ceph/src/erasure-code/jerasure/gf-complete/examples/gf_example_3.c

   1 /*
   2  * GF-Complete: A Comprehensive Open Source Library for Galois Field Arithmetic
   3  * James S. Plank, Ethan L. Miller, Kevin M. Greenan,
   4  * Benjamin A. Arnold, John A. Burnum, Adam W. Disney, Allen C. McBride.
   5  *
   6  * gf_example_3.c
   7  *
   8  * Identical to example_2 except it works in GF(2^64)
   9  */
  10
  11 #include <stdio.h>
  12 #include <getopt.h>
  13 #include <stdint.h>
  14 #include <string.h>
  15 #include <stdlib.h>
  16 #include <time.h>
  17
  18 #include "gf_complete.h"
  19 #include "gf_rand.h"
  20
  21 void usage(char *s)
  22 {
  23   fprintf(stderr, "usage: gf_example_3\n");
  24   exit(1);
  25 }
  26
  27 int main(int argc, char **argv)
  28 {
  29   uint64_t a, b, c;
  30   uint64_t *r1, *r2;
  31   int i;
  32   gf_t gf;
  33
  34   if (argc != 1) usage(NULL);
  35
  36   /* Get two random numbers in a and b */
  37
  38   MOA_Seed(time(0));
  39   a = MOA_Random_64();
  40   b = MOA_Random_64();
  41
  42   /* Create the proper instance of the gf_t object using defaults: */
  43
  44   gf_init_easy(&gf, 64);
  45
  46   /* And multiply a and b using the galois field: */
  47
  48   c = gf.multiply.w64(&gf, a, b);
  49   printf("%llx * %llx = %llx\n", (long long unsigned int) a, (long long unsigned int) b, (long long unsigned int) c);
  50
  51   /* Divide the product by a and b */
  52
  53   printf("%llx / %llx = %llx\n", (long long unsigned int) c, (long long unsigned int) a, (long long unsigned int) gf.divide.w64(&gf, c, a));
  54   printf("%llx / %llx = %llx\n", (long long unsigned int) c, (long long unsigned int) b, (long long unsigned int) gf.divide.w64(&gf, c, b));
  55
  56   r1 = (uint64_t *) malloc(32);
  57   r2 = (uint64_t *) malloc(32);
  58
  59   r1[0] = b;
  60
  61   for (i = 1; i < 4; i++) r1[i] = MOA_Random_64();
  62
  63   gf.multiply_region.w64(&gf, r1, r2, a, 32, 0);
  64
  65   printf("\nmultiply_region by %llx\n\n", (long long unsigned int) a);
  66   printf("R1 (the source):  ");
  67   for (i = 0; i < 4; i++) printf(" %016llx", (long long unsigned int) r1[i]);
  68
  69   printf("\nR2 (the product): ");
  70   for (i = 0; i < 4; i++) printf(" %016llx", (long long unsigned int) r2[i]);
  71   printf("\n");
  72
  73   exit(0);
  74 }