anchor.diff:  
   (defun event-wait (event)
     "Wait until EVENT's state is not NIL."
  +  (check-type event event)
     (%run-on-wired-stack-without-interrupts (sp fp event)
       (acquire-place-spinlock *big-wait-for-objects-lock*)
       (let ((self (current-thread)))
  
positive.code:              (:area :wired)))
  
  (defun condition-wait (condition-variable mutex &optional timeout)
    (assert (mutex-held-p mutex))
    (check-mutex-release-consistence mutex)
    (ensure-interrupts-enabled)
  
negative.code:   (contested-count 0))
  
  (defun acquire-mutex (mutex &optional (wait-p t))
    (check-type mutex mutex)
    (let ((self (current-thread)))
      ;; Fast path - try to lock.
      (when (eql (sys.int::cas (mutex-state mutex) :unlocked :locked) :unlocked)
  