Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!cornell!uw-beaver!ssc-vax!cxsea!blm
From: blm@cxsea.UUCP (Brian Matthews)
Newsgroups: comp.std.c
Subject: Re: volatile registers
Message-ID: <2592@cxsea.UUCP>
Date: 6 Jan 89 17:14:38 GMT
References: <141@bms-at.UUCP> <275@twwells.uucp> <15166@mimsy.UUCP> <9236@smoke.BRL.MIL> <15171@mimsy.UUCP> <9316@ihlpb.ATT.COM> <2337@cuux <10720@rpp386.Dallas.TX.US>
Reply-To: blm@cxsea.UUCP (Brian Matthews)
Organization: Computer X Inc.
Lines: 32

The Beach Bum (jfh@rpp386.Dallas.TX.US) writes:
|A common usage is in interrupt [ software ] handlers where the
|signal catching routine sets a flag and returns.
|
|The proper definition for such a flag should be
|
|in catch.c:
|--
|int	sigflag;
|
|int	catch (sig)
|{
|	...
|	sigflag = 1;
|	...
|}
|--
|then outside catch.c you must use
|
|extern	volatile int sigflag;

The spirit of the posting is correct, but there are a couple of technical
errors.

First, the type of sigflag should be sig_atomic_t, not int.  Second, as
the function argument to signal is void (*fn)(int), catch should be a
void function.  See the signal handling section of the draft (section
4.7, I believe).

-- 
Brian L. Matthews  blm@cxsea.UUCP   ...{mnetor,uw-beaver!ssc-vax}!cxsea!blm
+1 206 251 6811    Computer X Inc. - a division of Motorola New Enterprises