126 строки
2.8 KiB
C
126 строки
2.8 KiB
C
#ident "$Id: mktables.c,v 1.2 2002/12/12 22:41:27 hpa Exp $"
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/* ----------------------------------------------------------------------- *
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*
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* Copyright 2002 H. Peter Anvin - All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
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* Bostom MA 02111-1307, USA; either version 2 of the License, or
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* (at your option) any later version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* mktables.c
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*
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* Make RAID-6 tables. This is a host user space program to be run at
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* compile time.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <inttypes.h>
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#include <stdlib.h>
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#include <time.h>
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static uint8_t gfmul(uint8_t a, uint8_t b)
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{
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uint8_t v = 0;
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while ( b ) {
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if ( b & 1 ) v ^= a;
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a = (a << 1) ^ (a & 0x80 ? 0x1d : 0);
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b >>= 1;
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}
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return v;
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}
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static uint8_t gfpow(uint8_t a, int b)
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{
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uint8_t v = 1;
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b %= 255;
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if ( b < 0 )
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b += 255;
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while ( b ) {
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if ( b & 1 ) v = gfmul(v,a);
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a = gfmul(a,a);
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b >>= 1;
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}
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return v;
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}
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int main(int argc, char *argv[])
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{
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int i, j, k;
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uint8_t v;
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uint8_t exptbl[256], invtbl[256];
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printf("#include \"raid6.h\"\n");
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/* Compute multiplication table */
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printf("\nconst u8 __attribute__((aligned(256)))\n"
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"raid6_gfmul[256][256] =\n"
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"{\n");
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for ( i = 0 ; i < 256 ; i++ ) {
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printf("\t{\n");
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for ( j = 0 ; j < 256 ; j += 8 ) {
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printf("\t\t");
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for ( k = 0 ; k < 8 ; k++ ) {
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printf("0x%02x, ", gfmul(i,j+k));
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}
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printf("\n");
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}
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printf("\t},\n");
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}
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printf("};\n");
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/* Compute power-of-2 table (exponent) */
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v = 1;
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printf("\nconst u8 __attribute__((aligned(256)))\n"
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"raid6_gfexp[256] =\n"
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"{\n");
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for ( i = 0 ; i < 256 ; i += 8 ) {
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printf("\t");
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for ( j = 0 ; j < 8 ; j++ ) {
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exptbl[i+j] = v;
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printf("0x%02x, ", v);
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v = gfmul(v,2);
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if ( v == 1 ) v = 0; /* For entry 255, not a real entry */
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}
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printf("\n");
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}
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printf("};\n");
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/* Compute inverse table x^-1 == x^254 */
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printf("\nconst u8 __attribute__((aligned(256)))\n"
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"raid6_gfinv[256] =\n"
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"{\n");
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for ( i = 0 ; i < 256 ; i += 8 ) {
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printf("\t");
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for ( j = 0 ; j < 8 ; j++ ) {
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invtbl[i+j] = v = gfpow(i+j,254);
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printf("0x%02x, ", v);
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}
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printf("\n");
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}
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printf("};\n");
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/* Compute inv(2^x + 1) (exponent-xor-inverse) table */
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printf("\nconst u8 __attribute__((aligned(256)))\n"
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"raid6_gfexi[256] =\n"
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"{\n");
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for ( i = 0 ; i < 256 ; i += 8 ) {
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printf("\t");
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for ( j = 0 ; j < 8 ; j++ ) {
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printf("0x%02x, ", invtbl[exptbl[i+j]^1]);
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}
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printf("\n");
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}
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printf("};\n\n");
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return 0;
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}
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