anchor.diff:           (td->xfer-info (td->xfer-info ohci)))
       (loop
          for prev-td = NIL then td
  -       for td-phys-addr = (logandc2 (ed-tdq-head ed) #x0F) then (td-next-td td)
  +       for td-phys-addr = (ed-tdq-head-tdq-addr ed) then (td-next-td td)
          for td = (phys-addr->array td-phys-addr)
          for msg-xfer-info = (gethash td td->xfer-info)
          when (eq buf (xfer-info-buf msg-xfer-info)) do
  
positive.code:            condition-code)))
  
        (setf dummy-td msg-td ;; re-use previous td as "dummy" td
              msg-td (phys-addr->array (ed-tdq-head ed))
              msg-xfer-info (gethash msg-td (td->xfer-info ohci))
  
  
  
negative.code:            condition-code)))
  
        (setf dummy-td msg-td ;; re-use previous td as "dummy" td
              msg-td (phys-addr->array (ed-tdq-head-tdq-addr ed))
              msg-xfer-info (gethash msg-td (td->xfer-info ohci))
  
              ;; clean up dummy-td
  