From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rene Herman <rene.herman@keyaccess.nl>
Date: Wed, 10 Aug 2005 23:03:14 +0000
Subject: [KJ] Re: Log2 all through the kernel?
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Erik Mouw wrote:

> On Wed, Aug 10, 2005 at 05:54:44PM +0200, Oliver Korpilla wrote:
> 
>>Wouldn't it be more sensible to supply one portable one, with bit
>>shifts, and people with a need for O(1) timing could implement it using
>>an array?
> 
> 
> Send a patch to the linux-kernel mailing list and see what happens.

Sticking a few defines in a header somewhere should do, I believe:

#define floor_log2(x) (fls(x) - 1)
#define ceil_log2(x) (fls((x) - 1)

fls() is both defined in the kernel and a gcc builtin.

Rene.

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