diff --git a/src/klotski_core/ffi/tmain.cc b/src/klotski_core/ffi/tmain.cc
index 9790602..1fb430a 100644
--- a/src/klotski_core/ffi/tmain.cc
+++ b/src/klotski_core/ffi/tmain.cc
@@ -15,7 +15,10 @@ void tmain() {
     printf("tmain start\n");
 
 //    klotski::RawCode::from_common_code(0x1A9BF0C00).is_horizontal_mirror();
-    klotski::RawCode::from_common_code(0x1A9BF0C00).to_horizontal_mirror();
+//    auto ret = klotski::RawCode::from_common_code(0x1A9BF0C00).to_horizontal_mirror();
+    auto ret = klotski::RawCode::from_common_code(0x4FEA13400).to_horizontal_mirror();
+
+    std::cout << ret.to_common_code() << std::endl << ret << std::endl;
 
     return;
 
diff --git a/src/klotski_core/raw_code/mirror.cc b/src/klotski_core/raw_code/mirror.cc
index 64eb28f..d187349 100644
--- a/src/klotski_core/raw_code/mirror.cc
+++ b/src/klotski_core/raw_code/mirror.cc
@@ -43,6 +43,15 @@ bool RawCode::is_horizontal_mirror(const RawCode &raw_code) const {
 
 #include <iostream>
 
+///   MASK_MIRROR_A   |   MASK_MIRROR_B
+///  111 000 000 000  |  000 111 000 000
+///  111 000 000 000  |  000 111 000 000
+///  111 000 000 000  |  000 111 000 000
+///  111 000 000 000  |  000 111 000 000
+///  111 000 000 000  |  000 111 000 000
+constexpr uint64_t MASK_MIRROR_A = 0x0'007'007'007'007'007;
+constexpr uint64_t MASK_MIRROR_B = 0x0'038'038'038'038'038;
+
 void horizontal_fill(uint64_t &raw_code) {
     for (int addr = 0; addr < 60; addr += 3) { // traverse every 3-bits
         switch ((raw_code >> addr) & 0b111) {
@@ -59,17 +68,13 @@ void horizontal_fill(uint64_t &raw_code) {
 }
 
 void horizontal_clear(uint64_t &raw_code) {
-
     for (int addr = 0; addr < 60; addr += 3) { // traverse every 3-bits
-
         switch ((raw_code >> addr) & 0b111) {
             case B_1x2:
             case B_2x2:
-                raw_code |= (uint64_t)0b111 << (addr + 3);
+                raw_code |= (uint64_t)0b111 << (addr + 3); // reset as original block
         }
-
     }
-
 }
 
 uint64_t RawCode::vertical_mirror(uint64_t raw_code) {
@@ -80,19 +85,10 @@ uint64_t RawCode::vertical_mirror(uint64_t raw_code) {
 }
 
 uint64_t RawCode::horizontal_mirror(uint64_t raw_code) {
-
-    // TODO: horizontal mirror convert
-
-    // fill -> mirror -> unfill
-
     horizontal_fill(raw_code);
-
-    // flip raw code
-
+    raw_code = ((raw_code >> 9) & MASK_MIRROR_A) | ((raw_code >> 3) & MASK_MIRROR_B)
+        | ((raw_code & MASK_MIRROR_B) << 3) | ((raw_code & MASK_MIRROR_A) << 9); // flip raw code
     horizontal_clear(raw_code);
-
-    std::cout << RawCode::unsafe_create(raw_code) << std::endl;
-
     return raw_code;
 }
 
@@ -103,19 +99,8 @@ bool RawCode::vertical_mirror_check(uint64_t raw_code) {
     return false;
 }
 
-
-
-
 bool RawCode::horizontal_mirror_check(uint64_t raw_code) {
-    ///      MASK_A              MASK_B
-    ///  111 000 000 000  |  000 111 000 000
-    ///  111 000 000 000  |  000 111 000 000
-    ///  111 000 000 000  |  000 111 000 000
-    ///  111 000 000 000  |  000 111 000 000
-    ///  111 000 000 000  |  000 111 000 000
-    constexpr uint64_t MASK_A = 0x0'007'007'007'007'007;
-    constexpr uint64_t MASK_B = 0x0'038'038'038'038'038;
-
     horizontal_fill(raw_code);
-    return ((raw_code >> 9 ^ raw_code) & MASK_A) && ((raw_code >> 3 ^ raw_code) & MASK_B);
+    return ((raw_code ^ (raw_code >> 9)) & MASK_MIRROR_A)
+        && ((raw_code ^ (raw_code >> 3)) & MASK_MIRROR_B);
 }