Bitwise logical `nor' of two integers
When integers are viewed in their two's complement representation,
lognor returns the bitwise logical `nor' of the first with the
The guard for lognor requires its arguments to be integers.
Lognor is defined in Common Lisp. See any Common Lisp documentation for
(defun lognor (i j)
(declare (xargs :guard (and (integerp i) (integerp j))))
(lognot (logior i j)))