package diningphilosophers1;

/* * @author webster*/
public class Semaphore extends Object	
{
        private int count;
        private int max_count=0;
        private int waiting_count = 0;
        private int num_threads_eating = 0;

	public Semaphore (int initial_count, int maximum_count)
	{
		if (max_count == 0 && maximum_count >= initial_count)
		{
			count = initial_count;
			max_count=maximum_count;
		}
	}

	public Semaphore()
	{
		count = 1;
		max_count=1;	
	}

	public synchronized void P()
	{
                if (count == 0)
		{
			waiting_count++;
			try{
				wait();
			}
			catch (Exception e){}
                        num_threads_eating ++;
		}
		else
		{
			num_threads_eating ++;
 			count--;
		}
	}
	public synchronized void V()
	{
		if (waiting_count > 0)
		{
			waiting_count--;
			try{
				notify();
			}
			catch (Exception e){}
                        num_threads_eating--;

		}
		else
		{
			if (count < max_count)
			{
				count++;
				num_threads_eating--;
			}
		}
	}
	
}// end semaphore