The function foreign-slot-offset
returns the offset in
bytes of a slot in a foreign struct type.
(defcstruct timeval (tv-secs :long) (tv-usecs :long)) CFFI> (foreign-slot-offset 'timeval 'tv-secs) => 0 CFFI> (foreign-slot-offset 'timeval 'tv-usecs) => 4
defcstruct
foreign-slot-names
foreign-slot-pointer
foreign-slot-value