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From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: Interpretation of volatile - two questions
Message-ID: <12382@smoke.BRL.MIL>
Date: 19 Mar 90 23:01:45 GMT
References: <2604A628.8521@paris.ics.uci.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 10

In article <2604A628.8521@paris.ics.uci.edu> rfg@paris.ics.uci.edu (Ronald Guilmette) writes:
>does the standard (a) permit, (b) require, or (c) prohibit the assignment
>statement shown to access the c2 field of the "struct s" pointed to by
>memory_mapped_device_p?

It requires that the implementation document its rules for access to
volatile objects, which presumably should include cases of access to
such an object as a side effect of accessing a non-volatile one, as
in your example.  Obviously choice (b) would have been silly and
choice (c) would be an impossible constraint on some architectures.