diff --git a/src/custom_types.h b/src/custom_types.h
index b112981..cea3a94 100644
--- a/src/custom_types.h
+++ b/src/custom_types.h
@@ -6,7 +6,7 @@ struct vehicle_config{
     uint16_t magic = CONFIG_MAGIC;
     bool auto_detect_track = true;
     uint8_t num_tracks = 0;
-    uint8_t selected_track = 0;
+    uint8_t track_fallback = 0;
 };
 
 struct lat_lng {
@@ -35,3 +35,31 @@ struct gps_data {
     gps_sub_data speed;
     gps_sub_data course;
 };
+
+inline void gps_sub_copy_from_volatile(gps_sub_data& dst, const volatile gps_sub_data& src) {
+    dst.age   = src.age;
+    dst.valid = src.valid;
+    dst.value = src.value;
+}
+
+inline void gps_sub_copy_to_volatile(volatile gps_sub_data& dst, const gps_sub_data& src) {
+    dst.age   = src.age;
+    dst.valid = src.valid;
+    dst.value = src.value;
+}
+
+inline void gps_copy_from_volatile(gps_data& dst, const volatile gps_data& src) {
+    gps_sub_copy_from_volatile(dst.altitude, src.altitude);
+    gps_sub_copy_from_volatile(dst.lat,      src.lat);
+    gps_sub_copy_from_volatile(dst.lng,      src.lng);
+    gps_sub_copy_from_volatile(dst.speed,    src.speed);
+    gps_sub_copy_from_volatile(dst.course,   src.course);
+}
+
+inline void gps_copy_to_volatile(volatile gps_data& dst, const gps_data& src) {
+    gps_sub_copy_to_volatile(dst.altitude, src.altitude);
+    gps_sub_copy_to_volatile(dst.lat,      src.lat);
+    gps_sub_copy_to_volatile(dst.lng,      src.lng);
+    gps_sub_copy_to_volatile(dst.speed,    src.speed);
+    gps_sub_copy_to_volatile(dst.course,   src.course);
+}
\ No newline at end of file