//@author: j.n.magee 11/11/96
//adapted by mh, 02/04/03


/********************************************************/
//
// The Semaphore Class
// up() is the V operation
// down() is the P operation
//
public class BinSemaphore {

    private boolean value;

    public BinSemaphore (boolean initial) {
/*	if (initial<0) {
	    System.exit(1); // out of range error
	} else {                                    */
	    value = initial;
/*	} // if                                     */
    } // Semaphore

    synchronized public void up() {
        value = true;
        notify();  // notifyAll() ?
    } // up

    synchronized public void down() {
	try {        
	    while (!value) {
	        wait();
	    } // end while
        value = false;
	} catch(InterruptedException e){}
    } // down

} // class BinSemaphore