diff --git a/klotski/main.cc b/klotski/main.cc
index 408e1a0..250412d 100644
--- a/klotski/main.cc
+++ b/klotski/main.cc
@@ -38,37 +38,13 @@ int main() {
 //    printf("%d\n", s.tiny_encode(0x6EC0F8800));
 //    printf("%09lX\n", s.tiny_decode(14323231));
 
+//    auto s = ShortCode();
+//    auto s = ShortCode(ShortCode::Mode::NORMAL);
+    auto s = ShortCode(ShortCode::Mode::FAST);
 
-//    if (CommonCode::check(0x4FEA13400)) {
-//        std::cout << "true" << std::endl;
-//    } else {
-//        std::cout << "false" << std::endl;
-//    }
-
-//    uint32_t sum = 0;
-    for (uint32_t head = 0; head < 16; ++head) {
-        auto prefix = (uint64_t)head << 32;
-        for (uint64_t range = 0; range < 0x100000000; ++range) {
-            uint64_t code = prefix | range;
-            if (CommonCode::check(code)) {
-                printf("%09lX\n", code);
-//                ++sum;
-            }
-//            if (range % 0x1000000 == 0) {
-//                std::cout << range / 0x1000000 << std::endl;
-//            }
-        }
-    }
-//    std::cout << "sum: " << sum << std::endl;
-
-//    uint64_t error_code = 0x02EFFF7C0;
-//    uint64_t error_code = 0x07B4EFC00;
-
-//    if (CommonCode::check(error_code)) {
-//        std::cout << "true" << std::endl;
-//    } else {
-//        std::cout << "false" << std::endl;
-//    }
+    std::cout << "start" << std::endl;
+    std::cout << s.check_mode() << std::endl;
+    std::cout << "complete" << std::endl;
 
     return 0;
 }
diff --git a/klotski/short_code.cc b/klotski/short_code.cc
index 38985ba..b785796 100644
--- a/klotski/short_code.cc
+++ b/klotski/short_code.cc
@@ -99,3 +99,36 @@ uint32_t ShortCode::tiny_encode(uint64_t common_code) {
     }
     return ALL_CASES_OFFSET[head] + RANGE_PREFIX_OFFSET[head][prefix] + offset;
 }
+
+uint32_t ShortCode::zip_short_code(uint64_t common_code) { // common_code --zip--> short_code
+
+    // TODO: confirm common_code valid
+
+    // TODO: check Mode => NORMAL / FAST
+
+    // TODO: usage fast_encode or tiny_encode
+
+    return 0;
+}
+
+uint64_t ShortCode::unzip_short_code(uint32_t short_code) { // short_code --unzip--> common_code
+
+    // TODO: confirm short_code valid
+
+    // TODO: check Mode => NORMAL / FAST
+
+    // TODO: usage fast_decode / tiny_decode
+
+    return 0;
+}
+
+enum ShortCode::Mode ShortCode::check_mode() { // ensure speed up enabled and return current mode
+    if (!all_cases_list.empty()) {
+        return ShortCode::Mode::FAST; // fast mode already enabled
+    }
+    if (!basic_ranges.empty()) {
+        return ShortCode::Mode::NORMAL; // normal mode already enabled
+    }
+    speed_up(ShortCode::Mode::NORMAL); // class without initialized -> enter normal mode
+    return ShortCode::Mode::NORMAL; // use normal mode
+}
diff --git a/klotski/short_code.h b/klotski/short_code.h
index ee9ce49..1066992 100644
--- a/klotski/short_code.h
+++ b/klotski/short_code.h
@@ -18,19 +18,24 @@ public:
     void speed_up(enum Mode mode);
     explicit ShortCode(enum Mode mode);
 
-//    uint32_t zip_short_code(uint64_t code);
-//    uint64_t unzip_short_code(uint32_t short_code);
+    uint32_t zip_short_code(uint64_t common_code);
+    uint64_t unzip_short_code(uint32_t short_code);
 
-    uint64_t fast_decode(uint32_t short_code);
-    uint32_t fast_encode(uint64_t common_code);
+    enum Mode check_mode();
 
-    uint64_t tiny_decode(uint32_t short_code);
-    uint32_t tiny_encode(uint64_t common_code);
 
 private:
 //    std::vector<uint64_t> all_cases_list;                  // short_code -> common_code
 //    std::unordered_map<uint64_t, uint32_t> all_cases_dict; // common_code -> short_code
 
+    const uint32_t SHORT_CODE_LIMIT = 29334498;
+
+    uint64_t fast_decode(uint32_t short_code);
+    uint32_t fast_encode(uint64_t common_code);
+
+    uint64_t tiny_decode(uint32_t short_code);
+    uint32_t tiny_encode(uint64_t common_code);
+
     void build_mappings();
     void build_base_ranges();