Author: Robert Hyatt
Date: 12:39:51 10/09/99
Go up one level in this thread
On October 09, 1999 at 13:55:25, Dave Gomboc wrote: >On October 09, 1999 at 13:02:38, Christophe Theron wrote: > >>On October 09, 1999 at 07:30:48, Vincent Lejeune wrote: >> >>>On October 08, 1999 at 16:43:37, Christophe Theron wrote: >>> >>>>On October 08, 1999 at 06:14:23, Vincent Lejeune wrote: >>>> >>>>>On October 08, 1999 at 04:16:57, Christophe Theron wrote: >>>>> >>>>>>On October 08, 1999 at 03:42:54, Dave Gomboc wrote: >>>>>> >>>>>>>On October 07, 1999 at 23:29:05, Christophe Theron wrote: >>>>>>> >>>>>>>>That's a real problem on PC. >>>>>>>> >>>>>>>>The timer clicks 65536 times in 1 hour, which makes something close to 18.2 >>>>>>>>times per second, or a 0.05s timer resolution. >>>>>>>> >>>>>>>>This numbers come from the prehistoric IBM PC 4.77MHz and have never been >>>>>>>>changed in 20 years, for compatibility reasons. >>>>>>>> >>>>>>>>Even Windows programmers did not dare to change this. You have time functions in >>>>>>>>Windows, they returns values in milliseconds, but still the resolution is about >>>>>>>>0.05s!!! >>>>>>> >>>>>>>Use performance tick counts if you develop for Win32. (Actually, I am not 100% >>>>>>>sure that Win98 supports them. :-( WinNT does for sure.) Their resolution is >>>>>>>very good. >>>>>>> >>>>>>>Dave >>>>>> >>>>>>Not sure this works. In the experiences I have done, the timer resolution was >>>>>>always 0.05s. I'm pressimistic about getting something more accurate under >>>>>>Windows 9x. >>>>>> >>>>>>This is not a big problem anyway... >>>>>> >>>>>> >>>>>> Christophe >>>>> >>>>>I've tested the gettickcount() Win32 api, it's documented as have a 1 >>>>>millisecond time resolution and it have it effectivly. >>>>> >>>>>The win32 functions are usable in all Windows programming language (C++ (Borland >>>>>and Microsoft), Delphi, ...) >>>> >>>> >>>>Good to know. Thanks. >>>> >>>> >>>> Christophe >>> >>>the gettickcount() function have one little drawback: it's a 32 bits variable. >>>So every (about) 47 days, the counter going back to 0, you need to add simple >>>test if the gettickcount()-starttime is < 0. >> >>The (hand written) function I use currently has exactly the same problem, so it >>is not a killer for me. >> >> >> Christophe > >Note that this bug has existed since 1995, and took more than three years to >discover. Apparently, machines that stay up for 47 days are not too common in >the Windows world. :-) > >Dave I have always used "wall clock time" for important games, and have had to correct the time on going past midnight always...
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