Rep spec still not possible.

["Petter Fryklund" <qsbpefr@esavionics.se>]

   generic
      type Indices is range <>;
   package Structure is
      type My_Array is array (Indices) of Integer;

      type S is record
         X,Y : Integer;
         A : My_Array;
      end record;

      My_Array_Length : constant Integer :=
        Integer ((Indices'Last - Indices'First + 1) * 8);

      for S use record
         X at 0 range 0 .. 31;
         Y at 4 range 0 .. 31;
         A at 8 range 0 .. My_Array_Length - 1; <--- Expression not static.
      end record;

   end Structure;

I've been in this alley before but I didn't find may way around, does
anybody have any suggestions?