From 09022de1f55708bcfe8b2bf206d818055c34d49e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 4 Jul 2012 00:29:57 -0400
Subject: [PATCH] Improve documentation about MULE encoding.
This commit improves the comments in pg_wchar.h and creates #define symbols
for some formerly hard-coded values. No substantive code changes.
Tatsuo Ishii and Tom Lane
---
.../euc_tw_and_big5/euc_tw_and_big5.c | 17 +-
src/backend/utils/mb/wchar.c | 6 +
src/include/mb/pg_wchar.h | 145 ++++++++++++------
3 files changed, 110 insertions(+), 58 deletions(-)
diff --git a/src/backend/utils/mb/conversion_procs/euc_tw_and_big5/euc_tw_and_big5.c b/src/backend/utils/mb/conversion_procs/euc_tw_and_big5/euc_tw_and_big5.c
index a266824b6bc..ed0e0c185cc 100644
--- a/src/backend/utils/mb/conversion_procs/euc_tw_and_big5/euc_tw_and_big5.c
+++ b/src/backend/utils/mb/conversion_procs/euc_tw_and_big5/euc_tw_and_big5.c
@@ -168,7 +168,8 @@ euc_tw2mic(const unsigned char *euc, unsigned char *p, int len)
*p++ = LC_CNS11643_2;
else
{
- *p++ = 0x9d; /* LCPRV2 */
+ /* other planes are MULE private charsets */
+ *p++ = LCPRV2_B;
*p++ = c1 - 0xa3 + LC_CNS11643_3;
}
*p++ = euc[2];
@@ -235,9 +236,9 @@ mic2euc_tw(const unsigned char *mic, unsigned char *p, int len)
*p++ = mic[1];
*p++ = mic[2];
}
- else if (c1 == 0x9d &&
+ else if (c1 == LCPRV2_B &&
mic[1] >= LC_CNS11643_3 && mic[1] <= LC_CNS11643_7)
- { /* LCPRV2? */
+ {
*p++ = SS2;
*p++ = mic[1] - LC_CNS11643_3 + 0xa3;
*p++ = mic[2];
@@ -286,10 +287,9 @@ big52mic(const unsigned char *big5, unsigned char *p, int len)
cnsBuf = BIG5toCNS(big5buf, &lc);
if (lc != 0)
{
+ /* Planes 3 and 4 are MULE private charsets */
if (lc == LC_CNS11643_3 || lc == LC_CNS11643_4)
- {
- *p++ = 0x9d; /* LCPRV2 */
- }
+ *p++ = LCPRV2_B;
*p++ = lc; /* Plane No. */
*p++ = (cnsBuf >> 8) & 0x00ff;
*p++ = cnsBuf & 0x00ff;
@@ -332,10 +332,9 @@ mic2big5(const unsigned char *mic, unsigned char *p, int len)
if (l < 0)
report_invalid_encoding(PG_MULE_INTERNAL,
(const char *) mic, len);
- /* 0x9d means LCPRV2 */
- if (c1 == LC_CNS11643_1 || c1 == LC_CNS11643_2 || c1 == 0x9d)
+ if (c1 == LC_CNS11643_1 || c1 == LC_CNS11643_2 || c1 == LCPRV2_B)
{
- if (c1 == 0x9d)
+ if (c1 == LCPRV2_B)
{
c1 = mic[1]; /* get plane no. */
cnsBuf = (mic[2] << 8) | mic[3];
diff --git a/src/backend/utils/mb/wchar.c b/src/backend/utils/mb/wchar.c
index 03d68119d1c..2e1db5ebf4b 100644
--- a/src/backend/utils/mb/wchar.c
+++ b/src/backend/utils/mb/wchar.c
@@ -742,6 +742,12 @@ pg_mule_dsplen(const unsigned char *s)
{
int len;
+ /*
+ * Note: it's not really appropriate to assume that all multibyte charsets
+ * are double-wide on screen. But this seems an okay approximation for
+ * the MULE charsets we currently support.
+ */
+
if (IS_LC1(*s))
len = 1;
else if (IS_LCPRV1(*s))
diff --git a/src/include/mb/pg_wchar.h b/src/include/mb/pg_wchar.h
index d456309486c..1d6d9554bd4 100644
--- a/src/include/mb/pg_wchar.h
+++ b/src/include/mb/pg_wchar.h
@@ -36,36 +36,60 @@ typedef unsigned int pg_wchar;
#define ISSJISHEAD(c) (((c) >= 0x81 && (c) <= 0x9f) || ((c) >= 0xe0 && (c) <= 0xfc))
#define ISSJISTAIL(c) (((c) >= 0x40 && (c) <= 0x7e) || ((c) >= 0x80 && (c) <= 0xfc))
-/*
- * Leading byte types or leading prefix byte for MULE internal code.
- * See http://www.xemacs.org for more details. (there is a doc titled
- * "XEmacs Internals Manual", "MULE Character Sets and Encodings"
- * section.)
- */
-/*
- * Is a leading byte for "official" single byte encodings?
