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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,13ab88b30e0f779d
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2002-12-28 07:59:07 PST
Newsgroups: comp.lang.ada
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!uunet!sea.uu.net!sac.uu.net!ash.uu.net!world!news
From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: Efficient Matrix?
User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2
Sender: news@world.std.com (Mr Usenet Himself)
Message-ID: <wccn0mqqgng.fsf@shell01.TheWorld.com>
Date: Sat, 28 Dec 2002 15:58:43 GMT
Content-Type: text/plain; charset=us-ascii
References: <3e0b2a66_4@news.bluewin.ch>
 <slrnb0mvgq.j0i.adi@drcomp.erfurt.thur.de>
 <Vg9FFjG215C+Ewh5@grazebrook.demon.co.uk>
 <slrnb0o8pi.ma5.adi@drcomp.erfurt.thur.de>
 <wccadir1jrt.fsf@shell01.TheWorld.com>
 <slrnb0r842.2n7.adi@drcomp.erfurt.thur.de>
NNTP-Posting-Host: shell01.theworld.com
Mime-Version: 1.0
Organization: The World Public Access UNIX, Brookline, MA
Xref: archiver1.google.com comp.lang.ada:32359
Date: 2002-12-28T15:58:43+00:00
List-Id: <comp.lang.ada>

Adrian Knoth <adi@drcomp.erfurt.thur.de> writes:

> Robert A Duff <bobduff@shell01.TheWorld.com> wrote:
> 
> > Compilers are required to pack tightly in this case (one bit per Boolean
> > component).  I.e., Matrix'Component_Size will be 1 if there's a pragma
> > Pack.  See RM-13.2(9).
> 
> Hmm?

Looks like a compiler bug to me.  It seems to me that RM-13.2(9) implies
packed arrays of Boolean have 'Component_Size = 1.  Don't you think so?

> with Ada.Text_IO; use Ada.Text_IO;
> 
> procedure bla is
> 
>    type MATRIX is array (Positive range <>, Positive range <>) of Boolean;
>    type POINTER_MATRIX is access all MATRIX;
> 
>    pragma Pack (MATRIX);
> 
>    type my_matrix is array (Positive range <>, Positive range <>) of Boolean;
> 
>    A : POINTER_MATRIX := new MATRIX (1 .. 10000, 1 .. 5000);
> 
> begin
>    Put_Line (Integer'Image (MATRIX'Component_Size));
>    Put_Line (Integer'Image (my_matrix'Component_Size));
> end bla;
> 
> 
> adi@drcomp:/tmp$ ./bla
>  8
>  8
> adi@drcomp:/tmp$
>  
> > It's got nothing to do with the fact that the thing is heap allocated,
> > nor the fact that the bounds are not known at compile time.
> 
> For the variable A it is even known, but I was not able to determine
> a valuable difference in memory-comsumption.

So what size is A.all?

- Bob