From: Lars-Peter Clausen <lars@metafoo.de>
To: Jonathan Cameron <jic23@kernel.org>,
"zhaoxiu.zeng" <zhaoxiu.zeng@gmail.com>,
Michael Hennerich <Michael.Hennerich@analog.com>,
Hartmut Knaack <knaack.h@gmx.de>,
Peter Meerwald <pmeerw@pmeerw.net>
Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org
Subject: Re: [PATCH 28/31] iio: gyro: use parity32 in adxrs450.c
Date: Mon, 28 Mar 2016 10:50:13 +0200 [thread overview]
Message-ID: <56F8F045.7060409@metafoo.de> (raw)
In-Reply-To: <56F8ECDE.3010701@kernel.org>
On 03/28/2016 10:35 AM, Jonathan Cameron wrote:
> On 27/03/16 08:42, zhaoxiu.zeng wrote:
>> From: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com>
>>
>> Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com>
> Interesting. Whilst obviously correct I wonder if this obscures the
> intent of the code a little. Lars, what do you think?
The parity function is newly introduced in this series and can be more
efficient that just hw_weight() & 1 on certain architectures. Since the
result is the same using it is certainly an improvement. But ...
[...]
>> - if (!(hweight32(tx) & 1))
>> - tx |= ADXRS450_P;
>> + tx |= !parity32(tx) * ADXRS450_P;
... this should still be
if (!parity32(tx))
tx |= ADXRS450_P;
Otherwise it's a bit too much obfuscated for my taste. Just leave it to the
compiler to optimize it as it sees it fit.
prev parent reply other threads:[~2016-03-28 8:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1458788612-4367-1-git-send-email-zhaoxiu.zeng@gmail.com>
2016-03-27 7:42 ` [PATCH 28/31] iio: gyro: use parity32 in adxrs450.c zhaoxiu.zeng
2016-03-28 8:35 ` Jonathan Cameron
2016-03-28 8:50 ` Lars-Peter Clausen [this message]
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