diff --git a/nasal_ast.h b/nasal_ast.h
index d9bcba9..ddaeaf5 100644
--- a/nasal_ast.h
+++ b/nasal_ast.h
@@ -122,8 +122,7 @@ const char* ast_name[]=
     "multi-assign",
     "continue",
     "break",
-    "return",
-    nullptr
+    "return"
 };
 
 class nasal_ast
diff --git a/nasal_builtin.h b/nasal_builtin.h
index e0c5a55..05a8061 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -774,17 +774,15 @@ nas_ref builtin_read(nas_ref* local,nasal_gc& gc)
     nas_ref len=local[3];
     if(!fd.objchk(nas_obj::file))
         return builtin_err("read","not a valid filehandle");
-    if(buf.type!=vm_str)
-        return builtin_err("read","\"buf\" must be string");
-    if(buf.val.gcobj->unmut)
-        return builtin_err("read","\"buf\" is not a mutable string");
+    if(buf.type!=vm_str || buf.val.gcobj->unmut)
+        return builtin_err("read","\"buf\" must be mutable string");
     if(len.type!=vm_num)
         return builtin_err("read","\"len\" must be number");
     if(len.num()<=0 || len.num()>=(1<<30))
         return builtin_err("read","\"len\" less than 1 or too large");
     char* buff=new char[(usize)len.num()+1];
     if(!buff)
-        return builtin_err("read","memory allocation error");
+        return builtin_err("read","malloc failed");
     f64 res=fread(buff,1,len.num(),(FILE*)fd.obj().ptr);
     buf.str()=buff;
     delete []buff;
@@ -1120,6 +1118,8 @@ nas_ref builtin_dlopen(nas_ref* local,nasal_gc& gc)
         return builtin_err("dlopen","\"libname\" must be string");
 #ifdef _WIN32
     wchar_t* str=new wchar_t[dlname.str().size()+1];
+    if(!str)
+        return builtin_err("dlopen","malloc failed");
     memset(str,0,sizeof(wchar_t)*dlname.str().size()+1);
     mbstowcs(str,dlname.str().c_str(),dlname.str().size()+1);
     void* ptr=LoadLibraryW(str);
@@ -1201,17 +1201,17 @@ string tohex(u32 num)
     }
     return str;
 }
-string md5(const string& source)
+string md5(const string& src)
 {
     std::vector<u32> buff;
-    u32 num=((source.length()+8)>>6)+1;
-    u32 buffsize=num<<4;
+    usize num=((src.length()+8)>>6)+1;
+    usize buffsize=num<<4;
     buff.resize(buffsize,0);
-    for(u32 i=0;i<source.length();i++)
-        buff[i>>2]|=((unsigned char)source[i])<<((i&0x3)<<3);
-    buff[source.length()>>2]|=0x80<<(((source.length()%4))<<3);
-    buff[buffsize-2]=(source.length()<<3)&0xffffffff;
-    buff[buffsize-1]=((source.length()<<3)>>32)&0xffffffff;
+    for(usize i=0;i<src.length();i++)
+        buff[i>>2]|=((u8)src[i])<<((i&0x3)<<3);
+    buff[src.length()>>2]|=0x80<<(((src.length()%4))<<3);
+    buff[buffsize-2]=(src.length()<<3)&0xffffffff;
+    buff[buffsize-1]=((src.length()<<3)>>32)&0xffffffff;
 
     // u32(abs(sin(i+1))*(2pow32))
     const u32 k[]={
diff --git a/nasal_codegen.h b/nasal_codegen.h
index d10fea4..c4fe46f 100644
--- a/nasal_codegen.h
+++ b/nasal_codegen.h
@@ -80,87 +80,83 @@ enum op_code:u8
     op_ret     // return
 };
 
