Add an ORB topic that can be subscribed for notification of changes in the parameter set.

apps/systemlib/param/param.h

@@ -48,36 +48,11 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+#include "drivers/drv_param.h"
+
 /** Maximum size of the parameter backing file */
 #define PARAM_FILE_MAXSIZE	4096
 
-/**
- * Parameter types.
- */
-typedef enum param_type_e {
-	/* globally-known parameter types */
-	PARAM_TYPE_INT32 = 0,
-	PARAM_TYPE_FLOAT,
-
-	/* structure parameters; size is encoded in the type value */
-	PARAM_TYPE_STRUCT = 100,
-	PARAM_TYPE_STRUCT_MAX = 16384 + PARAM_TYPE_STRUCT,
-
-	PARAM_TYPE_UNKNOWN = 0xffff
-} param_type_t;
-
-/**
- * Parameter handle.
- *
- * Parameters are represented by parameter handles, which can
- * be obtained by looking up (or creating?) parameters.
- */
-typedef uintptr_t	param_t;
-
-/**
- * Handle returned when a parameter cannot be found.
- */
-#define PARAM_INVALID	((uintptr_t)0xffffffff)
 
 /**
  * Look up a parameter by name.