usleep in uClibc/uClinux

[Drasko DRASKOVIC]

Hi all,
in uClibc/include/unistd.h I can see :

#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
/* Set an alarm to go off (generating a SIGALRM signal) in VALUE
   microseconds.  If INTERVAL is nonzero, when the alarm goes off, the
   timer is reset to go off every INTERVAL microseconds thereafter.
   Returns the number of microseconds remaining before the alarm.  */
extern __useconds_t ualarm (__useconds_t __value, __useconds_t __interval)
     __THROW;

/* Sleep USECONDS microseconds, or until a signal arrives that is not blocked
   or ignored.

   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern int usleep (__useconds_t __useconds);
#endif

So, usleep() is defined only if __USE_BSD.

1) Why so ?

2) What if I do not use BSD system, but uClinux ?

Thanks and best regards,
Drasko