Actually bit addition in ALU is usually implemented using an XOR gate (with an AND gate to compute carry)...But as "diff" is essentially addition (over compleme

Actually bit addition in ALU is usually implemented using an XOR gate (with an AND gate to compute carry)...But as "diff" is essentially addition (over complement numbers), they mean the same thing... Also note that XOR is associative -- that's the key to prove the XOR swapping... For those who are interested in binary tricks, there are several good resources: * HAKMEM, http://goo.gl/F6sBjt http://goo.gl/F6sBjt * Hacker's Delight, http://goo.gl/llQumw http://goo.gl/llQumw