diff --git a/makefile b/makefile
index e7f9d92..3df0450 100644
--- a/makefile
+++ b/makefile
@@ -30,8 +30,10 @@ test:nasal
 	@ ./nasal -op -t -d test/pi.nas
 	@ ./nasal -op -t -d test/prime.nas
 	@ ./nasal -op -t -d test/props_sim.nas
+	@ ./nasal -op -e test/qrcode.nas
 	@ ./nasal -op -t -d test/quick_sort.nas
 	@ ./nasal -op -e test/scalar.nas
+	-@ ./nasal -op -t test/snake.nas
 	@ ./nasal -op -e test/trait.nas
 	-@ ./nasal -op -t test/tetris.nas
 	@ ./nasal -op -t -d test/turingmachine.nas
diff --git a/nasal_codegen.h b/nasal_codegen.h
index c5af598..50c6174 100644
--- a/nasal_codegen.h
+++ b/nasal_codegen.h
@@ -166,7 +166,7 @@ struct
 
 struct opcode
 {
-    uint16_t op;  // opcode
+    uint8_t op;  // opcode
     uint16_t fidx;// source code file index
     uint32_t num; // imm num
     uint32_t line;// line of source code
@@ -200,6 +200,11 @@ private:
     std::unordered_map<std::string,int> global;
     // local  : max 32768 upvalues 65536 values
     std::list<std::unordered_map<std::string,int>> local;
+
+    // func end stack, reserved for print
+    std::stack<uint32_t> fbstk;
+    std::stack<uint32_t> festk;
+    
     
     void die(std::string,const uint32_t);
     void regist_number(const double);
@@ -613,7 +618,7 @@ void nasal_codegen::multi_def(const nasal_ast& ast)
 {
     auto& ids=ast[0].child();
     int size=ids.size();
-    if(ast[1].type()==ast_multi_scalar)
+    if(ast[1].type()==ast_multi_scalar) // (var a,b,c)=(c,b,a);
     {
         auto& vals=ast[1].child();
         for(int i=0;i<size;++i)
@@ -625,7 +630,7 @@ void nasal_codegen::multi_def(const nasal_ast& ast)
                 gen(op_loadl,local_find(str),ids[i].line());
         }
     }
-    else
+    else // (var a,b,c)=[0,1,2];
     {
         calc_gen(ast[1]);
         for(int i=0;i<size;++i)
@@ -1138,7 +1143,32 @@ void nasal_codegen::print_op(uint32_t index)
 {
     // print opcode index,opcode name,opcode immediate number
     const opcode& c=code[index];
-    printf("0x%.8x: %s ",index,code_table[c.op].name);
+    if(!festk.empty() && index==festk.top())
+    {
+        printf("<0x%x>;\n\n",fbstk.top());
+        fbstk.pop();
+        festk.pop();
+    }
+    if(c.op==op_newf)
+    {
+        printf("\nfunc <0x%x>:\n",index);
+        for(uint32_t i=index;i<code.size();++i)
+            if(code[i].op==op_jmp)
+            {
+                fbstk.push(index);
+                festk.push(code[i].num);
+                break;
+            }
+    }
+    printf("  0x%.8x:       %.2x %.2x %.2x %.2x %.2x        %s  ",
+        index,
+        c.op,
+        uint8_t((c.num&0xff000000)>>24),
+        uint8_t((c.num&0x00ff0000)>>16),
+        uint8_t((c.num&0x0000ff00)>>8),
+        uint8_t(c.num&0x000000ff),
+        code_table[c.op].name
+    );
     // print detail info
     switch(c.op)
     {
@@ -1170,9 +1200,10 @@ void nasal_codegen::print_op(uint32_t index)
 void nasal_codegen::print()
 {
     for(auto& num:num_res)
-        std::cout<<".number "<<num<<'\n';
+        std::cout<<"  .number "<<num<<'\n';
     for(auto& str:str_res)
-        std::cout<<".symbol \""<<rawstr(str)<<"\"\n";
+        std::cout<<"  .symbol \""<<rawstr(str)<<"\"\n";
+    std::cout<<"\n";
     for(uint32_t i=0;i<code.size();++i)
         print_op(i);
 }
diff --git a/nasal_vm.h b/nasal_vm.h
index 5965dc3..1251036 100644
--- a/nasal_vm.h
+++ b/nasal_vm.h
@@ -509,7 +509,7 @@ inline void nasal_vm::opr_lnkeqc()
 
