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(),
    exec/semaphores.h