MD_NTXDESC
memset(sc->sc_txdescs, 0, sizeof(struct tdes) * MD_NTXDESC);
sc->sc_txdescs[MD_NTXDESC - 1].t0 = htole32(T0_LD); /* tie off */
SCX_CDTXSYNC(sc, 0, MD_NTXDESC,
sc->sc_txfree = MD_NTXDESC;
if (sc->sc_txfree != MD_NTXDESC) {
#define MD_NTXDESC_MASK (MD_NTXDESC - 1)
struct tdes cd_txdescs[MD_NTXDESC];
if ((__x + __n) > MD_NTXDESC) { \
(MD_NTXDESC - __x), (ops)); \
__n -= (MD_NTXDESC - __x); \