minix/commands/swifi/tests/rnd.c

   1 /*
   2 rnd.c
   3
   4 Generate random numbers
   5 */
   6
   7 #include <stdarg.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <unistd.h>
  12
  13 static char *progname;
  14
  15 static void fatal(char *fmt, ...);
  16 static void usage(void);
  17
  18 int main(int argc, char *argv[])
  19 {
  20         int c, i, count;
  21         unsigned long n, v, high, modulus;
  22         unsigned seed;
  23         char *check;
  24         char *c_arg, *m_arg, *s_arg;
  25
  26         (progname=strrchr(argv[0],'/')) ? progname++ : (progname=argv[0]);
  27
  28         c_arg= m_arg= s_arg= NULL;
  29         while (c= getopt(argc, argv, "?c:m:s:"), c != -1)
  30         {
  31                 switch(c)
  32                 {
  33                 case 'c': c_arg= optarg; break;
  34                 case 'm': m_arg= optarg; break;
  35                 case 's': s_arg= optarg; break;
  36                 default:
  37                         fatal("getopt failed: '%c'", c);
  38                 }
  39         }
  40         if (optind != argc)
  41                 usage();
  42         if (c_arg)
  43         {
  44                 count= strtol(c_arg, &check, 0);
  45                 if (check[0] != '\0')
  46                         fatal("bad count '%s'", c_arg);
  47         }
  48         else
  49                 count= 1;
  50         if (m_arg)
  51         {
  52                 modulus= strtoul(m_arg, &check, 0);
  53                 if (check[0] != '\0' || modulus == 0)
  54                         fatal("bad modulus '%s'", m_arg);
  55                 n= 0x80000000UL / modulus;
  56                 if (n == 0)
  57                         fatal("bad modulus %lu (too big)", modulus);
  58                 high= n * modulus;
  59         }
  60         else
  61                 modulus= high= 0x80000000UL;
  62         if (s_arg)
  63         {
  64                 seed= strtol(s_arg, &check, 0);
  65                 if (check[0] != '\0')
  66                         fatal("bad seed '%s'", s_arg);
  67                 srandom(seed);
  68         }
  69
  70         for (i= 0; i<count; i++)
  71         {
  72                 do
  73                 {
  74                         v= random();
  75                 } while (v > high);
  76
  77                 printf("%lu\n", v % modulus);
  78         }
  79 }
  80
  81 static void fatal(char *fmt, ...)
  82 {
  83         va_list ap;
  84
  85         fprintf(stderr, "%s: ", progname);
  86         va_start(ap, fmt);
  87         vfprintf(stderr, fmt, ap);
  88         va_end(ap);
  89         fprintf(stderr, "\n");
  90         exit(1);
  91 }
  92
  93 static void usage(void)
  94 {
  95         fprintf(stderr, "Usage: rnd [-c <count>] [-m <modulus>] [-s <seed>]\n");
  96         exit(1);
  97 }