Posted on 2010-07-30 09:17
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基礎知識-經驗之談
GBK和BIG5都是雙字節字符，也就是用兩個位符來表示一個漢字。要判斷是否漢字，就必須知道它的有效范圍，下面是第一個位和第二個位的有效范圍：
GBK范圍：
1st byte | 2nd byte
0×81~0xfe | 0×40~0×7e and 0×80~0xfe
BIG5范圍：
1st byte | 2nd byte
0×81~0xfe | 0×40~0×7e and 0xa1~0xfe
下面是來自libiconv的關于GBK（cp936）和BIG5（cp950）的兩段代碼，相信還是相當有用的。
Download:
cp936.h
/**//*
* Copyright (C) 2005 Free Software Foundation, Inc.
* This file is part of the GNU LIBICONV Library.
*
* The GNU LIBICONV Library is free software; you can redistribute it
* and/or modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* The GNU LIBICONV Library is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with the GNU LIBICONV Library; see the file COPYING.LIB.
* If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
* Fifth Floor, Boston, MA 02110-1301, USA.
*/
/**//*
* CP936
*/
/**//*
* The IANA has CP936 as an alias of GBK. But GBK is an official Chinese
* specification, whereas CP936 is de-facto maintained by Microsoft. And,
* of course, Microsoft modified CP936 since 1999.
*
* The differences from GBK are:
*
* 1. A single character:
*
* code CP936.TXT
* 0x80 0x20AC # EURO SIGN
*
* Some variants of CP936 (in JDK, Windows-2000, ICU) also add:
*
* 2. Private area mappings:
*
* code Unicode
* 0x{A1..A2}{40..7E,80..A0} U+E4C6..U+E585
* 0x{AA..AF,F8..FE}{A1..FE} U+E000..U+E4C5
*
* We add them too because, although there are backward compatibility problems
* when a character from a private area is moved to an official Unicode code
* point, they are useful for some people in practice.
*/
static int cp936_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
{
/**//* Try GBK first. */
{
int ret = ces_gbk_mbtowc(conv,pwc,s,n);
if (ret != RET_ILSEQ)
return ret;
}
/**//* Then handle the additional mappings. */
{
unsigned char c = *s;
if (c == 0x80) {
*pwc = 0x20ac;
return 1;
}
/**//* User-defined characters */
if (c >= 0xa1 && c <= 0xa2) {
if (n < 2)
return RET_TOOFEW(0);
{
unsigned char c2 = s[1];
if ((c2 >= 0x40 && c2 < 0x7f) || (c2 >= 0x80 && c2 < 0xa1)) {
*pwc = 0xe4c6 + 96 * (c - 0xa1) + (c2 - (c2 >= 0x80 ? 0x41 : 0x40));
return 2;
}
}
} else if ((c >= 0xaa && c < 0xb0) || (c >= 0xf8 && c < 0xff)) {
if (n < 2)
return RET_TOOFEW(0);
{
unsigned char c2 = s[1];
if (c2 >= 0xa1 && c2 < 0xff) {
*pwc = 0xe000 + 94 * (c - (c >= 0xf8 ? 0xf2 : 0xaa)) + (c2 - 0xa1);
return 2;
}
}
}
}
return RET_ILSEQ;
}
static int cp936_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
{
/**//* Try GBK first. */
{
int ret = ces_gbk_wctomb(conv,r,wc,n);
if (ret != RET_ILUNI)
return ret;
}
/**//* Then handle the additional mappings. */
if (wc >= 0xe000 && wc < 0xe586) {
/**//* User-defined characters */
if (n < 2)
return RET_TOOFEW(0);
if (wc < 0xe4c6) {
unsigned int i = wc - 0xe000;
unsigned int c1 = i / 94;
unsigned int c2 = i % 94;
r[0] = c1 + (c1 < 6 ? 0xaa : 0xf2);
r[1] = c2 + 0xa1;
return 2;
} else {
unsigned int i = wc - 0xe4c6;
unsigned int c1 = i / 96;
unsigned int c2 = i % 96;
r[0] = c1 + 0xa1;
r[1] = c2 + (c2 < 0x3f ? 0x40 : 0x41);
return 2;
}
} else if (wc == 0x20ac) {
r[0] = 0x80;
return 1;
}
return RET_ILUNI;
}
接下來是BIG5的cp950：
Download: cp950.h
/**//*
* Copyright (C) 1999-2001, 2005 Free Software Foundation, Inc.
* This file is part of the GNU LIBICONV Library.
*
* The GNU LIBICONV Library is free software; you can redistribute it
* and/or modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* The GNU LIBICONV Library is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with the GNU LIBICONV Library; see the file COPYING.LIB.
* If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
* Fifth Floor, Boston, MA 02110-1301, USA.
