12b.c

// Producer-Consumer problem using semaphores

#include <stdio.h>
#include <stdlib.h>

int mutex = 1, full = 0, empty = 3, x = 0;

int main(int argc, char const *argv[])
{
  int ch;
  void producer();
  void consumer();
  int wait(int);
  int signal(int);

  while (1)
  {
    printf("\n");
    printf("\n1.Produce\n2.Consume\n3.Exit");
    printf("\nEnter your choice:");
    scanf("%d", &ch);
    switch (ch)
    {
    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);
}