From owner-freebsd-hackers Wed Jan 31 15:56: 2 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from xena.gsicomp.on.ca (cr677933-a.ktchnr1.on.wave.home.com [24.43.230.149]) by hub.freebsd.org (Postfix) with ESMTP id C647E37B491; Wed, 31 Jan 2001 15:55:40 -0800 (PST) Received: from hermes (hermes.gsicomp.on.ca [192.168.0.18]) by xena.gsicomp.on.ca (8.11.1/8.9.3) with SMTP id f0VNrsi11237; Wed, 31 Jan 2001 18:53:55 -0500 (EST) (envelope-from matt@gsicomp.on.ca) Message-ID: <00df01c08be2$3ff1e0e0$1200a8c0@gsicomp.on.ca> From: "Matthew Emmerton" To: "John Baldwin" Cc: References: Subject: Re: Atomic bit operations Date: Wed, 31 Jan 2001 19:02:20 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > On 31-Jan-01 Matthew Emmerton wrote: > > Hi all, > > > > I've taken a look around for an implementation of atomic bit operations in > > FreeBSD (similar to Linux' asm/bitopt.h, which include clear_bit() and > > test_and_set_bit()) but haven't found any. The only thing I've found are > > the atomic clear/set/add/sub routines in machine/atomic.h. > > > > Do we have an implementation of atomic bit operations, and if we don't, > > would we like some? > > Erm, atomic_set() sets's bits, and atomic_clear() clear's bits. Anything else > you might need can be done with atomic_cmpset() anyways. Where are these functions implemented? /usr/include/machine/atomic.h just has atomic_set_XXX and clear_XXX primitives, which work on char/short/longs, but not individual bits. I presume that I could wrap the char operations with something that takes 0x01 and bit-shifts it appropriately so that atomic_set/clear could be used. However, certain other primitives are missing, such as an atomic test-and-set operation. Under the current scheme this would have to be done by two independent operations, which is not useful when atomicitiy is required. -- Matt Emmerton To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message