mixer: use an enum for airmode

src/lib/mixer/mixer.h

@@ -140,6 +140,12 @@
 class __EXPORT Mixer
 {
 public:
+	enum class Airmode : int32_t {
+		disabled = 0,
+		roll_pitch = 1,
+		roll_pitch_yaw = 2
+	};
+
 	/** next mixer in a list */
 	Mixer				*_next;
 
@@ -223,7 +229,7 @@ public:
 	 *
 	 * @param[in]  airmode   Select airmode type (0 = disabled, 1 = roll/pitch, 2 = roll/pitch/yaw)
 	 */
-	virtual void set_airmode(int32_t airmode) {};
+	virtual void set_airmode(Airmode airmode) {};
 
 protected:
 	/** client-supplied callback used when fetching control values */
@@ -419,7 +425,7 @@ public:
 	 */
 	void	set_thrust_factor(float val) override;
 
-	void 	set_airmode(int32_t airmode) override;
+	void 	set_airmode(Airmode airmode) override;
 
 private:
 	Mixer				*_first;	/**< linked list of mixers */
@@ -667,7 +673,7 @@ public:
 	 */
 	void			set_thrust_factor(float val) override { _thrust_factor = val; }
 
-	void 			set_airmode(int32_t airmode) override;
+	void 			set_airmode(Airmode airmode) override;
 
 	union saturation_status {
 		struct {
@@ -694,7 +700,7 @@ private:
 	float 				_delta_out_max;
 	float 				_thrust_factor;
 
-	uint32_t			_airmode;
+	Airmode				_airmode;
 
 	void update_saturation_status(unsigned index, bool clipping_high, bool clipping_low);
 	saturation_status _saturation_status;

src/lib/mixer/mixer_group.cpp

@@ -188,7 +188,7 @@ MixerGroup::set_thrust_factor(float val)
 }
 
 void
-MixerGroup::set_airmode(int32_t airmode)
+MixerGroup::set_airmode(Airmode airmode)
 {
 	Mixer	*mixer = _first;
 

src/lib/mixer/mixer_multirotor.cpp

@@ -72,7 +72,7 @@ MultirotorMixer::MultirotorMixer(ControlCallback control_cb,
 	_idle_speed(-1.0f + idle_speed * 2.0f),	/* shift to output range here to avoid runtime calculation */
 	_delta_out_max(0.0f),
 	_thrust_factor(0.0f),
-	_airmode(0),
+	_airmode(Airmode::disabled),
 	_rotor_count(_config_rotor_count[(MultirotorGeometryUnderlyingType)geometry]),
 	_rotors(_config_index[(MultirotorGeometryUnderlyingType)geometry]),
 	_outputs_prev(new float[_rotor_count])
@@ -214,7 +214,7 @@ MultirotorMixer::mix(float *outputs, unsigned space)
 		boost = 1.0f - ((max_out - thrust) * roll_pitch_scale + thrust);
 	}
 
-	if (_airmode == 0) {
+	if (_airmode == Airmode::disabled) {
 		// disable positive boosting if not in air-mode
 		// boosting can only be positive when min_out < 0.0
 		// roll_pitch_scale is reduced accordingly
@@ -425,7 +425,7 @@ MultirotorMixer::update_saturation_status(unsigned index, bool clipping_high, bo
 }
 
 void
-MultirotorMixer::set_airmode(int32_t airmode)
+MultirotorMixer::set_airmode(Airmode airmode)
 {
 	_airmode = airmode;
 }