- */
-#define IS_LC1(c) ((unsigned char)(c) >= 0x81 && (unsigned char)(c) <= 0x8d)
-/*
- * Is a prefix byte for "private" single byte encodings?
- */
-#define IS_LCPRV1(c) ((unsigned char)(c) == 0x9a || (unsigned char)(c) == 0x9b)
-/*
- * Is a leading byte for "official" multibyte encodings?
- */
-#define IS_LC2(c) ((unsigned char)(c) >= 0x90 && (unsigned char)(c) <= 0x99)
-/*
- * Is a prefix byte for "private" multibyte encodings?
- */
-#define IS_LCPRV2(c) ((unsigned char)(c) == 0x9c || (unsigned char)(c) == 0x9d)
-
/*----------------------------------------------------
- * leading characters
+ * MULE Internal Encoding (MIC)
+ *
+ * This encoding follows the design used within XEmacs; it is meant to
+ * subsume many externally-defined character sets. Each character includes
+ * identification of the character set it belongs to, so the encoding is
+ * general but somewhat bulky.
+ *
+ * Currently PostgreSQL supports 5 types of MULE character sets:
+ *
+ * 1) 1-byte ASCII characters. Each byte is below 0x80.
+ *
+ * 2) "Official" single byte charsets such as ISO-8859-1 (Latin1).
+ * Each MULE character consists of 2 bytes: LC1 + C1, where LC1 is
+ * an identifier for the charset (in the range 0x81 to 0x8d) and C1
+ * is the character code (in the range 0xa0 to 0xff).
+ *
+ * 3) "Private" single byte charsets such as SISHENG. Each MULE
+ * character consists of 3 bytes: LCPRV1 + LC12 + C1, where LCPRV1
+ * is a private-charset flag, LC12 is an identifier for the charset,
+ * and C1 is the character code (in the range 0xa0 to 0xff).
+ * LCPRV1 is either 0x9a (if LC12 is in the range 0xa0 to 0xdf)
+ * or 0x9b (if LC12 is in the range 0xe0 to 0xef).
+ *
+ * 4) "Official" multibyte charsets such as JIS X0208. Each MULE
+ * character consists of 3 bytes: LC2 + C1 + C2, where LC2 is
+ * an identifier for the charset (in the range 0x90 to 0x99) and C1
+ * and C2 form the character code (each in the range 0xa0 to 0xff).
+ *
+ * 5) "Private" multibyte charsets such as CNS 11643-1992 Plane 3.
+ * Each MULE character consists of 4 bytes: LCPRV2 + LC22 + C1 + C2,
+ * where LCPRV2 is a private-charset flag, LC22 is an identifier for
+ * the charset, and C1 and C2 form the character code (each in the range
+ * 0xa0 to 0xff). LCPRV2 is either 0x9c (if LC22 is in the range 0xf0
+ * to 0xf4) or 0x9d (if LC22 is in the range 0xf5 to 0xfe).
+ *
+ * "Official" encodings are those that have been assigned code numbers by
+ * the XEmacs project; "private" encodings have Postgres-specific charset
+ * identifiers.
+ *
+ * See the "XEmacs Internals Manual", available at http://www.xemacs.org,
+ * for more details. Note that for historical reasons, Postgres'
+ * private-charset flag values do not match what XEmacs says they should be,
+ * so this isn't really exactly MULE (not that private charsets would be
+ * interoperable anyway).
*----------------------------------------------------
*/
/*
- * Official single byte encodings (0x81-0x8e)
+ * Charset identifiers (also called "leading bytes" in the MULE documentation)
+ */
+
+/*
+ * Charset IDs for official single byte encodings (0x81-0x8e)
*/
#define LC_ISO8859_1 0x81 /* ISO8859 Latin 1 */
#define LC_ISO8859_2 0x82 /* ISO8859 Latin 2 */
@@ -79,21 +103,19 @@ typedef unsigned int pg_wchar;
#define LC_JISX0201R 0x8a /* Japanese 1 byte Roman */
/* Note that 0x8b seems to be unused as of Emacs 20.7.
* However, there might be a chance that 0x8b could be used
- * in later version of Emacs.
+ * in later versions of Emacs.
*/
#define LC_KOI8_R 0x8b /* Cyrillic KOI8-R */
-#define LC_KOI8_U 0x8b /* Cyrillic KOI8-U */
#define LC_ISO8859_5 0x8c /* ISO8859 Cyrillic */
#define LC_ISO8859_9 0x8d /* ISO8859 Latin 5 (not supported yet) */
/* #define FREE 0x8e free (unused) */
+/* #define CONTROL_1 0x8f control characters (unused) */
-/*
- * Unused
- */
-#define CONTROL_1 0x8f /* control characters (unused) */
+/* Is a leading byte for "official" single byte encodings? */
+#define IS_LC1(c) ((unsigned char)(c) >= 0x81 && (unsigned char)(c) <= 0x8d)
/*
- * Official multibyte byte encodings (0x90-0x99)
+ * Charset IDs for official multibyte encodings (0x90-0x99)
* 0x9a-0x9d are free. 0x9e and 0x9f are reserved.
