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Re: [Gcl-devel] foreign function call

From: Camm Maguire
Subject: Re: [Gcl-devel] foreign function call
Date: 28 Sep 2004 11:39:02 -0400
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2

Greetings, and please excuse the delayed reply!

This should be quite straightforward in GCL, providing one recognizes
that standard C has no multiple value return type, so that one must do
this part from lisp.

Here are a few examples which should illustrate the basic machinery:
clines, defentry, and defcfun.  You can also check the gcl-si docs

(clines "
static double
square(double x) {

   return x*x;



(defentry square (double) (double square))

(clines "
static double
first_value(double x,double y) {

   return x+y;


(defentry first-value (double double) (double first_value))

(clines "
static double
second_value(double x,double y) {

   return x-y;


(defentry second-value (double double) (double second_value))

(defun foo (x y) (values (first-value x y) (second-value x y)))

(defCfun "static object two_object_list(object x,object y)"
  "object z,f,s;"
  ((+ x y) f)
  ((- x y) s)
  ((list f s) z)
  "return z;")

(defentry two-object-list (object object) (object two_object_list))

(defun bar (x y) (let ((l (two-object-list x y))) (values (first l) (second 
Top level.
>(compile-file "/tmp/f.l")

Compiling /tmp/f.l.
End of Pass 1.  
End of Pass 2.  
OPTIMIZE levels: Safety=0 (No runtime error checking), Space=0, Speed=3
Finished compiling /tmp/f.l.

>(load "/tmp/f.o")

Loading /tmp/f.o
start address -T 0x83ec830 Finished loading /tmp/f.o

>(bar 1.2 4.3)


>(foo 1.2 4.3)



Not sure about C vs. C++ issues, but my understanding is that the
latter is backward compatible with the former.

One can also reference code in external C libraries -- see the docs
for compiler::link in this case.

Please feel free to write back if questions persist.

Take care,

Marcio Fuzeto Gameiro <address@hidden> writes:

> I would like to know how (if possible) I can call a C++ function from
> Lisp? I need to be able to pass some values (floats/doubles) to the
> C++ function, and the function should return multiple values (like two
> doubles for example). Does any one now how to do this?
> Thanks,
>       Marcio.
> _______________________________________________
> Gcl-devel mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/gcl-devel

Camm Maguire                                            address@hidden
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah

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