Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!oliveb!amiga!cbmvax!bryce
From: bryce@cbmvax.UUCP (Bryce Nesbitt)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Official Warnings...
Message-ID: <6988@cbmvax.UUCP>
Date: 25 May 89 23:52:07 GMT
References: <3082@haven.umd.edu> <11394@well.UUCP> <3773@sugar.hackercorp.com>
Reply-To: bryce@cbmvax.UUCP (Bryce Nesbitt)
Organization: Commodore Technology, West Chester, PA
Lines: 20

In article <3773@sugar.hackercorp.com> karl@sugar.hackercorp.com (Karl Lehenbauer) writes:
>
>Isn't TAS useful on a single CPU system, though, for providing fast,
>uninterruptable test and set for use as a semaphore, without having 
>to turn off interrupts?

For a single CPU system, the BSET and BCLR instructions are identical
to TAS.  The 68000 does not interrupt instructions in the middle.
TAS is only needed for multiple CPUs.

BSET and BCLR first test, then set bits. "poof".  DON'T USE TAS.



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