ar_tx_status
struct ar_tx_status *ds;
ds = &((struct ar_tx_status *)sc->txsring)[sc->txscur];
size = AR9003_NTXSTATUS * sizeof(struct ar_tx_status);
AR9003_NTXSTATUS * sizeof(struct ar_tx_status));
memset(sc->txsring, 0, AR9003_NTXSTATUS * sizeof(struct ar_tx_status));