diff --git a/src/klotski/ffi/codec.cc b/src/klotski/ffi/codec.cc
index b859223..8606ef2 100644
--- a/src/klotski/ffi/codec.cc
+++ b/src/klotski/ffi/codec.cc
@@ -106,6 +106,30 @@ bool common_code_to_short_code(uint64_t common_code, uint32_t *short_code) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
+const uint32_t short_code_string_size = 6;
+
+bool short_code_to_string(uint32_t short_code, char short_code_str[]) {
+    if (!ShortCode::check(short_code)) {
+        return false;
+    }
+    std::string str = ShortCode::unsafe_create(short_code).to_string();
+    strcpy(short_code_str, str.c_str());
+    return true;
+}
+
+bool short_code_from_string(const char short_code_str[], uint32_t *short_code) {
+    try {
+        *short_code = ShortCode::from_string(short_code_str).unwrap();
+    } catch (...) {
+        return false;
+    }
+    return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+const uint32_t common_code_string_size = 10;
+
 bool common_code_to_string(uint64_t common_code, char common_code_str[]) {
     if (!CommonCode::check(common_code)) {
         return false;
diff --git a/src/klotski/ffi/klotski.h b/src/klotski/ffi/klotski.h
index b48b4dd..ec2d715 100644
--- a/src/klotski/ffi/klotski.h
+++ b/src/klotski/ffi/klotski.h
@@ -17,10 +17,12 @@ extern "C" {
 }
 #endif
 
-/// klotski codec interface
+/// -------------------------------- klotski codec interface --------------------------------
+
 #ifdef __cplusplus
 extern "C" {
 #endif
+    /// short code warm up api
     extern void short_code_enable();
     extern void short_code_enable_fast();
     extern bool is_short_code_available();
@@ -37,9 +39,13 @@ extern "C" {
     extern bool short_code_to_common_code(uint32_t short_code, uint64_t *common_code);
     extern bool common_code_to_short_code(uint64_t common_code, uint32_t *short_code);
 
-    // TODO: short code string convert
+    /// output char[] buffer at least 6-bytes
+    extern const uint32_t short_code_string_size;
+    extern bool short_code_to_string(uint32_t short_code, char short_code_str[]);
+    extern bool short_code_from_string(const char short_code_str[], uint32_t *short_code);
 
     /// output char[] buffer at least 10-bytes
+    extern const uint32_t common_code_string_size;
     extern bool common_code_to_string(uint64_t common_code, char common_code_str[]);
     extern bool common_code_to_string_shorten(uint64_t common_code, char common_code_str[]);
     extern bool common_code_from_string(const char common_code_str[], uint64_t *common_code);
diff --git a/src/main.c b/src/main.c
index ae5d66f..43e4d6c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -11,23 +11,24 @@ int main() {
 
     uint64_t raw_code;
     uint32_t short_code;
-    uint64_t common_code = 0x1A9BF0C00;
-
-//    short_code_enable_fast();
-//
-//    if (!common_code_to_raw_code(common_code, &raw_code)) {
-//        printf("error\n");
-//    } else {
-//        printf("raw code -> %015lX\n", raw_code);
-//    }
-//
-//    if (!common_code_to_short_code(common_code, &short_code)) {
-//        printf("error\n");
-//    } else {
-//        printf("short code -> %d\n", short_code);
-//    }
-
-    char common_code_str[10];
+//    uint64_t common_code = 0x1A9BF0C00;
+    uint64_t common_code = 0x4FEA13400;
+
+    short_code_enable_fast();
+
+    if (!common_code_to_raw_code(common_code, &raw_code)) {
+        printf("error\n");
+    } else {
+        printf("raw code -> %015lX\n", raw_code);
+    }
+
+    if (!common_code_to_short_code(common_code, &short_code)) {
+        printf("error\n");
+    } else {
+        printf("short code -> %d\n", short_code);
+    }
+
+    char common_code_str[common_code_string_size];
     if (!common_code_to_string(common_code, common_code_str)) {
         printf("error\n");
     } else {
@@ -44,6 +45,18 @@ int main() {
         printf("common code -> %09lX\n", common_code);
     }
 
+    char short_code_str[short_code_string_size];
+    if (!short_code_to_string(short_code, short_code_str)) {
+        printf("error\n");
+    } else {
+        printf("string -> %s\n", short_code_str);
+    }
+    if (!short_code_from_string(short_code_str, &short_code)) {
+        printf("error\n");
+    } else {
+        printf("short code -> %d\n", short_code);
+    }
+
 //    printf("cli exit\n");
     return 0;
 }