Use the G_RC_AUX macro when possible. Added more comments. Remove unused code

ArduPlane/ArduPlane.pde

@@ -39,7 +39,6 @@ version 2.1 of the License, or (at your option) any later version.
 #include <AP_DCM.h>         // ArduPilot Mega DCM Library
 #include <PID.h>            // PID library
 #include <RC_Channel.h>     // RC Channel Library
-//#include <RC_Channel/RC_Channel_aux.h> // Auxiliary RC Channel Library (Channels 5..8)
 #include <AP_RangeFinder.h>	// Range finder library
 #include <ModeFilter.h>
 #include <AP_Camera.h>		// Photo or video camera

ArduPlane/Attitude.pde

@@ -274,14 +274,14 @@ static void set_servos(void)
 		}
 		g.channel_throttle.radio_out 	= g.channel_throttle.radio_in;
 		g.channel_rudder.radio_out 		= g.channel_rudder.radio_in;
-		if (g_rc_function[RC_Channel_aux::k_aileron] != NULL) g_rc_function[RC_Channel_aux::k_aileron]->radio_out = g_rc_function[RC_Channel_aux::k_aileron]->radio_in;
+		G_RC_AUX(k_aileron)->radio_out	= g_rc_function[RC_Channel_aux::k_aileron]->radio_in;
 
 	} else {
 		if (g.mix_mode == 0) {
 			g.channel_roll.calc_pwm();
 			g.channel_pitch.calc_pwm();
 			g.channel_rudder.calc_pwm();
-			if (g_rc_function[RC_Channel_aux::k_aileron] != NULL) {
+			if (g_rc_function[RC_Channel_aux::k_aileron]) {
 				g_rc_function[RC_Channel_aux::k_aileron]->servo_out = g.channel_roll.servo_out;
 				g_rc_function[RC_Channel_aux::k_aileron]->calc_pwm();
 			}
@@ -315,7 +315,7 @@ static void set_servos(void)
 	}
 	
 	if(control_mode <= FLY_BY_WIRE_B) {
-		if (g_rc_function[RC_Channel_aux::k_flap_auto] != NULL) g_rc_function[RC_Channel_aux::k_flap_auto]->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_in;
+		G_RC_AUX(k_flap_auto)->radio_out = g_rc_function[RC_Channel_aux::k_flap_auto]->radio_in;
 	} else if (control_mode >= FLY_BY_WIRE_C) {	
 		if (g.airspeed_enabled == true) {  
 			flapSpeedSource = g.airspeed_cruise;
@@ -323,11 +323,11 @@ static void set_servos(void)
 			flapSpeedSource = g.throttle_cruise;
 		}
 		if ( flapSpeedSource > g.flap_1_speed) {
-			if (g_rc_function[RC_Channel_aux::k_flap_auto] != NULL) g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = 0;
+			G_RC_AUX(k_flap_auto)->servo_out = 0;
 		} else if (flapSpeedSource > g.flap_2_speed) {
-			if (g_rc_function[RC_Channel_aux::k_flap_auto] != NULL) g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = g.flap_1_percent;
+			G_RC_AUX(k_flap_auto)->servo_out = g.flap_1_percent;
 		} else {
-			if (g_rc_function[RC_Channel_aux::k_flap_auto] != NULL) g_rc_function[RC_Channel_aux::k_flap_auto]->servo_out = g.flap_2_percent;
+			G_RC_AUX(k_flap_auto)->servo_out = g.flap_2_percent;
 		}
 	}
 	

libraries/RC_Channel/RC_Channel_aux.cpp

@@ -21,6 +21,7 @@ RC_Channel_aux::closest_limit(int16_t angle)
 	while (min >= 1800) min -= 3600;
 	while (max < -1800) max += 3600;
 	while (max >= 1800) max -= 3600;
+	// This is done every time because the user might change the min, max values on the fly
 	set_range(min, max);
 
 	// If the angle is outside servo limits, saturate the angle to the closest limit
@@ -44,6 +45,7 @@ RC_Channel_aux::closest_limit(int16_t angle)
 void
 RC_Channel_aux::output_ch(unsigned char ch_nr)
 {
+	// take care or two corner cases
 	switch(function)
 	{
 	case k_none: 		// disabled
@@ -52,26 +54,14 @@ RC_Channel_aux::output_ch(unsigned char ch_nr)
 	case k_manual:		// manual
 		radio_out = radio_in;
 		break;
-	case k_flap:		// flaps
-	case k_flap_auto:	// flaps automated
-	case k_aileron:		// aileron
-	case k_flaperon:	// flaperon (flaps and aileron combined, needs two independent servos one for each wing)
-	case k_mount_yaw:	// mount yaw (pan)
-	case k_mount_pitch:	// mount pitch (tilt)
-	case k_mount_roll:	// mount roll
-	case k_cam_trigger:	// camera trigger
-	case k_cam_open:	// camera open
-	case k_egg_drop:	// egg drop
-	case k_nr_aux_servo_functions: // dummy, just to avoid a compiler warning
-	default:
-		break;
 	}
 
 	APM_RC.OutputCh(ch_nr, radio_out);
 }
 
-// update the g_rc_function array from pointers to rc_x channels
-// This should be done periodically because the user might change the configuration and
+// Update the g_rc_function array of pointers to rc_x channels
+// This is to be done before rc_init so that the channels get correctly initialized.
+// It also should be called periodically because the user might change the configuration and
 // expects the changes to take effect instantly
 void update_aux_servo_function(RC_Channel_aux* rc_5, RC_Channel_aux* rc_6, RC_Channel_aux* rc_7, RC_Channel_aux* rc_8)
 {