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Date:   Tue, 26 Mar 2019 11:53:12 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Lukas Wunner <lukas@wunner.de>
Cc:     William Breathitt Gray <vilhelm.gray@gmail.com>,
        linus.walleij@linaro.org, bgolaszewski@baylibre.com,
        akpm@linux-foundation.org, linux-gpio@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux@rasmusvillemoes.dk, yamada.masahiro@socionext.com,
        linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
        geert@linux-m68k.org, preid@electromag.com.au,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v12 01/11] bitops: Introduce the for_each_set_clump8 macro
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On Tue, Mar 26, 2019 at 10:43:45AM +0100, Lukas Wunner wrote:
> On Tue, Mar 26, 2019 at 12:14:22PM +0900, William Breathitt Gray wrote:
> > On Mon, Mar 25, 2019 at 10:38:54AM +0100, Lukas Wunner wrote:

> > Is this the sort of implementation you had in mind:
> > 
> >         offset = find_next_bit(addr, size, offset);
> >         if (offset == size)
> >                 return size;
> > 
> >         offset -= offset % 8;
> >         *clump = bitmap_get_value8(addr, size, offset);
> > 
> >         return offset;
> 
> Almost.  I'd use round_down() instead of "offset -= offset % 8".
> Then it's just a single cheap logical and operation at runtime.

> I'd try to avoid copying around the clump value and use a pointer
> to u8 instead.

u8 might be inconvenient in environment where everything else is type of
unsigned long.

-- 
With Best Regards,
Andy Shevchenko