*/
#define LC_JISX0208_1978 0x90 /* Japanese Kanji, old JIS (not supported) */
@@ -108,45 +130,70 @@ typedef unsigned int pg_wchar;
#define LC_BIG5_1 0x98 /* Plane 1 Chinese traditional (not supported) */
#define LC_BIG5_2 0x99 /* Plane 1 Chinese traditional (not supported) */
+/* Is a leading byte for "official" multibyte encodings? */
+#define IS_LC2(c) ((unsigned char)(c) >= 0x90 && (unsigned char)(c) <= 0x99)
+
/*
- * Private single byte encodings (0xa0-0xef)
+ * Postgres-specific prefix bytes for "private" single byte encodings
+ * (According to the MULE docs, we should be using 0x9e for this)
*/
-#define LC_SISHENG 0xa0/* Chinese SiSheng characters for
- * PinYin/ZhuYin (not supported) */
-#define LC_IPA 0xa1/* IPA (International Phonetic Association)
- * (not supported) */
-#define LC_VISCII_LOWER 0xa2/* Vietnamese VISCII1.1 lower-case (not
- * supported) */
-#define LC_VISCII_UPPER 0xa3/* Vietnamese VISCII1.1 upper-case (not
- * supported) */
+#define LCPRV1_A 0x9a
+#define LCPRV1_B 0x9b
+#define IS_LCPRV1(c) ((unsigned char)(c) == LCPRV1_A || (unsigned char)(c) == LCPRV1_B)
+
+/*
+ * Postgres-specific prefix bytes for "private" multibyte encodings
+ * (According to the MULE docs, we should be using 0x9f for this)
+ */
+#define LCPRV2_A 0x9c
+#define LCPRV2_B 0x9d
+#define IS_LCPRV2(c) ((unsigned char)(c) == LCPRV2_A || (unsigned char)(c) == LCPRV2_B)
+
+/*
+ * Charset IDs for private single byte encodings (0xa0-0xef)
+ */
+#define LC_SISHENG 0xa0 /* Chinese SiSheng characters for
+ * PinYin/ZhuYin (not supported) */
+#define LC_IPA 0xa1 /* IPA (International Phonetic Association)
+ * (not supported) */
+#define LC_VISCII_LOWER 0xa2 /* Vietnamese VISCII1.1 lower-case (not
+ * supported) */
+#define LC_VISCII_UPPER 0xa3 /* Vietnamese VISCII1.1 upper-case (not
+ * supported) */
#define LC_ARABIC_DIGIT 0xa4 /* Arabic digit (not supported) */
#define LC_ARABIC_1_COLUMN 0xa5 /* Arabic 1-column (not supported) */
#define LC_ASCII_RIGHT_TO_LEFT 0xa6 /* ASCII (left half of ISO8859-1) with
* right-to-left direction (not
* supported) */
-#define LC_LAO 0xa7/* Lao characters (ISO10646 0E80..0EDF) (not
- * supported) */
+#define LC_LAO 0xa7 /* Lao characters (ISO10646 0E80..0EDF)
+ * (not supported) */
#define LC_ARABIC_2_COLUMN 0xa8 /* Arabic 1-column (not supported) */
/*
- * Private multibyte encodings (0xf0-0xff)
+ * Charset IDs for private multibyte encodings (0xf0-0xff)
*/
-#define LC_INDIAN_1_COLUMN 0xf0/* Indian charset for 1-column width glypps
- * (not supported) */
-#define LC_TIBETAN_1_COLUMN 0xf1 /* Tibetan 1 column glyph (not supported) */
+#define LC_INDIAN_1_COLUMN 0xf0 /* Indian charset for 1-column width glyphs
+ * (not supported) */
+#define LC_TIBETAN_1_COLUMN 0xf1 /* Tibetan 1-column width glyphs
+ * (not supported) */
#define LC_ETHIOPIC 0xf5 /* Ethiopic characters (not supported) */
#define LC_CNS11643_3 0xf6 /* CNS 11643-1992 Plane 3 */
#define LC_CNS11643_4 0xf7 /* CNS 11643-1992 Plane 4 */
#define LC_CNS11643_5 0xf8 /* CNS 11643-1992 Plane 5 */
#define LC_CNS11643_6 0xf9 /* CNS 11643-1992 Plane 6 */
#define LC_CNS11643_7 0xfa /* CNS 11643-1992 Plane 7 */
-#define LC_INDIAN_2_COLUMN 0xfb/* Indian charset for 2-column width glypps
- * (not supported) */
+#define LC_INDIAN_2_COLUMN 0xfb /* Indian charset for 2-column width glyphs
+ * (not supported) */
#define LC_TIBETAN 0xfc /* Tibetan (not supported) */
/* #define FREE 0xfd free (unused) */
/* #define FREE 0xfe free (unused) */
/* #define FREE 0xff free (unused) */
+/*----------------------------------------------------
+ * end of MULE stuff
+ *----------------------------------------------------
+ */
+
/*
* PostgreSQL encoding identifiers
*
--
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