Description

   The getclock function sets the current value of the clock
   specified by clktyp into the location pointed to by tp.

   The clktyp argument is given as a symbolic constant name,
   as defined in the <timers.h> header file. Only the TIMEOFDAY
   symbolic constant, which specifies the normal time-of-day clock
   to access for systemwide time, is supported.

   For the clock specified by TIMEOFDAY, the value returned by
   this function is the elapsed time since the Epoch. The Epoch
   is referenced to 00:00:00 UTC (Coordinated Universal Time) 1 Jan
   1970.

   The getclock function returns a timespec structure, which is
   defined in the <timers.h> header file as follows:

    struct  timespec {

     unsigned long  tv_sec   /* Elapsed time in seconds since the Epoch*/
     long           tv_nsec  /* Elapsed time as a fraction of a second */
                             /* since the Epoch (in nanoseconds)       */

    };