diff --git a/main.cpp b/main.cpp
index 1445c96..2bd2fb4 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,6 +1,7 @@
 #include <cstdio>
 #include <cstdint>
 
+#define B_empty 0x6 // undefined case
 #define B_space 0x0
 #define B_fill  0x7
 #define B_1x2   0x1
@@ -8,6 +9,16 @@
 #define B_1x1   0x3
 #define B_2x2   0x4
 
+#define C_1x1 int64_t(0x3)
+#define C_1x2 int64_t(0x39)
+#define C_2x1 int64_t(0x7002)
+#define C_2x2 int64_t(0x3F03C)
+
+#define F_1x1 int64_t(0x7)
+#define F_1x2 int64_t(0x3F)
+#define F_2x1 int64_t(0x7007)
+#define F_2x2 int64_t(0x3F03F)
+
 /*
 
   uint64_t -> 0000 + [xxx] * 20
@@ -27,6 +38,34 @@
 
 */
 
+/*
+======================================================
+
+ 1x1 -> 011 000 000 000 -> 0000 0000 0011 -> 0x3
+
+ 1x2 -> 001 111 000 000 -> 0000 0011 1001 -> 0x39
+
+ 2x1 -> 010 000 000 000 -> 0000 0000 0010 -> 0x7002
+        111 000 000 000 -> 0000 0000 0111
+
+ 2x2 -> 100 111 000 000 -> 0000 0011 1100 -> 0x3F03C
+        111 111 000 000 -> 0000 0011 1111
+
+======================================================
+
+ 1x1 -> 111 000 000 000 -> 0000 0000 0111 -> 0x7
+
+ 1x2 -> 111 111 000 000 -> 0000 0011 1111 -> 0x3F
+
+ 2x1 -> 111 000 000 000 -> 0000 0000 0111 -> 0x7007
+        111 000 000 000 -> 0000 0000 0111
+
+ 2x2 -> 111 111 000 000 -> 0000 0011 1111 -> 0x3F03F
+        111 111 000 000 -> 0000 0011 1111
+
+======================================================
+*/
+
 void graph_output(uint64_t code) {
     for (int i = 0; i < 20; ++i) {
         switch (code & 0x7) {
@@ -58,9 +97,42 @@ void graph_output(uint64_t code) {
     }
 }
 
+uint64_t compact_code(uint64_t code) {
+    int block_num = 0;
+    uint64_t ret = 0;
+    uint32_t range = 0;
+    for (int addr = 0; code; ++addr, code >>= 3) {
+        switch (code & 0x7) {
+            case B_space:
+                range <<= 2;
+                break;
+            case B_1x2:
+                (range <<= 2) |= 0x1;
+                break;
+            case B_2x1:
+                (range <<= 2) |= 0x2;
+                break;
+            case B_1x1:
+                (range <<= 2) |= 0x3;
+                break;
+            case B_2x2:
+                ret |= uint64_t(addr) << 32;
+            default:
+                continue;
+        }
+        ++block_num;
+    }
+    return ret | range << (16 - block_num) * 2;
+}
+
 int main() {
     printf("Klotski engine\n");
 
+    printf("%lx\n", compact_code(0x0E58FC85FFEBC4DB));
+    printf("%lx\n", compact_code(0x0603EDF5CAFFF5E2));
+
+    return 0;
+
     // 0x4FEA13400
     //  # # # @  |  011 011 011 010 => 0100 1101 1011 -> 4DB
     //  * * & @  |  100 111 010 111 => 1110 1011 1100 -> EBC