rate2ridx
ridx = rate2ridx(IEEE80211_RV(rs->rs_rates[i]));
ridx = rate2ridx(txr->dot11rate);
ridx = rate2ridx(tp->mgmtrate);
ridx = rate2ridx(tp->mcastrate);
ridx = rate2ridx(tp->ucastrate);
ridx = rate2ridx(IEEE80211_RATE_MCS | 0x4); /* MCS4 */
ridx = rate2ridx(IEEE80211_RV(rate));
ridx = rate2ridx(IEEE80211_RV(rate));
ridx = rate2ridx(params->ibp_rate0);
ridx = rate2ridx(IEEE80211_RV(rate));
ridx = rate2ridx(params->ibp_rate0);