IE_RBD_BUFLEN
sc->ie_bus_write16(sc, IE_RBD_BUFLEN(sc->rbds,n),
sc->ie_bus_read16(sc, IE_RBD_BUFLEN(sc->rbds,n)));
off = IE_RBD_BUFLEN(rbbase, rbindex);
off = IE_RBD_BUFLEN(rbbase, sc->rbtail);
off = IE_RBD_BUFLEN(sc->rbds, n);