lib/raid6/mktables.c

   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
  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
  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
  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 }