From: Pekka Paalanen <ppaalanen@gmail.com>
To: Paul Gofman <pgofman@codeweavers.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH libdrm 2/2] include: Avoid potentially infinite loop in log2_int().
Date: Fri, 30 Oct 2020 13:07:39 +0200 [thread overview]
Message-ID: <20201030130739.0e6770c6@eldfell> (raw)
In-Reply-To: <20201028100602.168752-2-pgofman@codeweavers.com>
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On Wed, 28 Oct 2020 13:06:02 +0300
Paul Gofman <pgofman@codeweavers.com> wrote:
> Signed-off-by: Paul Gofman <pgofman@codeweavers.com>
> ---
> util_math.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/util_math.h b/util_math.h
> index e2fa95f5..f6bbe192 100644
> --- a/util_math.h
> +++ b/util_math.h
> @@ -38,6 +38,9 @@ static inline unsigned log2_int(unsigned x)
> if (x < 2) {
> return 0;
> }
> + if (x & 0x80000000) {
> + return 31;
> + }
> for (l = 2; ; l++) {
> if ((unsigned)(1 << l) > x) {
> return l - 1;
Hi,
I guess that does it, but it seems quite a lot of code that could be
a two-liner:
http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
Thanks,
pq
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next prev parent reply other threads:[~2020-10-30 11:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 10:06 [PATCH libdrm 1/2] include: Factor out log2_int() function Paul Gofman
2020-10-28 10:06 ` [PATCH libdrm 2/2] include: Avoid potentially infinite loop in log2_int() Paul Gofman
2020-10-30 11:07 ` Pekka Paalanen [this message]
2020-10-30 13:07 ` Paul Gofman
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