AP_GPS: Singleton

libraries/AP_GPS/AP_GPS.cpp

@@ -61,6 +61,8 @@ const uint32_t AP_GPS::_baudrates[] = {4800U, 19200U, 38400U, 115200U, 57600U, 9
 // right mode
 const char AP_GPS::_initialisation_blob[] = UBLOX_SET_BINARY MTK_SET_BINARY SIRF_SET_BINARY;
 
+AP_GPS *AP_GPS::_singleton;
+
 // table of user settable parameters
 const AP_Param::GroupInfo AP_GPS::var_info[] = {
     // @Param: TYPE
@@ -267,6 +269,11 @@ AP_GPS::AP_GPS()
                     "GPS initilisation blob is to large to be completely sent before the baud rate changes");
 
     AP_Param::setup_object_defaults(this, var_info);
+
+    if (_singleton != nullptr) {
+        AP_HAL::panic("AP_GPS must be singleton");
+    }
+    _singleton = this;
 }
 
 /// Startup initialisation.

libraries/AP_GPS/AP_GPS.h

@@ -72,6 +72,10 @@ public:
     AP_GPS(const AP_GPS &other) = delete;
     AP_GPS &operator=(const AP_GPS&) = delete;
 
+    static AP_GPS &gps() {
+        return *_singleton;
+    }
+
     // GPS driver types
     enum GPS_Type {
         GPS_TYPE_NONE  = 0,
@@ -443,6 +447,8 @@ protected:
 private:
     AP_GPS();
 
+    static AP_GPS *_singleton;
+
     // returns the desired gps update rate in milliseconds
     // this does not provide any guarantee that the GPS is updating at the requested
     // rate it is simply a helper for use in the backends for determining what rate