/*
 * Example of threads and semaphores.
 * To compile:  g++ -lpthread -lrt mutex.cpp
 */

#define _REENTRANT
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <semaphore.h>

using namespace std;

void *threadfunc(void *arg);
int rand(void);
sem_t twoex;



int main(int argc, char *argv[]){
    int count = atoi(argv[1]);
    int i;			// counter
    pthread_t tid[10];		// creats an array of threads   

    printf("count = %d\n", count);
    srand(time(NULL));		// seed the random number generator
    
    sem_init(&twoex, 0, 2);

    for(i = 1; i <= count; i++){
	//create thread for each struct. Each thread has own threadfunc.    
	pthread_create(&tid[count], NULL, threadfunc, NULL);        
    }
    
    for(i = 1; i <= count; i++){
	pthread_join(tid[count], NULL);                             
    }

    printf("Threads all done");
}




void *threadfunc(void *arg)  {
    int i, j;
    float c;
    int x;

  for(i = 1; i <= 3; i++){
      sem_wait(&twoex);
      printf("Thread %d in there...\n", pthread_self());
      for(c = 0;  c <= 1000000 ;c += .1) x = x * 129834 / 1234 % 4314;
      printf("Thread %d outta there...\n", pthread_self());
      sem_post(&twoex);
      sleep(rand()%4 + 2);
  }  
  
  pthread_exit(0);
}