+/*
+ * Above this height, the baro sensor doesn't work
+ */
+#define AO_MAX_BARO_HEIGHT 12000
+
+/*
+ * Above this speed, baro measurements are unreliable
+ */
+#define AO_MAX_BARO_SPEED 200
+
+static void
+ao_kalman_predict(void)
+{
+#ifdef AO_FLIGHT_TEST
+ if (ao_flight_tick - ao_flight_prev_tick > 5) {
+ ao_k_height += ((int32_t) ao_speed * AO_K_STEP_10 +
+ (int32_t) ao_accel * AO_K_STEP_2_2_10) >> 4;
+ ao_k_speed += (int32_t) ao_accel * AO_K_STEP_10;
+
+ return;
+ }
+ if (ao_flight_debug) {
+ printf ("predict speed %g + (%g * %g) = %g\n",
+ ao_k_speed / (65536.0 * 16.0), ao_accel / 16.0, AO_K_STEP_100 / 65536.0,
+ (ao_k_speed + (int32_t) ao_accel * AO_K_STEP_100) / (65536.0 * 16.0));
+ }
+#endif
+ ao_k_height += ((int32_t) ao_speed * AO_K_STEP_100 +
+ (int32_t) ao_accel * AO_K_STEP_2_2_100) >> 4;
+ ao_k_speed += (int32_t) ao_accel * AO_K_STEP_100;
+}
+
+static __pdata int16_t ao_error_h;
+static __pdata int16_t ao_raw_alt;
+static __pdata int16_t ao_raw_height;
+static __pdata int16_t ao_error_h_sq_avg;
+
+static void
+ao_kalman_err_height(void)
+{
+ int16_t e;
+ int16_t height_distrust;
+#if HAS_ACCEL
+ int16_t speed_distrust;
+#endif
+
+ ao_error_h = ao_raw_height - (int16_t) (ao_k_height >> 16);
+
+ e = ao_error_h;
+ if (e < 0)
+ e = -e;
+ if (e > 127)
+ e = 127;
+#if HAS_ACCEL
+ ao_error_h_sq_avg -= ao_error_h_sq_avg >> 2;
+ ao_error_h_sq_avg += (e * e) >> 2;
+#else
+ ao_error_h_sq_avg -= ao_error_h_sq_avg >> 4;
+ ao_error_h_sq_avg += (e * e) >> 4;
+#endif
+
+ height_distrust = ao_raw_height - AO_MAX_BARO_HEIGHT;
+#if HAS_ACCEL
+ /* speed is stored * 16, but we need to ramp between 200 and 328, so
+ * we want to multiply by 2. The result is a shift by 3.
+ */
+ speed_distrust = (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) >> (4 - 1);
+ if (speed_distrust <= 0)
+ speed_distrust = 0;
+ else if (speed_distrust > height_distrust)
+ height_distrust = speed_distrust;
+#endif
+ if (height_distrust <= 0)
+ height_distrust = 0;
+
+ if (height_distrust) {
+#ifdef AO_FLIGHT_TEST
+ int old_ao_error_h = ao_error_h;
+#endif
+ if (height_distrust > 0x100)
+ height_distrust = 0x100;
+ ao_error_h = (int16_t) (((int32_t) ao_error_h * (0x100 - height_distrust)) >> 8);
+#ifdef AO_FLIGHT_TEST
+ if (ao_flight_debug) {
+ printf("over height %g over speed %g distrust: %g height: error %d -> %d\n",
+ (double) (ao_raw_height - AO_MAX_BARO_HEIGHT),
+ (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) / 16.0,
+ height_distrust / 256.0,
+ old_ao_error_h, ao_error_h);
+ }
+#endif
+ }
+}
+
+static void
+ao_kalman_correct_baro(void)
+{
+ ao_kalman_err_height();
+#ifdef AO_FLIGHT_TEST
+ if (ao_flight_tick - ao_flight_prev_tick > 5) {
+ ao_k_height += (int32_t) AO_BARO_K0_10 * ao_error_h;
+ ao_k_speed += (int32_t) AO_BARO_K1_10 * ao_error_h;
+ ao_k_accel += (int32_t) AO_BARO_K2_10 * ao_error_h;
+ return;
+ }
+#endif
+ ao_k_height += (int32_t) AO_BARO_K0_100 * ao_error_h;
+ ao_k_speed += (int32_t) AO_BARO_K1_100 * ao_error_h;
+ ao_k_accel += (int32_t) AO_BARO_K2_100 * ao_error_h;
+}
+
+#if HAS_ACCEL
+static __pdata int16_t ao_error_a;
+static __pdata int32_t ao_accel_scale;
+