Small improvements in system lib

src/modules/systemlib/conversions.h

@@ -43,11 +43,7 @@
 #define CONVERSIONS_H_
 #include <float.h>
 #include <stdint.h>
-
-#define CONSTANTS_ONE_G						9.80665f		// m/s^2
-#define CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C	1.225f			// kg/m^3
-#define CONSTANTS_AIR_GAS_CONST				287.1f 			// J/(kg * K)
-#define CONSTANTS_ABSOLUTE_NULL_CELSIUS		-273.15f		// °C
+#include <systemlib/geo/geo.h>
 
 __BEGIN_DECLS
 

src/modules/systemlib/geo/geo.h

@@ -45,9 +45,23 @@
  * Additional functions - @author Doug Weibel <douglas.weibel@colorado.edu>
  */
 
+#pragma once
+
+__BEGIN_DECLS
 
 #include <stdbool.h>
 
+#define CONSTANTS_ONE_G					9.80665f		/* m/s^2		*/
+#define CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C		1.225f			/* kg/m^3		*/
+#define CONSTANTS_AIR_GAS_CONST				287.1f 			/* J/(kg * K)		*/
+#define CONSTANTS_ABSOLUTE_NULL_CELSIUS			-273.15f		/* °C			*/
+#define CONSTANTS_RADIUS_OF_EARTH			6371000			/* meters (m)		*/
+
+/* compatibility aliases */
+#define RADIUS_OF_EARTH		CONSTANTS_RADIUS_OF_EARTH
+#define GRAVITY_MSS		CONSTANTS_ONE_G
+
+// XXX remove
 struct crosstrack_error_s {
 	bool past_end;		// Flag indicating we are past the end of the line/arc segment
 	float distance;		// Distance in meters to closest point on line/arc
@@ -111,3 +125,5 @@ __EXPORT float _wrap_180(float bearing);
 __EXPORT float _wrap_360(float bearing);
 __EXPORT float _wrap_pi(float bearing);
 __EXPORT float _wrap_2pi(float bearing);
+
+__END_DECLS

src/modules/systemlib/pid/pid.h

@@ -53,6 +53,8 @@
 
 #include <stdint.h>
 
+__BEGIN_DECLS
+
 /* PID_MODE_DERIVATIV_CALC calculates discrete derivative from previous error
  * val_dot in pid_calculate() will be ignored */
 #define PID_MODE_DERIVATIV_CALC	0
@@ -87,5 +89,6 @@ __EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, flo
 
 __EXPORT void pid_reset_integral(PID_t *pid);
 
+__END_DECLS
 
 #endif /* PID_H_ */