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 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,90212413571e3e8b,start
X-Google-Attributes: gid103376,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!eweka.nl!lightspeed.eweka.nl!feeder1.cambrium.nl!feed.tweaknews.nl!193.141.40.65.MISMATCH!npeer.de.kpn-eurorings.net!npeer-ng1.kpn.DE!newsfeed00.sul.t-online.de!newsfeedt0.toon.t-online.de!newsmm00.sul.t-online.de!t-online.de!news.t-online.com!not-for-mail
From: Erik Baigar <erik@baigar.de>
Newsgroups: comp.lang.ada
Subject: Endian-problem/bug with system.bit_ops (gnat3.15)...
Date: Sat, 15 Mar 2008 08:58:12 +0100
Organization: T-Online
Message-ID: <47DB8194.62FE76B0@baigar.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Trace: news.t-online.com 1205568276 02 3970 bfjEOrbOX2-g3Ud 080315 08:04:36
X-Complaints-To: usenet-abuse@t-online.de
X-ID: Z4GKyOZGgeqXuuK0iM1oFJQauB+Z-pnTbiZP4ea4NV0qm+WHppqiUn
X-Mailer: Mozilla 4.76C-SGI [en] (X11; I; IRIX 6.5 IP22)
X-Accept-Language: en
Xref: g2news1.google.com comp.lang.ada:20412
Date: 2008-03-15T08:58:12+01:00
List-Id: <comp.lang.ada>


Dear Ada users,

in porting an application from Meridian's Ada83 to gnat3.15 I
encountered
some issues with the system.bit_ops. They (especially the Bit_And which 
I used) show behaviour which depends on the processor used:

The code contains expressions of the form
 
  Bit_And ( MEMORY (OPERAND_ADDRESS)'Address,18, ACCUMULATOR'Address,18,
            ACCUMULATOR'Address);

which are used in the simulation of a vintage processor. I used length
18 here since the processor has 18-bit registers. This code works well
on the Intel (little endian) platform but fails on SPARC (big endian).
It required some investigation to locate the problem, but replacing 
the length 18 by 32 (all are integers here), i.e. using

  Bit_And ( MEMORY (OPERAND_ADDRESS)'Address,32, ACCUMULATOR'Address,32,
            ACCUMULATOR'Address);

solved the problem and the code now runs on little and big endian 
systems. I know, system.bit_ops are version dependent and non portable,
but I'd not expect behaviour depending on the target system at the 
first glance... 

   Regards,

      Erik.