Multi-Dimensional Arrays and MCL's FFI

[DOYLE@SISU.MGH.HARVARD.EDU]

There was an article on using the component manager
in Develop 12 (December 1992) for a simple math
example (there is source and a working component which
accompany the article). I think that the component was written in 
Think C. 

We've found that components are an excellent way of dynamically
linking in code for things that are easier in C (such as handling
things at interrupt time) or that talk to hardware (in which
case it is like a driver).

One of our engineers (Kee Luk) wrote the following
code to call the Develop component from MCL:

;;; Math Component Interface
;;; Not copyrighted. But, if you do make millions of $$ from this,
;;; don't spend it all in one place :-)
(defvar math-component)

(deftrap _ComponentMultiply ((CI 
(:POINTER :COMPONENTINSTANCERECORD)) 
(p1 (:INTEGER)) (p2 (:INTEGER)) (result (:POINTER :INTEGER)))
   (:STACK :SIGNED-LONG)
   (:STACK-TRAP #xA82A :D0 0 CI p1 p2
	 result ((+ (ASH 8 16) 2) :SIGNED-LONGINT)))

(deftrap _ComponentDivide ((CI (:POINTER :COMPONENTINSTANCERECORD))
 (p1 (:INTEGER)) (p2 (:INTEGER)) 
(result (:POINTER :INTEGER)))
   (:STACK :SIGNED-LONG)
   (:STACK-TRAP #xA82A :D0 0 CI p1 p2 result 
	((+ (ASH 8 16) 1) :SIGNED-LONGINT)))

(defun init-math-component ()
  (setf math-component (#_OPENDEFAULTCOMPONENT :|math| 0))
  (if (%null-ptr-p math-component)
    (format t "~&Can not locate math component")
    math-component))

(defun exit-math-component ()
  (#_CLOSECOMPONENT math-component))

(defun multiply-with-component (p1 p2)
  (%stack-block ((answer-buffer 2))
  (unless (%null-ptr-p math-component)
    (let ((rc (#_ComponentMultiply math-component 
	p1 p2 answer-buffer)))
      (if (zerop rc)
        (format t "~&~a * ~a = ~a" p1 p2
	(%get-signed-word answer-buffer))
        (format t "~&Error *** return code ~a" rc))))))

(defun divide-with-component (p1 p2)
  (%stack-block ((answer-buffer 2))
  (unless (%null-ptr-p math-component)
    (let ((rc (#_ComponentDivide math-component p1 p2 answer-buffer)))
      (if (zerop rc)
        (format t "~&~a / ~a = ~a" p1 p2 (%get-signed-word answer-buffer))
        (format t "~&Error *** return code ~a" rc))))))

#|
(init-math-component)
(multiply-with-component 3 -4)
(divide-with-component 2 -2)
(exit-math-component)
|#