drivers/md/mktables.c

   1 #ident "$Id: mktables.c,v 1.2 2002/12/12 22:41:27 hpa Exp $"
   2 /* ----------------------------------------------------------------------- *
   3  *
   4  *   Copyright 2002 H. Peter Anvin - All Rights Reserved
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   9  *   Bostom MA 02111-1307, USA; either version 2 of the License, or
  10  *   (at your option) any later version; incorporated herein by reference.
  11  *
  12  * ----------------------------------------------------------------------- */
  13
  14 /*
  15  * mktables.c
  16  *
  17  * Make RAID-6 tables.  This is a host user space program to be run at
  18  * compile time.
  19  */
  20
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <inttypes.h>
  24 #include <stdlib.h>
  25 #include <time.h>
  26
  27 static uint8_t gfmul(uint8_t a, uint8_t b)
  28 {
  29   uint8_t v = 0;
  30
  31   while ( b ) {
  32     if ( b & 1 ) v ^= a;
  33     a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);
  34     b >>= 1;
  35   }
  36   return v;
  37 }
  38
  39 static uint8_t gfpow(uint8_t a, int b)
  40 {
  41   uint8_t v = 1;
  42
  43   b %= 255;
  44   if ( b < 0 )
  45     b += 255;
  46
  47   while ( b ) {
  48     if ( b & 1 ) v = gfmul(v,a);
  49     a = gfmul(a,a);
  50     b >>= 1;
  51   }
  52   return v;
  53 }
  54
  55 int main(int argc, char *argv[])
  56 {
  57   int i, j, k;
  58   uint8_t v;
  59   uint8_t exptbl[256], invtbl[256];
  60
  61   printf("#include \"raid6.h\"\n");
  62
  63   /* Compute multiplication table */
  64   printf("\nconst u8  __attribute__((aligned(256)))\n"
  65          "raid6_gfmul[256][256] =\n"
  66          "{\n");
  67   for ( i = 0 ; i < 256 ; i++ ) {
  68     printf("\t{\n");
  69     for ( j = 0 ; j < 256 ; j += 8 ) {
  70       printf("\t\t");
  71       for ( k = 0 ; k < 8 ; k++ ) {
  72         printf("0x%02x, ", gfmul(i,j+k));
  73       }
  74       printf("\n");
  75     }
  76     printf("\t},\n");
  77   }
  78   printf("};\n");
  79
  80   /* Compute power-of-2 table (exponent) */
  81   v = 1;
  82   printf("\nconst u8 __attribute__((aligned(256)))\n"
  83          "raid6_gfexp[256] =\n"
  84          "{\n");
  85   for ( i = 0 ; i < 256 ; i += 8 ) {
  86     printf("\t");
  87     for ( j = 0 ; j < 8 ; j++ ) {
  88       exptbl[i+j] = v;
  89       printf("0x%02x, ", v);
  90       v = gfmul(v,2);
  91       if ( v == 1 ) v = 0;      /* For entry 255, not a real entry */
  92     }
  93     printf("\n");
  94   }
  95   printf("};\n");
  96
  97   /* Compute inverse table x^-1 == x^254 */
  98   printf("\nconst u8 __attribute__((aligned(256)))\n"
  99          "raid6_gfinv[256] =\n"
 100          "{\n");
 101   for ( i = 0 ; i < 256 ; i += 8 ) {
 102     printf("\t");
 103     for ( j = 0 ; j < 8 ; j++ ) {
 104       invtbl[i+j] = v = gfpow(i+j,254);
 105       printf("0x%02x, ", v);
 106     }
 107     printf("\n");
 108   }
 109   printf("};\n");
 110
 111   /* Compute inv(2^x + 1) (exponent-xor-inverse) table */
 112   printf("\nconst u8 __attribute__((aligned(256)))\n"
 113          "raid6_gfexi[256] =\n"
 114          "{\n");
 115   for ( i = 0 ; i < 256 ; i += 8 ) {
 116     printf("\t");
 117     for ( j = 0 ; j < 8 ; j++ ) {
 118       printf("0x%02x, ", invtbl[exptbl[i+j]^1]);
 119     }
 120     printf("\n");
 121   }
 122   printf("};\n\n");
 123
 124   return 0;
 125 }