#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;
}
