Re: [math-fun] History of swap/exch computer instructions ?

On 14 Mar 2018 at 17:59, Tom Karzes wrote:

If you don't have bitwise XOR, you can do the same thing with addition and subtraction, provided overflow is ignored and you always get the correct low-order bits of the result:

A <- A + B B <- A - B A <- A - B // Note that B is now the original A

That's true, but the xor-and-xor hack allows you to mess with arbitrary (and non adjacent) bits in the middle of the words. /B\ Bernie Cosell bernie@fantasyfarm.com -- Too many people; too few sheep --