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

//**********************************************************

class MutexLoop extends Thread {

    private BinSemaphore mutex;
    private char ch;

    MutexLoop (BinSemaphore sema, char toPrint) {
		mutex=sema;
		ch = toPrint;
    } 

    public void run() {
        for (int i=0;i<MutexDemo.LENGTH;i++)  {
            Simulate.doSomething();			// pre action

            mutex.down();					// get mutual exclusion 
			
			System.out.println();	 		//critical section
	    	for (int j=0;j<MutexDemo.WIDTH;j++) {	
		   		 System.out.print(ch);
		   		 Simulate.doSomething();
            }
            
            mutex.up();						//release mutual exclusion

  	   		Simulate.doSomething();			// post action
        } // for
      
    } // run

} // class MutexLoop

//********************************************************

class Simulate {

    public static void doSomething() {
        if (Math.random()<0.5) {
            try { Thread.sleep(200);} catch(InterruptedException e){};
            //used instead of Thread.yield() to ensure portability
        }
    }

} // class Simulate

 
//*********************************************************

public class MutexDemoBinSemaphore {

    static final int WIDTH = 30;	    // line width to weave 
    static final int LENGTH = 50; 		// number of lines to be weaved


    public static void main (String[] argv) {

	BinSemaphore mutex = new BinSemaphore(true);	
	Thread a = new MutexLoop(mutex,'a');	// process instances
	Thread b = new MutexLoop(mutex,'b');
	Thread c = new MutexLoop(mutex,'c');

	System.out.println(" -- begin of MutexDemoBinSemaphore -- ");

	a.start();				// start of the processes
    b.start();
	c.start();
	
	try{
		c.join();
		b.join();
		a.join();
	} catch (Exception e) {}
	
	System.out.println("\n -- end of MutexDemoBinSemaphore -- ");

    } // main
	
} // class MutexDemo

//**********************************************************