lib/raid6/mktables.c

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This source file includes following definitions.
gfmul
gfpow
main
   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("#include <linux/export.h>\n");
  60         printf("#include <linux/raid/pq.h>\n");
  61 
  62         /* Compute multiplication table */
  63         printf("\nconst u8  __attribute__((aligned(256)))\n"
  64                 "raid6_gfmul[256][256] =\n"
  65                 "{\n");
  66         for (i = 0; i < 256; i++) {
  67                 printf("\t{\n");
  68                 for (j = 0; j < 256; j += 8) {
  69                         printf("\t\t");
  70                         for (k = 0; k < 8; k++)
  71                                 printf("0x%02x,%c", gfmul(i, j + k),
  72                                        (k == 7) ? '\n' : ' ');
  73                 }
  74                 printf("\t},\n");
  75         }
  76         printf("};\n");
  77         printf("#ifdef __KERNEL__\n");
  78         printf("EXPORT_SYMBOL(raid6_gfmul);\n");
  79         printf("#endif\n");
  80 
  81         /* Compute vector multiplication table */
  82         printf("\nconst u8  __attribute__((aligned(256)))\n"
  83                 "raid6_vgfmul[256][32] =\n"
  84                 "{\n");
  85         for (i = 0; i < 256; i++) {
  86                 printf("\t{\n");
  87                 for (j = 0; j < 16; j += 8) {
  88                         printf("\t\t");
  89                         for (k = 0; k < 8; k++)
  90                                 printf("0x%02x,%c", gfmul(i, j + k),
  91                                        (k == 7) ? '\n' : ' ');
  92                 }
  93                 for (j = 0; j < 16; j += 8) {
  94                         printf("\t\t");
  95                         for (k = 0; k < 8; k++)
  96                                 printf("0x%02x,%c", gfmul(i, (j + k) << 4),
  97                                        (k == 7) ? '\n' : ' ');
  98                 }
  99                 printf("\t},\n");
 100         }
 101         printf("};\n");
 102         printf("#ifdef __KERNEL__\n");
 103         printf("EXPORT_SYMBOL(raid6_vgfmul);\n");
 104         printf("#endif\n");
 105 
 106         /* Compute power-of-2 table (exponent) */
 107         v = 1;
 108         printf("\nconst u8 __attribute__((aligned(256)))\n"
 109                "raid6_gfexp[256] =\n" "{\n");
 110         for (i = 0; i < 256; i += 8) {
 111                 printf("\t");
 112                 for (j = 0; j < 8; j++) {
 113                         exptbl[i + j] = v;
 114                         printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
 115                         v = gfmul(v, 2);
 116                         if (v == 1)
 117                                 v = 0;  /* For entry 255, not a real entry */
 118                 }
 119         }
 120         printf("};\n");
 121         printf("#ifdef __KERNEL__\n");
 122         printf("EXPORT_SYMBOL(raid6_gfexp);\n");
 123         printf("#endif\n");
 124 
 125         /* Compute log-of-2 table */
 126         printf("\nconst u8 __attribute__((aligned(256)))\n"
 127                "raid6_gflog[256] =\n" "{\n");
 128         for (i = 0; i < 256; i += 8) {
 129                 printf("\t");
 130                 for (j = 0; j < 8; j++) {
 131                         v = 255;
 132                         for (k = 0; k < 256; k++)
 133                                 if (exptbl[k] == (i + j)) {
 134                                         v = k;
 135                                         break;
 136                                 }
 137                         printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
 138                 }
 139         }
 140         printf("};\n");
 141         printf("#ifdef __KERNEL__\n");
 142         printf("EXPORT_SYMBOL(raid6_gflog);\n");
 143         printf("#endif\n");
 144 
 145         /* Compute inverse table x^-1 == x^254 */
 146         printf("\nconst u8 __attribute__((aligned(256)))\n"
 147                "raid6_gfinv[256] =\n" "{\n");
 148         for (i = 0; i < 256; i += 8) {
 149                 printf("\t");
 150                 for (j = 0; j < 8; j++) {
 151                         invtbl[i + j] = v = gfpow(i + j, 254);
 152                         printf("0x%02x,%c", v, (j == 7) ? '\n' : ' ');
 153                 }
 154         }
 155         printf("};\n");
 156         printf("#ifdef __KERNEL__\n");
 157         printf("EXPORT_SYMBOL(raid6_gfinv);\n");
 158         printf("#endif\n");
 159 
 160         /* Compute inv(2^x + 1) (exponent-xor-inverse) table */
 161         printf("\nconst u8 __attribute__((aligned(256)))\n"
 162                "raid6_gfexi[256] =\n" "{\n");
 163         for (i = 0; i < 256; i += 8) {
 164                 printf("\t");
 165                 for (j = 0; j < 8; j++)
 166                         printf("0x%02x,%c", invtbl[exptbl[i + j] ^ 1],
 167                                (j == 7) ? '\n' : ' ');
 168         }
 169         printf("};\n");
 170         printf("#ifdef __KERNEL__\n");
 171         printf("EXPORT_SYMBOL(raid6_gfexi);\n");
 172         printf("#endif\n");
 173 
 174         return 0;
 175 }
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root/lib/raid6/mktables.c

DEFINITIONS
