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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Does Ada support endiannes?
Date: Wed, 14 Dec 2011 19:16:46 +0100
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Date: 2011-12-14T19:16:46+01:00
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On Wed, 14 Dec 2011 08:16:02 -0800 (PST), Gerd wrote:

> On 13 Dez., 15:19, Gautier write-only <gautier_niou...@hotmail.com>
> wrote:
> 
> Are you sure the "/" and mod would work correct?

Always. Arithmetic is complete in the sense that any possible function can
be implemented using these operations.

> Assume, that the Value 16#000000FF# shall be converted to
> 16#FF000000#
>
> Native : Integer := 16#000000FF#;
> 
> Remote : Integer;
> 
> Remote := 16#01000000# * ()Native mod 16#000000FF#); -- overflow!

Either it is not Integer (e.g. Unsigned_32) or else overflow is not an
error but a legal outcome indicating protocol error, for example. The
decision depends on the application.

Note that if you used a representation clause and/or Unchecked_Conversion,
you would have to use X'Valid attribute in order to check obtained value
for being an integer.

For all cases where arithmetic would raise Constraint_Error, X'Value should
yield false, which is not guaranteed of course. This is another reason why
not to use representation clauses, because some illegal representation
might get misinterpreted as proper values.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de