Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!ucsd!ucsdhub!hp-sdd!hplabs!hpda!hpcuhb!hpindda!mharper
From: mharper@hpindda.HP.COM (Michael J. Harper)
Newsgroups: comp.sys.mac.programmer
Subject: Re: what the heck is "reentrant"?
Message-ID: <7390012@hpindda.HP.COM>
Date: 5 Aug 88 14:25:22 GMT
References: <730049@hpcilzb.HP.COM>
Organization: HP Information Networks, Cupertino, CA
Lines: 13

The best example of reentrant code that I've come
across is an interrupt service routine.

Suppose you get an interrupt and you're running your
ISR.  If this ISR gets interrupted with the SAME
interrupt and the SAME ISR gets run again, both
invocations of the ISR must be able to complete
normally.  (Think of an ISR that increments a
counter for example.)  If both invocations of the
same code can complete normally, then the code
is "reentrant," i.e. it can be reentered without
adverse effects.

Michael J. Harper