ceph/src/erasure-code/jerasure/gf-complete/tools/gf_mult.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_mult.c
   7  *
   8  * Multiplies two numbers in gf_2^w
   9  */
  10
  11 #include <stdio.h>
  12 #include <getopt.h>
  13 #include <stdint.h>
  14 #include <string.h>
  15 #include <stdlib.h>
  16
  17 #include "gf_complete.h"
  18 #include "gf_method.h"
  19 #include "gf_general.h"
  20
  21 void usage(int why)
  22 {
  23   fprintf(stderr, "usage: gf_mult a b w [method] - does multiplication of a and b in GF(2^w)\n");
  24   if (why == 'W') {
  25     fprintf(stderr, "Bad w.\n");
  26     fprintf(stderr, "Legal w are: 1 - 32, 64 and 128.\n");
  27     fprintf(stderr, "Append 'h' to w to treat a, b and the product as hexadecimal.\n");
  28     fprintf(stderr, "w=128 is hex only (i.e. '128' will be an error - do '128h')\n");
  29   }
  30   if (why == 'A') fprintf(stderr, "Bad a\n");
  31   if (why == 'B') fprintf(stderr, "Bad b\n");
  32   if (why == 'M') {
  33     fprintf(stderr, "Bad Method Specification: ");
  34     gf_error();
  35   }
  36   exit(1);
  37 }
  38
  39 int main(int argc, char **argv)
  40 {
  41   int hex, w;
  42   gf_t gf;
  43   gf_general_t a, b, c;
  44   char output[50];
  45
  46   if (argc < 4) usage(' ');
  47
  48   if (sscanf(argv[3], "%d", &w) == 0) usage('W');
  49   if (w <= 0 || (w > 32 && w != 64 && w != 128)) usage('W');
  50
  51   hex = (strchr(argv[3], 'h') != NULL);
  52   if (!hex && w == 128) usage('W');
  53
  54   if (argc == 4) {
  55     if (gf_init_easy(&gf, w) == 0) usage('M');
  56   } else {
  57     if (create_gf_from_argv(&gf, w, argc, argv, 4) == 0) usage('M');
  58   }
  59
  60   if (!gf_general_s_to_val(&a, w, argv[1], hex)) usage('A');
  61   if (!gf_general_s_to_val(&b, w, argv[2], hex)) usage('B');
  62
  63   gf_general_multiply(&gf, &a, &b, &c);
  64   gf_general_val_to_s(&c, w, output, hex);
  65
  66   printf("%s\n", output);
  67   exit(0);
  68 }