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From: wemagor@fms0.cca.rockwell.com (Wayne Magor)
Subject: Re: Ada83 or DEC Ada: Feature or bug?
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References: <360ecv$kq1@hacker.demon.co.uk>
Date: Mon, 26 Sep 1994 23:38:18 GMT
Date: 1994-09-26T23:38:18+00:00
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In article <360ecv$kq1@hacker.demon.co.uk>, steve@hacker.demon.co.uk (Stephen M. Youndt) writes:
>
>Is it a feature of Ada83 or DEC Ada that makes it impossible to work with
>unsigned values? MAX_INT always bites back with CONSTRAINT_ERROR when I try
>to do any real work with unsigned 32bit values (i.e. SYSTEM.UNSIGNED_LONGWORD).
>Both I and my coworkers find this terribly annoying. Is this part of Ada83
>or a DEC Ada peculiarity? If Ada83, will it be fixed in 9X?

This was a problem with Ada83 which is fixed in Ada-9X.  DEC defined
System.Unsigned_Longword like this:

   type UNSIGNED_LONGWORD is range -2_147_483_648 .. 2_147_483_647;
   for  UNSIGNED_LONGWORD'SIZE use 32;

whereas they defined System.Unsigned_Word like this:

   type UNSIGNED_WORD is range 0 .. 65535;
   for  UNSIGNED_WORD'SIZE use 16;

You can't really use Unsigned_Longword for much of anything except to
interface to other routines.

Wayne.