SITL: add param in SIM_Precland to enable return dist to target

libraries/SITL/SIM_Precland.cpp

@@ -105,6 +105,13 @@ const AP_Param::GroupInfo SIM_Precland::var_info[] = {
     // @User: Advanced
     AP_GROUPINFO("ORIENT", 9, SIM_Precland, _orient, ROTATION_PITCH_90),
 
+    // @Param: OPTIONS
+    // @DisplayName: SIM_Precland extra options
+    // @Description: SIM_Precland extra options
+    // @Bitmask: 0: Enable target distance
+    // @User: Advanced
+    AP_GROUPINFO("OPTIONS",  10, SIM_Precland, _options, 0),
+
     AP_GROUPEND
 };
 

libraries/SITL/SIM_Precland.h

@@ -41,6 +41,11 @@ public:
     void set_default_location(float lat, float lon, int16_t yaw);
     static const struct AP_Param::GroupInfo var_info[];
 
+    // enum for SIM_PLD_OPTIONS parameter
+    enum class Option : uint8_t {
+        ENABLE_TARGET_DISTANCE   = (1U << 0),
+    };
+
     AP_Int8 _enable;
     AP_Float _device_lat;
     AP_Float _device_lon;
@@ -51,6 +56,7 @@ public:
     AP_Float _alt_limit;
     AP_Float _dist_limit;
     AP_Int8 _orient;
+    AP_Enum<Option> _options;
     bool _over_precland_base;
 
     enum PreclandType {
@@ -58,6 +64,10 @@ public:
         PRECLAND_TYPE_CONE = 1,
         PRECLAND_TYPE_SPHERE = 2,
     };
+
+    bool option_enabled(Option option) const {
+        return (_options & uint8_t(option)) != 0;
+    }
 private:
     uint32_t _last_update_ms;
     bool _healthy;