diff --git a/src/backend/utils/mb/wchar.c b/src/backend/utils/mb/wchar.c
index 0e19a6075f6..5dbc01032ac 100644
--- a/src/backend/utils/mb/wchar.c
+++ b/src/backend/utils/mb/wchar.c
@@ -1,7 +1,7 @@
 /*
  * conversion functions between pg_wchar and multibyte streams.
  * Tatsuo Ishii
- * $Id: wchar.c,v 1.34 2003/09/25 06:58:05 petere Exp $
+ * $Id: wchar.c,v 1.34.2.1 2005/12/24 10:40:55 ishii Exp $
  *
  * WIN1250 client encoding updated by Pavel Behal
  *
@@ -52,7 +52,6 @@ pg_ascii_mblen(const unsigned char *s)
 /*
  * EUC
  */
-
 static int	pg_euc2wchar_with_len
 			(const unsigned char *from, pg_wchar *to, int len)
 {
@@ -60,26 +59,26 @@ static int	pg_euc2wchar_with_len
 
 	while (len > 0 && *from)
 	{
-		if (*from == SS2 && len >= 2)
+		if (*from == SS2 && len >= 2)	/* JIS X 0201 (so called "1 byte KANA") */
 		{
 			from++;
-			*to = 0xff & *from++;
+			*to = (SS2 << 8) | *from++;
 			len -= 2;
 		}
-		else if (*from == SS3 && len >= 3)
+		else if (*from == SS3 && len >= 3)		/* JIS X 0212 KANJI */
 		{
 			from++;
-			*to = *from++ << 8;
-			*to |= 0x3f & *from++;
+			*to = (SS3 << 16) | (*from++ << 8);
+			*to |= *from++;
 			len -= 3;
 		}
-		else if ((*from & 0x80) && len >= 2)
+		else if ((*from & 0x80) && len >= 2)	/* JIS X 0208 KANJI */
 		{
 			*to = *from++ << 8;
 			*to |= *from++;
 			len -= 2;
 		}
-		else
+		else	/* must be ASCII */
 		{
 			*to = *from++;
 			len--;
@@ -139,6 +138,7 @@ pg_euckr_mblen(const unsigned char *s)
 
 /*
  * EUC_CN
+ *
  */
 static int	pg_euccn2wchar_with_len
 			(const unsigned char *from, pg_wchar *to, int len)
@@ -147,21 +147,21 @@ static int	pg_euccn2wchar_with_len
 
 	while (len > 0 && *from)
 	{
-		if (*from == SS2 && len >= 3)
+		if (*from == SS2 && len >= 3)	/* code set 2 (unused?) */
 		{
 			from++;
-			*to = 0x3f00 & (*from++ << 8);
-			*to = *from++;
+			*to = (SS2 << 16) | (*from++ << 8);
+			*to |= *from++;
 			len -= 3;
 		}
-		else if (*from == SS3 && len >= 3)
+		else if (*from == SS3 && len >= 3)		/* code set 3 (unsed ?) */
 		{
 			from++;
-			*to = *from++ << 8;
-			*to |= 0x3f & *from++;
+			*to = (SS3 << 16) | (*from++ << 8);
+			*to |= *from++;
 			len -= 3;
 		}
-		else if ((*from & 0x80) && len >= 2)
+		else if ((*from & 0x80) && len >= 2)	/* code set 1 */
 		{
 			*to = *from++ << 8;
 			*to |= *from++;
@@ -193,6 +193,7 @@ pg_euccn_mblen(const unsigned char *s)
 
 /*
  * EUC_TW
+ *
  */
 static int	pg_euctw2wchar_with_len
 			(const unsigned char *from, pg_wchar *to, int len)
@@ -201,22 +202,22 @@ static int	pg_euctw2wchar_with_len
 
 	while (len > 0 && *from)
 	{
-		if (*from == SS2 && len >= 4)
+		if (*from == SS2 && len >= 4)	/* code set 2 */
 		{
 			from++;
-			*to = *from++ << 16;
+			*to = (SS2 << 24) | (*from++ << 16) ;
 			*to |= *from++ << 8;
 			*to |= *from++;
 			len -= 4;
 		}
-		else if (*from == SS3 && len >= 3)
+		else if (*from == SS3 && len >= 3)		/* code set 3 (unused?) */
 		{
 			from++;
-			*to = *from++ << 8;
-			*to |= 0x3f & *from++;
+			*to = (SS3 << 16) | (*from++ << 8);
+			*to |= *from++;
 			len -= 3;
 		}
-		else if ((*from & 0x80) && len >= 2)
+		else if ((*from & 0x80) && len >= 2)	/* code set 2 */
 		{
 			*to = *from++ << 8;
 			*to |= *from++;