ural_ack_rate
ackrate = ural_ack_rate(ic, rate);
dur += ural_txtime(RAL_CTS_SIZE, ural_ack_rate(ic,
int ural_ack_rate(struct ieee80211com *, int);
dur = ural_txtime(RAL_ACK_SIZE, ural_ack_rate(ic, rate),