mavlink: send MOUNT_STATUS msg if subscribed

This adds the message MOUNT_STATUS to report about the attitude of a
gimbal.

src/modules/mavlink/mavlink_messages.cpp

@@ -89,6 +89,7 @@
 #include <uORB/topics/vision_position_estimate.h>
 #include <uORB/topics/vtol_vehicle_status.h>
 #include <uORB/topics/wind_estimate.h>
+#include <uORB/topics/mount_status.h>
 #include <uORB/uORB.h>
 
 
@@ -3457,6 +3458,72 @@ protected:
 	}
 };
 
+class MavlinkStreamMountStatus : public MavlinkStream
+{
+public:
+	const char *get_name() const
+	{
+		return MavlinkStreamMountStatus::get_name_static();
+	}
+
+	static const char *get_name_static()
+	{
+		return "MOUNT_STATUS";
+	}
+
+	static uint16_t get_id_static()
+	{
+		return MAVLINK_MSG_ID_MOUNT_STATUS;
+	}
+
+	uint16_t get_id()
+	{
+		return get_id_static();
+	}
+
+	static MavlinkStream *new_instance(Mavlink *mavlink)
+	{
+		return new MavlinkStreamMountStatus(mavlink);
+	}
+
+	unsigned get_size()
+	{
+		return (_mount_status_time > 0) ? MAVLINK_MSG_ID_MOUNT_STATUS_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES : 0;
+	}
+
+private:
+	MavlinkOrbSubscription *_mount_status_sub;
+	uint64_t _mount_status_time;
+
+	/* do not allow top copying this class */
+	MavlinkStreamMountStatus(MavlinkStreamMountStatus &);
+	MavlinkStreamMountStatus &operator = (const MavlinkStreamMountStatus &);
+
+protected:
+	explicit MavlinkStreamMountStatus(Mavlink *mavlink) : MavlinkStream(mavlink),
+		_mount_status_sub(_mavlink->add_orb_subscription(ORB_ID(mount_status))),
+		_mount_status_time(0)
+	{}
+
+	void send(const hrt_abstime t)
+	{
+		struct mount_status_s mount_status = {};
+
+		bool updated = _mount_status_sub->update(&_mount_status_time, &mount_status);
+
+		if (updated) {
+
+			mavlink_mount_status_t msg = {};
+
+			msg.roll = 180.0f / M_PI_F * mount_status.attitude_euler_angle[0];
+			msg.pitch = 180.0f / M_PI_F * mount_status.attitude_euler_angle[1];
+			msg.yaw = 180.0f / M_PI_F * mount_status.attitude_euler_angle[2];
+
+			mavlink_msg_mount_status_send_struct(_mavlink->get_channel(), &msg);
+		}
+	}
+};
+
 const StreamListItem *streams_list[] = {
 	new StreamListItem(&MavlinkStreamHeartbeat::new_instance, &MavlinkStreamHeartbeat::get_name_static, &MavlinkStreamHeartbeat::get_id_static),
 	new StreamListItem(&MavlinkStreamStatustext::new_instance, &MavlinkStreamStatustext::get_name_static, &MavlinkStreamStatustext::get_id_static),
@@ -3501,5 +3568,6 @@ const StreamListItem *streams_list[] = {
 	new StreamListItem(&MavlinkStreamAltitude::new_instance, &MavlinkStreamAltitude::get_name_static, &MavlinkStreamAltitude::get_id_static),
 	new StreamListItem(&MavlinkStreamADSBVehicle::new_instance, &MavlinkStreamADSBVehicle::get_name_static, &MavlinkStreamADSBVehicle::get_id_static),
 	new StreamListItem(&MavlinkStreamWind::new_instance, &MavlinkStreamWind::get_name_static, &MavlinkStreamWind::get_id_static),
+	new StreamListItem(&MavlinkStreamMountStatus::new_instance, &MavlinkStreamMountStatus::get_name_static, &MavlinkStreamMountStatus::get_id_static),
 	nullptr
 };