Date: Thu, 26 Jul 2001 15:49:58 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Arun Sharma <arun@sharmas.dhs.org> Cc: hackers@FreeBSD.org, Bernd Walter <ticso@mail.cicely.de> Subject: Re: Need a clean room implementation of this function Message-ID: <XFMail.010726154958.jhb@FreeBSD.org> In-Reply-To: <20010726151100.D23264@sharmas.dhs.org>
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On 26-Jul-01 Arun Sharma wrote: > On Thu, Jul 26, 2001 at 11:59:27PM +0200, Bernd Walter wrote: >> [...] >> ATOMIC_ASM(set, char, "orb %b2,%0", v) >> ATOMIC_ASM(clear, char, "andb %b2,%0", ~v) >> [...] > > That does set, not test-and-set. What I want is exactly what the Intel > BTS instruction does: atomically test and set a bit. Unfortunately that is very ia32 specific. The code would be more friendly on alpha and ia64 at least if the algo was changed to use cmpset on a word instead of test-and-set of a bit. If you want, I can look at the code to see where it uses test_and_set() to determine how hard that would be. (It might be very easy to do.) -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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