diff --git a/stl/sort.nas b/stl/sort.nas
index e3ed1aa..2b04e47 100644
--- a/stl/sort.nas
+++ b/stl/sort.nas
@@ -1,18 +1,26 @@
 # sort.nas
 # valkmjolnir 2021/4/2
-var sort=func(vec,left,right,cmp=func(a,b){return a<=b;}){
-    if(left>=right) return nil;
-    var (L,R,tmp)=(left,right,vec[left]);
-    while(left<right){
-        while(left<right and cmp(tmp,vec[right]))
-            right-=1;
-        while(left<right and cmp(vec[left],tmp))
-            left+=1;
-        if(left!=right)
-            (vec[left],vec[right])=(vec[right],vec[left]);
+
+# please make sure the compare function has the function like <= or >=
+# only using < or > may cause infinite loop or the program may crash
+var sort=func(){
+    srand(); # be aware! this causes global changes
+    return func(vec,left,right,cmp=func(a,b){return a<=b;}){
+        if(left>=right) return nil;
+        var base=left+int(rand()*(right-left));
+        (vec[left],vec[base])=(vec[base],vec[left]);
+        var (i,j,tmp)=(left,right,vec[left]);
+        while(i!=j){
+            while(i<j and cmp(tmp,vec[j]))
+                j-=1;
+            vec[i]=vec[j];
+            while(i<j and cmp(vec[i],tmp))
+                i+=1;
+            vec[j]=vec[i];
+        }
+        vec[i]=tmp;
+        sort(vec,left,i-1,cmp);
+        sort(vec,i+1,right,cmp);
+        return nil;
     }
-    (vec[L],vec[left])=(vec[left],tmp);
-    sort(vec,L,left-1,cmp);
-    sort(vec,left+1,R,cmp);
-    return nil;
-}
\ No newline at end of file
+}();
\ No newline at end of file
diff --git a/test/calc.nas b/test/calc.nas
index cd6863e..05dfccd 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -117,22 +117,25 @@ var column=func(number){
 
 var calc=func(codetype,files,path=""){
     println(codetype);
-    var (bytes,line,semi,line_cnt,semi_cnt)=(0,0,0,0,0);
+    var (bytes,ctx,line,semi,line_cnt,semi_cnt)=(0,"",0,0,0,0);
     forindex(var i;files){
         var s=io.fin(getname(path~files[i]));
         (line_cnt,semi_cnt)=(count(s,'\n'),count(s,';'));
         println(rightpad(files[i],padding_length),'| ',
             column(line_cnt),'line | ',
             column(semi_cnt),'semi | ',
-            rightpad(str(int(size(s)/1024)),6),'kb');
+            rightpad(str(int(size(s)/1024)),6),'kb | ',
+            md5(s),' |');
         bytes+=size(s);
+        ctx~=s;
         line+=line_cnt;
         semi+=semi_cnt;
     }
     println(rightpad("total:",padding_length),'| ',
         column(line),'line | ',
         column(semi),'semi | ',
-        rightpad(str(int(bytes/1024)),6),'kb');
+        rightpad(str(int(bytes/1024)),6),'kb | ',
+        md5(ctx),' |\n');
     return int(bytes/1024);
 }
 
@@ -140,4 +143,4 @@ var all=calc("source code:",source)
     +calc("lib:",lib,"stl/")
     +calc("test file:",testfile,"test/")
     +calc("module:",module,"module/");
-println('\n',rightpad("total:",padding_length),'| ',rightpad(str(all),6),'kb');
\ No newline at end of file
+println(rightpad("total:",padding_length),'| ',rightpad(str(all),6),'kb');
\ No newline at end of file