-struct
+const char* code_table[]=
 {
-    u8 type;
-    const char* name;
-}code_table[]=
-{
-    {op_exit,  "exit  "},
-    {op_intg,  "intg  "},
-    {op_intl,  "intl  "},
-    {op_loadg, "loadg "},
-    {op_loadl, "loadl "},
-    {op_loadu, "loadu "},
-    {op_pnum,  "pnum  "},
-    {op_pnil,  "pnil  "},
-    {op_pstr,  "pstr  "},
-    {op_newv,  "newv  "},
-    {op_newh,  "newh  "},
-    {op_newf,  "newf  "},
-    {op_happ,  "happ  "},
-    {op_para,  "para  "},
-    {op_deft,  "def   "},
-    {op_dyn,   "dyn   "},
-    {op_unot,  "not   "},
-    {op_usub,  "usub  "},
-    {op_add,   "add   "},
-    {op_sub,   "sub   "},
-    {op_mul,   "mult  "},
-    {op_div,   "div   "},
-    {op_lnk,   "lnk   "},
-    {op_addc,  "addc  "},
-    {op_subc,  "subc  "},
-    {op_mulc,  "multc "},
-    {op_divc,  "divc  "},
-    {op_lnkc,  "lnkc  "},
-    {op_addeq, "addeq "},
-    {op_subeq, "subeq "},
-    {op_muleq, "muleq "},
-    {op_diveq, "diveq "},
-    {op_lnkeq, "lnkeq "},
-    {op_addeqc,"addeqc"},
-    {op_subeqc,"subeqc"},
-    {op_muleqc,"muleqc"},
-    {op_diveqc,"diveqc"},
-    {op_lnkeqc,"lnkeqc"},
-    {op_meq,   "meq   "},
-    {op_eq,    "eq    "},
-    {op_neq,   "neq   "},
-    {op_less,  "less  "},
-    {op_leq,   "leq   "},
-    {op_grt,   "grt   "},
-    {op_geq,   "geq   "},
-    {op_lessc, "lessc "},
-    {op_leqc,  "leqc  "},
-    {op_grtc,  "grtc  "},
-    {op_geqc,  "geqc  "},
-    {op_pop,   "pop   "},
-    {op_jmp,   "jmp   "},
-    {op_jt,    "jt    "},
-    {op_jf,    "jf    "},
-    {op_cnt,   "cnt   "},
-    {op_findex,"findx "},
-    {op_feach, "feach "},
-    {op_callg, "callg "},
-    {op_calll, "calll "},
-    {op_upval, "upval "},
-    {op_callv, "callv "},
-    {op_callvi,"callvi"},
-    {op_callh, "callh "},
-    {op_callfv,"callfv"},
-    {op_callfh,"callfh"},
-    {op_callb, "callb "},
-    {op_slcbeg,"slcbeg"},
-    {op_slcend,"slcend"},
-    {op_slc,   "slc   "},
-    {op_slc2,  "slc2  "},
-    {op_mcallg,"mcallg"},
-    {op_mcalll,"mcalll"},
-    {op_mupval,"mupval"},
-    {op_mcallv,"mcallv"},
-    {op_mcallh,"mcallh"},
-    {op_ret,   "ret   "}
+    "exit  ",
+    "intg  ",
+    "intl  ",
+    "loadg ",
+    "loadl ",
+    "loadu ",
+    "pnum  ",
+    "pnil  ",
+    "pstr  ",
+    "newv  ",
+    "newh  ",
+    "newf  ",
+    "happ  ",
+    "para  ",
+    "def   ",
+    "dyn   ",
+    "not   ",
+    "usub  ",
+    "add   ",
+    "sub   ",
+    "mult  ",
+    "div   ",
+    "lnk   ",
+    "addc  ",
+    "subc  ",
+    "multc ",
+    "divc  ",
+    "lnkc  ",
+    "addeq ",
+    "subeq ",
+    "muleq ",
+    "diveq ",
+    "lnkeq ",
+    "addeqc",
+    "subeqc",
+    "muleqc",
+    "diveqc",
+    "lnkeqc",
+    "meq   ",
+    "eq    ",
+    "neq   ",
+    "less  ",
+    "leq   ",
+    "grt   ",
+    "geq   ",
+    "lessc ",
+    "leqc  ",
+    "grtc  ",
+    "geqc  ",
+    "pop   ",
+    "jmp   ",
+    "jt    ",
+    "jf    ",
+    "cnt   ",
+    "findx ",
+    "feach ",
+    "callg ",
+    "calll ",
+    "upval ",
+    "callv ",
+    "callvi",
+    "callh ",
+    "callfv",
+    "callfh",
+    "callb ",
+    "slcbeg",
+    "slcend",
+    "slc   ",
+    "slc2  ",
+    "mcallg",
+    "mcalll",
+    "mupval",
+    "mcallv",
+    "mcallh",
+    "ret   "
 };
 
