From: William Breathitt Gray <vilhelm.gray@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linux-Arch <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 0/8] Introduce the for_each_set_clump macro
Date: Sat, 16 Jun 2018 15:16:24 -0400 [thread overview]
Message-ID: <20180616191624.GA20211@sophia> (raw)
In-Reply-To: <CAHp75VcGuJ0+qzUZZW=1VSeXmf_rht0tJvCH+yBsXPZz0z8qHA@mail.gmail.com>
On Wed, May 16, 2018 at 11:08:28PM +0300, Andy Shevchenko wrote:
>On Wed, May 16, 2018 at 5:03 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>> On Tue, May 15, 2018 at 6:22 PM, William Breathitt Gray
>> <vilhelm.gray@gmail.com> wrote:
>>
>>> For example, suppose you would like to iterate over a 16-bit integer 4
>>> bits at a time, skipping over 4-bit groups with no set bit, where XXXX
>>> represents the current 4-bit group:
>>>
>>> Example: 1011 1110 0000 1111
>>> First loop: 1011 1110 0000 XXXX
>>> Second loop: 1011 XXXX 0000 1111
>>> Third loop: XXXX 1110 0000 1111
>>>
>>> Each iteration of the loop returns the next 4-bit group that has at
>>> least one set bit.
>>>
>>> The for_each_set_clump macro has six parameters:
>>>
>>> * clump: set to current clump index for the iteration
>>> * index: set to current bitmap word index for the iteration
>>> * offset: bits offset of the found clump in the bitmap word
>>> * bits: bitmap to search within
>>> * size: bitmap size in number of clumps
>>> * clump_size: clump size in number of bits
>>>
>>> The clump_size argument can be an arbitrary number of bits and is not
>>> required to be a multiple of 2.
>>
>> I must say I'm impressed. Very nice arithmetics going on there.
>>
>> If I can get some ACK for the bitops patch I'd be happy to merge
>> it all through the GPIO tree. The users are pretty clear cut.
>
>Give me also some time to go through proposed API, I think it might
>have needed more alignment with existing find_* and for_* helpers.
Hi Andy,
Are there any additional changes you would like me to make before this
patchset is merged through the GPIO tree?
William Breathitt Gray
>
>> BTW: if I could, I would pull out Donald Knuth's "The Art of Computer
>> Programming vol 4A" chapter 7.1.3 "Bitwise Tricks and Techniques"
>> to see what he has to say about the subject, but I don't have
>> that book as it turns out.
>
>I can also add the Standford collection of bit algos here:
>
>https://graphics.stanford.edu/~seander/bithacks.html
>
>--
>With Best Regards,
>Andy Shevchenko
next prev parent reply other threads:[~2018-06-16 19:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-15 16:22 [PATCH v4 0/8] Introduce the for_each_set_clump macro William Breathitt Gray
2018-05-15 16:22 ` William Breathitt Gray
2018-05-15 16:22 ` [PATCH v4 1/8] bitops: " William Breathitt Gray
2018-05-15 16:22 ` William Breathitt Gray
2018-05-15 16:22 ` [PATCH v4 2/8] lib/test_bitmap.c: Add for_each_set_clump test cases William Breathitt Gray
2018-05-15 16:22 ` William Breathitt Gray
2018-05-15 16:22 ` [PATCH v4 3/8] gpio: 104-dio-48e: Utilize for_each_set_clump macro William Breathitt Gray
2018-05-15 16:22 ` William Breathitt Gray
2018-05-15 16:22 ` [PATCH v4 4/8] gpio: 104-idi-48: " William Breathitt Gray
2018-05-15 16:22 ` William Breathitt Gray
2018-05-15 16:23 ` [PATCH v4 5/8] gpio: gpio-mm: " William Breathitt Gray
2018-05-15 16:23 ` William Breathitt Gray
2018-05-15 16:23 ` [PATCH v4 6/8] gpio: ws16c48: " William Breathitt Gray
2018-05-15 16:23 ` William Breathitt Gray
2018-05-15 16:23 ` [PATCH v4 7/8] gpio: pci-idio-16: " William Breathitt Gray
2018-05-15 16:23 ` William Breathitt Gray
2018-05-15 16:23 ` [PATCH v4 8/8] gpio: pcie-idio-24: " William Breathitt Gray
2018-05-15 16:23 ` William Breathitt Gray
2018-05-16 14:03 ` [PATCH v4 0/8] Introduce the " Linus Walleij
2018-05-16 14:03 ` Linus Walleij
2018-05-16 20:08 ` Andy Shevchenko
2018-05-16 20:08 ` Andy Shevchenko
2018-06-16 19:16 ` William Breathitt Gray [this message]
2018-06-16 19:16 ` William Breathitt Gray
2018-09-05 15:04 ` William Breathitt Gray
2018-09-05 15:04 ` William Breathitt Gray
2018-09-10 7:54 ` Linus Walleij
2018-09-10 7:54 ` Linus Walleij
2018-09-10 14:47 ` Andy Shevchenko
2018-09-10 14:47 ` Andy Shevchenko
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