new generic freertos task interface

returnvalues/HasReturnvaluesIF.h

@@ -15,7 +15,15 @@ public:
 	static const ReturnValue_t RETURN_FAILED = 1;
 	virtual ~HasReturnvaluesIF() {}
 
-	static ReturnValue_t makeReturnCode(uint8_t interfaceId, uint8_t number) {
+	/**
+	 * It is discouraged to use the input parameters 0,0 and 0,1 as this
+	 * will generate the RETURN_OK and RETURN_FAILED returnvalues.
+	 * @param interfaceId
+	 * @param number
+	 * @return
+	 */
+	static constexpr ReturnValue_t makeReturnCode(uint8_t interfaceId,
+			uint8_t number) {
 	    return (interfaceId << 8) + number;
 	}
 };