Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!math.mit.edu!drw
From: drw@fibonacci.math.mit.edu (Dale R. Worley)
Newsgroups: comp.std.c
Subject: volatile
Message-ID: <DRW.89Oct26001311@fibonacci.math.mit.edu>
Date: 26 Oct 89 04:13:11 GMT
References: <1989Oct25.020542.13354@cc.Columbia.NCR.COM>
Sender: root@bloom-beacon.MIT.EDU
Organization: MIT Dept. of Mathematics, Cambridge, MA, USA
Lines: 12
In-reply-to: haug@cc.Columbia.NCR.COM's message of 25 Oct 89 02:05:42 GMT

In article <1989Oct25.020542.13354@cc.Columbia.NCR.COM> haug@cc.Columbia.NCR.COM writes:

   I understand the usage of volatile to indicate that a value may change for
   reasons that are not necesarily apparent (hardware registers, interrupts, etc)
   and so must be read from memory each time they are referenced.  My question is:
   must the value be written each time it is assigned[?]

Yes.  I remember seeing a statement in the draft standard that both
reads and writes to a volatile l-value must be as in the "abstract
machine".

Dale			drw@math.mit.edu