NAME
	AttemptSemaphore -- try to obtain without blocking

   SYNOPSIS
	success = AttemptSemaphore(signalSemaphore)
	D0			   A0

	 LONG AttemptSemaphore(struct  SignalSemaphore *);

   FUNCTION
	This call is similar to  ObtainSemaphore(), except that it will not
	block if the semaphore could not be locked.

   INPUT
       signalSemaphore -- an initialized signal semaphore structure

   RESULT
	success -- TRUE if the semaphore was locked, false if some
	    other task already possessed the semaphore.

    NOTE
	This call does NOT preserve registers.

   SEE ALSO
	 ObtainSemaphore()  ObtainSemaphoreShared(),  ReleaseSemaphore(),
	 sc:include/exec/semaphores.h