What is the most efficient algorithm for finding ~A XOR B? (Note that ~ is the complement function, done by reversing each 1 bit into 0 and each 0 into 1 bit, and XOR is the exclusive or function)
For example, ~4 XOR 6 = ~010 = 101 = 5 and ~6 XOR 9 = ~1111 = 0
You can simply use ==.
A XNOR B is same as == operator because:
A B NXOR 
F F T
F T F
T F F
T T T
Complement of XOR