diff --git a/version3.0/main.cpp b/version3.0/main.cpp
index 52eabba..e08d29c 100644
--- a/version3.0/main.cpp
+++ b/version3.0/main.cpp
@@ -13,12 +13,13 @@ void help()
 {
 	std::cout<<">> [\"file\"] input a file."<<std::endl;
 	std::cout<<">> [clear ] clear the screen."<<std::endl;
-	std::cout<<">> [del   ] clear the source code."<<std::endl;
+	std::cout<<">> [del   ] clear the input filename."<<std::endl;
 	std::cout<<">> [rs    ] print source code."<<std::endl;
 	std::cout<<">> [lex   ] use lexer to turn code into tokens."<<std::endl;
 	std::cout<<">> [ast   ] do parsing and check the abstract syntax tree."<<std::endl;
-	std::cout<<">> [run   ] run code."<<std::endl;
+	std::cout<<">> [run   ] run abstract syntax tree."<<std::endl;
 	std::cout<<">> [exec  ] generate byte code."<<std::endl;
+	std::cout<<">> [erun  ] run byte code."<<std::endl;
 	std::cout<<">> [logo  ] print logo of nasal ."<<std::endl;
 	std::cout<<">> [exit  ] quit nasal interpreter."<<std::endl;
 	return;
@@ -52,6 +53,11 @@ void die(std::string stage,std::string filename)
 
 void lex_func()
 {
+	if(!resource.input_file(inputfile))
+	{
+		die("resource",inputfile);
+		return;
+	}
 	lexer.scanner(resource.get_file());
 	if(lexer.get_error())
 	{
@@ -64,6 +70,11 @@ void lex_func()
 
 void ast_print()
 {
+	if(!resource.input_file(inputfile))
+	{
+		die("resource",inputfile);
+		return;
+	}
 	lexer.scanner(resource.get_file());
 	if(lexer.get_error())
 	{
@@ -82,6 +93,11 @@ void ast_print()
 }
 void runtime_start()
 {
+	if(!resource.input_file(inputfile))
+	{
+		die("resource",inputfile);
+		return;
+	}
 	lexer.scanner(resource.get_file());
 	if(lexer.get_error())
 	{
@@ -108,6 +124,11 @@ void runtime_start()
 
 void codegen_start()
 {
+	if(!resource.input_file(inputfile))
+	{
+		die("resource",inputfile);
+		return;
+	}
 	lexer.scanner(resource.get_file());
 	if(lexer.get_error())
 	{
@@ -128,7 +149,25 @@ void codegen_start()
 		return;
 	}
 	runtime.set_root(preprocessor.get_root());
-	code_generator.main_progress(inputfile+".naexec",preprocessor.get_root());
+	code_generator.output_exec(inputfile+".naexec",preprocessor.get_root());
+	if(code_generator.get_error())
+	{
+		die("code",inputfile);
+		return;
+	}
+	return;
+}
+
+void execution_start()
+{
+	code_generator.load_exec(inputfile,preprocessor.get_root());
+	if(code_generator.get_error())
+	{
+		die("code",inputfile);
+		return;
+	}
+	runtime.set_root(preprocessor.get_root());
+	runtime.run();
 	return;
 }
 
@@ -175,7 +214,10 @@ int main()
 		else if(command=="del")
 			del_func();
 		else if(command=="rs")
-			resource.print_file();
+		{
+			if(resource.input_file(inputfile))
+				resource.print_file();
+		}
 		else if(command=="lex")
 			lex_func();
 		else if(command=="ast")
@@ -184,6 +226,8 @@ int main()
 			runtime_start();
 		else if(command=="exec")
 			codegen_start();
+		else if(command=="erun")
+			execution_start();
 		else if(command=="logo")
 			logo();
 		else if(command=="exit")
@@ -191,7 +235,13 @@ int main()
 		else
 		{
 			inputfile=command;
-			resource.input_file(inputfile);
+			std::ifstream fin(command);
+			if(fin.fail())
+			{
+				std::cout<<">> [file] cannot open file \""<<command<<"\"."<<std::endl;
+				inputfile="null";
+			}
+			fin.close();
 		}
 	}
     return 0;
diff --git a/version3.0/nasal_codegen.h b/version3.0/nasal_codegen.h
index c951d35..f69b26e 100644
--- a/version3.0/nasal_codegen.h
+++ b/version3.0/nasal_codegen.h
@@ -2,16 +2,8 @@
 #define __NASAL_CODEGEN_H__
 
