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NNTP-Posting-Date: Fri, 14 Oct 2005 17:54:20 -0500
From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: changing alignment of built-in boolean
References: <1129320236.007525.185300@g44g2000cwa.googlegroups.com>
Date: Sat, 15 Oct 2005 00:55:43 +0200
Message-ID: <8764rzhfo0.fsf@ludovic-brenta.org>
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Date: 2005-10-15T00:55:43+02:00
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invalidemail@aerojockey.com writes:

> Is it possible, in GNAT, to force the built-in Boolean type to use
> 4-byte (32-bit) alignment?  Reason: I have to interface some Ada code
> to a package that insists on 32-bit variables on 4-byte-aligned
> addresses.
>
> Feel free to suggest some other strategy for accomplishing this, though
> I'd prefer not to make extensive changes to the Ada code (such as
> changing it to use a subtype of Boolean).
>
> I'm using GNAT 3.15p on HPUX.
>
> Thanks.

type T is record
   B : Boolean;
   ...
end record;

for T use record
   B at 0 range 0 .. 31;
   ...
end record;

package P is
   subtype External_Boolean is Boolean;
   for External_Boolean'Size use 32;
   for External_Boolean'Alignment use 32;

   procedure External (B : in External_Boolean);
   pragma Import (C, External, "some_function");
end P;

-- 
Ludovic Brenta.