Pointer functions (FFI for Emacs)

(ffi-pointer+ POINTER NUMBER). Pointer math in Lisp.
(ffi-pointer-null-p POINTER). Return t if the argument is a null pointer. If the argument is not a pointer or is not null, return nil.
(ffi-pointer= POINTER1 POINTER2). Return t if the two pointers are equal, nil if not.
(ffi-allocate TYPE-OR-NUMBER). Allocate some memory. If a type is given, allocates according to the type’s size. If a number is given, allocates that many bytes. The returned memory will not be automatically reclaimed; you must use ffi-free for that.
(ffi-free POINTER). Free some memory allocated with ffi-allocate or ffi-make-c-string.