MultiThreading_Part_A/Semaphore_Implementation/Semaphore_Implementation.c

#include <stdlib.h>
#include <assert.h>
#include <stdbool.h>
#include "Semaphore_Implementation.h"

sema_t*
sema_get_new_semaphore() {

	sema_t* sema = calloc(1, sizeof(sema_t));
	return sema;

}

void
sema_init(sema_t* sema, int permit_counter) {

	sema->permit_counter = permit_counter;
	pthread_cond_init(&sema->cv, NULL);
	pthread_mutex_init(&sema->mutex, NULL);

}

/*
	Without using Pending Signals
*/

void
sema_wait(sema_t* sema) {

	pthread_mutex_lock(&sema->mutex);
	sema->permit_counter--;
	if (sema->permit_counter < 0) {
		pthread_cond_wait(&sema->cv, &sema->mutex);
	}
	pthread_mutex_unlock(&sema->mutex);

}

void
sema_post(sema_t* sema) {

	bool any_thread_waiting;
	pthread_mutex_lock(&sema->mutex);

	any_thread_waiting = sema->permit_counter < 0 ? true : false;
	sema->permit_counter++;

	if (any_thread_waiting) {
		pthread_cond_signal(&sema->cv);
	}
	pthread_mutex_unlock(&sema->mutex);

}

void
sema_destroy(sema_t* sema) {

	sema->permit_counter = 0;
	pthread_mutex_unlock(&sema->mutex);
	pthread_cond_destroy(&sema->cv);
	pthread_mutex_destroy(&sema->mutex);

}

int
sema_getvalue(sema_t* sema) {

	return sema->permit_counter;

}