#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; }