From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Subject: Re: Interfaces.C questions
Date: Fri, 17 Mar 2017 23:57:58 +0200
Date: 2017-03-17T23:57:58+02:00 [thread overview]
Message-ID: <ej34f6F6sj3U1@mid.individual.net> (raw)
In-Reply-To: <ej31ppF6c01U1@mid.individual.net>
On 17-03-17 23:12 , hreba wrote:
> 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?
Using pointers is possible, but functions with "out" or "in out"
parameters are allowed in the Ada 2012 standard. Check your compiler; it
may by default use the Ada 2005 rules and may need a command-line option
(perhaps -gnat2012) to use Ada 2012 rules.
> 2. On my platform size_t is C.int. How can I define size_t in a
> platform-independent way?
Don't define it; use Interfaces.C.size_t.
> 3. The C function above needs a pointer to a function as parameter. Is
> my translation to Ada correct?
Looks ok to me, but you didn't show the C prototype of the function (the
gsl_function type?) so I can't compare the two.
--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .
next prev parent reply other threads:[~2017-03-17 21:57 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-17 21:12 Interfaces.C questions hreba
2017-03-17 21:57 ` Niklas Holsti [this message]
2017-03-17 22:14 ` Jeffrey R. Carter
2017-03-17 22:24 ` Dmitry A. Kazakov
2017-03-21 21:08 ` Michael B.
2017-03-21 21:28 ` Dmitry A. Kazakov
2017-03-21 21:31 ` Simon Wright
2017-03-22 20:35 ` Randy Brukardt
2017-03-18 15:46 ` hreba
2017-03-18 16:26 ` Jeffrey R. Carter
2017-03-18 16:27 ` Jeffrey R. Carter
2017-03-19 7:03 ` Keith Thompson
2017-03-18 23:24 ` Leo Brewin
2017-03-19 12:17 ` hreba
2017-03-20 9:44 ` Leo Brewin
2017-03-19 7:00 ` Keith Thompson
2017-03-19 12:05 ` Per Sandberg
2017-03-19 18:39 ` hreba
2017-03-19 19:22 ` Simon Wright
2017-03-19 19:49 ` hreba
2017-03-19 23:53 ` Simon Wright
2017-03-20 11:12 ` hreba
2017-03-20 14:04 ` hreba
2017-03-22 11:21 ` hreba
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