AP_Mission: added MIS_AUTORESTART parameter

- added MIS_AUTORESTART parameter, defaults to 0
- added start_or_resume() function to either start or resume a mission
based on that parameter value

libraries/AP_Mission/AP_Mission.cpp

@@ -15,6 +15,12 @@ const AP_Param::GroupInfo AP_Mission::var_info[] PROGMEM = {
     // @User: Advanced
     AP_GROUPINFO("TOTAL",  0, AP_Mission, _cmd_total, 0),
 
+    // @Param: AUTORESET
+    // @DisplayName: Controls whether to reset mission when switching to auto
+    // @Description: When set to 0 it will continue a previous auto mission, when set to 1 it will restart from the first waypoint
+    // @Values: 0:Continue Mission, 1:Reset Mission
+    AP_GROUPINFO("AUTORESET",  1, AP_Mission, _auto_reset, 0),
+
     AP_GROUPEND
 };
 
@@ -100,6 +106,15 @@ void AP_Mission::resume()
     }
 }
 
+void AP_Mission::start_or_resume()
+{
+    if (_auto_reset) {
+        start();
+    } else {
+        resume();
+    }
+}
+
 /// clear - clears out mission
 ///     returns true if mission was running so it could not be cleared
 bool AP_Mission::clear()

libraries/AP_Mission/AP_Mission.h

@@ -213,6 +213,9 @@ public:
     ///     previous running commands will be re-initialised
     void resume();
 
+    /// start_or_resume - if MIS_AUTORESTART=0 this will call resume(), otherwise it will call start()
+    void start_or_resume();
+
     /// clear - clears out mission
     ///     returns true if mission was running so it could not be cleared
     bool clear();
@@ -355,7 +358,8 @@ private:
     const AP_AHRS&   _ahrs;      // used only for home position
 
     // parameters
-    AP_Int16                _cmd_total; // total number of commands in the mission
+    AP_Int16                _cmd_total;  // total number of commands in the mission
+    AP_Int8                 _auto_reset; // when true the mission will reset to the start when initiated
 
     // pointer to main program functions
     mission_cmd_fn_t        _cmd_start_fn;  // pointer to function which will be called when a new command is started