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From: Tom Moran <tmoran@bix.com>
Subject: aliased & packed?
Date: 1997/05/09
Message-ID: <33734C0C.6904@bix.com>#1/1
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Organization: InterNex Information Services 1-800-595-3333
Reply-To: tmoran@bix.com
Newsgroups: comp.lang.ada
Date: 1997-05-09T00:00:00+00:00
List-Id: <comp.lang.ada>


Clearly you can't do it.  I'd like to use pragma Pack for bits in a
black/white bitmap array.  That's easy to manipulate.  But to actually
display it I need to do a system call and pass the address.  If it
wasn't packed, Image'unchecked_access would be appropriate.  But
that won't work because Image would have to be aliased, and it can't
be because it's packed. Must I drop 'Pack' and make it an array of
bytes and do my own masking, shifting, etc?  What's the cleanest/most
portable/best way to accomplish the task?