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Re: [Chicken-users] Is there another way to return data from a C functio
From: |
Eduardo Cavazos |
Subject: |
Re: [Chicken-users] Is there another way to return data from a C function? |
Date: |
Sun, 17 Jun 2007 16:30:20 -0500 |
User-agent: |
KMail/1.9.1 |
Felix wrote:
> On 6/12/07, Eduardo Cavazos <address@hidden> wrote:
> > That only works with the compiler (csc). Is there a way to box/unbox data
> > in the interpreter so I can call xquerypointer from csi? Just curious as
> > it's easier to experiment via csi instead of recompiling my file each
> > time a change is made.
>
> You could create a wrapper function that does the xquerypointer call
> and returns its data and compile the function into a dynamically
> loadable library with "-s". Then "load" the generated file into the
> interpreter.
Thanks Felix!
Something else I had in mind was to make "foreign boxes":
(define (make-ulong-box)
(let-location ((val unsigned-long))
(lambda (op)
(case op
((get)
val)
((set)
(lambda (new-val)
(set! val new-val)))
((box)
(location val))))))
I made those for uinteger and integer as well, and compiled them
as "foreign-boxes.so".
Then I was able to use xquerypointer from csi as follows:
;; make the boxes
(define root (make-ulong-box))
(define child (make-ulong-box))
(define root-x (make-integer-box))
(define root-y (make-integer-box))
(define win-x (make-integer-box))
(define win-y (make-integer-box))
(define mask (make-uinteger-box))
;; call xquerypointer
(xquerypointer (dpy 'ptr)
((dpy 'default-root) 'id)
(root 'box)
(child 'box)
(root-x 'box)
(root-y 'box)
(win-x 'box)
(win-y 'box)
(mask 'box))
;; look at some box values
(list (win-x 'get)
(win-y 'get))
Ed