Dekker's Algorithm

CASE A: P1 wants to enter its critical section
        P2 is in its non-critical section
        P1 sets needLock1 to 1
        P1 sets turn to 2
        P1 waits until turn is 1 or needLock2 is 0
        P1 immediately enters its critical section

CASE B: P1 is in its critical section
        P2 wants to enter its critical section
        P2 sets needLock2 to 1
        P2 sets turn to 1
        P2 waits until turn is 2 or needLock1 is 0
        P2 blocked until P1 leaves its critical section
               and sets needLock1 to 0

CASE C: P1 and P2 both complete their
        non-critical sections; both want
        to simultaneously enter their
        critical sections.

        P1 sets needLock1 to 1
        P1 gets interrupted
        P2 sets needLock2 to 1
        P2 sets turn to 1
        P2 is blocked
        P1 sets turn to 2
        P1 is blocked
        P2 enters its critical section
        P2 sets needLock2 to 0
        P1 enters its critical section
        P1 sets needLock1 to 0