From: Andrew Morton <akpm@linux-foundation.org>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
christian.brauner@ubuntu.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] bitops: simplify get_count_order_long()
Date: Mon, 25 May 2020 13:41:10 -0700 [thread overview]
Message-ID: <20200525134110.5737dd603d5fa1230e2f7ece@linux-foundation.org> (raw)
In-Reply-To: <20200525153216.GD1634618@smile.fi.intel.com>
On Mon, 25 May 2020 18:32:16 +0300 Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> On Mon, May 25, 2020 at 02:43:12PM +0000, Wei Yang wrote:
> > On Mon, May 25, 2020 at 12:14:58PM +0300, Andy Shevchenko wrote:
> > >On Sun, May 24, 2020 at 12:35:51PM +0000, Wei Yang wrote:
> > >> These two cases could be unified into one.
> > >
> > >Care to provide a test case which supports your change?
I hurt my brain convincing myself, so I got practical:
int fls(unsigned int x)
{
return x ? sizeof(x) * 8 - __builtin_clz(x) : 0;
}
static int get_count_order(unsigned l)
{
if (l == 0)
return -1;
else if (l & (l - 1UL))
return fls(l);
else
return fls(l) - 1;
}
static int get_count_order2(unsigned long l)
{
if (l == 0)
return -1;
return fls(--l);
}
main()
{
unsigned i;
for (i = 1; i < 64; i++) {
printf("%d %d\n", get_count_order(i),
get_count_order2(i));
}
}
> >
> > Hmm.. where should I put the test? tools/testing/selftests/ ?
>
> I guess into test_bitops.c [1]? I though it eventually should make kernel, but I don't see it.
>
> Andrew, can you apply that or do you need Jesse to resend?
>
Got it.
next prev parent reply other threads:[~2020-05-25 20:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-24 12:35 [PATCH] bitops: simplify get_count_order_long() Wei Yang
2020-05-25 9:14 ` Andy Shevchenko
2020-05-25 14:43 ` Wei Yang
2020-05-25 15:32 ` Andy Shevchenko
2020-05-25 20:41 ` Andrew Morton [this message]
2020-05-25 21:57 ` Wei Yang
2020-05-25 22:31 ` Andrew Morton
2020-05-27 22:45 ` Wei Yang
2020-05-27 23:05 ` Andrew Morton
2020-05-28 22:18 ` Wei Yang
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