 struct opcode
@@ -198,7 +194,7 @@ void opcode::print(const char* header,
              <<std::setw(2)<<std::setfill('0')<<((num>>16)&0xff)<<" "
              <<std::setw(2)<<std::setfill('0')<<((num>>8)&0xff)<<" "
              <<std::setw(2)<<std::setfill('0')<<(num&0xff)
-             <<"        "<<code_table[op].name<<"  "<<std::dec;
+             <<"        "<<code_table[op]<<"  "<<std::dec;
     switch(op)
     {
         case op_addeq: case op_subeq:  case op_muleq: case op_diveq:
diff --git a/nasal_dbg.h b/nasal_dbg.h
index 96f63a8..f22704c 100644
--- a/nasal_dbg.h
+++ b/nasal_dbg.h
@@ -104,7 +104,7 @@ void nasal_dbg::opcallsort(const u64* arr)
             std::clog<<"\n ...";
             break;
         }
-        std::clog<<"\n "<<code_table[i.first].name
+        std::clog<<"\n "<<code_table[i.first]
                  <<" : "<<i.second<<" ("<<rate<<"%)";
     }
     std::clog<<"\n total  : "<<total<<'\n';
diff --git a/test/calc.nas b/test/calc.nas
index ac5c3d8..a4d221a 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -1,85 +1,85 @@
 var source=[
-    "main.cpp              ",
-    "nasal_ast.h           ",
-    "nasal_builtin.h       ",
-    "nasal_codegen.h       ",
-    "nasal_dbg.h           ",
-    "nasal_err.h           ",
-    "nasal_gc.h            ",
-    "nasal_import.h        ",
-    "nasal_lexer.h         ",
-    "nasal_opt.h           ",
-    "nasal_parse.h         ",
-    "nasal_vm.h            ",
-    "nasal.h               "
+    "main.cpp         ",
+    "nasal_ast.h      ",
+    "nasal_builtin.h  ",
+    "nasal_codegen.h  ",
+    "nasal_dbg.h      ",
+    "nasal_err.h      ",
+    "nasal_gc.h       ",
+    "nasal_import.h   ",
+    "nasal_lexer.h    ",
+    "nasal_opt.h      ",
+    "nasal_parse.h    ",
+    "nasal_vm.h       ",
+    "nasal.h          "
 ];
 
 var lib=[
-    "stl/fg_env.nas        ",
-    "stl/file.nas          ",
-    "stl/lib.nas           ",
-    "stl/list.nas          ",
-    "stl/log.nas           ",
-    "stl/module.nas        ",
-    "stl/process_bar.nas   ",
-    "stl/queue.nas         ",
-    "stl/result.nas        ",
-    "stl/sort.nas          ",
-    "stl/stack.nas         "
+    "fg_env.nas       ",
+    "file.nas         ",
+    "lib.nas          ",
+    "list.nas         ",
+    "log.nas          ",
+    "module.nas       ",
+    "process_bar.nas  ",
+    "queue.nas        ",
+    "result.nas       ",
+    "sort.nas         ",
+    "stack.nas        "
 ];
 
