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Re: Problem with GetTickCount on Linux [message #36467 is a reply to message #36465]

Wed, 30 May 2012 12:16

Zbych
Messages: 326
Registered: July 2009

Senior Member

Hi Steffen,

CLOCK_MONOTONIC is what I was looking for for Smile

But I think it is not obligatory on all platforms.

Quote:

On POSIX systems on which these functions are available, the symbol _POSIX_TIMERS is defined in <unistd.h> to a value greater than 0. The symbols _POSIX_MONOTONIC_CLOCK, _POSIX_CPUTIME, _POSIX_THREAD_CPUTIME indicate that CLOCK_MONOTONIC, CLOCK_PROCESS_CPUTIME_ID, CLOCK_THREAD_CPUTIME_ID are available.

So maybe GetTickCount should fall back to gettimeofday in case of error?

#ifdef PLATFORM_POSIX
dword GetTickCount() {
#if defined(_POSIX_TIMERS) && defined(_POSIX_MONOTONIC_CLOCK)
	static bool no_monotonic = false;
	if (!no_monotonic)
	{
		struct timespec tp;
		if (clock_gettime(CLOCK_MONOTONIC, &tp) == 0)
		{
			return (dword)((tp.tv_sec * 1000) + (tp.tv_nsec / 1000000));
		}
		no_monotonic = true;
		LOG("MONOTONIC CLOCK ERROR");
	}
#endif
	struct timeval tv[1];
	struct timezone tz[1];
	memset(tz, 0, sizeof(tz));
	gettimeofday(tv, tz);
	return (dword)tv->tv_sec * 1000 + tv->tv_usec / 1000;
}

#endif

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