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Date:      Fri, 6 Oct 2000 10:03:35 +0100 (BST)
From:      Doug Rabson <dfr@nlsystems.com>
To:        Mike Smith <msmith@freebsd.org>
Cc:        John Baldwin <jhb@freebsd.org>, cvs-committers@freebsd.org, cvs-all@freebsd.org
Subject:   Re: cvs commit: src/sys/alpha/include atomic.h src/sys/i386/include atomic.h 
Message-ID:  <Pine.BSF.4.21.0010061002400.94692-100000@salmon.nlsystems.com>
In-Reply-To: <200010052235.e95MZ2h03295@mass.osd.bsdi.com>

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On Thu, 5 Oct 2000, Mike Smith wrote:

> > jhb         2000/10/05 15:19:50 PDT
> > 
> >   Modified files:
> >     sys/alpha/include    atomic.h 
> >     sys/i386/include     atomic.h 
> >   Log:
> >   Add atomic_readandclear_int and atomic_readandclear_long.
> 
> Um, isn't this just exchange-with-zero?

For alpha, readandclear is marginally more efficient since you don't need
to read the original value in order to have something to pass as a compare
value for cmpset.

-- 
Doug Rabson				Mail:  dfr@nlsystems.com
					Phone: +44 20 8348 6160




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