From 8650229ad4245e4d684c9c28653b7c31d5f1c19f Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Wed, 2 Oct 2019 20:54:10 +1000
Subject: [PATCH] AP_ADSB: added singleton interface

---
 libraries/AP_ADSB/AP_ADSB.cpp | 18 ++++++++++++++++++
 libraries/AP_ADSB/AP_ADSB.h   | 19 +++++++++++++++----
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/libraries/AP_ADSB/AP_ADSB.cpp b/libraries/AP_ADSB/AP_ADSB.cpp
index b815aefb9a..28fcaed8f1 100644
--- a/libraries/AP_ADSB/AP_ADSB.cpp
+++ b/libraries/AP_ADSB/AP_ADSB.cpp
@@ -50,6 +50,8 @@
 
 extern const AP_HAL::HAL& hal;
 
+AP_ADSB *AP_ADSB::_singleton;
+
 // table of user settable parameters
 const AP_Param::GroupInfo AP_ADSB::var_info[] = {
     // @Param: ENABLE
@@ -159,6 +161,16 @@ const AP_Param::GroupInfo AP_ADSB::var_info[] = {
     AP_GROUPEND
 };
 
+// constructor
+AP_ADSB::AP_ADSB()
+{
+    AP_Param::setup_object_defaults(this, var_info);
+    if (_singleton != nullptr) {
+        AP_HAL::panic("AP_ADSB must be singleton");
+    }
+    _singleton = this;
+}
+
 /*
  * Initialize variables and allocate memory for array
  */
@@ -940,3 +952,9 @@ void AP_ADSB::write_log(const adsb_vehicle_t &vehicle)
     };
     AP::logger().WriteBlock(&pkt, sizeof(pkt));
 }
+
+AP_ADSB *AP::ADSB()
+{
+    return AP_ADSB::get_singleton();
+}
+
diff --git a/libraries/AP_ADSB/AP_ADSB.h b/libraries/AP_ADSB/AP_ADSB.h
index 17fcc9d5e3..954970bedf 100644
--- a/libraries/AP_ADSB/AP_ADSB.h
+++ b/libraries/AP_ADSB/AP_ADSB.h
@@ -29,10 +29,8 @@
 
 class AP_ADSB {
 public:
-    AP_ADSB()
-    {
-        AP_Param::setup_object_defaults(this, var_info);
-    }
+    // constructor
+    AP_ADSB();
 
     /* Do not allow copies */
     AP_ADSB(const AP_ADSB &other) = delete;
@@ -88,7 +86,14 @@ public:
     // confirm a value is a valid callsign
     static bool is_valid_callsign(uint16_t octal) WARN_IF_UNUSED;
 
+    // get singleton instance
+    static AP_ADSB *get_singleton(void) {
+        return _singleton;
+    }
+
 private:
+    static AP_ADSB *_singleton;
+
     // initialize _vehicle_list
     void init();
 
@@ -202,4 +207,10 @@ private:
         SPECIAL_ONLY    = 1,
         ALL             = 2
     };
+
+
+};
+
+namespace AP {
+    AP_ADSB *ADSB();
 };