ATH_RHIST_SIZE
for (i = 0; i < ATH_RHIST_SIZE; i++)
an->an_rx_hist_next = ATH_RHIST_SIZE-1;
i = ATH_RHIST_SIZE-1;
if (++(an->an_rx_hist_next) == ATH_RHIST_SIZE)
struct ath_recv_hist an_rx_hist[ATH_RHIST_SIZE];