/****************************************************************
* Name:         main                                            *
* Synopsis:     Entry point for all Concordance programs.       *
****************************************************************/

main()
{
 char key;
 char mark[10000];
 int i, n, num, step, start, file;
 text line;

   /* Initialize screen and open data base. */

   initialize();
   file = open("con","w");
   cursor(3,0);
   puts(0,0,"This program calculates and displays the prime numbers");
   puts(1,0,"between 3 and 1000.  It then displays how long it took.");
   puts(2,0,"Press any key to begin...");
   getkey();
   start = clock();
   num = 0;
   for(n = 3; n < 1000; n = n + 2)
      if(mark[n] == 0)
      {
         write(file,str(n,5,0),5);
         step = 2 * n;
         for(i = 3 * n; i < 1000; i = i + step)
            mark[i] = -1;
         num = num + 1;
      }
  line = "It takes "+str((clock() - start)/1000)+" seconds to find "+
          str(num)+" primes.";
  writeln(file,"",0);
  writeln(file,line,len(line));
  close(file);
  getkey();
} /* main() */

/****************************************************************
* Name:         initialize                                      *
* Synopsis:     Set global variables to initial values          *
* Action:       Global variables are set for system calls       *
****************************************************************/

int color, ESC;

initialize()
{
   color = 31;
   ESC = 27;
   clsc(color);
   cursor(0,0);
}  /* initialize() */

/****************************************************************
* Name:         clsc                                                    *
* Synopsis:     Clear the screen                                *
* Results:      Screen is cleared                               *
* Error:        None                                            *
* Parameters:   Screen color                                    *
* Action:       Scroll() is called to clear the entire screen   *
****************************************************************/
clsc(int color)
{
   scroll(0, 0, 24, 79, 0, 1, color);
}   /* clsc() */