 var testfile=[
-    "test/ascii-art.nas    ",
-    "test/auto_crash.nas   ",
-    "test/bf.nas           ",
-    "test/bfcolored.nas    ",
-    "test/bfconvertor.nas  ",
-    "test/bfs.nas          ",
-    "test/bigloop.nas      ",
-    "test/bp.nas           ",
-    "test/calc.nas         ",
-    "test/choice.nas       ",
-    "test/class.nas        ",
-    "test/coroutine.nas    ",
-    "test/diff.nas         ",
-    "test/exception.nas    ",
-    "test/fib.nas          ",
-    "test/filesystem.nas   ",
-    "test/hexdump.nas      ",
-    "test/httptest.nas     ",
-    "test/json.nas         ",
-    "test/leetcode1319.nas ",
-    "test/lexer.nas        ",
-    "test/life.nas         ",
-    "test/loop.nas         ",
-    "test/mandel.nas       ",
-    "test/mandelbrot.nas   ",
-    "test/md5.nas          ",
-    "test/md5compare.nas   ",
-    "test/module_test.nas  ",
-    "test/nasal_test.nas   ",
-    "test/occupation.nas   ",
-    "test/pi.nas           ",
-    "test/prime.nas        ",
-    "test/qrcode.nas       ",
-    "test/quick_sort.nas   ",
-    "test/scalar.nas       ",
-    "test/snake.nas        ",
-    "test/tetris.nas       ",
-    "test/trait.nas        ",
-    "test/turingmachine.nas",
-    "test/utf8chk.nas      ",
-    "test/wavecollapse.nas ",
-    "test/ycombinator.nas  "
+    "ascii-art.nas    ",
+    "auto_crash.nas   ",
+    "bf.nas           ",
+    "bfcolored.nas    ",
+    "bfconvertor.nas  ",
+    "bfs.nas          ",
+    "bigloop.nas      ",
+    "bp.nas           ",
+    "calc.nas         ",
+    "choice.nas       ",
+    "class.nas        ",
+    "coroutine.nas    ",
+    "diff.nas         ",
+    "exception.nas    ",
+    "fib.nas          ",
+    "filesystem.nas   ",
+    "hexdump.nas      ",
+    "httptest.nas     ",
+    "json.nas         ",
+    "leetcode1319.nas ",
+    "lexer.nas        ",
+    "life.nas         ",
+    "loop.nas         ",
+    "mandel.nas       ",
+    "mandelbrot.nas   ",
+    "md5.nas          ",
+    "md5compare.nas   ",
+    "module_test.nas  ",
+    "nasal_test.nas   ",
+    "occupation.nas   ",
+    "pi.nas           ",
+    "prime.nas        ",
+    "qrcode.nas       ",
+    "quick_sort.nas   ",
+    "scalar.nas       ",
+    "snake.nas        ",
+    "tetris.nas       ",
+    "trait.nas        ",
+    "turingmachine.nas",
+    "utf8chk.nas      ",
+    "wavecollapse.nas ",
+    "ycombinator.nas  "
 ];
 
 var module=[
-    "module/fib.cpp        ",
-    "module/keyboard.cpp   ",
-    "module/nasocket.cpp   ",
-    "module/libfib.nas     ",
-    "module/libkey.nas     ",
-    "module/libsock.nas    "
+    "fib.cpp          ",
+    "keyboard.cpp     ",
+    "nasocket.cpp     ",
+    "libfib.nas       ",
+    "libkey.nas       ",
+    "libsock.nas      "
 ];
 
 var getname=func(s){
@@ -95,22 +95,21 @@ var count=func(s,c){
     return cnt;
 }
 
-var calc=func(codetype,files){
+var calc=func(codetype,files,path=""){
     println(codetype);
     var (bytes,line,semi,line_cnt,semi_cnt)=(0,0,0,0,0);
     forindex(var i;files){
-        var s=io.fin(getname(files[i]));
+        var s=io.fin(getname(path~files[i]));
         (line_cnt,semi_cnt)=(count(s,'\n'),count(s,';'));
-        println(files[i],'| ',line_cnt,' \tline | ',semi_cnt,' \tsemi');
+        println(files[i],'| ',line_cnt,'\tline | ',semi_cnt,' \tsemi');
         bytes+=size(s);
         line+=line_cnt;
         semi+=semi_cnt;
     }
-    println('total:                | ',line,' \tline | ',semi,' \tsemi');
-    println('                      | ',bytes,'\tbytes| ',int(bytes/1024),' \tkb');
+    println('total:           | ',line,'\tline | ',semi,' \tsemi');
+    println('                 | ',int(bytes/1024),'\tkb');
+    return int(bytes/1024);
 }
 
