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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Forcing GNAT to use 32-bit load/store instructions on ARM?
Date: Wed, 02 Jul 2014 08:30:44 +0100
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Date: 2014-07-02T08:30:44+01:00
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daniel.dmk@googlemail.com writes:

> Thanks for this suggestion, I'll define the reserved bits in the
> register, and use static checks to enforce that they are not modified
> from their reset value in the code.

You could use something like

   type Reserved_Bit is range 0 .. 0 with Size => 1;
   type Reserved is array (Natural range <>) of Reserved_Bit
     with Component_Size => 1;

   ...

   type T is record
      A : Boolean;            -- at bit 0
      Res : Reserved (1 .. 6);
      B : Boolean;            -- at bit 7
   end record with Size => 8;

(with representation clauses as indicated)