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/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2 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,%c", gfmul(i, j + k),
(k == 7) ? '\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,%c", v, (j == 7) ? '\n' : ' ');
v = gfmul(v, 2);
if (v == 1)
v = 0; /* For entry 255, not a real entry */
}
}
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,%c", v, (j == 7) ? '\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,%c", invtbl[exptbl[i + j] ^ 1],
(j == 7) ? '\n' : ' ');
}
printf("};\n");
return 0;
}
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