linux-kernel - Re: [PATCH V2 mmots] fs/hfsplus/wrapper.c: replace shift loop by fls

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Message-ID: <1400541748.14238.58.camel@joe-AO725>
Date:	Mon, 19 May 2014 16:22:28 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Fabian Frederick <fabf@...net.be>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 mmots] fs/hfsplus/wrapper.c: replace shift loop by fls

On Mon, 2014-05-19 at 16:09 -0700, Andrew Morton wrote:
> On Fri, 16 May 2014 22:38:15 +0200 Fabian Frederick <fabf@...net.be> wrote:
> > Replace while blocksize;shift by fls -1
[]
> fls() always makes my brain hurt.  ilog() is nicer?

Maybe take an aspirin?

ilog2(n) is effectively fls(n) - 1 but n can be
either u64 or u64 and ilog2 is compile-time
optimized when n is constant.

blocksize is a non-const u32 here.


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