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From: mheaney@ni.net (Matthew Heaney)
Subject: Rules for Representation of Subtypes
Date: 1996/09/22
Message-ID: <mheaney-ya023080002209961353500001@news.ni.net>#1/1
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organization: Estormza Software
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newsgroups: comp.lang.ada
Date: 1996-09-22T00:00:00+00:00
List-Id: <comp.lang.ada>


I've always been curious about the rules for representation of subtypes. 
For example, if I make a declaration like this:

   A_Small_Integer : Integer range 0 .. 255;  -- assume type Integer is 4 bytes

then is an implementation allowed to use fewer than 4 bytes to represent
A_Small_Integer?

Suppose I'm on a Unix system and I do this

   read (fd, A_Small_Integer'Address, 4);

If the representation of A_Small_Integer is only 1 byte, then obviously I'm
in trouble.  Am I required to specify the size of objects?

   A_Small_Integer : Integer range 0 .. 255;
   for A_Small_Integer'Size use 32;                     -- required?

matt
mheaney@ni.net

--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
mheaney@ni.net
(818) 985-1271