Index: ext/riconv.c
===================================================================
--- ext/riconv.c
+++ ext/riconv.c
@@ -24,132 +24,98 @@
 static const char* cs_ms932 = "MS932";
 static const char* cs_utf8 = "UTF-8";
 
-/* Regexp::matchのラッパー */
+VALUE objIconvJ2R;
+VALUE objIconvR2J;
+char* charcode;
+
+/* wrap Regexp::match */
 static int regxp_is_match(VALUE str, VALUE regxp)
 {
     return rb_funcall(str, rb_intern("match"), 1, RREGEXP(regxp)) != Qnil ? 1 : 0 ;
 }
 
-/* RUBY_PLATFORMから類推してWindowsなら1を、そうでなければ0を返す */
+/* result true if windows */
 static int platform_is_windows()
 {
-  VALUE platform = rb_const_get(rb_cObject, rb_intern("RUBY_PLATFORM"));
+    VALUE platform = rb_const_get(rb_cObject, rb_intern("RUBY_PLATFORM"));
     return regxp_is_match(platform, rb_str_new2("msvcrt|mswin|bccwin|mingw|cygwin"))
-      ? 1
-      : 0;
+	? 1
+	: 0;
 }
 
 /*
- * RUBY_PLATFORMと$KCODEを元にIconvで有効な適当な文字コード名を返す
- * TODO: 実行環境のLOCALE,LANG,LC_ALL等も参考にする
+ * Get better charcode name
  */
-static char* get_charset_name()
+static char* get_charcode_name()
 {
     char* result = NULL;
-    ID id_Iconv = rb_intern("Iconv");
-    
-    if (rb_const_defined(rb_cObject, id_Iconv))
-      {
-        VALUE kcode = rb_gv_get("$KCODE");
-        VALUE platform = rb_const_get(rb_cObject, rb_intern("RUBY_PLATFORM"));
-        char* kcodep = (TYPE(kcode) == T_STRING) ? StringValuePtr(kcode) : "";
 
-        switch(toupper(*kcodep))
-        {
-        case 'E':
-            result = (char*)cs_eucjp;
-            break;
-        case 'S':
-          if (platform_is_windows())
-            {
-              result = (char*)cs_cp932;
-            }
-          else
-            {
-              result = (char*)cs_sjis;
-            }
-          break;
-        case 'N':
-          if (platform_is_windows())
-            {
-              result = (char*)cs_cp932;
-            }
-          else
-            {
-                result = NULL;
-            }
-            break;
-        case 'U':
-        default:
-            result = NULL;
-            break;
-        }
-      }else{
-        result = NULL;
-      }
+    VALUE kcode = rb_gv_get("$KCODE");
+    char* kcodep = (TYPE(kcode) == T_STRING) ? StringValuePtr(kcode) : "";
+
+    switch(toupper(*kcodep))
+    {
+	case 'E':
+	    result = (char*)cs_eucjp;
+	    break;
+	case 'S':
+	    if (platform_is_windows())
+	    {
+		result = (char*)cs_cp932;
+	    }
+	    else
+	    {
+		result = (char*)cs_sjis;
+	    }
+	    break;
+	case 'N':
+	    if (platform_is_windows())
+	    {
+		//for ruby1.8. YARV support better m17n.
+		result = (char*)cs_cp932;
+	    }
+	    else
+	    {
+		result = (char*)cs_utf8;
+	    }
+	    break;
+	case 'U':
+	default:
+	    result = (char*)cs_utf8;
+	    break;
+    }
     return result;
 }
 
-/*
- * 拡張ライブラリのIconvがある場合は1,ない場合は0を返す
- */
-static int has_exticonv()
-{
-	ID id_Iconv = rb_intern("Iconv");
-        VALUE Iconv = rb_const_get(rb_cObject, id_Iconv);
-	if(Iconv == Qnil)
-	{
-	        return 0;
-	}
-	else
-	{
-		return 1;
-	}
-}
-
 VALUE exticonv_local_to_utf8(VALUE local_string)
 {
-	char* cs = get_charset_name();
-	if(cs)
-	{
-		return exticonv_cc(local_string, cs, cs_utf8);
-	}
-	else
-	{
-		return local_string;
-	}
+    if(charcode && charcode[0] != 'U')
+    {
+	return rb_ary_entry(rb_funcall(objIconvR2J, rb_intern("iconv"), 1, local_string), 0);
+    }
+    else
+    {
+	return local_string;
+    }
 }
 
 VALUE exticonv_utf8_to_local(VALUE utf8_string)
 {
-	char* cs = get_charset_name();
-	if(cs)
-	{
-		return exticonv_cc(utf8_string, cs_utf8, cs);
-	}
-	else
-	{
-		return utf8_string;
-	}
+    if(charcode && charcode[0] != 'U')
+    {
+	return rb_ary_entry(rb_funcall(objIconvJ2R, rb_intern("iconv"), 1, utf8_string), 0);
+    }
+    else
+    {
+	return utf8_string;
+    }
 }
 
-VALUE exticonv_cc(VALUE original_string, const char* from, const char* to)
+void exticonv_init()
 {
-	return exticonv_vv(original_string, rb_str_new2(from), rb_str_new2(to));
+    VALUE rb_iconv_klass = rb_const_get(rb_cObject, rb_intern("Iconv"));
+    ID sym_new = rb_intern("new");
+    charcode = get_charcode_name();
+    objIconvJ2R = rb_funcall(rb_iconv_klass, sym_new, 2, rb_str_new2(cs_utf8), rb_str_new2(charcode));
+    objIconvR2J = rb_funcall(rb_iconv_klass, sym_new, 2, rb_str_new2(charcode), rb_str_new2(cs_utf8));
 }
-
-VALUE exticonv_vv(VALUE original_string, VALUE from, VALUE to)
-{
-	if(has_exticonv())
-	{
-		ID id_Iconv = rb_intern("Iconv");
-		ID id_iconv = rb_intern("iconv");
-		VALUE Iconv = rb_const_get(rb_cObject, id_Iconv);
-		return rb_ary_entry(rb_funcall(Iconv, id_iconv, 3, to, from, original_string), 0);
-	}
-	else
-	{
-		//iconvがなければそのまま返す
-		return original_string;
-	}
-}
Index: ext/riconv.h
===================================================================
--- ext/riconv.h
+++ ext/riconv.h
@@ -19,7 +19,6 @@
 
 extern VALUE exticonv_local_to_utf8(VALUE);
 extern VALUE exticonv_utf8_to_local(VALUE);
-extern VALUE exticonv_cc(VALUE, const char*, const char*);
-extern VALUE exticonv_vv(VALUE, VALUE, VALUE);
+extern void exticonv_init();
 
 #endif /* _RICONV_H */
Index: ext/rjb.c
===================================================================
--- ext/rjb.c
+++ ext/rjb.c
@@ -2692,6 +2692,7 @@
 void Init_rjbcore()
 {
     rb_protect((VALUE(*)(VALUE))rb_require, (VALUE)"iconv", NULL);
+    exticonv_init();
 
     rjb_loaded_classes = rb_hash_new();
     OBJ_FREEZE(rjb_loaded_classes);