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=0.4 required=5.0 tests=AC_FROM_MANY_DOTS,BAYES_00,
	PP_MIME_FAKE_ASCII_TEXT autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,fce935e9f3aa1da8
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII
From: "Egil H. H�vik" <egil.harald.hoevik@REMOVEkongsberg.com>
Newsgroups: comp.lang.ada
References: <2ph6fjFkpsahU1@uni-berlin.de> <41342a34@193.71.169.73>
Subject: Re: Interfacing with C: access/out parameters
Date: Tue, 31 Aug 2004 11:11:01 +0200
Organization: Kongsberg Defence & Aerospace
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106
NNTP-Posting-Host: 193.71.174.141
Message-ID: <41343c0e@193.71.169.73>
X-Trace: 31 Aug 2004 10:51:26 +0200, 193.71.174.141
Path: 
 g2news1.google.com!news2.google.com!proxad.net!newsfeed.stueberl.de!feed.news.tiscali.de!uio.no!193.75.75.20.MISMATCH!news.eunet.no!193.71.169.73!193.71.174.141
Xref: g2news1.google.com comp.lang.ada:3199
Date: 2004-08-31T11:11:01+02:00
List-Id: <comp.lang.ada>


"Egil H. H�vik" <egil.harald.hoevik@REMOVEkongsberg.com> wrote in message
news:41342a34@193.71.169.73...
>
> "Jano" <notelacreas@porfavor.no> wrote in message
> news:2ph6fjFkpsahU1@uni-berlin.de...
> > Hi,
> <snip>
> >
> > function Blah (Datum : access Data) return C.Int;
> > pragma Import (C, Blah);
> >
> >
> > Procedure Ada_Blah (Datum : out Data);
> > -- May raise some exception
> >
> > And my doubt, finally, is: can I ensure somehow that Datum is passed by
> > reference?, so I can do inside Ada_Blah [1]:
> >
> > Helper : aliased Datum;
> > For Helper'Address use Datum'Address;
> > if Thin_Package.Blah (Helper'Access) = Error_Value then
> >     raise My_Error;
> > end if;
> >
>
> Well, you say Data is a record type, so what's wrong with:
>
> procedure Ada_Blah( Datum : out Data ) is
>    function Blah( Datum : Data ) return C.int;
>    pragma Import( C, Blah );
> begin
>    if Thin_Package.Blah(Datum) = Error_Value then

hmm... Copy-Paste error here... Should be Blah(Datum), minus Thin_Package


>       raise My_Error;
>    end if;
> end Ada_Blah;
>
>
> B.3(65): "An Ada function corresponds to a non-void C function"
> B.3(69): "An Ada parameter of a record type T, of any mode, is passed as a
> t* argument
>    to a C function, where t is the C type corresponding to the Ada type
T."
>
>
> ~egilhh
>
>