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

#define BUF_SIZE 10
#define NUM_PRODUCED 20

int buf[BUF_SIZE];
int empty, full, mutex; /*semaphore ids*/

void * producerFunction (void *arg)
{
	int i, in = 0, nextProduced;
	for (i=0; i<NUM_PRODUCED; i++) {
		nextProduced = i;
		printf("Producing %d\n", nextProduced);
		fflush(NULL);
		decreaseSemaphore(empty);
		decreaseSemaphore(mutex);
		buf[in] = nextProduced;
		in = (in + 1) % BUF_SIZE;
		increaseSemaphore(mutex);
		increaseSemaphore(full);
	}
	return NULL;
}

void * consumerFunction (void *arg)
{
	int i, out = 0, nextConsumed;
	for (i=0; i<NUM_PRODUCED; i++) {
		decreaseSemaphore(full);
		decreaseSemaphore(mutex);
		nextConsumed = buf[out];
		out = (out + 1) % BUF_SIZE;
		increaseSemaphore(mutex);
		increaseSemaphore(empty);
		printf("Consuming %d\n",i);
		fflush(NULL);
	}
	return NULL;
}


int main()
{
	pthread_t producer, consumer;
	pthread_attr_t attr;

	/* initialize and set the thread attributes */
	pthread_attr_init( &attr );
	pthread_attr_setdetachstate( &attr, PTHREAD_CREATE_JOINABLE );

	/*initialize semaphores*/
	mutex = initializeSemaphore(1492,1);
	empty = initializeSemaphore(1493,BUF_SIZE);
	full  = initializeSemaphore(1494,0);


	/* creating threads */
	if (pthread_create(&producer,&attr,producerFunction,NULL) != 0) {
		fprintf(stderr,"Creating producer thread failed!");
		return 1;
	}
	if (pthread_create(&consumer,&attr,consumerFunction,NULL) != 0) {
		fprintf(stderr,"Creating consumer thread failed!");
		return 1;
	}

	/* joining threads (== waiting for them to exit) */
	if ( pthread_join(producer,NULL) != 0 ) {
		fprintf(stderr,"Joing producer thread failed!");
		return 1;
	}
	if ( pthread_join(consumer,NULL) != 0 ) {
		fprintf(stderr,"Joing consumer thread failed!");
		return 1;
	}

	return 0;
}