From: Roland Dreier <rdreier@cisco.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
Bart Van Assche <bart.vanassche@gmail.com>,
David Dillow <dave@thedillows.org>
Subject: Re: [PATCH] log2.h: Macro-ize is_power_of_2() for use in BUILD_BUG_ON
Date: Wed, 06 Jan 2010 12:44:05 -0800 [thread overview]
Message-ID: <aday6kbt14a.fsf@roland-alpha.cisco.com> (raw)
In-Reply-To: <20100106123306.ac85e557.akpm@linux-foundation.org> (Andrew Morton's message of "Wed, 6 Jan 2010 12:33:06 -0800")
> Perhaps we can avoid worrying about that via
> #define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
> BUILD_BUG_ON((n != 0 && ((n & (n - 1)) == 0)))
Having something so specific to this particular case makes me feel like
maybe it's just not worth it. At least in the case I'm looking at, we
could just have:
/*
* The code relies on FOO being a power of 2. If you break this,
* you're dumb.
*/
#define FOO_SHIFT 6
#define FOO (1 << FOO_SHIFT)
Your thoughts?
- R.
next prev parent reply other threads:[~2010-01-06 20:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-06 20:21 [PATCH] log2.h: Macro-ize is_power_of_2() for use in BUILD_BUG_ON Roland Dreier
2010-01-06 20:33 ` Andrew Morton
2010-01-06 20:44 ` Roland Dreier [this message]
2010-01-06 21:15 ` David Dillow
2010-01-06 21:42 ` Andrew Morton
2010-01-06 23:02 ` [PATCH] Add BUILD_BUG_ON_NOT_POWER_OF_2() Roland Dreier
2010-01-06 23:09 ` Andrew Morton
2010-01-07 7:33 ` Bart Van Assche
2010-01-07 7:51 ` Roland Dreier
2010-01-07 8:36 ` Robert P. J. Day
2010-01-07 16:45 ` Stefan Richter
2010-01-06 21:23 ` [PATCH] log2.h: Macro-ize is_power_of_2() for use in BUILD_BUG_ON Roland Dreier
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