added control / nav mixing

git-svn-id: https://arducopter.googlecode.com/svn/trunk@944 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/RC_Channel/RC_Channel.cpp

@@ -63,6 +63,12 @@ RC_Channel::set_pwm(int pwm)
 	}
 }
 
+int
+RC_Channel::control_mix(float value)
+{
+	return (1 - abs(control_in / _high)) * value + control_in;
+}
+
 // are we below a threshold?
 boolean
 RC_Channel::get_failsafe(void)

libraries/RC_Channel/RC_Channel.h

@@ -42,7 +42,9 @@ class RC_Channel
 	// value generated from PWM
 	int16_t 	control_in;
 	int8_t 		dead_zone; // used to keep noise down and create a dead zone.
-
+	
+	int			control_mix(float value);
+	
 	// current values to the servos - degrees * 100 (approx assuming servo is -45 to 45 degrees except [3] is 0 to 100
 	int16_t 	servo_out;