Home | History | Annotate | Download | only in tests 
      1 /** An OpenMP example.
      2  *  Based on the example listed on the following web page:
      3  *  http://developers.sun.com/sunstudio/downloads/ssx/tha/tha_using.html
      4  */
      5 
      6 
      7 #include <assert.h>
      8 #include <math.h>
      9 #include <omp.h>
     10 #include <stdio.h>
     11 #include <stdlib.h>
     12 #include <unistd.h>  // getopt()
     13 #include "../../drd/drd.h"
     14 
     15 
     16 static int is_prime(int* const pflag, int v)
     17 {
     18   int i;
     19   int bound = floor(sqrt ((double)v)) + 1;
     20 
     21   for (i = 2; i < bound; i++)
     22   {
     23     /* No need to check against known composites */
     24     if (!pflag[i])
     25       continue;
     26     if (v % i == 0)
     27     {
     28       pflag[v] = 0;
     29       return 0;
     30     }
     31   }
     32   return (v > 1);
     33 }
     34 
     35 int main(int argc, char **argv)
     36 {
     37   int i;
     38   int total = 0;
     39   int trace_total = 0;
     40   int silent = 0;
     41   int n;
     42   int num_threads = 2;
     43   int optchar;
     44   int* primes;
     45   int* pflag;
     46 
     47   while ((optchar = getopt(argc, argv, "qt:v")) != EOF)
     48   {
     49     switch (optchar)
     50     {
     51     case 'q':
     52       silent = 1;
     53       break;
     54     case 't':
     55       num_threads = atoi(optarg);
     56       break;
     57     case 'v':
     58       trace_total = 1;
     59       break;
     60     default:
     61       fprintf(stderr, "Error: unknown option '%c'.\n", optchar);
     62       return 1;
     63     }
     64   }
     65 
     66   if (optind + 1 != argc)
     67   {
     68     fprintf(stderr, "Error: wrong number of arguments.\n");
     69     return 1;
     70   }
     71   n = atoi(argv[optind]);
     72 
     73   // Not the most user-friendly way to do error checking, but better than
     74   // nothing.
     75   assert(n > 2);
     76   assert(num_threads >= 1);
     77 
     78   primes = malloc(n * sizeof(primes[0]));
     79   pflag  = malloc(n * sizeof(pflag[0]));
     80 
     81   omp_set_num_threads(num_threads);
     82   omp_set_dynamic(0);
     83 
     84   for (i = 0; i < n; i++) {
     85     pflag[i] = 1;
     86   }
     87 
     88   if (trace_total)
     89     DRD_TRACE_VAR(total);
     90 
     91 #pragma omp parallel for
     92   for (i = 2; i < n; i++)
     93   {
     94     if (is_prime(pflag, i))
     95     {
     96       primes[total] = i;
     97       total++;
     98     }
     99   }
    100   if (! silent)
    101   {
    102     printf("Number of prime numbers between 2 and %d: %d\n",
    103            n, total);
    104     for (i = 0; i < total; i++)
    105     {
    106       printf("%d\n", primes[i]);
    107     }
    108   }
    109 
    110   free(pflag);
    111   free(primes);
    112 
    113   return 0;
    114 }
    115