//compile gcc -o cond1.exe -pthread cond1.c
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#define COUNT_DONE  10
#define COUNT_HALT1  3
#define COUNT_HALT2  6
	 
//global variables
pthread_mutex_t count_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t  condition_var = PTHREAD_COND_INITIALIZER;
int  count = 0;

//thread functions
void *functionCount1(void *);
void *functionCount2(void *);
	 
int main(void )
{
   pthread_t thread1, thread2;
   int val = 0;

   if( pthread_create( &thread1, NULL, functionCount1, (void *)&val) != 0)
   {
	fprintf(stderr,"pthread_creat() failed\n");
	exit(1);
   }
   if( pthread_create( &thread2, NULL, functionCount2, (void *)&val) !=  0 )
   {
        fprintf(stderr,"Second pthread_creat() failed\n");
        exit(1);
   }


   pthread_join( thread1, NULL);
   pthread_join( thread2, NULL);

   printf("Final count: %d\n",count);

   exit(EXIT_SUCCESS);
}
//
// Write numbers 1-3 and 8-10 as permitted by functionCount2()
void *functionCount1( void * val)
{
      for(;;)
      {
	  // Lock mutex and then wait for signal to relase mutex
	  pthread_mutex_lock( &count_mutex );
	  // Wait while functionCount2() operates on count
	  // mutex unlocked if condition variable in functionCount2() signaled.
	  pthread_cond_wait( &condition_var, &count_mutex );
	  count++;
	  printf("Counter value functionCount1: %d\n",count);

	  pthread_mutex_unlock( &count_mutex );
	 
	  if(count >= COUNT_DONE) pthread_exit(NULL);
      }
}
	 
// Write numbers 4-7

void *functionCount2(void * val)
{
      for(;;)
      {
          pthread_mutex_lock( &count_mutex );
	  if( count < COUNT_HALT1 || count > COUNT_HALT2 )
	  {
	      // Condition of if statement has been met.
	      // Signal to free waiting thread by freeing the mutex.
	      // Note: functionCount1() is now permitted to modify "count".
	      pthread_cond_signal( &condition_var );
	  }
	  else
	  {
	      count++;
	      printf("Counter value functionCount2: %d\n",count);
	  }
	 
	  pthread_mutex_unlock( &count_mutex );
	 
	  if(count >= COUNT_DONE) pthread_exit(NULL);
       }
	 
}