From cefebb9699760b23b1298ee46a0d72ae22b6ecd8 Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Thu, 4 Jul 2013 15:48:01 +0200
Subject: Small improvements in system lib

---
 src/modules/systemlib/conversions.h |  6 +-----
 src/modules/systemlib/geo/geo.h     | 16 ++++++++++++++++
 src/modules/systemlib/pid/pid.h     |  3 +++
 3 files changed, 20 insertions(+), 5 deletions(-)

(limited to 'src/modules')

diff --git a/src/modules/systemlib/conversions.h b/src/modules/systemlib/conversions.h
index 5d485b01f..064426f21 100644
--- a/src/modules/systemlib/conversions.h
+++ b/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
 
diff --git a/src/modules/systemlib/geo/geo.h b/src/modules/systemlib/geo/geo.h
index 84097b49f..dadec51ec 100644
--- a/src/modules/systemlib/geo/geo.h
+++ b/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
diff --git a/src/modules/systemlib/pid/pid.h b/src/modules/systemlib/pid/pid.h
index 714bf988f..eca228464 100644
--- a/src/modules/systemlib/pid/pid.h
+++ b/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_ */
-- 
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