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From: David Laight <David.Laight@ACULAB.COM>
To: "'Vaittinen, Matti'" <Matti.Vaittinen@fi.rohmeurope.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>, Jiri Kosina <trivial@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Yury Norov <yury.norov@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
Geert Uytterhoeven <geert+renesas@glider.be>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/4] bitops: Add single_bit_set()
Date: Tue, 23 Nov 2021 10:42:45 +0000 [thread overview]
Message-ID: <874db8b91ff04001a8958f100a614ed8@AcuMS.aculab.com> (raw)
In-Reply-To: <e2675600-7b04-19b0-79ce-28a4e1d1f225@fi.rohmeurope.com>
From: Vaittinen, Matti
> Sent: 22 November 2021 13:19
>
> On 11/22/21 14:57, Andy Shevchenko wrote:
> > On Mon, Nov 22, 2021 at 12:42:21PM +0000, Vaittinen, Matti wrote:
> >> On 11/22/21 13:28, Andy Shevchenko wrote:
> >>> On Mon, Nov 22, 2021 at 01:03:25PM +0200, Matti Vaittinen wrote:
> >
> > What do you mean by this?
> >
> > hweight() will return you the number of the non-zero elements in the set.
>
> Exactly. The function I added did only check if given set of bits had
> only one bit set.
Checking for exactly one bit can use the (x & (x - 1)) check on
non-zero values - which may even be better on some cpus with a
popcnt instruction.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-11-23 10:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 11:03 [PATCH 0/4] Provide event map helper for regulator drivers Matti Vaittinen
2021-11-22 11:03 ` [PATCH 1/4] bitops: Add single_bit_set() Matti Vaittinen
2021-11-22 11:28 ` Andy Shevchenko
2021-11-22 12:42 ` Vaittinen, Matti
2021-11-22 12:57 ` Andy Shevchenko
2021-11-22 13:00 ` Andy Shevchenko
2021-11-22 13:18 ` Vaittinen, Matti
2021-11-23 10:42 ` David Laight [this message]
2021-11-23 10:47 ` Andy Shevchenko
2021-11-23 10:58 ` David Laight
2021-11-23 13:43 ` 'Andy Shevchenko'
2021-11-23 14:36 ` David Laight
2021-11-23 11:42 ` Vaittinen, Matti
2021-11-22 17:54 ` Yury Norov
2021-11-22 19:56 ` Andy Shevchenko
2021-11-23 7:51 ` Yury Norov
2021-11-23 5:26 ` Vaittinen, Matti
2021-11-23 7:33 ` Yury Norov
2021-11-23 9:03 ` Andy Shevchenko
2021-11-23 9:10 ` Geert Uytterhoeven
2021-11-22 11:03 ` [PATCH 2/4] regulators: Add regulator_err2notif() helper Matti Vaittinen
2021-11-22 11:04 ` [PATCH 3/4] regulators: irq_helper: Provide helper for trivial IRQ notifications Matti Vaittinen
2021-11-22 11:48 ` Andy Shevchenko
2021-11-22 12:44 ` Vaittinen, Matti
2021-11-22 11:04 ` [PATCH 4/4] regulator: Drop unnecessary struct member Matti Vaittinen
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