From: Arnd Bergmann <arnd@arndb.de>
To: David Howells <dhowells@redhat.com>
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Subject: Re: [PATCH] MPILIB: Provide count_leading/trailing_zeros() based on arch functions
Date: Fri, 20 Jul 2012 22:02:28 +0000 [thread overview]
Message-ID: <201207202202.28723.arnd@arndb.de> (raw)
In-Reply-To: <5723.1342794099@warthog.procyon.org.uk>
On Friday 20 July 2012, David Howells wrote:
>
> Arnd Bergmann <arnd@arndb.de> wrote:
>
> > I don't generally like to put stuff into asm-generic when it's unlikely
> > to be overridden by architectures. It would really belong into
> > include/linux, but then again we have all the other bitops in asm-generic
> > as well, so whatever...
>
> Some arches (such as Sparc, I think) have count-leading-zero instructions.
But I guess they would still use the same definition of
+static inline int count_leading_zeros(unsigned long x)
+{
+ if (sizeof(x) == 4)
+ return BITS_PER_LONG - fls(x);
+ else
+ return BITS_PER_LONG - fls64(x);
+}
and just provide their own fls().
Arnd
next prev parent reply other threads:[~2012-07-21 8:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 12:56 [PATCH] MPILIB: Provide count_leading/trailing_zeros() based on arch functions David Howells
2012-07-20 13:53 ` Arnd Bergmann
2012-07-20 14:21 ` David Howells
2012-07-20 22:02 ` Arnd Bergmann [this message]
2012-07-21 0:46 ` David Miller
2012-08-10 12:51 ` Jan Engelhardt
2012-08-10 21:08 ` David Miller
-- strict thread matches above, loose matches on Subject: below --
2012-07-06 15:45 David Howells
2012-07-13 4:04 ` James Morris
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