From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Thread: 103376,c370342fe303517b
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!postnews.google.com!a75g2000cwd.googlegroups.com!not-for-mail
From: artifact.one@googlemail.com
Newsgroups: comp.lang.ada
Subject: Re: C Interface example
Date: 3 Feb 2007 11:55:03 -0800
Organization: http://groups.google.com
Message-ID: <1170532503.164182.253710@a75g2000cwd.googlegroups.com>
References: <1170526166.831811.237660@h3g2000cwc.googlegroups.com>
   <ncKdnZXwW7GYelnYnZ2dnUVZ_oSnnZ2d@comcast.com>
NNTP-Posting-Host: 81.179.242.178
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
X-Trace: posting.google.com 1170532514 3393 127.0.0.1 (3 Feb 2007 19:55:14
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Sat, 3 Feb 2007 19:55:14 +0000 (UTC)
In-Reply-To: <ncKdnZXwW7GYelnYnZ2dnUVZ_oSnnZ2d@comcast.com>
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux i686; en-US;
 rv:1.8.1) Gecko/20060601 Firefox/2.0 (Ubuntu-edgy),gzip(gfe),gzip(gfe)
Complaints-To: groups-abuse@google.com
Injection-Info: a75g2000cwd.googlegroups.com; posting-host=81.179.242.178;
   posting-account=3t6ROQ0AAABpbovmj4Qol-vmGur4qb-2
Xref: g2news2.google.com comp.lang.ada:8895
Date: 2007-02-03T11:55:03-08:00
List-Id: <comp.lang.ada>

On Feb 3, 7:48 pm, tmo...@acm.org wrote:
> > float *vec_addNf(float *, float *, unsigned int);
> > Now what would be the most simple and portable way to write
> > a vector,ads and vector.adb file? (Specification and body, in case
> > reading all that just for an example on interfacing...
>
>   If you want to call an existing C routine, not rewriting it in Ada,
> then the literal translation of the calling interface is:
>
>   type p_float is access all interfaces.c.c_float;
>
>   function vec_addNf(va, vb : in p_float; n : in interfaces.c.unsigned)
>   return p_float;
>   pragma import(C, vec_addNf, "vec_addNf");
>   -- Note: Do this if you really have a C calling convention.
>   -- If you are running on MS Windows, you probably want "StdCall"
>   -- instead of "C"
>
> and then use it like this
>   type vectors is array(interfaces.c.unsigned range <>)
>     of aliased interfaces.c.c_float;
>   va, vb : vectors(1 .. 100);
>   trash : p_float;
>   ...
>   trash := vec_addNf(va(va'first)'unchecked_access,
>                      vb(vb'first)'unchecked_access,
>                      va'length);
>
> If you were going to be doing a lot of complex calls on va, vb, vc, and vd
> you might want instead
>
> N : interfaces.c.unsigned := 123;
> va_data, vb_data, vc_data, vd_data : vectors(1 .. N);
> va : constant p_float := va_data(va_data'first)'unchecked_access;
> vb : constant p_float := vb_data(vb_data'first)'unchecked_access;
> vc : constant p_float := vc_data(vc_data'first)'unchecked_access;
> vd : constant p_float := vd_data(vd_data'first)'unchecked_access;
>
> so you could write things like
>
>   trash := vec_addNf(vec_addNf(va,vb,N),vec_addNf(vc,vd,N), N);

Thanks.

I will end up using some sort of preprocessor for all this stuff, but
I like to know how it works beforehand.

MC