Re: [AD] Add timeBeginPeriod(1) to wtimer.c

["Tobias Scheuer" <tobing@xxxxxxxxxx>]

I think it affects the timers more generally, so it also affects the timers
in allegro's separate timer threads. Didn't go into all the details, and I
don't have a decent profiler at home, so I couldn't find out where exactly
the slowdown comes from. Maybe I should try to Quantify this at work... 

> it changes the resolution of the rest() and timeGetTime()  but it 
> doesn't slow down the app itself.
> how could it ?
> 
> 
> 
> Tobias Scheuer wrote:
> > I have tried that. The documentation says that each call to
> timeBeginPeriod
> > has to be matched by a call to timeEndPeriod, so that#s why I have also
> > called that function. If I leave that out, the timeBeginPeriod(1)
> remains
> > active, which causes some overall slowdown of the whole program (as
> > mentioned in the forum). 
> > 
> > 
> >>timeBeginPeriod only needs to be called once for the whole process.
> >>not each time rest is called.
> >>
> >>
> >>
> >>
> >>>Hi all,
> >>>
> >>>as already discussed in the forum, I would propose to change the
> current
> >>>implementation of tim_win32_rest in wtimer.c to the following:
> >>>
> >>>[code]
> >>>/* tim_win32_rest:
> >>> *  Rests the specified amount of milliseconds.
> >>> */
> >>>static void tim_win32_rest(unsigned int time, AL_METHOD(void, callback,
> >>>(void)))
> >>>{
> >>>   unsigned int start;
> >>>   unsigned int ms = time;
> >>>
> >>>   const MMRESULT rc = timeBeginPeriod(1);
> >>>   if (callback) {
> >>>      start = timeGetTime();
> >>>      while (timeGetTime() - start < ms)
> >>>         (*callback)();
> >>>   }
> >>>   else {
> >>>      Sleep(ms);
> >>>   }
> >>>   if( rc == TIMERR_NOERROR )
> >>>     timeEndPeriod(1);
> >>>}
> >>>[/code]
> >>>
> >>>The new lines are the call to timeBeginPeriod(1); and the 
> >>>correcponding call
> >>>to timeEndPeriod(1); in case the first call was successful.
> >>>
> >>>This affects only windows, and increases the accuracy of calls to 
> >>>rest(n).
> >>>
> >>>For the discussions, refer to the following threads:
> >>>
> >>>http://www.allegro.cc/forums/view_thread.php?_id=456146
> >>>http://www.allegro.cc/forums/view_thread.php?_id=453116
> >>>
> >>>As this is my very first contribution, please forgive if anything is 
> >>>not in
> >>>the right format or otherwise unexpected.
> >>>
> >>>Thanks for consideration!
> >>>
> >>>Best regards Tobias
> >>>
> >>>-- 
> >>>http://www.staedtebauen.de <http://www.staedtebauen.de/>
> >>>
> >>>
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> >>
> >>
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> > 
> > 
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> 
> 
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