diff --git a/test/hexdump.nas b/test/hexdump.nas
index fb62c54..8ed5aa0 100644
--- a/test/hexdump.nas
+++ b/test/hexdump.nas
@@ -1,5 +1,9 @@
+# hexdump.nas by ValKmjolnir
+# 2021/8/13
+
 import("lib.nas");
 
+# init
 var hex_num=[
     '0','1','2','3',
     '4','5','6','7',
@@ -9,17 +13,79 @@ var hex_num=[
 var hex=[];
 foreach(var i;hex_num)
     foreach(var j;hex_num)
-        append(hex,'0x'~i~j);
-var s=io.fin("lib.nas");
+        append(hex,i~j);
 
+# read file
+var s=func()
+{
+    var filename=[
+        "nasal.h",
+        "main.cpp",
+        "nasal_ast.h",
+        "nasal_builtin.h",
+        "nasal_codegen.h",
+        "nasal_gc.h",
+        "nasal_import.h",
+        "nasal_lexer.h",
+        "nasal_parse.h",
+        "nasal_vm.h",
+    ];
+    var ret="";
+    foreach(var elem;filename)
+        ret~=io.fin(elem);
+    return ret;
+}();
+
+# used to change line and control the spaces
 var cnt=0;
-print(0,'\t');
-for(var i=0;i<size(s);i+=1){
-    if(cnt==8){
-        cnt=0;
-        print('\n',i,'\t');
-    }
-    cnt+=1;
-    print(hex[s[i]],' ');
+
+# used to print hex index
+var hex_index=[0,0,0,0];
+
+# print binary in text format
+var textprint=func(index)
+{
+    print(' |');
+    for(var i=index-cnt;i<index;i+=1)
+        print((0<=s[i] and s[i]<32)?'.':chr(s[i]));
+    for(var i=cnt;i<16;i+=1)
+        print('.');
+    print('|\n');
 }
-print('\n');
\ No newline at end of file
+
+# print index
+var indexprint=func(index)
+{
+    forindex(var i;hex_index)
+    {
+        hex_index[i]=index-int(index/256)*256;
+        index=int(index/256);
+    }
+    for(var i=3;i>=0;i-=1)
+        print(hex[hex_index[i]]);
+    print('  ');
+    return;
+}
+
+# main
+func()
+{
+    indexprint(0);
+    for(var i=0;i<size(s);i+=1)
+    {
+        if(cnt==16){
+            textprint(i);
+            cnt=0;
+            indexprint(i);
+        }elsif(cnt==8){
+            print(' ');
+        }
+        cnt+=1;
+        print(hex[s[i]],' ');
+    }
+    for(var l=cnt;l<16;l+=1)
+        print('   ');
+    if(cnt<8)
+        print(' ');
+    textprint(i);
+}();
\ No newline at end of file