Operating System

Consumer Producer problem

#include<stdio.h>
#include<stdlib.h>
int mutex = 1, full = 0, empty = 3, x = 0;
int
main ()
{
  int n;
  void producer ();
  void consumer ();
  int wait (int);
  int signal (int);
  printf ("\n1.Producer\n2.Consumer\n3.Exit");
  while (1)
	{
	  printf ("\nEnter your choice:");
	  scanf ("%d", &n);
	  switch (n)
		{
		case 1:
		  if ((mutex == 1) && (empty != 0))
			producer ();
		  else
			printf ("Buffer is full!!");
		  break;
		case 2:
		  if ((mutex == 1) && (full != 0))
			consumer ();
		  else
			printf ("Buffer is empty!!");
		  break;
		case 3:
		  exit (0);
		  break;
		}
	}
  return 0;
}

int
wait (int s)
{
  return (--s);
}

int
signal (int s)
{
  return (++s);
}

void
producer ()
{
  mutex = wait (mutex);
  full = signal (full);
  empty = wait (empty);
  x++;
  printf ("\nProducer produces the item %d", x);
  mutex = signal (mutex);
}

void
consumer ()
{
  mutex = wait (mutex);
  full = wait (full);
  empty = signal (empty);
  printf ("\nConsumer consumes item %d", x);
  x--;
  mutex = signal (mutex);
}