"
85		"raid6_vgfmul[256][32] =\n"
86		"{\n");
87	for (i = 0; i < 256; i++) {
88		printf("\t{\n");
89		for (j = 0; j < 16; j += 8) {
90			printf("\t\t");
91			for (k = 0; k < 8; k++)
92				printf("0x%02x,%c", gfmul(i, j + k),
93				       (k == 7) ? '\n' : ' ');
94		}
95		for (j = 0; j < 16; j += 8) {
96			printf("\t\t");
97			for (k = 0; k < 8; k++)
98				printf("0x%02x,%c", gfmul(i, (j + k) << 4),
99				       (k == 7) ? '\n' : ' ');
100		}
101		printf("\t},\n");
102	}
103	printf("};\n");
104	printf("#ifdef __KERNEL__\n");
105	printf("EXPORT_SYMBOL(raid6_vgfmul);\n");
106	printf("#endif\n");
107
108	/* Compute power-of-2 table (exponent) */
109	v = 1;
110	printf("\nconst u8 __attribute__((aligned(256)))\n"
111	       "raid6_gfexp[256] =\n" "{\n");
112	for (i = 0; i < 256; i += 8) {
113		printf("\t");
114		for (j = 0; j < 8; j++) {
115			exptbl[i + j] = v;
116			printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
117			v = gfmul(v, 2);
118			if (v == 1)
119				v = 0;	/* For entry 255, not a real entry */
120		}
121	}
122	printf("};\n");
123	printf("#ifdef __KERNEL__\n");
124	printf("EXPORT_SYMBOL(raid6_gfexp);\n");
125	printf("#endif\n");
126
127	/* Compute log-of-2 table */
128	printf("\nconst u8 __attribute__((aligned(256)))\n"
129	       "raid6_gflog[256] =\n" "{\n");
130	for (i = 0; i < 256; i += 8) {
131		printf("\t");
132		for (j = 0; j < 8; j++) {
133			v = 255;
134			for (k = 0; k < 256; k++)
135				if (exptbl[k] == (i + j)) {
136					v = k;
137					break;
138				}
139			printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
140		}
141	}
142	printf("};\n");
143	printf("#ifdef __KERNEL__\n");
144	printf("EXPORT_SYMBOL(raid6_gflog);\n");
145	printf("#endif\n");
146
147	/* Compute inverse table x^-1 == x^254 */
148	printf("\nconst u8 __attribute__((aligned(256)))\n"
149	       "raid6_gfinv[256] =\n" "{\n");
150	for (i = 0; i < 256; i += 8) {
151		printf("\t");
152		for (j = 0; j < 8; j++) {
153			invtbl[i + j] = v = gfpow(i + j, 254);
154			printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
155		}
156	}
157	printf("};\n");
158	printf("#ifdef __KERNEL__\n");
159	printf("EXPORT_SYMBOL(raid6_gfinv);\n");
160	printf("#endif\n");
161
162	/* Compute inv(2^x + 1) (exponent-xor-inverse) table */
163	printf("\nconst u8 __attribute__((aligned(256)))\n"
164	       "raid6_gfexi[256] =\n" "{\n");
165	for (i = 0; i < 256; i += 8) {
166		printf("\t");
167		for (j = 0; j < 8; j++)
168			printf("0x%02x,%c", invtbl[exptbl[i + j] ^ 1],
169			       (j == 7) ? '\n' : ' ');
170	}
171	printf("};\n");
172	printf("#ifdef __KERNEL__\n");
173	printf("EXPORT_SYMBOL(raid6_gfexi);\n");
174	printf("#endif\n");
175
176	return 0;
177}
178