lib/raid6/mktables.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* -*- linux-c -*- ------------------------------------------------------- *
0003  *
0004  *   Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
0005  *
0006  * ----------------------------------------------------------------------- */
0007
0008 /*
0009  * mktables.c
0010  *
0011  * Make RAID-6 tables.  This is a host user space program to be run at
0012  * compile time.
0013  */
0014
0015 #include <stdio.h>
0016 #include <string.h>
0017 #include <inttypes.h>
0018 #include <stdlib.h>
0019 #include <time.h>
0020
0021 static uint8_t gfmul(uint8_t a, uint8_t b)
0022 {
0023     uint8_t v = 0;
0024
0025     while (b) {
0026         if (b & 1)
0027             v ^= a;
0028         a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);
0029         b >>= 1;
0030     }
0031
0032     return v;
0033 }
0034
0035 static uint8_t gfpow(uint8_t a, int b)
0036 {
0037     uint8_t v = 1;
0038
0039     b %= 255;
0040     if (b < 0)
0041         b += 255;
0042
0043     while (b) {
0044         if (b & 1)
0045             v = gfmul(v, a);
0046         a = gfmul(a, a);
0047         b >>= 1;
0048     }
0049
0050     return v;
0051 }
0052
0053 int main(int argc, char *argv[])
0054 {
0055     int i, j, k;
0056     uint8_t v;
0057     uint8_t exptbl[256], invtbl[256];
0058
0059     printf("#include <linux/export.h>\n");
0060     printf("#include <linux/raid/pq.h>\n");
0061
0062     /* Compute multiplication table */
0063     printf("\nconst u8  __attribute__((aligned(256)))\n"
0064         "raid6_gfmul[256][256] =\n"
0065         "{\n");
0066     for (i = 0; i < 256; i++) {
0067         printf("\t{\n");
0068         for (j = 0; j < 256; j += 8) {
0069             printf("\t\t");
0070             for (k = 0; k < 8; k++)
0071                 printf("0x%02x,%c", gfmul(i, j + k),
0072                        (k == 7) ? '\n' : ' ');
0073         }
0074         printf("\t},\n");
0075     }
0076     printf("};\n");
0077     printf("#ifdef __KERNEL__\n");
0078     printf("EXPORT_SYMBOL(raid6_gfmul);\n");
0079     printf("#endif\n");
0080
0081     /* Compute vector multiplication table */
0082     printf("\nconst u8  __attribute__((aligned(256)))\n"
0083         "raid6_vgfmul[256][32] =\n"
0084         "{\n");
0085     for (i = 0; i < 256; i++) {
0086         printf("\t{\n");
0087         for (j = 0; j < 16; j += 8) {
0088             printf("\t\t");
0089             for (k = 0; k < 8; k++)
0090                 printf("0x%02x,%c", gfmul(i, j + k),
0091                        (k == 7) ? '\n' : ' ');
0092         }
0093         for (j = 0; j < 16; j += 8) {
0094             printf("\t\t");
0095             for (k = 0; k < 8; k++)
0096                 printf("0x%02x,%c", gfmul(i, (j + k) << 4),
0097                        (k == 7) ? '\n' : ' ');
0098         }
0099         printf("\t},\n");
0100     }
0101     printf("};\n");
0102     printf("#ifdef __KERNEL__\n");
0103     printf("EXPORT_SYMBOL(raid6_vgfmul);\n");
0104     printf("#endif\n");
0105
0106     /* Compute power-of-2 table (exponent) */
0107     v = 1;
0108     printf("\nconst u8 __attribute__((aligned(256)))\n"
0109            "raid6_gfexp[256] =\n" "{\n");
0110     for (i = 0; i < 256; i += 8) {
0111         printf("\t");
0112         for (j = 0; j < 8; j++) {
0113             exptbl[i + j] = v;
0114             printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
0115             v = gfmul(v, 2);
0116             if (v == 1)
0117                 v = 0;  /* For entry 255, not a real entry */
0118         }
0119     }
0120     printf("};\n");
0121     printf("#ifdef __KERNEL__\n");
0122     printf("EXPORT_SYMBOL(raid6_gfexp);\n");
0123     printf("#endif\n");
0124
0125     /* Compute log-of-2 table */
0126     printf("\nconst u8 __attribute__((aligned(256)))\n"
0127            "raid6_gflog[256] =\n" "{\n");
0128     for (i = 0; i < 256; i += 8) {
0129         printf("\t");
0130         for (j = 0; j < 8; j++) {
0131             v = 255;
0132             for (k = 0; k < 256; k++)
0133                 if (exptbl[k] == (i + j)) {
0134                     v = k;
0135                     break;
0136                 }
0137             printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
0138         }
0139     }
0140     printf("};\n");
0141     printf("#ifdef __KERNEL__\n");
0142     printf("EXPORT_SYMBOL(raid6_gflog);\n");
0143     printf("#endif\n");
0144
0145     /* Compute inverse table x^-1 == x^254 */
0146     printf("\nconst u8 __attribute__((aligned(256)))\n"
0147            "raid6_gfinv[256] =\n" "{\n");
0148     for (i = 0; i < 256; i += 8) {
0149         printf("\t");
0150         for (j = 0; j < 8; j++) {
0151             invtbl[i + j] = v = gfpow(i + j, 254);
0152             printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
0153         }
0154     }
0155     printf("};\n");
0156     printf("#ifdef __KERNEL__\n");
0157     printf("EXPORT_SYMBOL(raid6_gfinv);\n");
0158     printf("#endif\n");
0159
0160     /* Compute inv(2^x + 1) (exponent-xor-inverse) table */
0161     printf("\nconst u8 __attribute__((aligned(256)))\n"
0162            "raid6_gfexi[256] =\n" "{\n");
0163     for (i = 0; i < 256; i += 8) {
0164         printf("\t");
0165         for (j = 0; j < 8; j++)
0166             printf("0x%02x,%c", invtbl[exptbl[i + j] ^ 1],
0167                    (j == 7) ? '\n' : ' ');
0168     }
0169     printf("};\n");
0170     printf("#ifdef __KERNEL__\n");
0171     printf("EXPORT_SYMBOL(raid6_gfexi);\n");
0172     printf("#endif\n");
0173
0174     return 0;
0175 }