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Newsgroups: comp.lang.ada
Subject: Re: Bitmanipulation in Ada
From: Bernd.Specht@gmx.com (Bernd Specht)
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Date: 20 Aug 2004 21:20:49 GMT
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Date: 2004-08-20T23:20:49+02:00
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Jean-Pierre Rosen <rosen@adalog.fr> wrote in
news:1394gc.kok.ln@skymaster: 

> Bernd Specht a �crit :
> 
>> Always? What do you think about bitscrambling software which has to
>> treat data alternating as bitvector and as integer value in a loop
>> like this (not exeactly this for securitity reasons):
>> 
>> ...
>> loop
>>   declare
>>     x : boolean;
>>   begin
>>      x := b(k);
>>      b(k) := b(32 - k);
>>      b (32 - k) := x;
>>      I := I * prime1 mod prime2;
>>   end;
>> end loop;
>> 
> 
> Such software does not use signed integers, but modular integers. And 
> you have all the bit operations you need on modular integers.


In fact, thats right :-o

Can I declare full 32-bit modular types? Ada itself has no 32-bit unsigned 
(except in Interfaces.C). Natural is only a *subrange* from Integer.