anchor.diff:  ;;; Input
   ;;;-------------------------------------------------------------------------
   
  -(declaim (notinline %read-once))
  +(declaim (inline %read-once))
   (defun %read-once (fd read-fn iobuf)
     (declare (type function read-fn)
              (type iobuf iobuf))
  
positive.code:         :eof
          (progn (incf (iobuf-end iobuf) nbytes) nbytes))))
  
  (declaim (notinline %read-once/no-hang))
  (defun %read-once/no-hang (fd read-fn iobuf)
    (declare (type function read-fn)
             (type iobuf iobuf))
  
negative.code:                (iobuf-end-space-length iobuf))
      (isys:ewouldblock () nil)))
  
  (declaim (inline %fill-ibuf/no-hang))
  (defun %fill-ibuf/no-hang (iobuf fd read-fn)
    (declare (type iobuf iobuf))
    (let ((nbytes (%read-once/no-hang fd read-fn iobuf)))
  