* [Gitorious] Activity: konrada updated merge request for k...
@ 2013-02-07 10:17 Gitorious
2013-02-07 10:38 ` [PATCH] cangen: use long long in time computation for -g to support >2.1s Marc Kleine-Budde
0 siblings, 1 reply; 6+ messages in thread
From: Gitorious @ 2013-02-07 10:17 UTC (permalink / raw)
To: mkl
Hello bet-frogger,
One of your favorites has a new activity:
------------------------------------------------------------------------
konrada updated merge request for konradas-can-utils with can-utils.
The merge request is at https://gitorious.org/linux-can/can-utils/merge_requests/1
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] cangen: use long long in time computation for -g to support >2.1s
2013-02-07 10:17 [Gitorious] Activity: konrada updated merge request for k Gitorious
@ 2013-02-07 10:38 ` Marc Kleine-Budde
2013-02-07 10:41 ` Marc Kleine-Budde
0 siblings, 1 reply; 6+ messages in thread
From: Marc Kleine-Budde @ 2013-02-07 10:38 UTC (permalink / raw)
To: linux-can; +Cc: Konrad Anton, Marc Kleine-Budde
From: Konrad Anton <konrad.anton@awinia.de>
The computation of nanosleep times for the "-g" option to cangen.c (delay
between sends) overflows when more than 2100ms are given.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
This is the pull gitorious pull reqeust transformed into a standard git one. :)
Marc
cangen.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/cangen.c b/cangen.c
index 7518c12..db4c803 100644
--- a/cangen.c
+++ b/cangen.c
@@ -269,7 +269,7 @@ int main(int argc, char **argv)
}
ts.tv_sec = gap / 1000;
- ts.tv_nsec = ((int)(gap * 1000000)) % 1000000000;
+ ts.tv_nsec = (long)(((long long)(gap * 1000000)) % 1000000000ll);
/* recognize obviously missing commandline option */
if (id_mode == MODE_FIX && frame.can_id > 0x7FF && !extended) {
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] cangen: use long long in time computation for -g to support >2.1s
2013-02-07 10:38 ` [PATCH] cangen: use long long in time computation for -g to support >2.1s Marc Kleine-Budde
@ 2013-02-07 10:41 ` Marc Kleine-Budde
2013-02-07 11:04 ` Konrad Anton
0 siblings, 1 reply; 6+ messages in thread
From: Marc Kleine-Budde @ 2013-02-07 10:41 UTC (permalink / raw)
To: Marc Kleine-Budde; +Cc: linux-can, Konrad Anton
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Hello Konrad,
we're a bit oldschool and discuss the code on the
linux-can@vger.kernel.org mailinglist. Feel free to subscribe.
On 02/07/2013 11:38 AM, Marc Kleine-Budde wrote:
> From: Konrad Anton <konrad.anton@awinia.de>
>
> The computation of nanosleep times for the "-g" option to cangen.c (delay
> between sends) overflows when more than 2100ms are given.
>
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
>
> This is the pull gitorious pull reqeust transformed into a standard git one. :)
>
> Marc
>
> cangen.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/cangen.c b/cangen.c
> index 7518c12..db4c803 100644
> --- a/cangen.c
> +++ b/cangen.c
> @@ -269,7 +269,7 @@ int main(int argc, char **argv)
> }
>
> ts.tv_sec = gap / 1000;
> - ts.tv_nsec = ((int)(gap * 1000000)) % 1000000000;
> + ts.tv_nsec = (long)(((long long)(gap * 1000000)) % 1000000000ll);
What's going on here exactly?
gap is a double - Will it be converted into an int before multiplication
with 1000000? IIRC there is a difference between "gap * 1000000" and
"gap * 1000000.0". In the latter the multiplication is done in floating
point, because of the ".0".
Marc
>
> /* recognize obviously missing commandline option */
> if (id_mode == MODE_FIX && frame.can_id > 0x7FF && !extended) {
>
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cangen: use long long in time computation for -g to support >2.1s
2013-02-07 10:41 ` Marc Kleine-Budde
@ 2013-02-07 11:04 ` Konrad Anton
2013-02-07 12:57 ` Marc Kleine-Budde
0 siblings, 1 reply; 6+ messages in thread
From: Konrad Anton @ 2013-02-07 11:04 UTC (permalink / raw)
To: linux-can
Hello,
On 07.02.2013 11:41, Marc Kleine-Budde wrote:
> we're a bit oldschool and discuss the code on the
> linux-can@vger.kernel.org mailinglist. Feel free to subscribe.
