ff code

[ST7990@SIUCVMB.SIU.EDU]

This question has to do with the c code in
mcl2.0:examples:ff-examples.c. I'd like an explanation of the following
code:

           define cdr(x) (* (long *) (x))

           define car(x) (* (Ptr *) (((long)(x) + 7)))

           define macptr_ptr(x) (*((*Ptr *)

These functions can be called by

               caller(y)
               long *y;
               { car (*y); cdr(*y); macptr_ptr(*y)}

The c function <caller> is defined as
             (deffcfun (caller "caller")((cons :lisp-ref)) :novalue)
and called with
             (caller (cons (_newptr 5) 10)).

Thank you.
Chris Ryan (SIUC)