 // unfinished
-
-enum bytecode
-{
-    code_nop=0,
-
-    code_number_list,
-    code_string_list,
-    code_symbol_list,
-};
-
+// now it can output ast but it is not byte code yet
+// please wait...
 class nasal_codegen
 {
 private:
@@ -19,22 +11,16 @@ private:
     std::vector<std::string> string_list;
     std::vector<std::string> symbol_list;
     int error;
-    void die(std::string);
     void init();
     void output_int(unsigned int,std::ofstream&);
-    void generate_root(nasal_ast&,std::ofstream&);
-    void generate_number_list(std::ofstream&);
-    void generate_string_list(std::ofstream&);
-    void generate_symbol_list(std::ofstream&);
+    void output_root(nasal_ast&,std::ofstream&);
+    unsigned int input_int(std::ifstream&);
+    void input_root(nasal_ast&,std::ifstream&);
 public:
     nasal_codegen();
-    void main_progress(std::string,nasal_ast&);
-};
-
-class nasal_bytecode_runtime
-{
-private:
-public:
+    int get_error();
+    void output_exec(std::string,nasal_ast&);
+    void load_exec(std::string,nasal_ast&);
 };
 
 nasal_codegen::nasal_codegen()
@@ -46,11 +32,9 @@ nasal_codegen::nasal_codegen()
     return;
 }
 
-void nasal_codegen::die(std::string info)
+int nasal_codegen::get_error()
 {
-    ++error;
-    std::cout<<">> [code] "<<info<<std::endl;
-    return;
+    return error;
 }
 
 void nasal_codegen::init()
@@ -75,71 +59,34 @@ void nasal_codegen::output_int(unsigned int num,std::ofstream& fout)
     return;
 }
 
-void nasal_codegen::generate_root(nasal_ast& root,std::ofstream& fout)
+void nasal_codegen::output_root(nasal_ast& root,std::ofstream& fout)
 {
+    output_int(ast_begin,fout);
+    unsigned int type=root.get_type();
+    output_int(type,fout);
     std::vector<nasal_ast>& ref_vec=root.get_children();
     int root_children_size=ref_vec.size();
-    for(int i=0;i<root_children_size;++i)
+    output_int(root_children_size,fout);
+    if(type==ast_number || type==ast_string || type==ast_identifier || type==ast_dynamic_id || type==ast_call_hash)
     {
-        switch(ref_vec[i].get_type())
-        {
-            case ast_definition:break;
-            case ast_multi_assign:break;
-            case ast_conditional:break;
-            case ast_while:case ast_for:case ast_forindex:case ast_foreach:
-                break;
-            case ast_nil:case ast_number:case ast_string:case ast_function:break;
-            case ast_identifier:
-            case ast_vector:case ast_hash:
-            case ast_call:
-            case ast_equal:case ast_add_equal:case ast_sub_equal:case ast_mult_equal:case ast_div_equal:case ast_link_equal:
-            case ast_unary_sub:case ast_unary_not:
-            case ast_add:case ast_sub:case ast_mult:case ast_div:case ast_link:
-            case ast_trinocular:break;
-            case ast_break:die("break in main.");break;
-            case ast_continue:die("continue in main.");break;
-            case ast_return:die("return in main.");break;
-        }
-        if(error)
-            break;
+        std::string tmp=root.get_str();
+        for(int i=0;i<tmp.length();++i)
+            fout<<(unsigned char)tmp[i];
+        fout<<'\0';
     }
-    output_int(code_nop,fout);
-    return;
-}
-void nasal_codegen::generate_number_list(std::ofstream& fout)
-{
-    output_int(code_number_list,fout);
-    int size=number_list.size();
-    output_int(size,fout);
-    for(int i=0;i<size;++i)
-        fout<<number_list[i]<<"\0";
-    return;
-}
-void nasal_codegen::generate_string_list(std::ofstream& fout)
-{
-    output_int(code_string_list,fout);
-    int size=string_list.size();
-    output_int(size,fout);
-    for(int i=0;i<size;++i)
-        fout<<string_list[i]<<"\0";
-    return;
-}
-void nasal_codegen::generate_symbol_list(std::ofstream& fout)
-{
-    output_int(code_symbol_list,fout);
-    int size=symbol_list.size();
-    output_int(size,fout);
-    for(int i=0;i<size;++i)
-        fout<<symbol_list[i]<<"\0";
+    for(int i=0;i<root_children_size;++i)
+        output_root(ref_vec[i],fout);
+    output_int(ast_end,fout);
     return;
 }
 
