Re: [PATCH 1/4] bitops: Add single_bit_set()

["Vaittinen, Matti" <Matti.Vaittinen@fi.rohmeurope.com>]

On 11/23/21 12:42, David Laight wrote:
> 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

Thanks! This was educating. I admit I had to launch a calculator with 
bit editor to see where this went to. I doubt I had ever noticed such 
possibility if I didn't send the original patch. I guess this is the 
true power of the collaboration ;)

Best Regards
--Matti

-- 
The Linux Kernel guy at ROHM Semiconductors

Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

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