FlightTasks: adapt POSIX convention to return negative values on error

src/lib/FlightTasks/FlightTasks.hpp

@@ -57,7 +57,7 @@ public:
 
 	/**
 	 * Call regularly in the control loop cycle to execute the task
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	int update()
 	{
@@ -87,7 +87,7 @@ public:
 
 	/**
 	 * Switch to the next task in the available list (for testing)
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	void switch_task()
 	{
@@ -97,7 +97,7 @@ public:
 	/**
 	 * Switch to a specific task (for normal usage)
 	 * @param task number to switch to
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	int switch_task(int task_number)
 	{

src/lib/FlightTasks/tasks/FlightTask.cpp

@@ -10,18 +10,20 @@ int FlightTask::update()
 	_deltatime  = math::min((_time_stamp_current - _time_stamp_last), _timeout) / 1e6f;
 	_time_stamp_last = _time_stamp_current;
 	updateSubscriptions();
-	_evaluate_vehicle_position();
-	return 0;
+	int ret = _evaluate_vehicle_position();
+	return ret;
 }
 
-void FlightTask::_evaluate_vehicle_position()
+int FlightTask::_evaluate_vehicle_position()
 {
 	if ((_time_stamp_current - _sub_vehicle_local_position.get().timestamp) < _timeout) {
 		_position = matrix::Vector3f(&_sub_vehicle_local_position.get().x);
 		_velocity = matrix::Vector3f(&_sub_vehicle_local_position.get().vx);
 		_yaw = _sub_vehicle_local_position.get().yaw;
+		return 0;
 
 	} else {
 		_velocity.zero(); /* default velocity is all zero */
+		return -1;
 	}
 }

src/lib/FlightTasks/tasks/FlightTask.hpp

@@ -59,7 +59,7 @@ public:
 
 	/**
 	 * Call once on the event where you switch to the task
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	virtual int activate()
 	{
@@ -70,13 +70,13 @@ public:
 
 	/**
 	 * Call once on the event of switching away from the task
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	virtual int disable() { return 0; };
 
 	/**
 	 * To be called regularly in the control loop cycle to execute the task
-	 * @return 0 on success, >0 on error
+	 * @return 0 on success, <0 on error
 	 */
 	virtual int update();
 
@@ -122,5 +122,5 @@ private:
 
 	vehicle_local_position_setpoint_s _vehicle_local_position_setpoint; /**< Output position setpoint that every task has */
 
-	void _evaluate_vehicle_position();
+	int _evaluate_vehicle_position();
 };

src/lib/FlightTasks/tasks/FlightTaskManual.cpp

@@ -136,7 +136,7 @@ int FlightTaskManual::_evaluate_sticks()
 
 	} else {
 		_sticks.zero(); /* default is all zero */
-		return 1;
+		return -1;
 	}
 }