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drivers/md/mktables.c
2.52 KB
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/* -*- 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 * the terms of the GNU General Public License version 2 or (at your * option) any later version; incorporated herein by reference. |
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* * ----------------------------------------------------------------------- */ /* * 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) { |
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uint8_t v = 0; while (b) { if (b & 1) v ^= a; a = (a << 1) ^ (a & 0x80 ? 0x1d : 0); b >>= 1; } return v; |
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} static uint8_t gfpow(uint8_t a, int b) { |
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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; |
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} int main(int argc, char *argv[]) { |
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int i, j, k; uint8_t v; uint8_t exptbl[256], invtbl[256]; printf("#include \"raid6.h\" "); /* Compute multiplication table */ printf(" const u8 __attribute__((aligned(256))) " "raid6_gfmul[256][256] = " "{ "); for (i = 0; i < 256; i++) { printf("\t{ "); for (j = 0; j < 256; j += 8) { printf("\t\t"); for (k = 0; k < 8; k++) |
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printf("0x%02x,%c", gfmul(i, j + k), (k == 7) ? ' ' : ' '); |
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} printf("\t}, "); } printf("}; "); /* Compute power-of-2 table (exponent) */ v = 1; printf(" const u8 __attribute__((aligned(256))) " |
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"raid6_gfexp[256] = " "{ "); |
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for (i = 0; i < 256; i += 8) { printf("\t"); for (j = 0; j < 8; j++) { |
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exptbl[i + j] = v; printf("0x%02x,%c", v, (j == 7) ? ' ' : ' '); |
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v = gfmul(v, 2); if (v == 1) v = 0; /* For entry 255, not a real entry */ } |
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} printf("}; "); /* Compute inverse table x^-1 == x^254 */ printf(" const u8 __attribute__((aligned(256))) " |
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"raid6_gfinv[256] = " "{ "); |
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for (i = 0; i < 256; i += 8) { printf("\t"); for (j = 0; j < 8; j++) { |
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invtbl[i + j] = v = gfpow(i + j, 254); printf("0x%02x,%c", v, (j == 7) ? ' ' : ' '); |
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} |
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} printf("}; "); /* Compute inv(2^x + 1) (exponent-xor-inverse) table */ printf(" const u8 __attribute__((aligned(256))) " |
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"raid6_gfexi[256] = " "{ "); |
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for (i = 0; i < 256; i += 8) { printf("\t"); for (j = 0; j < 8; j++) |
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printf("0x%02x,%c", invtbl[exptbl[i + j] ^ 1], (j == 7) ? ' ' : ' '); |
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} |
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printf("}; "); |
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return 0; |
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} |