anchor.diff:  
   
   ;;;-------------------------------------------------------------------------
  -;;; IO-POSITION
  -;;;-------------------------------------------------------------------------
  -
  -(defmethod zstream-io-position ((buffer single-channel-buffer))
  +;;; POSITION
  +;;;-------------------------------------------------------------------------
  +
  +(defmethod zstream-position ((buffer single-channel-buffer) &key direction)
  +  (declare (ignore direction))
     (with-synchronized-buffer (buffer :input)
       (let ((position (device-position (zstream-device buffer))))
         ;; FIXME: signal proper condition
  
positive.code: 
  (defmethod %zstream-write-vector :after ((buffer single-channel-buffer)
                                           vector start end timeout)
    (setf (%scb-dirtyp buffer) t))
  
  (defmethod zstream-write-vector ((buffer memory-buffer) vector
  
negative.code: 
  (defmethod zstream-fill-input ((buffer single-channel-buffer) &key timeout)
    (with-synchronized-buffer (buffer :input)
      (%zstream-flush-output buffer timeout)
      (%zstream-fill-input buffer timeout)))
  
  (defmethod zstream-fill-input ((buffer dual-channel-buffer) &key timeout)
  