WMCOM_RING_SIZE
sc->sc_rbuf = malloc(WMCOM_RING_SIZE << 1, M_DEVBUF, M_WAITOK);
sc->sc_rbavail = WMCOM_RING_SIZE;
if (put >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))
sc->sc_rbavail = WMCOM_RING_SIZE;
scc = cc = WMCOM_RING_SIZE - sc->sc_rbavail;
if (get >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))
get -= (WMCOM_RING_SIZE << 1);
if (get >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))