diff --git a/version3.0/main.cpp b/version3.0/main.cpp
index f324603..52eabba 100644
--- a/version3.0/main.cpp
+++ b/version3.0/main.cpp
@@ -4,6 +4,7 @@ nasal_resource resource;
 nasal_lexer    lexer;
 nasal_parse    parse;
 nasal_import   preprocessor;
+nasal_codegen  code_generator;
 std::string    command;
 std::string    inputfile="null";
 nasal_runtime  runtime;
@@ -17,6 +18,7 @@ void help()
 	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<<">> [exec  ] generate byte code."<<std::endl;
 	std::cout<<">> [logo  ] print logo of nasal ."<<std::endl;
 	std::cout<<">> [exit  ] quit nasal interpreter."<<std::endl;
 	return;
@@ -104,6 +106,32 @@ void runtime_start()
 	return;
 }
 
+void codegen_start()
+{
+	lexer.scanner(resource.get_file());
+	if(lexer.get_error())
+	{
+		die("lexer",inputfile);
+		return;
+	}
+	parse.set_toklist(lexer.get_token_list());
+	parse.main_process();
+	if(parse.get_error())
+	{
+		die("parse",inputfile);
+		return;
+	}
+	preprocessor.preprocessing(parse.get_root());
+	if(preprocessor.get_error())
+	{
+		die("import",inputfile);
+		return;
+	}
+	runtime.set_root(preprocessor.get_root());
+	code_generator.main_progress(inputfile+".naexec",preprocessor.get_root());
+	return;
+}
+
 int main()
 {
 #ifdef _WIN32
@@ -154,6 +182,8 @@ int main()
 			ast_print();
 		else if(command=="run")
 			runtime_start();
+		else if(command=="exec")
+			codegen_start();
 		else if(command=="logo")
 			logo();
 		else if(command=="exit")
diff --git a/version3.0/nasal.h b/version3.0/nasal.h
index fcef3c1..87ca069 100644
--- a/version3.0/nasal.h
+++ b/version3.0/nasal.h
@@ -25,6 +25,7 @@
 #include "nasal_ast.h"
 #include "nasal_parse.h"
 #include "nasal_import.h"
+#include "nasal_codegen.h"
 #include "nasal_gc.h"
 #include "nasal_runtime.h"
 #include "nasal_builtin.h"
diff --git a/version3.0/nasal_codegen.h b/version3.0/nasal_codegen.h
new file mode 100644
index 0000000..c951d35
--- /dev/null
+++ b/version3.0/nasal_codegen.h
@@ -0,0 +1,158 @@
+#ifndef __NASAL_CODEGEN_H__
+#define __NASAL_CODEGEN_H__
+
+// unfinished
+
+enum bytecode
+{
+    code_nop=0,
+
+    code_number_list,
+    code_string_list,
+    code_symbol_list,
+};
+
+class nasal_codegen
+{
+private:
+    std::vector<std::string> number_list;
+    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&);
+public:
+    nasal_codegen();
+    void main_progress(std::string,nasal_ast&);
+};
+
+class nasal_bytecode_runtime
+{
+private:
+public:
+};
+
+nasal_codegen::nasal_codegen()
+{
+    error=0;
+    number_list.clear();
+    string_list.clear();
+    symbol_list.clear();
+    return;
+}
+
+void nasal_codegen::die(std::string info)
+{
+    ++error;
+    std::cout<<">> [code] "<<info<<std::endl;
+    return;
+}
+
+void nasal_codegen::init()
+{
+    error=0;
+    number_list.clear();
+    string_list.clear();
+    symbol_list.clear();
+    return;
+}
+
+void nasal_codegen::output_int(unsigned int num,std::ofstream& fout)
+{
+    unsigned int get_byte=0xff000000;
+    int offset=24;
+    for(int i=0;i<4;++i)
+    {
+        fout<<(unsigned char)((get_byte&num)>>offset);
+        get_byte>>=8;
+        offset-=8;
+    }
+    return;
+}
+
+void nasal_codegen::generate_root(nasal_ast& root,std::ofstream& 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)
+    {
+        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;
+    }
+    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";
+    return;
+}
+
+void nasal_codegen::main_progress(std::string filename,nasal_ast& root)
+{
+    this->init();
+    std::ofstream fout(filename,std::ios::binary);
+    if(fout.fail())
+    {
+        std::cout<<">> [code] cannot generate file \""<<filename<<"\"."<<std::endl;
+        fout.close();
+        return;
+    }
+    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);
+    fout.close();
+    return;
+}
+
+#endif
\ No newline at end of file
diff --git a/version3.0/nasal_import.h b/version3.0/nasal_import.h
index 40b7156..0d73749 100644
--- a/version3.0/nasal_import.h
+++ b/version3.0/nasal_import.h
@@ -107,20 +107,20 @@ nasal_ast nasal_import::file_import(nasal_ast& node)
     // start importing...
     if(!import_src.input_file(filename))
     {
-        die(filename,"resource");
+        this->die(filename,"resource");
         return tmp;
     }
     import_lex.scanner(import_src.get_file());
     if(import_lex.get_error())
     {
-        die(filename,"lexer");
+        this->die(filename,"lexer");
         return tmp;
     }
     import_par.set_toklist(import_lex.get_token_list());
     import_par.main_process();
     if(import_par.get_error())
     {
-        die(filename,"parser");
+        this->die(filename,"parser");
         return tmp;
     }
     tmp=import_par.get_root();