[SDL] Higher precision SDL_GetTicks()?

Patrick Baggett baggett.patrick at gmail.com
Wed Feb 8 07:27:03 PST 2012


On Tue, Feb 7, 2012 at 11:10 PM, Forest Hale <havoc at ghdigital.com> wrote:

> For Linux I just use:
>    struct timespec ts;
>    clock_gettime(CLOCK_MONOTONIC, &ts);
>    return (double) ts.tv_sec + ts.tv_nsec / 1000000000.0;
>
>
Yep -- that's what's in SDL ;)


> On 02/07/2012 01:14 PM, Patrick Baggett wrote:
> > Well, Wiki probably isn't the best source for this, but:
> >
> > http://en.wikipedia.org/wiki/Time_Stamp_Counter
> >
> > In particular, (since it looks like MacOS implies Intel CPUs about 99%
> of the time)
> >
> > For Pentium 4 processors, Intel Xeon processors (family [0FH], models
> [03H and higher]); for Intel Core Solo and Intel Core Duo processors
> (family [06H], model [0EH]); for the Intel Xeon processor
> > 5100 series and Intel Core 2 Duo processors (family [06H], model [0FH]);
> for Intel Core 2 and Intel Xeon processors (family [06H], display_model
> [17H]); for Intel Atom processors (family [06H],
> > display_model [1CH]): the time-stamp counter increments at a constant
> rate. That rate may be set by the maximum core-clock to bus-clock ratio of
> the processor or may be set by the maximum resolved
> > frequency at which the processor is booted. The maximum resolved
> frequency may differ from the maximum qualified frequency of the processor.
> >
> > This is probably true of Intel i3/5/7 as well, so you should be
> reasonably safe.
> >
> > If you look at http://hg.libsdl.org/SDL/rev/6bd701987ba9 on line 5.25,
> you can see that these are implemented in a reasonable way for UNIX-like
> OSes, so you should be able to use the above-mentioned
> > SDL functions portably. Unless you're running on older AMD CPUs (K8, not
> K10), then I wouldn't worry too much. I don't think you'll need to mess
> with the power management unless you're running on an
> > older machine.
> >
> >
> >
> >
> > _______________________________________________
> > SDL mailing list
> > SDL at lists.libsdl.org
> > http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org
>
>
> --
> LordHavoc
> Author of DarkPlaces Quake1 engine -
> http://icculus.org/twilight/darkplaces
> Co-designer of Nexuiz - http://alientrap.org/nexuiz
> "War does not prove who is right, it proves who is left." - Unknown
> "Any sufficiently advanced technology is indistinguishable from a rigged
> demo." - James Klass
> "A game is a series of interesting choices." - Sid Meier
>
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