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#ident "$Id: mktables.c,v 1.2 2002/12/12 22:41:27 hpa Exp $"

/* ----------------------------------------------------------------------- *

 *

 *   Copyright 2002 H. Peter Anvin - All Rights Reserved

 *

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,

 *   Bostom MA 02111-1307, USA; either version 2 of the License, or

 *   (at your option) any later version; incorporated herein by reference.

 *

 * ----------------------------------------------------------------------- */

/*

 * mktables.c

 *

 * Make RAID-6 tables.  This is a host user space program to be run at

 * compile time.

 */

#include <stdio.h>

#include <string.h>

#include <inttypes.h>

#include <stdlib.h>

#include <time.h>

static uint8_t gfmul(uint8_t a, uint8_t b)

{

  uint8_t v = 0;

  while ( b ) {

    if ( b & 1 ) v ^= a;

    a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);

    b >>= 1;

  }

  return v;

}

static uint8_t gfpow(uint8_t a, int b)

{

  uint8_t v = 1;

  b %= 255;

  if ( b < 0 )

    b += 255;

  while ( b ) {

    if ( b & 1 ) v = gfmul(v,a);

    a = gfmul(a,a);

    b >>= 1;

  }

  return v;

}

int main(int argc, char *argv[])

{

  int i, j, k;

  uint8_t v;

  uint8_t exptbl[256], invtbl[256];

  printf("#include \"raid6.h\"\n");

  /* Compute multiplication table */

  printf("\nconst u8  __attribute__((aligned(256)))\n"

         "raid6_gfmul[256][256] =\n"

         "{\n");

  for ( i = 0 ; i < 256 ; i++ ) {

    printf("\t{\n");

    for ( j = 0 ; j < 256 ; j += 8 ) {

      printf("\t\t");

      for ( k = 0 ; k < 8 ; k++ ) {

        printf("0x%02x, ", gfmul(i,j+k));

      }

      printf("\n");

    }

    printf("\t},\n");

  }

  printf("};\n");

  /* Compute power-of-2 table (exponent) */

  v = 1;

  printf("\nconst u8 __attribute__((aligned(256)))\n"

         "raid6_gfexp[256] =\n"

         "{\n");

  for ( i = 0 ; i < 256 ; i += 8 ) {

    printf("\t");

    for ( j = 0 ; j < 8 ; j++ ) {

      exptbl[i+j] = v;

      printf("0x%02x, ", v);

      v = gfmul(v,2);

      if ( v == 1 ) v = 0;       /* For entry 255, not a real entry */

    }

    printf("\n");

  }

  printf("};\n");

  /* Compute inverse table x^-1 == x^254 */

  printf("\nconst u8 __attribute__((aligned(256)))\n"

         "raid6_gfinv[256] =\n"

         "{\n");

  for ( i = 0 ; i < 256 ; i += 8 ) {

    printf("\t");

    for ( j = 0 ; j < 8 ; j++ ) {

      invtbl[i+j] = v = gfpow(i+j,254);

      printf("0x%02x, ", v);

    }

    printf("\n");

  }

  printf("};\n");

  /* Compute inv(2^x + 1) (exponent-xor-inverse) table */

  printf("\nconst u8 __attribute__((aligned(256)))\n"

         "raid6_gfexi[256] =\n"

         "{\n");

  for ( i = 0 ; i < 256 ; i += 8 ) {

    printf("\t");

    for ( j = 0 ; j < 8 ; j++ ) {

      printf("0x%02x, ", invtbl[exptbl[i+j]^1]);

    }

    printf("\n");

  }

  printf("};\n\n");

  return 0;

}