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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD,
	FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,d8ff1403929a72c0
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.66.78.106 with SMTP id a10mr1508225pax.14.1344321863595;
        Mon, 06 Aug 2012 23:44:23 -0700 (PDT)
Path: 
 g9ni2910154pbo.0!nntp.google.com!border1.nntp.dca.giganews.com!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!ctu-peer!ctu-gate!news.nctu.edu.tw!usenet.stanford.edu!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
From: Shark8 <onewingedshark@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Interfacing between Ada and C: records and structs
Date: Wed, 1 Aug 2012 21:39:46 -0700 (PDT)
Organization: http://groups.google.com
Message-ID: <6ba3c3f2-0cb6-454e-a61d-ebdd4e51528a@googlegroups.com>
References: <296e271a-967b-4dfb-8dca-f278ecfae03d@googlegroups.com>
 <a7qi6qFoc3U1@mid.individual.net>
 <5813d3d2-8a9f-4a08-bf09-db3c62847593@googlegroups.com>
NNTP-Posting-Host: 69.20.190.126
Mime-Version: 1.0
X-Trace: posting.google.com 1343885090 20004 127.0.0.1 (2 Aug 2012 05:24:50
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Thu, 2 Aug 2012 05:24:50 +0000 (UTC)
In-Reply-To: <5813d3d2-8a9f-4a08-bf09-db3c62847593@googlegroups.com>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=69.20.190.126;
 posting-account=lJ3JNwoAAAAQfH3VV9vttJLkThaxtTfC
User-Agent: G2/1.0
Content-Type: text/plain; charset=ISO-8859-1
Date: 2012-08-01T21:39:46-07:00
List-Id: <comp.lang.ada>

> Digging into the POSIX module:
> 
> 
> 
> private
> 
>   type Dummy is tagged null record;
> 
>   type Mutex is record
> 
>     Mutex : aliased POSIX.C.pthread_mutex_t;
> 
>     D : Dummy;
> 
>   end record
> 
> 
> 
> > 
> 
> > Have you checked that in Ada, pthread_mutex_t'Size is 192?
> 
> > 
> 
> 
> 
> In the POSIX.C package:
> 
> ALIGNMENT : constant := Natural'Min(Standard'Maximum_Alignment, 8);
> 
> type pthread_mutex_t'Alignment use ALIGNMENT;
> 
> type pthread_mutex_t'Size use 192;
> 
> 
> 
> However, when I write a simple test program I get 256 bits from 'Size, I'm not sure why...

Try adding Pragma Pack( DATA_STRUCTURE ); to the record.