xref: /linux/lib/raid6/mktables.c (revision a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0)
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 
gfmul(uint8_t a,uint8_t b)21 static 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 
gfpow(uint8_t a,int b)35 static 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 
main(int argc,char * argv[])53 int 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