anchor.diff:  
   (defmethod device-write ((buffer single-channel-buffer) vector start end
                            &optional timeout)
  -  (with-synchronized-buffer (buffer :input)
  +  (with-synchronized-buffer (buffer :output)
       ;; If the previous operation was a read, flush the read buffer
       ;; and reposition the file offset accordingly
       (%buffer-clear-input buffer)
  
positive.code: ;;;-----------------------------------------------------------------------------
  
  (defmethod buffer-flush-output ((buffer single-channel-buffer) &optional timeout)
    (with-synchronized-buffer (buffer :input)
      (when (eql :write (last-io-op-of buffer))
        (%buffer-flush-output buffer timeout))))
  
  
negative.code: ;;;-----------------------------------------------------------------------------
  
  (defmethod buffer-clear-output ((buffer single-channel-buffer))
    (with-synchronized-buffer (buffer :output)
      (when (eql :write (last-io-op-of buffer))
        (iobuf-reset (output-iobuf-of buffer)))))
  
  