 inline void nasal_vm::opr_meq()
 {
-    mem_addr[0]=(--gc.top)[0];
+    mem_addr[0]=(--gc.top)[0]; // pop old mem_addr[0] and replace it
     mem_addr=nullptr;
 }
 inline void nasal_vm::opr_eq()
diff --git a/test/calc.nas b/test/calc.nas
index b1af03e..e219d89 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -49,14 +49,17 @@ var testfile=[
     "test/loop.nas         ",
     "test/mandel.nas       ",
     "test/mandelbrot.nas   ",
+    "test/md5.nas          ",
     "test/module_test.nas  ",
     "test/nasal_test.nas   ",
     "test/pi.nas           ",
     "test/prime.nas        ",
     "test/props_sim.nas    ",
     "test/props.nas        ",
+    "test/qrcode.nas       ",
     "test/quick_sort.nas   ",
     "test/scalar.nas       ",
+    "test/snake.nas        ",
     "test/tetris.nas       ",
     "test/trait.nas        ",
     "test/turingmachine.nas",
diff --git a/test/md5.nas b/test/md5.nas
new file mode 100644
index 0000000..cd2a087
--- /dev/null
+++ b/test/md5.nas
@@ -0,0 +1,109 @@
+import("lib.nas");
+
+var md5=func(s){
+    var K=[
+        0xd76aa478,0xe8c7b756,0x242070db,0xc1bdceee,
+        0xf57c0faf,0x4787c62a,0xa8304613,0xfd469501,0x698098d8,
+        0x8b44f7af,0xffff5bb1,0x895cd7be,0x6b901122,0xfd987193,
+        0xa679438e,0x49b40821,0xf61e2562,0xc040b340,0x265e5a51,
+        0xe9b6c7aa,0xd62f105d,0x02441453,0xd8a1e681,0xe7d3fbc8,
+        0x21e1cde6,0xc33707d6,0xf4d50d87,0x455a14ed,0xa9e3e905,
+        0xfcefa3f8,0x676f02d9,0x8d2a4c8a,0xfffa3942,0x8771f681,
+        0x6d9d6122,0xfde5380c,0xa4beea44,0x4bdecfa9,0xf6bb4b60,
+        0xbebfbc70,0x289b7ec6,0xeaa127fa,0xd4ef3085,0x04881d05,
+        0xd9d4d039,0xe6db99e5,0x1fa27cf8,0xc4ac5665,0xf4292244,
+        0x432aff97,0xab9423a7,0xfc93a039,0x655b59c3,0x8f0ccc92,
+        0xffeff47d,0x85845dd1,0x6fa87e4f,0xfe2ce6e0,0xa3014314,
+        0x4e0811a1,0xf7537e82,0xbd3af235,0x2ad7d2bb,0xeb86d391
+    ];
+    var S=[
+        7,12,17,22,
+        7,12,17,22,
+        7,12,17,22,
+        7,12,17,22,
+        5,9,14,20,
+        5,9,14,20,
+        5,9,14,20,
+        5,9,14,20,
+        4,11,16,23,
+        4,11,16,23,
+        4,11,16,23,
+        4,11,16,23,
+        6,10,15,21,
+        6,10,15,21,
+        6,10,15,21,
+        6,10,15,21
+    ]
+    var l=func(num,cx){
+        for(var i=0;i<cx;i+=1)
+            num=bits.bitand(0xffffffff,num*2);
+        return num;
+    }
+    var r=func(num,cx){
+        for(var i=0;i<cx;i+=1)
+            num=int(num/2);
+        return num;
+    }
+    var rol=func(num,cx){
+        if(cx>32)
+            cx=cx-int(cx/32)*32;
+        return bits.bitor(l(num,cx),r(num,32-cx));
+    }
+    var F=func(x,y,z){
+        return bits.bitor(
+            bits.bitand(x,y),
+            bits.bitand(bits.bitnot(x),z)
+        );
+    }
+    var G=func(x,y,z){
+        return bits.bitor(
+            bits.bitand(x,z),
+            bits.bitand(y,bits.bitnot(z))
+        );
+    }
+    var H=func(x,y,z){
+        return bits.bitxor(bits.bitxor(x,y),z);
+    }
+    var I=func(x,y,z){
+        return bits.bitor(
+            bits.bitxor(x,y),
+            bits.bitnot(z)
+        );
+    }
+
+    var len=size(s);
+    var res=[];
+    var v=[256,128,64,32,16,8,4,2,1];
+    for(var i=0;i<size(s);i+=1){
+        var c=s[i];
+        foreach(var j;v){
+            append(res,bits.bitand(c,j)?1:0);
+        }
+    }
+    var mod=size(res)-int(size(res)/512)*512;
+    if(mod==0){
+        append(res,1);
+        mod+=1;
+        for(;mod<448;mod+=1)
+            append(res,0);
+    }elsif(mod<448){
+        append(res,1);
+        mod+=1;
+        for(;mod<448;mod+=1)
+            append(res,0);
+    }elsif(mod>448){
+        append(res,1);
+        mod+=1;
+        for(;mod<512+448;mod+=1)
+            append(res,0);
+    }
+    var tmp=[];
+
+    var A=0x01234567;
+    var B=0x89abcdef;
+    var C=0xfedcba98;
+    var D=0x76543210;
+    println(res,' ',size(res));
+}
+
+md5("helloworld");
\ No newline at end of file