+
+ if (prev_state != null) {
+
+ /* Preserve any existing gps data */
+ npad = prev_state.npad;
+ gps = prev_state.gps;
+ pad_lat = prev_state.pad_lat;
+ pad_lon = prev_state.pad_lon;
+ pad_alt = prev_state.pad_alt;
+
+ /* make sure the clock is monotonic */
+ while (tick < prev_state.tick)
+ tick += 65536;
+
+ time_change = (tick - prev_state.tick) / 100.0;
+
+ /* compute barometric speed */
+
+ double height_change = height - prev_state.height;
+ if (time_change > 0)
+ baro_speed = (prev_state.baro_speed * 3 + (height_change / time_change)) / 4.0;
+ else
+ baro_speed = prev_state.baro_speed;
+ } else {
+ npad = 0;
+ gps = null;
+ baro_speed = 0;
+ time_change = 0;
+ }
+