AP_AdvancedFailSafe: add singleton getter

libraries/AP_AdvancedFailsafe/AP_AdvancedFailsafe.cpp

@@ -27,6 +27,8 @@
 #include <AP_GPS/AP_GPS.h>
 #include <AP_Baro/AP_Baro.h>
 
+AP_AdvancedFailsafe *AP_AdvancedFailsafe::_singleton;
+
 extern const AP_HAL::HAL& hal;
 
 // table of user settable parameters
@@ -453,3 +455,12 @@ void AP_AdvancedFailsafe::max_range_update(void)
         _terminate.set_and_notify(1);
     }
 }
+
+namespace AP {
+
+AP_AdvancedFailsafe *advancedfailsafe()
+{
+    return AP_AdvancedFailsafe::get_singleton();
+}
+
+};

libraries/AP_AdvancedFailsafe/AP_AdvancedFailsafe.h

@@ -48,18 +48,31 @@ public:
         TERMINATE_ACTION_LAND      = 43
     };
 
+    /* Do not allow copies */
+    AP_AdvancedFailsafe(const AP_AdvancedFailsafe &other) = delete;
+    AP_AdvancedFailsafe &operator=(const AP_AdvancedFailsafe&) = delete;
+
     // Constructor
     AP_AdvancedFailsafe(AP_Mission &_mission) :
         mission(_mission)
         {
             AP_Param::setup_object_defaults(this, var_info);
+            if (_singleton != nullptr) {
+                AP_HAL::panic("AP_Logger must be singleton");
+            }
 
+            _singleton = this;
             _state = STATE_PREFLIGHT;
             _terminate.set(0);
 
             _saved_wp = 0;
         }
 
+    // get singleton instance
+    static AP_AdvancedFailsafe *get_singleton(void) {
+        return _singleton;
+    }
+
     bool enabled() { return _enable; }
 
     // check that everything is OK
@@ -147,6 +160,12 @@ protected:
     bool check_altlimit(void);
 
 private:
+    static AP_AdvancedFailsafe *_singleton;
+
     // update maximum range check
     void max_range_update();
 };
+
+namespace AP {
+    AP_AdvancedFailsafe *advancedfailsafe();
+};