-calc("source code:",source);
-calc("lib:",lib);
-calc("test file:",testfile);
-calc("module:",module);
\ No newline at end of file
+var all=calc("source code:",source)+calc("lib:",lib,"stl/")+calc("test file:",testfile,"test/")+calc("module:",module,"module/");
+println('\ntotal:           | ',all,'\tkb');
\ No newline at end of file
diff --git a/test/md5compare.nas b/test/md5compare.nas
index 32b25ba..96c5894 100644
--- a/test/md5compare.nas
+++ b/test/md5compare.nas
@@ -9,112 +9,78 @@ var compare=func(){
         "^","&","*","(",")","-","=","\\","|","[","]","{","}","`"," ","\t","?"
     ];
     return func(begin,end){
+        var byte=0;
         var total=end-begin;
+        var timestamp=maketimestamp();
+        timestamp.stamp();
         var bar=process_bar.bar(front:os.platform()=="windows"?"sharp":"block",back:"point",sep:"line",length:50);
         for(var i=begin;i<end;i+=1){
             var s="";
             for(var j=0;j<i;j+=1){
                 s~=ch[rand()*size(ch)];
             }
+            byte+=size(s);
             var res=md5(s);
             if(cmp(res,_md5(s))){
                 die("error: "~str(i));
             }
-            print(" ",bar.bar((i-begin+1)/total)," (",i-begin+1,"/",total,")\t",res," max byte: ",end-1,"    \r");
+            print(" ",bar.bar((i-begin+1)/total)," (",i-begin+1,"/",total,")\t",res," byte: ",byte," elapsed time: ",timestamp.elapsedMSec(),"    \r");
         }
         print("\n");
     };
 }();
 
