1  #include <stdlib.h>
       2  #include <stdio.h>
       3  #include <string.h>
       4  #include <omp.h>
       5  
       6  #define MAX	1000
       7  
       8  void main1()
       9  {
      10    int i, N1, N2, step;
      11    int a[MAX], b[MAX];
      12  
      13    N1 = rand () % 13;
      14    N2 = rand () % (MAX - 51) + 50;
      15    step = rand () % 7 + 1;
      16  
      17    printf ("N1 = %d\nN2 = %d\nstep = %d\n", N1, N2, step);
      18  
      19    for (i = N1; i <= N2; i += step)
      20      a[i] = 42+ i;
      21  
      22    /* COUNTING UP (<).  Fill in array 'b' in parallel.  */
      23    memset (b, 0, sizeof b);
      24  #pragma omp parallel shared(a,b,N1,N2,step) private(i)
      25    {
      26  #pragma omp for
      27      for (i = N1; i < N2; i += step)
      28        b[i] = a[i];
      29    }
      30  
      31    /* COUNTING UP (<).  Check that all the cells were filled in properly.  */
      32    for (i = N1; i < N2; i += step)
      33      if (a[i] != b[i])
      34        abort ();
      35  
      36    printf ("for (i = %d; i < %d; i += %d) [OK]\n", N1, N2, step);
      37  
      38    /* COUNTING UP (<=).  Fill in array 'b' in parallel.  */
      39    memset (b, 0, sizeof b);
      40  #pragma omp parallel shared(a,b,N1,N2,step) private(i)
      41    {
      42  #pragma omp for
      43      for (i = N1; i <= N2; i += step)
      44        b[i] = a[i];
      45    }
      46  
      47    /* COUNTING UP (<=).  Check that all the cells were filled in properly.  */
      48    for (i = N1; i <= N2; i += step)
      49      if (a[i] != b[i])
      50        abort ();
      51  
      52    printf ("for (i = %d; i <= %d; i += %d) [OK]\n", N1, N2, step);
      53  
      54    /* COUNTING DOWN (>).  Fill in array 'b' in parallel.  */
      55    memset (b, 0, sizeof b);
      56  #pragma omp parallel shared(a,b,N1,N2,step) private(i)
      57    {
      58  #pragma omp for
      59      for (i = N2; i > N1; i -= step)
      60        b[i] = a[i];
      61    }
      62  
      63    /* COUNTING DOWN (>).  Check that all the cells were filled in properly.  */
      64    for (i = N2; i > N1; i -= step)
      65      if (a[i] != b[i])
      66        abort ();
      67  
      68    printf ("for (i = %d; i > %d; i -= %d) [OK]\n", N2, N1, step);
      69  
      70    /* COUNTING DOWN (>=).  Fill in array 'b' in parallel.  */
      71    memset (b, 0, sizeof b);
      72  #pragma omp parallel shared(a,b,N1,N2,step) private(i)
      73    {
      74  #pragma omp for
      75      for (i = N2; i >= N1; i -= step)
      76        b[i] = a[i];
      77    }
      78  
      79    /* COUNTING DOWN (>=).  Check that all the cells were filled in properly.  */
      80    for (i = N2; i >= N1; i -= step)
      81      if (a[i] != b[i])
      82        abort ();
      83  
      84    printf ("for (i = %d; i >= %d; i -= %d) [OK]\n", N2, N1, step);
      85  }
      86  
      87  int
      88  main ()
      89  {
      90    int i;
      91  
      92    srand (0);
      93    for (i = 0; i < 10; ++i)
      94      main1();
      95    return 0;
      96  }