linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Florian La Roche <florian.laroche@googlemail.com>
To: linux-kernel@vger.kernel.org
Cc: Crt Mori <cmo@melexis.com>, Joe Perches <joe@perches.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Will Deacon <will.deacon@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Florian La Roche <Florian.LaRoche@googlemail.com>
Subject: int_sqrt() adjustments
Date: Thu, 24 Jan 2019 19:21:04 +0100	[thread overview]
Message-ID: <20190124182104.18022-1-Florian.LaRoche@googlemail.com> (raw)


__fls() is returning an unsigned long, but fls() and fls64() are
both returning a (signed) int.
As we need a signed int as right operand of "<<" (as Linus pointed out),
change __fls() to fls() for 32bit and also adjust masking the lowest bit
to be a signed int.
Now the 32bit and the 64bit version are again similar.

best regards,

Florian La Roche



Signed-off-by: Florian La Roche <Florian.LaRoche@googlemail.com>
---
 lib/int_sqrt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 30e0f9770f88..66eb93105812 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -23,7 +23,7 @@ unsigned long int_sqrt(unsigned long x)
 	if (x <= 1)
 		return x;
 
-	m = 1UL << (__fls(x) & ~1UL);
+	m = 1UL << ((fls(x) - 1) & ~1L);
 	while (m != 0) {
 		b = y + m;
 		y >>= 1;
@@ -52,7 +52,7 @@ u32 int_sqrt64(u64 x)
 	if (x <= ULONG_MAX)
 		return int_sqrt((unsigned long) x);
 
-	m = 1ULL << ((fls64(x) - 1) & ~1ULL);
+	m = 1ULL << ((fls64(x) - 1) & ~1LL);
 	while (m != 0) {
 		b = y + m;
 		y >>= 1;
-- 
2.17.1


             reply	other threads:[~2019-01-24 18:21 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-24 18:21 Florian La Roche [this message]
2019-01-24 18:58 int_sqrt() adjustments Florian La Roche
2019-01-24 20:02 ` Linus Torvalds
2019-01-26 16:18 ` Florian La Roche

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190124182104.18022-1-Florian.LaRoche@googlemail.com \
    --to=florian.laroche@googlemail.com \
    --cc=cmo@melexis.com \
    --cc=dave@stgolabs.net \
    --cc=joe@perches.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=torvalds@linux-foundation.org \
    --cc=will.deacon@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).