--- codecvt_null.cpp.original	2003-11-01 08:41:00.000000000 +0300
+++ codecvt_null.cpp	2003-11-04 10:19:48.000000000 +0300
@@ -28,7 +28,10 @@
     char * & next2
 ) const {
     for(;first1 != last1; ++first1){
-        if(sizeof(wchar_t) >= (last2 - first2)){
+	// Per std::22.2.1.5.2/2, we can store no more that
+	// last2-first2 characters. If we need to more encode
+	// next internal char type, return 'partial'.
+        if(sizeof(wchar_t) > (last2 - first2)){
             next1 = first1;
             next2 = first2;
             return std::codecvt_base::partial;
@@ -52,7 +55,17 @@
     wchar_t * last2,
     wchar_t * & next2
 ) const {
+    // Process input characters until we've run of them,
+    // or the number of remaining characters is not
+    // enough to construct another output character,
+    // or we've run out of place for output characters.
     while(first2 != last2){
+	// Have we converted all input characters? 
+	// Return with 'ok', if so.
+	if (first1 == last1)
+	    break;
+	// Do we have less input characters than needed
+	// for a single output character?	    
         if(sizeof(wchar_t) > (last1 - first1)){
             next1 = first1;
             next2 = first2;