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From: Adrian Knoth <adi@thur.de>
Newsgroups: comp.lang.ada
Subject: Re: Bitwise XOR?
Date: 2 Oct 2003 08:30:50 GMT
Organization: loris.TV
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David N. Maez <sellout@dharmadevil.com> wrote:

>   x : integer;
>   y : integer;
>   x := x xor y;

> What am I missing?

There is no XOR defined for anything else than bits. You'll need
to mask the bits and recombine the result.

I did it some time ago, I'm not sure whether it is right, perhaps
it should be done on mod-datatypes.

   function "xor" (Left, Right : in Integer) return Integer is
      result : Integer := 0;
      leftrest : Integer := Left;
      rightrest : Integer := Right;
      boolleft, boolright : Boolean;

   begin
      for I in 0 .. Integer'Size - 1 loop
         if (leftrest mod 2 = 1) then
            boolleft := True;
         else
            boolleft := False;
         end if;

         leftrest := leftrest / 2;
         if (rightrest mod 2 = 1) then
            boolright := True;
         else
            boolright := False;
         end if;
         rightrest := rightrest / 2;

         if (boolleft xor boolright) then
            result := result + 2**(I);
         end if;
      end loop;

      return result;
   end "xor";


-- 
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