From: Bastian Bloessl <bastianbloessl@googlemail.com>
To: Nicolas Kaiser <nikai@nikai.net>
Cc: Michal Nazarewicz <mina86@mina86.com>,
linux-c-programming@vger.kernel.org
Subject: Re: duplicated modulo
Date: Fri, 01 Apr 2011 12:28:09 +0200 [thread overview]
Message-ID: <4D95A8B9.3070308@googlemail.com> (raw)
In-Reply-To: <20110401121916.34a567da@absol.kitzblitz>
Am 01.04.2011 12:19, schrieb Nicolas Kaiser:
> * "Michal Nazarewicz"<mina86@mina86.com>:
>> On Fri, 01 Apr 2011 11:41:13 +0200, Nicolas Kaiser wrote:
>>> I'm curious: a duplicated modulo operation can't possibly make
>>> any difference, can it?
>>>
>>> diff -u -p ./arch/powerpc/platforms/powermac/nvram.c
>>> /tmp/nothing/arch/powerpc/platforms/powermac/nvram.c
>>> --- ./arch/powerpc/platforms/powermac/nvram.c 2011-03-31
>>> 09:52:41.674292401 +0200
>>> +++ /tmp/nothing/arch/powerpc/platforms/powermac/nvram.c
>>> @@ -246,7 +246,6 @@ static u32 core99_calc_adler(u8 *buffer)
>>> high = 0;
>>> for (cnt=0; cnt<(NVRAM_SIZE-CORE99_ADLER_START); cnt++) {
>>> if ((cnt % 5000) == 0) {
>>> - high %= 65521UL;
>>> high %= 65521UL;
>>> }
>>> low += buffer[cnt];
>>
>> It's not just a module. It's also an assignment.
>
> Sure. But I fail to see where between
>
> a %= b;
> a %= b;
>
> and
>
> a = (a % b) % b;
>
> and
>
> a %= b;
>
> would be a difference?
Perhaps an issue with signed / unsigned, or long vs. int?
next prev parent reply other threads:[~2011-04-01 10:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 9:41 duplicated modulo Nicolas Kaiser
2011-04-01 9:50 ` Michal Nazarewicz
2011-04-01 10:19 ` Nicolas Kaiser
2011-04-01 9:30 ` Bogdan Cristea
2011-04-01 10:28 ` Bastian Bloessl [this message]
2011-04-01 11:20 ` Michal Nazarewicz
2011-04-04 8:26 ` Hendrik Visage
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=4D95A8B9.3070308@googlemail.com \
--to=bastianbloessl@googlemail.com \
--cc=linux-c-programming@vger.kernel.org \
--cc=mina86@mina86.com \
--cc=nikai@nikai.net \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.