Can you please put that information on the Gitorious page for the next
casual committer?
>> ts.tv_sec = gap / 1000;
>> - ts.tv_nsec = ((int)(gap * 1000000)) % 1000000000;
>> + ts.tv_nsec = (long)(((long long)(gap * 1000000)) % 1000000000ll);
>
> What's going on here exactly?
>
> gap is a double - Will it be converted into an int before multiplication
> with 1000000? IIRC there is a difference between "gap * 1000000" and
> "gap * 1000000.0". In the latter the multiplication is done in floating
> point, because of the ".0".
gap is a double.
(gap * 1000000) will cause 1000000 to be converted to intermediate
temp1 of type double,
temp1 will be truncated to long long temp2, losing its decimals,
temp2 will be moduloed by 1000000000ll in a long-long mod operation,
giving temp3.
temp3 will be truncated to as many bits as long has, and stored in long
tv_nsec.
I think it is safe.
--Konrad
--
------------------------------------------------------------------------
Konrad Anton
awinia gmbh, Software Consulting and Development
Max-Josef-Metzger-Str. 2, D-79111 Freiburg
Tel. +49 761 52 07 449 19
Fax. +49 761 52 07 449 10
EMail: konrad.anton@awinia.de
Handelsregister Nr.: HRB 706296, eingetragen beim Amtsgericht Freiburg
USt.-IdNr.: DE 275018159
Geschäftsführer: Marc Gossweiler, Bernd Wiedle
------------------------------------------------------------------------
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] cangen: use long long in time computation for -g to support >2.1s
2013-02-07 11:04 ` Konrad Anton
@ 2013-02-07 12:57 ` Marc Kleine-Budde
[not found] ` <5113A525.2030208@awinia.de>
0 siblings, 1 reply; 6+ messages in thread
From: Marc Kleine-Budde @ 2013-02-07 12:57 UTC (permalink / raw)
To: Konrad Anton; +Cc: linux-can
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On 02/07/2013 12:04 PM, Konrad Anton wrote:
> Hello,
>
> On 07.02.2013 11:41, Marc Kleine-Budde wrote:
>> we're a bit oldschool and discuss the code on the
>> linux-can@vger.kernel.org mailinglist. Feel free to subscribe.
>
> Can you please put that information on the Gitorious page for the next
> casual committer?
>
>
>>> ts.tv_sec = gap / 1000;
>>> - ts.tv_nsec = ((int)(gap * 1000000)) % 1000000000;
>>> + ts.tv_nsec = (long)(((long long)(gap * 1000000)) % 1000000000ll);
>>
>> What's going on here exactly?
>>
>> gap is a double - Will it be converted into an int before multiplication
>> with 1000000? IIRC there is a difference between "gap * 1000000" and
>> "gap * 1000000.0". In the latter the multiplication is done in floating
>> point, because of the ".0".
>
> gap is a double.
> (gap * 1000000) will cause 1000000 to be converted to intermediate temp1
> of type double,
> temp1 will be truncated to long long temp2, losing its decimals,
> temp2 will be moduloed by 1000000000ll in a long-long mod operation,
> giving temp3.
> temp3 will be truncated to as many bits as long has, and stored in long
> tv_nsec.
>
> I think it is safe.
Thanks for the details. Looks good. Can I add your Signed-off-by[1] to
the patch?
Marc
[1]
http://lxr.free-electrons.com/source/Documentation/SubmittingPatches#L298
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-02-07 13:03 UTC | newest]
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2013-02-07 10:17 [Gitorious] Activity: konrada updated merge request for k Gitorious
2013-02-07 10:38 ` [PATCH] cangen: use long long in time computation for -g to support >2.1s Marc Kleine-Budde
2013-02-07 10:41 ` Marc Kleine-Budde
2013-02-07 11:04 ` Konrad Anton
2013-02-07 12:57 ` Marc Kleine-Budde
[not found] ` <5113A525.2030208@awinia.de>
2013-02-07 13:02 ` Marc Kleine-Budde
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