/* -*- 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 <linux/raid/pq.h>
  ");
  	printf("#include <linux/export.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++)
  				printf("0x%02x,%c", gfmul(i, j + k),
  				       (k == 7) ? '
  ' : ' ');
  		}
  		printf("\t},
  ");
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_gfmul);
  ");
  	printf("#endif
  ");
  
  	/* Compute vector multiplication table */
  	printf("
  const u8  __attribute__((aligned(256)))
  "
  		"raid6_vgfmul[256][32] =
  "
  		"{
  ");
  	for (i = 0; i < 256; i++) {
  		printf("\t{
  ");
  		for (j = 0; j < 16; j += 8) {
  			printf("\t\t");
  			for (k = 0; k < 8; k++)
  				printf("0x%02x,%c", gfmul(i, j + k),
  				       (k == 7) ? '
  ' : ' ');
  		}
  		for (j = 0; j < 16; j += 8) {
  			printf("\t\t");
  			for (k = 0; k < 8; k++)
  				printf("0x%02x,%c", gfmul(i, (j + k) << 4),
  				       (k == 7) ? '
  ' : ' ');
  		}
  		printf("\t},
  ");
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_vgfmul);
  ");
  	printf("#endif
  ");
  
  	/* Compute power-of-2 table (exponent) */
  	v = 1;
  	printf("
  const u8 __attribute__((aligned(256)))
  "
  	       "raid6_gfexp[256] =
  " "{
  ");
  	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) ? '
  ' : ' ');
  			v = gfmul(v, 2);
  			if (v == 1)
  				v = 0;	/* For entry 255, not a real entry */
  		}
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_gfexp);
  ");
  	printf("#endif
  ");
  
  	/* Compute log-of-2 table */
  	printf("
  const u8 __attribute__((aligned(256)))
  "
  	       "raid6_gflog[256] =
  " "{
  ");
  	for (i = 0; i < 256; i += 8) {
  		printf("\t");
  		for (j = 0; j < 8; j++) {
  			v = 255;
  			for (k = 0; k < 256; k++)
  				if (exptbl[k] == (i + j)) {
  					v = k;
  					break;
  				}
  			printf("0x%02x,%c", v, (j == 7) ? '
  ' : ' ');
  		}
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_gflog);
  ");
  	printf("#endif
  ");
  
  	/* Compute inverse table x^-1 == x^254 */
  	printf("
  const u8 __attribute__((aligned(256)))
  "
  	       "raid6_gfinv[256] =
  " "{
  ");
  	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) ? '
  ' : ' ');
  		}
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_gfinv);
  ");
  	printf("#endif
  ");
  
  	/* Compute inv(2^x + 1) (exponent-xor-inverse) table */
  	printf("
  const u8 __attribute__((aligned(256)))
  "
  	       "raid6_gfexi[256] =
  " "{
  ");
  	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) ? '
  ' : ' ');
  	}
  	printf("};
  ");
  	printf("#ifdef __KERNEL__
  ");
  	printf("EXPORT_SYMBOL(raid6_gfexi);
  ");
  	printf("#endif
  ");
  
  	return 0;
  }