Path: utzoo!attcan!uunet!iscuva!jimc
From: jimc@iscuva.ISCS.COM (Jim Cathey)
Newsgroups: comp.sys.mac.programmer
Subject: Re: what the heck is "reentrant"?
Message-ID: <1837@iscuva.ISCS.COM>
Date: 5 Aug 88 23:21:12 GMT
References: <730049@hpcilzb.HP.COM> <104700046@p.cs.uiuc.edu>
Organization: ISC Systems Corporation, Spokane, WA
Lines: 27

In article <104700046@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
>Here are a few common ways to make something NON-reentrant:
>
>(1) Have a subroutine generate and execute its own assembly-language
>instructions.  Two separate threads of execution might try to write
>different instructions to the same place.

It is OK to generate and execute your own assembly-language instructions
provided you create them on the stack (since each invocation of the subroutine
gets its own stack frame).  On a 68020 you still must flush the cache after
you execute your routine or risk the wrath of the gods!

>(2) Old Fortran linkage.  One of the first proposed ways of...

Here's another (and I might add the easiest) way:

(3) Modifying global or static local variables (in C parlance).  (Unless you 
use semaphore techniques on them.)

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