// Parallel Computing
//
// Processor communication queue
//
// Author  Matthew Caryl
// Created 23.1.97

package Parallel;

public class CommunicationQueue {
	//
	// public interface
	//
	
	public CommunicationQueue() {
		// do nothing
		}
	
	public void enqueue(short b) {
		if (full())
			return;
		if (first + number < SIZE)
			queue[first + number] = b;
		else
			queue[first + number - SIZE] = b;
		number++;
		}
	
	public short dequeue() {
		short t = queue[first];
		
		first++;
		if (first == SIZE)
			first = 0;
		number--;
		
		return t;
		}
	
	public short usedSpace() {
		return number;
		}
	
	public short freeSpace() {
		return (short) (SIZE - number);
		}
	
	public boolean empty() {
		return number == 0;
		}
	
	public boolean full() {
		return number == SIZE;
		}	
	
	//
	// private interface
	//
	
	private static final short SIZE = 8;
	private final short[] queue = new short[SIZE];
	
	private short first = 0;
	private short number = 0;
	}