diff --git a/src/main.cc b/src/main.cc
index 1163c6c..bec7a0c 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -34,21 +34,21 @@ void get_status() {
 
 int main() {
 
-    get_status();
-    BasicRanges::build_basic_ranges();
-    get_status();
-    AllCases::build_all_cases();
-    get_status();
-
-    for (auto const &all_case : *AllCases::get_all_cases()) {
-        std::cout << "  " << all_case.size() << std::endl;
-    }
-
-    std::cout << BasicRanges::get_basic_ranges() << std::endl;
-    std::cout << AllCases::get_basic_ranges() << std::endl;
-
-    printf("%p\n", BasicRanges::get_status);
-    printf("%p\n", AllCases::get_status);
+//    get_status();
+//    BasicRanges::build_basic_ranges();
+//    get_status();
+//    AllCases::build_all_cases();
+//    get_status();
+//
+//    for (auto const &all_case : *AllCases::get_all_cases()) {
+//        std::cout << "  " << all_case.size() << std::endl;
+//    }
+//
+//    std::cout << BasicRanges::get_basic_ranges() << std::endl;
+//    std::cout << AllCases::get_basic_ranges() << std::endl;
+//
+//    printf("%p\n", BasicRanges::get_status);
+//    printf("%p\n", AllCases::get_status);
 
 
 //    std::cout << CommonCode::check(0x123456789) << std::endl;
@@ -67,23 +67,27 @@ int main() {
 //    std::cout << CommonCode(0x1A9BF0C00).to_string() << std::endl;
 
 
-//    std::cout << "start NORMAL speed up" << std::endl;
-////    ShortCode::speed_up(ShortCode::NORMAL);
-//    std::thread t1(ShortCode::speed_up, ShortCode::NORMAL);
-//    std::thread t2(ShortCode::speed_up, ShortCode::NORMAL);
-//    t1.join();
-//    t2.join();
-//    std::cout << "NORMAL speed up complete" << std::endl;
-//
-//    std::cout << "start FAST speed up" << std::endl;
-////    ShortCode::speed_up(ShortCode::FAST);
-//    std::thread t3(ShortCode::speed_up, ShortCode::FAST);
-//    std::thread t4(ShortCode::speed_up, ShortCode::FAST);
-//    t3.join();
-//    t4.join();
-//    std::cout << "FAST speed up complete" << std::endl;
-//
-//    std::cout << ShortCode::all_cases_list.size() << std::endl;
+//    std::cout << ShortCode::check_mode() << std::endl;
+
+    std::cout << "start NORMAL speed up" << std::endl;
+//    ShortCode::speed_up(ShortCode::NORMAL);
+    std::thread t1(ShortCode::speed_up, ShortCode::NORMAL);
+    std::thread t2(ShortCode::speed_up, ShortCode::NORMAL);
+    t1.join();
+    t2.join();
+    std::cout << "NORMAL speed up complete" << std::endl;
+
+    std::cout << ShortCode::check_mode() << std::endl;
+
+    std::cout << "start FAST speed up" << std::endl;
+//    ShortCode::speed_up(ShortCode::FAST);
+    std::thread t3(ShortCode::speed_up, ShortCode::FAST);
+    std::thread t4(ShortCode::speed_up, ShortCode::FAST);
+    t3.join();
+    t4.join();
+    std::cout << "FAST speed up complete" << std::endl;
+
+    std::cout << ShortCode::check_mode() << std::endl;
 
     return 0;
 }
diff --git a/src/short_code/short_code.cc b/src/short_code/short_code.cc
index 6d70279..5e708a3 100644
--- a/src/short_code/short_code.cc
+++ b/src/short_code/short_code.cc
@@ -3,10 +3,8 @@
 #include "basic_ranges.h"
 
 std::mutex ShortCode::map_building;
-
 bool ShortCode::fast_mode_available = false;
 bool ShortCode::normal_mode_available = false;
-
 std::vector<uint64_t> ShortCode::all_cases_list;
 std::unordered_map<uint64_t, uint32_t> ShortCode::all_cases_dict;
 
@@ -15,27 +13,28 @@ void ShortCode::speed_up(ShortCode::Mode mode) {
         return; // fast mode already available
     }
     if (mode == ShortCode::FAST) { // build fast mode data
-
-        // build_mappings
         build_mappings();
-
     } else if (mode == ShortCode::NORMAL && !normal_mode_available) { // build normal mode data
         BasicRanges::build_basic_ranges(); // blocking function
         normal_mode_available = true;
     }
-
 }
 
-void ShortCode::build_mappings() { // build fast search mappings
-
+ShortCode::Mode ShortCode::check_mode() { // ensure speed up enabled and return current mode
     if (fast_mode_available) {
-        return; // all cases map already built
+        return ShortCode::FAST; // fast mode already enabled
     }
+    if (normal_mode_available) {
+        return ShortCode::NORMAL; // normal mode already enabled
+    }
+    speed_up(ShortCode::Mode::NORMAL); // without initialized -> enter normal mode
+    return ShortCode::Mode::NORMAL; // use normal mode
+}
 
+/// ensure that fast_mode_available = false
+void ShortCode::build_mappings() { // build fast search mappings
     if (map_building.try_lock()) { // lock success -> start building
-
         AllCases::build_all_cases(); // blocking function
-
         for (int head = 0; head < 16; ++head) {
             uint64_t prefix = (uint64_t)head << 32;
             for (const auto &range : (*AllCases::get_all_cases())[head]) {
@@ -45,11 +44,9 @@ void ShortCode::build_mappings() { // build fast search mappings
         for (int index = 0; index < all_cases_list.size(); ++index) {
             all_cases_dict[all_cases_list[index]] = index; // common_code -> short_code
         }
-
         fast_mode_available = true; // set available flag
     } else { // another thread building
         map_building.lock(); // blocking waiting
     }
     map_building.unlock();
-
 }
diff --git a/src/short_code/short_code.h b/src/short_code/short_code.h
index 2c6f701..9ab0075 100644
--- a/src/short_code/short_code.h
+++ b/src/short_code/short_code.h
@@ -7,24 +7,19 @@
 
 class ShortCode {
 public:
-
     enum Mode {
         NORMAL, FAST
     };
-
-    static void build_mappings();
-
+    static enum Mode check_mode();
     static void speed_up(enum Mode mode);
 
-    static std::mutex map_building;
 
+private:
+    static std::mutex map_building;
     static bool fast_mode_available;
     static bool normal_mode_available;
-
-
-//    static std::vector<uint32_t> *basic_ranges;
-
     static std::vector<uint64_t> all_cases_list; // short_code -> common_code
     static std::unordered_map<uint64_t, uint32_t> all_cases_dict; // common_code -> short_code
 
+    static void build_mappings();
 };