linux-kernel - Re: [PATCH v4 0/8] Introduce the for_each_set

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Date:   Mon, 10 Sep 2018 17:47:24 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     William Breathitt Gray <vilhelm.gray@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-arch@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 0/8] Introduce the for_each_set_clump macro

On Mon, Sep 10, 2018 at 09:54:47AM +0200, Linus Walleij wrote:
> On Wed, Sep 5, 2018 at 5:04 PM William Breathitt Gray
> <vilhelm.gray@...il.com> wrote:
> > On Wed, May 16, 2018 at 04:03:51PM +0200, Linus Walleij wrote:
> > >On Tue, May 15, 2018 at 6:22 PM, William Breathitt Gray
> > ><vilhelm.gray@...il.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.
> > >
> > >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.
> > >
> > >Yours,
> > >Linus Walleij
> >
> > Hi Linus,
> >
> > I'd like to get this patchset merged, but I'm aware that we haven't yet
> > received additional ACKs in the past couple months. Are there any
> > changes you would like made, or should I resubmit this patchset with
> > additional CCs in the hopes of some ACKs for the bitops patch?
> 
> It seems Andy wanted some time and he had ~4 months now
> so either he forgot it or has way too much to do.

Sorry, indeed, it got piled under huge backlog I have.

> 
> I would say send this patch to Andrew Morton (the bitops patches)
> so he can decide on it. He has the right bird's eye view on this
> kind of things.

Agreed, and please add Rasmus as well.


-- 
With Best Regards,
Andy Shevchenko