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From: "Gerd" <GerdM.O@t-online.de>
Newsgroups: comp.lang.ada
Subject: Re: Any way of persuading GNAT/GCC to implement a true overlay and
 not a pointer?
Date: 3 Apr 2006 05:25:21 -0700
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Date: 2006-04-03T05:25:21-07:00
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Why not use an overlayed record for your data, something like this:

procedure Overlay is  -- your X
   type
      Sometype is record
         x: integer;
         y: integer;
        end record;

   type
      Othertype is array (1..2) of Integer;  -- your Y

   type
      OVL (b: Boolean) is record
        case b  is
          when true => s : Sometype;
          when false => o : Othertype;
        end case;
      end record;

   for OVL use record
                  s at 0 range 0..63;
                  o at 0 range 0..63;
                  b at 8 range 0..7;
               end record;

  data : OVL ( b=>true ); -- data with Y and X at the same address
        
begin
  null;
end Overlay;