 var filechecksum=func(){
-    var getname=func(s){
-        var (len,ch)=(size(s),' '[0]);
-        for(var i=0;i<len and s[i]!=ch;i+=1);
-        return substr(s,0,i);
-    }
     var files=[
-        "./stl/fg_env.nas        ",
-        "./stl/file.nas          ",
-        "./stl/lib.nas           ",
-        "./stl/list.nas          ",
-        "./stl/log.nas           ",
-        "./stl/module.nas        ",
-        "./stl/process_bar.nas   ",
-        "./stl/queue.nas         ",
-        "./stl/result.nas        ",
-        "./stl/sort.nas          ",
-        "./stl/stack.nas         ",
-        "./test/ascii-art.nas    ",
-        "./test/auto_crash.nas   ",
-        "./test/bf.nas           ",
-        "./test/bfcolored.nas    ",
-        "./test/bfconvertor.nas  ",
-        "./test/bfs.nas          ",
-        "./test/bigloop.nas      ",
-        "./test/bp.nas           ",
-        "./test/calc.nas         ",
-        "./test/choice.nas       ",
-        "./test/class.nas        ",
-        "./test/coroutine.nas    ",
-        "./test/diff.nas         ",
-        "./test/exception.nas    ",
-        "./test/fib.nas          ",
-        "./test/filesystem.nas   ",
-        "./test/hexdump.nas      ",
-        "./test/httptest.nas     ",
-        "./test/json.nas         ",
-        "./test/leetcode1319.nas ",
-        "./test/lexer.nas        ",
-        "./test/life.nas         ",
-        "./test/loop.nas         ",
-        "./test/mandel.nas       ",
-        "./test/mandelbrot.nas   ",
-        "./test/md5.nas          ",
-        "./test/md5compare.nas   ",
-        "./test/module_test.nas  ",
-        "./test/nasal_test.nas   ",
-        "./test/occupation.nas   ",
-        "./test/pi.nas           ",
-        "./test/prime.nas        ",
-        "./test/qrcode.nas       ",
-        "./test/quick_sort.nas   ",
-        "./test/scalar.nas       ",
-        "./test/snake.nas        ",
-        "./test/tetris.nas       ",
-        "./test/trait.nas        ",
-        "./test/turingmachine.nas",
-        "./test/utf8chk.nas      ",
-        "./test/wavecollapse.nas ",
-        "./test/ycombinator.nas  ",
-        "LICENSE                 ",
-        "main.cpp                ",
-        "makefile                ",
-        "nasal_ast.h             ",
-        "nasal_builtin.h         ",
-        "nasal_codegen.h         ",
-        "nasal_dbg.h             ",
-        "nasal_err.h             ",
-        "nasal_gc.h              ",
-        "nasal_import.h          ",
-        "nasal_lexer.h           ",
-        "nasal_opt.h             ",
-        "nasal_parse.h           ",
-        "nasal_vm.h              ",
-        "nasal.ebnf              ",
-        "nasal.h                 ",
-        "README.md               "
+        "./stl/fg_env.nas",        "./stl/file.nas",
+        "./stl/lib.nas",           "./stl/list.nas",
+        "./stl/log.nas",           "./stl/module.nas",
+        "./stl/process_bar.nas",   "./stl/queue.nas",
+        "./stl/result.nas",        "./stl/sort.nas",
+        "./stl/stack.nas",         "./test/ascii-art.nas",
+        "./test/auto_crash.nas",   "./test/bf.nas",
+        "./test/bfcolored.nas",    "./test/bfconvertor.nas",
+        "./test/bfs.nas",          "./test/bigloop.nas",
+        "./test/bp.nas",           "./test/calc.nas",
+        "./test/choice.nas",       "./test/class.nas",
+        "./test/coroutine.nas",    "./test/diff.nas",
+        "./test/exception.nas",    "./test/fib.nas",
+        "./test/filesystem.nas",   "./test/hexdump.nas",
+        "./test/httptest.nas",     "./test/json.nas",
+        "./test/leetcode1319.nas", "./test/lexer.nas",
+        "./test/life.nas",         "./test/loop.nas",
+        "./test/mandel.nas",       "./test/mandelbrot.nas",
+        "./test/md5.nas",          "./test/md5compare.nas",
+        "./test/module_test.nas",  "./test/nasal_test.nas",
+        "./test/occupation.nas",   "./test/pi.nas",
+        "./test/prime.nas",        "./test/qrcode.nas",
+        "./test/quick_sort.nas",   "./test/scalar.nas",
+        "./test/snake.nas",        "./test/tetris.nas",
+        "./test/trait.nas",        "./test/turingmachine.nas",
+        "./test/utf8chk.nas",      "./test/wavecollapse.nas",
+        "./test/ycombinator.nas",  "LICENSE",
+        "main.cpp",                "makefile",
+        "nasal_ast.h",             "nasal_builtin.h",
+        "nasal_codegen.h",         "nasal_dbg.h",
+        "nasal_err.h",             "nasal_gc.h",
+        "nasal_import.h",          "nasal_lexer.h",
+        "nasal_opt.h",             "nasal_parse.h",
+        "nasal_vm.h",              "nasal.ebnf",
+        "nasal.h",                 "README.md"
     ];
     var byte=0;
     var total=size(files);
+    var timestamp=maketimestamp();
+    timestamp.stamp();
     var bar=process_bar.bar(front:os.platform()=="windows"?"sharp":"block",back:"point",sep:"line",length:50);
     forindex(var i;files){
-        var f=io.fin(getname(files[i]));
+        var f=io.fin(files[i]);
         var res=md5(f);
         byte+=size(f);
         if(cmp(res,_md5(f))){
             die("error: "~files[i]);
         }
-        print(" ",bar.bar((i+1)/total)," (",i+1,"/",total,")\t",res,"     byte: ",byte,"    \r");
+        print(" ",bar.bar((i+1)/total)," (",i+1,"/",total,")\t",res," byte: ",byte," elapsed time: ",timestamp.elapsedMSec(),"    \r");
     }
     print("\n");
 }