/**
 * A pthread program illustrating how to
 * create a simple thread and some of the pthread API
 * This program implements the summation function where
 * the summation operation is run as a separate thread.
 *
 * gcc thrd.c -lpthread
 *
 * Figure 4.6
 *
 * @author Gagne, Galvin, Silberschatz
 * Operating System Concepts  - Seventh Edition
 * Copyright John Wiley & Sons - 2005.
 */

/* Modified by Krishna Sivalingam - Feb. 2006 */

#include <pthread.h>
#include <stdio.h>

int sum; /* this data is shared by the thread(s) */
double prod; /* this data is shared by the thread(s) */

void *runner1(void *param); /* the thread */
void *runner2(void *param); /* the thread */

int main(int argc, char *argv[])
{
  pthread_t tid1, tid2; /* the thread identifier */
  pthread_attr_t attr; /* set of attributes for the thread */

  if (argc != 2) {
    fprintf(stderr,"usage: a.out <integer value>\n");
    /*exit(1);*/
    return -1;
  }

  if (atoi(argv[1]) < 0) {
    fprintf(stderr,"Argument %d must be non-negative\n",atoi(argv[1]));
    /*exit(1);*/
    return -1;
}

  /* get the default attributes */
  pthread_attr_init(&attr);

  /* create the thread for summation */
  pthread_create(&tid2,&attr,runner2,argv[1]);
  pthread_create(&tid1,&attr,runner1,argv[1]);

  /* create the thread for factorial */


  /* now wait for threads to exit */
  pthread_join(tid1,NULL);

  pthread_join(tid2,NULL);

  printf("sum = %d; prod = %.0lf\n",sum, prod);
}

/**
 * The thread will begin control in this function
 */
void *runner1(void *param) 
{
  int i, upper = atoi(param);
  sum = 0;			/* Shared global variable. */


  if (upper > 0) {
    for (i = 1; i <= upper; i++)
      sum += i;
  }
  fprintf(stdout," Thread 1 sez: %.0lf\n", prod);  
  pthread_exit(0);
}

/**
 * The thread will begin control in this function
 */
void *runner2(void *param) 
{
  int i, upper = atoi(param);
  prod = 1.0;

  fprintf(stdout," Thread 2: %d\n", sum);
  if (upper > 0) {
    for (i = 1; i <= upper; i++)
      prod *= i;
  }

  
  pthread_exit(0);
}