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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Efficiency of code generated by Ada compilers
Date: Mon, 09 Aug 2010 15:05:23 -0400
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Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org> writes:

> On 08/09/2010 06:28 AM, Robert A Duff wrote:
>>
>> Signed integers work fine for that.  Except when you need
>> that one extra bit -- that's the problem.
>
> We've been able to do
>
> type T is range 0 .. 2 ** N - 1;
> for T'Size use N;
>
> since Ada 83.

Yes.  And T'Size = N by default in Ada >= 95, so I would write:

    pragma Assert(T'Size = N);

instead of the Size clause.

>...So the only problem is when you want the equivalent of
>
> type T is mod System.Max_Binary_Modulus;
>
> since System.Max_Binary_Modulus - 1 > System.Max_Integer.

Exactly.  (Well, I don't think that's required by the RM,
but in all Ada implementations it's probably the case
that Max_Binary_Modulus = 2*(Max_Integer+1).)

- Bob