Re: Interfaces.C questions

[Per Sandberg <per.s.sandberg@bahnhof.se>]

Why not use the compiler to generate the low-level bindings ??
	gcc -fdump-ada-spec

It works great takes 95% of the c headers, after generation its usually 
enough with some simple sed-scripts.

That way the binding generation could be 100% automated.

Have done that for some fairly large libraries 250 header-files that 
contains approx 18K ";" and 100K lines including blanks and comments.


/Per



Den 2017-03-17 kl. 22:12, skrev hreba:
> These are my first steps with Interfaces.C:
>
> ----------------------------------------------------------------------
> with Interfaces.C;
>
> package GSL is
>
>    package C renames Interfaces.C;
>
>    type size_t is new C.int;
>    type Real_Function is access function (x: C.double) return C.double;
>
>    function Bessel_J0 (x: C.double) return C.double;
>
>    function Integration_QNG
>      (f: Real_Function;
>       a, b, epsabs, epsrel: C.double;
>       result, abserr: out C.double;
>       neval: out size_t)
>      return C.int;
>
> private
>
>    pragma Import (C, Bessel_J0,        "gsl_sf_bessel_J0");
>    pragma Import (C, Integration_QNG,    "gsl_integration_qng");
>
> end GSL;
> ------------------------------------------------------------------------
>
> No problem with function Bessel_J0. But Integration_QNG gets me:
>
> gsl.ads:19:07: functions can only have "in" parameters.
>
> The C prototype of this function is:
>
> int gsl_integration_qng (const gsl function * f , double a , double b ,
> double epsabs , double epsrel , double * result , double * abserr , size
> t * neval )
>
> So my questions are:
>
> 1. How do I translate C functions which return non-void and which
> additionally use pointers for out parameters? Do I have to use pointers
> in my Ada program?
>
> 2. On my platform size_t is C.int. How can I define size_t in a
> platform-independent way?
>
> 3. The C function above needs a pointer to a function as parameter. Is
> my translation to Ada correct?
>