-void nasal_codegen::main_progress(std::string filename,nasal_ast& root)
+void nasal_codegen::output_exec(std::string filename,nasal_ast& root)
 {
     this->init();
     std::ofstream fout(filename,std::ios::binary);
     if(fout.fail())
     {
+        ++error;
         std::cout<<">> [code] cannot generate file \""<<filename<<"\"."<<std::endl;
         fout.close();
         return;
@@ -147,12 +94,85 @@ void nasal_codegen::main_progress(std::string filename,nasal_ast& root)
     unsigned char header[4]={0x40,0x56,0x4b,0x21};
     for(int i=0;i<4;++i)
         fout<<header[i];
-    generate_root(root,fout);
-    generate_number_list(fout);
-    generate_string_list(fout);
-    generate_symbol_list(fout);
+    output_root(root,fout);
     fout.close();
     return;
 }
 
+unsigned int nasal_codegen::input_int(std::ifstream& fin)
+{
+    unsigned int number=0;
+    unsigned char c;
+    for(int i=0;i<4;++i)
+    {
+        c=(unsigned char)fin.get();
+        number=(number<<8)+c;
+    }
+    return number;
+}
+
+void nasal_codegen::input_root(nasal_ast& root,std::ifstream& fin)
+{
+    unsigned int begin=input_int(fin);
+    if(begin!=ast_begin)
+    {
+        ++error;
+        std::cout<<">> [code] file format error: without ast_begin."<<std::endl;
+        return;
+    }
+    unsigned int type=input_int(fin);
+    unsigned int size=input_int(fin);
+    root.set_type(type);
+    if(type==ast_number || type==ast_string || type==ast_identifier || type==ast_dynamic_id || type==ast_call_hash)
+    {
+        std::string tmp="";
+        while(1)
+        {
+            unsigned char c=(unsigned char)fin.get();
+            if(!c || fin.eof()) break;
+            tmp+=c;
+        }
+        root.set_str(tmp);
+    }
+    for(int i=0;i<size;++i)
+    {
+        nasal_ast new_ast;
+        root.add_child(new_ast);
+        input_root(root.get_children().back(),fin);
+        if(error)
+            return;
+    }
+    unsigned int end=input_int(fin);
+    if(end!=ast_end)
+    {
+        ++error;
+        std::cout<<">> [code] file format error: without ast_end."<<std::endl;
+        return;
+    }
+    return;
+}
+
+void nasal_codegen::load_exec(std::string filename,nasal_ast& root)
+{
+    root.clear();
+    std::ifstream fin(filename,std::ios::binary);
+    if(fin.fail())
+    {
+        ++error;
+        std::cout<<">> [code] cannot open file\""<<filename<<"\"."<<std::endl;
+        fin.close();
+        return;
+    }
+    unsigned char header[4]={0x40,0x56,0x4b,0x21};
+    for(int i=0;i<4;++i)
+        if((unsigned char)fin.get()!=header[i])
+        {
+            ++error;
+            std::cout<<">> [code] \""<<filename<<"\" is not an executable file."<<std::endl;
+            return;
+        }
+    input_root(root,fin);
+    return;
+}
+
 #endif
\ No newline at end of file
diff --git a/version3.0/nasal_enum.h b/version3.0/nasal_enum.h
index 9adcc23..9b3a8c3 100644
--- a/version3.0/nasal_enum.h
+++ b/version3.0/nasal_enum.h
@@ -36,6 +36,7 @@ enum ast_node
     ast_multi_id,ast_multi_scalar,
     ast_definition,ast_multi_assign,
     ast_continue,ast_break,ast_return,
+    ast_begin,ast_end // reserved for code generator
 };
 
 std::string ast_str(int type)