*/
/**//*
* CP950
*/
/**//*
* Microsoft CP950 is a slightly extended and slightly modified version of
* BIG5. The differences between the EASTASIA/OTHER/BIG5.TXT and
* VENDORS/MICSFT/WINDOWS/CP950.TXT tables found on ftp.unicode.org are
* as follows:
*
* 1. Some characters in the BIG5 range are defined differently:
*
* code BIG5.TXT CP950.TXT
* 0xA145 0x2022 # BULLET 0x2027 # HYPHENATION POINT
* 0xA14E 0xFF64 # HALFWIDTH IDEOGRAPHIC COMMA
* 0xFE51 # SMALL IDEOGRAPHIC COMMA
* 0xA15A --- 0x2574 # BOX DRAWINGS LIGHT LEFT
* 0xA1C2 0x203E # OVERLINE 0x00AF # MACRON
* 0xA1C3 --- 0xFFE3 # FULLWIDTH MACRON
* 0xA1C5 --- 0x02CD # MODIFIER LETTER LOW MACRON
* 0xA1E3 0x223C # TILDE OPERATOR 0xFF5E # FULLWIDTH TILDE
* 0xA1F2 0x2641 # EARTH 0x2295 # CIRCLED PLUS
* 0xA1F3 0x2609 # SUN 0x2299 # CIRCLED DOT OPERATOR
* 0xA1FE --- 0xFF0F # FULLWIDTH SOLIDUS
* 0xA240 --- 0xFF3C # FULLWIDTH REVERSE SOLIDUS
* 0xA241 0xFF0F # FULLWIDTH SOLIDUS 0x2215 # DIVISION SLASH
* 0xA242 0xFF3C # FULLWIDTH REVERSE SOLIDUS
* 0xFE68 # SMALL REVERSE SOLIDUS
* 0xA244 0x00A5 # YEN SIGN 0xFFE5 # FULLWIDTH YEN SIGN
* 0xA246 0x00A2 # CENT SIGN 0xFFE0 # FULLWIDTH CENT SIGN
* 0xA247 0x00A3 # POUND SIGN 0xFFE1 # FULLWIDTH POUND SIGN
* 0xA2CC --- 0x5341
* 0xA2CE --- 0x5345
*
* 2. A small new row. See cp950ext.h.
*
* 3. CP950.TXT is lacking the range 0xC6A1..0xC7FC (Hiragana, Katakana,
* Cyrillic, circled digits, parenthesized digits).
*
* We implement this omission, because said range is marked "uncertain"
* in the unicode.org BIG5 table.
*
* The table found on Microsoft's website furthermore adds:
*
* 4. A single character:
*
* code CP950.TXT
* 0xA3E1 0x20AC # EURO SIGN
*
* Many variants of BIG5 or CP950 (in JDK, Solaris, OSF/1, Windows-2000, ICU,
* as well as our BIG5-2003 converter) also add:
*
* 5. Private area mappings:
*
* code Unicode
* 0x{81..8D}{40..7E,A1..FE} U+EEB8..U+F6B0
* 0x{8E..A0}{40..7E,A1..FE} U+E311..U+EEB7
* 0x{FA..FE}{40..7E,A1..FE} U+E000..U+E310
*
* We add them too because, although there are backward compatibility problems
* when a character from a private area is moved to an official Unicode code
* point, they are useful for some people in practice.
