ggCurTime(3)								GGI							      ggCurTime(3)

NAME

       ggCurTime, ggUSleep, ggUSlumber - Portable Time Routines

SYNOPSIS

       #include <ggi/gg.h>

       int ggCurTime(struct timeval *tv);

       int ggUSleep(int32_t usecs);

       void ggUSlumber(int32_t usecs);

DESCRIPTION

       ggCurTime fills the timeval structure pointed to by tv with the current time to the best precision available on the executing platform.

       ggUSleep sleeps for at least usecs microseconds, to the best precision available on the executing platform, but may be woken up by a signal
       or other unspecified condition.	It is not guaranteed that ggUSleep will wake up prematurely for any specific reason.  It is mainly  useful
       for points where the main objective is to avoid using CPU resources, not to perform accurate timing.

       ggUSlumber does the same thing as ggUSleep, but is guaranteed not to return until the allotted time has elapsed.  It is slightly less effi-
       cient than ggUSleep with reguard to CPU utilization.

       All times represent wall-clock (real, versus processor) times.

       The above routines are often simple macros rather than functions, and as such should not be used by reference.

       The above functions are threadsafe, but are not guaranteed to be safe to use in a thread that may  be  cancelled  during  their	execution.
       They  are  also not guaranteed to be safe to use in special contexts such as LibGG task handlers, signal handlers and asyncronous procedure
       calls.

RETURN VALUE

       ggCurTime returns GGI_OK on success, or a negative value on failure. On Windows, this function will never report a failure.   On  platforms
       where gettimeofday(2) is used, the error code is the one returned by gettimeofday.

       ggUSleep  returns  GGI_OK  when the alloted time interval has elapsed, or a non-zero value if the sleep was interrupted. On platforms where
       usleep(3) is used, the error code is the one return by usleep.

EXAMPLE

       A demonstration on how to measure a framerate.

       struct timeval start, stop, diff;
       long time_of_frame = 1;
       int framerate;

       ...

       ggCurTime(&start);

       /* do something here, i.e. render and display a frame */

       ggCurTime(&stop);
       diff.tv_sec = stop_tv.tv_sec - start_tv.tv_sec;
       diff.tv_usec = stop_tv.tv_usec - start_tv.tv_usec;

       if (diff.tv_usec < 0) {
	       diff.tv_usec += 1000000;
	       diff.tv_sec--;
       }
       time_of_frame = diff.tv_sec * 1000 + diff.tv_usec / 1000;
       if (time_of_frame == 0)
	       time_of_frame = 1;      /* CPU too fast? */
       printf("framerate: %i
", 1000 / time_of_framerate);

SEE ALSO

       gettimeofday(2), usleep(3)

libgg-1.0.x							    2005-08-26							      ggCurTime(3)