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