mixer lib: added methods to fetch the active trim values

Signed-off-by: Roman <bapstroman@gmail.com>

src/lib/mixer/mixer.h

@@ -204,6 +204,13 @@ public:
 	 */
 	virtual unsigned set_trim(float trim) = 0;
 
+	/**
+	 * @brief Get trim offset for this mixer
+	 *
+	 * @return the number of outputs this mixer feeds to
+	 */
+	virtual unsigned get_trim(float *trim) = 0;
+
 	/*
 	 * @brief      Sets the thrust factor used to calculate mapping from desired thrust to pwm.
 	 *
@@ -382,6 +389,13 @@ public:
 		return 0;
 	}
 
+	unsigned get_trims(int16_t *values);
+
+	unsigned get_trim(float *trim)
+	{
+		return 0;
+	}
+
 	/**
 	 * @brief      Sets the thrust factor used to calculate mapping from desired thrust to pwm.
 	 *
@@ -432,6 +446,11 @@ public:
 		return 0;
 	}
 
+	unsigned get_trim(float *trim)
+	{
+		return 0;
+	}
+
 };
 
 /**
@@ -507,6 +526,8 @@ public:
 
 	unsigned set_trim(float trim);
 
+	unsigned get_trim(float *trim);
+
 protected:
 
 private:
@@ -617,6 +638,11 @@ public:
 		return _rotor_count;
 	}
 
+	unsigned get_trim(float *trim)
+	{
+		return _rotor_count;
+	}
+
 	/**
 	 * @brief      Sets the thrust factor used to calculate mapping from desired thrust to pwm.
 	 *
@@ -732,6 +758,11 @@ public:
 		return 4;
 	}
 
+	unsigned get_trim(float *trim)
+	{
+		return 0;
+	}
+
 private:
 	mixer_heli_s			_mixer_info;
 

src/lib/mixer/mixer_group.cpp

@@ -145,6 +145,37 @@ MixerGroup::set_trims(int16_t *values, unsigned n)
 	return index;
 }
 
+/*
+ * get_trims() has no effect except for the SimpleMixer implementation for which get_trim()
+ * always returns the value one and sets the trim value.
+ * The only other existing implementation is MultirotorMixer, which ignores the trim value
+ * and returns _rotor_count.
+ */
+unsigned
+MixerGroup::get_trims(int16_t *values)
+{
+	Mixer	*mixer = _first;
+	unsigned index_mixer = 0;
+	unsigned index = 0;
+	float trim;
+
+	while (mixer != nullptr) {
+		trim = 0;
+		index_mixer += mixer->get_trim(&trim);
+
+		// MultirotorMixer returns the number of motors so we
+		// loop through index_mixer and set the same trim value for all motors
+		while (index < index_mixer) {
+			values[index] = trim * 10000;
+			index++;
+		}
+
+		mixer = mixer->_next;
+	}
+
+	return index;
+}
+
 void
 MixerGroup::set_thrust_factor(float val)
 {

src/lib/mixer/mixer_simple.cpp

@@ -78,6 +78,12 @@ unsigned SimpleMixer::set_trim(float trim)
 	return 1;
 }
 
+unsigned SimpleMixer::get_trim(float *trim)
+{
+	*trim = _pinfo->output_scaler.offset;
+	return 1;
+}
+
 int
 SimpleMixer::parse_output_scaler(const char *buf, unsigned &buflen, mixer_scaler_s &scaler)
 {