From: olof@austin.ibm.com (Olof Johansson)
To: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc64-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, Anton Blanchard <anton@samba.org>
Subject: Re: [PATCH 3/4] ppc64: Add driver for BPA iommu
Date: Thu, 28 Apr 2005 09:30:30 -0500 [thread overview]
Message-ID: <20050428143030.GC1023@austin.ibm.com> (raw)
In-Reply-To: <20050428140558.GB1023@austin.ibm.com>
On Thu, Apr 28, 2005 at 09:05:58AM -0500, Olof Johansson wrote:
> > +/* compute the hashed 6 bit index for the 4-way associative pte cache */
> > +static inline unsigned long
> > +get_ioc_hash(ioste iost_entry, unsigned long io_address)
> > +{
> > + unsigned long iopte = get_ioptep(iost_entry, io_address);
> > +
> > + return ((iopte & 0x000000000000001f8ul) >> 3)
> > + ^ ((iopte & 0x00000000000020000ul) >> 17)
> > + ^ ((iopte & 0x00000000000010000ul) >> 15)
> > + ^ ((iopte & 0x00000000000008000ul) >> 13)
> > + ^ ((iopte & 0x00000000000004000ul) >> 11)
> > + ^ ((iopte & 0x00000000000002000ul) >> 9)
> > + ^ ((iopte & 0x00000000000001000ul) >> 7);
>
> Can't you reverse the subword by just doing one XOR instead of 6?
Ugh, I wrote that before I had coffee. No you can't, you can just negate
the value by doing the XOR. Nevermind.
-Olof
next prev parent reply other threads:[~2005-04-28 14:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-28 7:54 [PATCH 0/4] ppc64: Introduce BPA platform Arnd Bergmann
2005-04-28 7:56 ` [PATCH 1/4] ppc64: add BPA platform type Arnd Bergmann
2005-04-28 7:58 ` [PATCH 2/4] ppc64: Add driver for BPA interrupt controllers Arnd Bergmann
2005-04-28 7:59 ` [PATCH 3/4] ppc64: Add driver for BPA iommu Arnd Bergmann
2005-04-28 14:05 ` Olof Johansson
2005-04-28 14:30 ` Olof Johansson [this message]
2005-04-29 4:35 ` Arnd Bergmann
2005-04-29 5:36 ` Olof Johansson
2005-04-29 5:48 ` Arnd Bergmann
2005-04-29 6:43 ` Benjamin Herrenschmidt
2005-04-29 8:31 ` Arnd Bergmann
2005-04-29 13:06 ` Paul Mackerras
2005-04-28 8:00 ` [PATCH 4/4] ppc64: Add SPU file system Arnd Bergmann
2005-04-28 14:44 ` [PATCH 0/4] ppc64: Introduce BPA platform Sonny Rao
2005-04-29 4:35 ` Arnd Bergmann
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