Pamef/ta1/MutexTypeD.java

class MutexTypeD extends Mutex {

	private volatile int turn;
	private volatile boolean[] flag;
	
	MutexTypeD() {
		turn = 0;

		flag = new boolean[2];
		flag[0] = flag[1] = false;
	}

	public void p(int id) {
		int other = 1 - id;
		flag[id] = true;

		while (flag[other] == true) {
			if (turn == other) {
				flag[id] = false;
				while (turn == other) Thread.yield();
				flag[id] = true;
			}
		}
	}

	public void v(int id) {
		turn = 1 - id;
		flag[id] = false;
	}

	public String toString() {
		return "D";
	}
}