*/
static const unsigned short cp950_2uni_pagea1[314] = {
/**//* 0xa1 */
0x3000, 0xff0c, 0x3001, 0x3002, 0xff0e, 0x2027, 0xff1b, 0xff1a,
0xff1f, 0xff01, 0xfe30, 0x2026, 0x2025, 0xfe50, 0xfe51, 0xfe52,
0x00b7, 0xfe54, 0xfe55, 0xfe56, 0xfe57, 0xff5c, 0x2013, 0xfe31,
0x2014, 0xfe33, 0x2574, 0xfe34, 0xfe4f, 0xff08, 0xff09, 0xfe35,
0xfe36, 0xff5b, 0xff5d, 0xfe37, 0xfe38, 0x3014, 0x3015, 0xfe39,
0xfe3a, 0x3010, 0x3011, 0xfe3b, 0xfe3c, 0x300a, 0x300b, 0xfe3d,
0xfe3e, 0x3008, 0x3009, 0xfe3f, 0xfe40, 0x300c, 0x300d, 0xfe41,
0xfe42, 0x300e, 0x300f, 0xfe43, 0xfe44, 0xfe59, 0xfe5a, 0xfe5b,
0xfe5c, 0xfe5d, 0xfe5e, 0x2018, 0x2019, 0x201c, 0x201d, 0x301d,
0x301e, 0x2035, 0x2032, 0xff03, 0xff06, 0xff0a, 0x203b, 0x00a7,
0x3003, 0x25cb, 0x25cf, 0x25b3, 0x25b2, 0x25ce, 0x2606, 0x2605,
0x25c7, 0x25c6, 0x25a1, 0x25a0, 0x25bd, 0x25bc, 0x32a3, 0x2105,
0x00af, 0xffe3, 0xff3f, 0x02cd, 0xfe49, 0xfe4a, 0xfe4d, 0xfe4e,
0xfe4b, 0xfe4c, 0xfe5f, 0xfe60, 0xfe61, 0xff0b, 0xff0d, 0x00d7,
0x00f7, 0x00b1, 0x221a, 0xff1c, 0xff1e, 0xff1d, 0x2266, 0x2267,
0x2260, 0x221e, 0x2252, 0x2261, 0xfe62, 0xfe63, 0xfe64, 0xfe65,
0xfe66, 0xff5e, 0x2229, 0x222a, 0x22a5, 0x2220, 0x221f, 0x22bf,
0x33d2, 0x33d1, 0x222b, 0x222e, 0x2235, 0x2234, 0x2640, 0x2642,
0x2295, 0x2299, 0x2191, 0x2193, 0x2190, 0x2192, 0x2196, 0x2197,
0x2199, 0x2198, 0x2225, 0x2223, 0xff0f,
/**//* 0xa2 */
0xff3c, 0x2215, 0xfe68, 0xff04, 0xffe5, 0x3012, 0xffe0, 0xffe1,
0xff05, 0xff20, 0x2103, 0x2109, 0xfe69, 0xfe6a, 0xfe6b, 0x33d5,
0x339c, 0x339d, 0x339e, 0x33ce, 0x33a1, 0x338e, 0x338f, 0x33c4,
0x00b0, 0x5159, 0x515b, 0x515e, 0x515d, 0x5161, 0x5163, 0x55e7,
0x74e9, 0x7cce, 0x2581, 0x2582, 0x2583, 0x2584, 0x2585, 0x2586,
0x2587, 0x2588, 0x258f, 0x258e, 0x258d, 0x258c, 0x258b, 0x258a,
0x2589, 0x253c, 0x2534, 0x252c, 0x2524, 0x251c, 0x2594, 0x2500,
0x2502, 0x2595, 0x250c, 0x2510, 0x2514, 0x2518, 0x256d, 0x256e,
0x2570, 0x256f, 0x2550, 0x255e, 0x256a, 0x2561, 0x25e2, 0x25e3,
0x25e5, 0x25e4, 0x2571, 0x2572, 0x2573, 0xff10, 0xff11, 0xff12,
0xff13, 0xff14, 0xff15, 0xff16, 0xff17, 0xff18, 0xff19, 0x2160,
0x2161, 0x2162, 0x2163, 0x2164, 0x2165, 0x2166, 0x2167, 0x2168,
0x2169, 0x3021, 0x3022, 0x3023, 0x3024, 0x3025, 0x3026, 0x3027,
0x3028, 0x3029, 0x5341, 0x5344, 0x5345, 0xff21, 0xff22, 0xff23,
0xff24, 0xff25, 0xff26, 0xff27, 0xff28, 0xff29, 0xff2a, 0xff2b,
0xff2c, 0xff2d, 0xff2e, 0xff2f, 0xff30, 0xff31, 0xff32, 0xff33,
0xff34, 0xff35, 0xff36, 0xff37, 0xff38, 0xff39, 0xff3a, 0xff41,
0xff42, 0xff43, 0xff44, 0xff45, 0xff46, 0xff47, 0xff48, 0xff49,
0xff4a, 0xff4b, 0xff4c, 0xff4d, 0xff4e, 0xff4f, 0xff50, 0xff51,
0xff52, 0xff53, 0xff54, 0xff55, 0xff56,
};
#include "cp950ext.h"
static int cp950_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
{
unsigned char c = *s;
/**//* Code set 0 (ASCII) */
if (c < 0x80)
return ascii_mbtowc(conv,pwc,s,n);
/**//* Code set 1 (BIG5 extended) */
if (c >= 0x81 && c < 0xff) {
if (n < 2)
return RET_TOOFEW(0);
{
unsigned char c2 = s[1];
if ((c2 >= 0x40 && c2 < 0x7f) || (c2 >= 0xa1 && c2 < 0xff)) {
if (c >= 0xa1) {
if (c < 0xa3) {
