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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: What shoudl GNAT do wrt variant record and representation
 clauses?
Date: Mon, 02 Feb 2015 09:04:27 +0000
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Date: 2015-02-02T09:04:27+00:00
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Lucretia <laguest9000@googlemail.com> writes:

>    for Pixel_Orders use
>       record
>          Indexed_Order at 0 range 0 .. 2;
>          Packed_Order  at 0 range 0 .. 3;
>          Array_Order   at 0 range 0 .. 3;
>       end record;

Pretty sure you're saying that you don't care what the top bit of the
4-bit field is if it contains an Indexed_Order. So sometimes it'll be
wrong.

I must say, since you're setting up constants, I'd have expected the
compiler to work out the required 32-bit Pixel_Format_Names value at
compile time from a zeroed base!

I wondered whether -gnatw.h would do the trick, but (4.9.1) it just says

gcc -c -gnatw.h pixel_formats.ads
pixel_formats.ads:124:10: warning: 32768-bit gap before component "Indexed_Order"
pixel_formats.ads:125:10: warning: 32768-bit gap before component "Packed_Order"
pixel_formats.ads:126:10: warning: 32768-bit gap before component "Array_Order"

:-)

(I changed the name of the package to save trouble downloading other stuff)