From: Nick Piggin <nickpiggin@yahoo.com.au>
To: "Robert P. J. Day" <rpjday@mindspring.com>
Cc: Linux kernel mailing list <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, Paul Mackerras <paulus@samba.org>,
dhowells@redhat.com, galak@kernel.crashing.org
Subject: Re: [PATCH] Add "is_power_of_2" checking to log2.h.
Date: Tue, 30 Jan 2007 23:25:56 +1100 [thread overview]
Message-ID: <45BF3954.8050106@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0701300543420.17991@CPE00045a9c397f-CM001225dbafb6>
Robert P. J. Day wrote:
> Add the inline function "is_power_of_2()" to log2.h, where the value
> zero is *not* considered to be a power of two.
>
> Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
>
> /*
> + * Determine whether some value is a power of two, where zero is
> + * *not* considered a power of two.
> + */
Why the qualifier? Zero *is* not a power of 2, is it?
> +
> +static inline __attribute__((const))
> +bool is_power_of_2(unsigned long n)
> +{
> + return (n != 0 && ((n & (n - 1)) == 0));
> +}
> +
> +/*
> * round up to nearest power of two
> */
> static inline __attribute__((const))
--
SUSE Labs, Novell Inc.
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next prev parent reply other threads:[~2007-01-30 12:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-30 11:06 [PATCH] Add "is_power_of_2" checking to log2.h Robert P. J. Day
2007-01-30 12:25 ` Nick Piggin [this message]
2007-01-30 12:56 ` Robert P. J. Day
2007-01-30 14:12 ` Jan Engelhardt
2007-01-30 14:45 ` Robert P. J. Day
2007-01-30 15:50 ` Jan Engelhardt
2007-01-30 16:00 ` Robert P. J. Day
2007-06-11 23:11 ` H. Peter Anvin
2007-01-31 10:13 ` Vegard Nossum
2007-01-31 10:47 ` Robert P. J. Day
2007-01-31 1:21 ` Nick Piggin
2007-01-31 7:20 ` Robert P. J. Day
2007-02-01 10:41 ` David Howells
2007-02-01 10:43 ` David Howells
2007-02-01 10:49 ` Robert P. J. Day
2007-02-01 12:39 ` Tim Schmielau
2007-02-01 20:17 ` Valdis.Kletnieks
2007-02-01 21:55 ` Tim Schmielau
2007-02-20 15:29 ` Mariusz Kozlowski
2007-02-20 15:56 ` Kumar Gala
2007-02-20 16:14 ` Mariusz Kozlowski
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