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From: dewar@cs.nyu.edu (Robert Dewar)
Newsgroups: comp.lang.ada
Subject: Re: Access type representations.
Date: 28 Oct 1994 12:52:01 -0400
Organization: Courant Institute of Mathematical Sciences
Message-ID: <38ra7h$jhc@gnat.cs.nyu.edu>
References: <9410281131.AA15384@eurocontrol.de>
 <CyDxsq.JFB@inmet.camb.inmet.com>
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Date: 1994-10-28T12:52:01-04:00
List-Id: <comp.lang.ada>

In addition to Tucker's list of non-pointer representations of access types,
consider also the GNAT representation for pointers to unconstrained types.
These are two words long, one word points to the template containing the
bounds, and the other word points to the data of the array. Eventually we
expect to change this second word so that it points to the virtual origin
of the array, instead of the actual origin, thus avoiding the need to
subtract lower bounds when indexing into the array, but we have not don
e this yet.