interfacing C and guile

interfacing C and guile

[Damien Mattei]

hi,
how do i declare in Guile a function that in C is of this type:
int foo(int,int,char *)
the problem i have is with the char *:
(define cfunc (foreign-library-function "libguile-cfunc" "openmp"
#:return-type int #:arg-types (list int int ????)))
i do not know what to put in place of ????

Regards,
Damien

note: what if const char* ? (not sure i need it)

Re: interfacing C and guile

[Damien Mattei]

there was a mistake in my previous post, i wanted to say int cfunc
(int,int,char *), suggestion answered to use '*:

(define cfunc (foreign-library-function "libguile-cfunc" "cfunc"
#:return-type int #:arg-types (list int int '*)))

works at this step but gives an error later:

(cfunc 3 27 "toto")
ice-9/boot-9.scm:1685:16: In procedure raise-exception:
In procedure foreign-call: Wrong type argument in position 1 (expecting
POINTER_P): "toto"

On Fri, Dec 30, 2022 at 10:36 AM Damien Mattei <damien.mattei@gmail.com>
wrote:

> hi,
> how do i declare in Guile a function that in C is of this type:
> int foo(int,int,char *)
> the problem i have is with the char *:
> (define cfunc (foreign-library-function "libguile-cfunc" "openmp"
> #:return-type int #:arg-types (list int int ????)))
> i do not know what to put in place of ????
>
> Regards,
> Damien
>
> note: what if const char* ? (not sure i need it)
>

Re: interfacing C and guile

[Olivier Dion via General Guile related discussions]

On Fri, 30 Dec 2022, Damien Mattei <damien.mattei@gmail.com> wrote:
> there was a mistake in my previous post, i wanted to say int cfunc
> (int,int,char *), suggestion answered to use '*:
>
> (define cfunc (foreign-library-function "libguile-cfunc" "cfunc"
> #:return-type int #:arg-types (list int int '*)))
>
> works at this step but gives an error later:
>
> (cfunc 3 27 "toto")
> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> In procedure foreign-call: Wrong type argument in position 1 (expecting
> POINTER_P): "toto"

Try (cfunc 3 27 (string->pointer "toto")). It's available in the module
(system foreign).

-- 
Olivier Dion
oldiob.dev

Re: interfacing C and guile

[Damien Mattei]

yes Olivier, i already found this solution a few hours ago digging in the
Guile doc:

https://www.gnu.org/software/guile/manual/html_node/Void-Pointers-and-Byte-Access.html
thanks
Damien

On Fri, Dec 30, 2022 at 5:03 PM Olivier Dion <olivier.dion@polymtl.ca>
wrote:

> On Fri, 30 Dec 2022, Damien Mattei <damien.mattei@gmail.com> wrote:
> > there was a mistake in my previous post, i wanted to say int cfunc
> > (int,int,char *), suggestion answered to use '*:
> >
> > (define cfunc (foreign-library-function "libguile-cfunc" "cfunc"
> > #:return-type int #:arg-types (list int int '*)))
> >
> > works at this step but gives an error later:
> >
> > (cfunc 3 27 "toto")
> > ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> > In procedure foreign-call: Wrong type argument in position 1 (expecting
> > POINTER_P): "toto"
>
> Try (cfunc 3 27 (string->pointer "toto")). It's available in the module
> (system foreign).
>
> --
> Olivier Dion
> oldiob.dev
>