Path: utzoo!utgpu!water!watmath!clyde!rutgers!tut.cis.ohio-state.edu!ukma!uflorida!codas!ateng!chip
From: chip@ateng.UUCP (Chip Salzenberg)
Newsgroups: comp.lang.c
Subject: Re: volatile
Message-ID: <212@ateng.UUCP>
Date: 31 Mar 88 19:33:59 GMT
References: <12578@brl-adm.ARPA> <1988Mar25.172355.348@utzoo.uucp> <588@imagine.PAWL.RPI.EDU> <1988Mar29.004454.2867@utzoo.uucp>
Reply-To: chip@ateng.UUCP (Chip Salzenberg)
Organization: A T Engineering, Tampa, FL
Lines: 30

In article <1988Mar29.004454.2867@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>Nobody is saying that the concept is not necessary in certain specialized
>situations.
>[...] the sort of code we're talking about isn't portable anyway.

What about signal handlers?

	/* begin example */

	volatile int hit = 0;

	int     foo();

	main()
	{
		signal(SIGINT, foo);
		while (!hit)
			;
		exit(0);
	}

	foo()
	{
		++hit;
	}

	/* end example */

Without volatile, you can't protect this program from being over-optimized.

>"Noalias must go.  This is non-negotiable."  --DMR
Definitely.
-- 
Chip Salzenberg                 "chip@ateng.UU.NET" or "codas!ateng!chip"
A T Engineering                 My employer's opinions are a trade secret.
       "Anything that works is better than anything that doesn't."