unsigned int i = 157 * (c - 0xa1) + (c2 - (c2 >= 0xa1 ? 0x62 : 0x40));
unsigned short wc = cp950_2uni_pagea1[i];
if (wc != 0xfffd) {
*pwc = (ucs4_t) wc;
return 2;
}
}
if (!((c == 0xc6 && c2 >= 0xa1) || c == 0xc7)) {
int ret = big5_mbtowc(conv,pwc,s,2);
if (ret != RET_ILSEQ)
return ret;
}
if (c == 0xa3 && c2 == 0xe1) {
*pwc = 0x20ac;
return 2;
}
if (c >= 0xfa) {
/**//* User-defined characters */
*pwc = 0xe000 + 157 * (c - 0xfa) + (c2 - (c2 >= 0xa1 ? 0x62 : 0x40));
return 2;
}
} else {
/**//* 0x81 <= c < 0xa1. */
/**//* User-defined characters */
*pwc = (c >= 0x8e ? 0xdb18 : 0xeeb8) + 157 * (c - 0x81)
+ (c2 - (c2 >= 0xa1 ? 0x62 : 0x40));
return 2;
}
}
}
if (c == 0xf9) {
int ret = cp950ext_mbtowc(conv,pwc,s,2);
if (ret != RET_ILSEQ)
return ret;
}
}
return RET_ILSEQ;
}
static int cp950_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
{
unsigned char buf[2];
int ret;
/**//* Code set 0 (ASCII) */
ret = ascii_wctomb(conv,r,wc,n);
if (ret != RET_ILUNI)
return ret;
/**//* Code set 1 (BIG5 extended) */
switch (wc >> 8) {
case 0x00:
if (wc == 0x00af) { buf[0] = 0xa1; buf[1] = 0xc2; ret = 2; break; }
if (wc == 0x00a2 || wc == 0x00a3 || wc == 0x00a4)
return RET_ILUNI;
break;
case 0x02:
if (wc == 0x02cd) { buf[0] = 0xa1; buf[1] = 0xc5; ret = 2; break; }
break;
case 0x20:
if (wc == 0x2027) { buf[0] = 0xa1; buf[1] = 0x45; ret = 2; break; }
if (wc == 0x20ac) { buf[0] = 0xa3; buf[1] = 0xe1; ret = 2; break; }
if (wc == 0x2022 || wc == 0x203e)
return RET_ILUNI;
break;
case 0x22:
if (wc == 0x2215) { buf[0] = 0xa2; buf[1] = 0x41; ret = 2; break; }
if (wc == 0x2295) { buf[0] = 0xa1; buf[1] = 0xf2; ret = 2; break; }
if (wc == 0x2299) { buf[0] = 0xa1; buf[1] = 0xf3; ret = 2; break; }
if (wc == 0x223c)
return RET_ILUNI;
break;
case 0x25:
if (wc == 0x2574) { buf[0] = 0xa1; buf[1] = 0x5a; ret = 2; break; }
break;
case 0x26:
if (wc == 0x2609 || wc == 0x2641)
return RET_ILUNI;
break;
case 0xe0: case 0xe1: case 0xe2: case 0xe3: case 0xe4: case 0xe5:
case 0xe6: case 0xe7: case 0xe8: case 0xe9: case 0xea: case 0xeb:
case 0xec: case 0xed: case 0xee: case 0xef: case 0xf0: case 0xf1:
case 0xf2: case 0xf3: case 0xf4: case 0xf5: case 0xf6:
{
/**//* User-defined characters */
unsigned int i = wc - 0xe000;
if (i < 5809) {
unsigned int c1 = i / 157;
unsigned int c2 = i % 157;
buf[0] = c1 + (c1 < 5 ? 0xfa : c1 < 24 ? 0x89 : 0x69);
buf[1] = c2 + (c2 < 0x3f ? 0x40 : 0x62);
ret = 2;
break;
}
}
break;
case 0xfe:
if (wc == 0xfe51) { buf[0] = 0xa1; buf[1] = 0x4e; ret = 2; break; }
if (wc == 0xfe68) { buf[0] = 0xa2; buf[1] = 0x42; ret = 2; break; }
break;
case 0xff:
if (wc == 0xff0f) { buf[0] = 0xa1; buf[1] = 0xfe; ret = 2; break; }
if (wc == 0xff3c) { buf[0] = 0xa2; buf[1] = 0x40; ret = 2; break; }
if (wc == 0xff5e) { buf[0] = 0xa1; buf[1] = 0xe3; ret = 2; break; }
if (wc == 0xffe0) { buf[0] = 0xa2; buf[1] = 0x46; ret = 2; break; }
if (wc == 0xffe1) { buf[0] = 0xa2; buf[1] = 0x47; ret = 2; break; }
if (wc == 0xffe3) { buf[0] = 0xa1; buf[1] = 0xc3; ret = 2; break; }
if (wc == 0xffe5) { buf[0] = 0xa2; buf[1] = 0x44; ret = 2; break; }
if (wc == 0xff64)
return RET_ILUNI;
break;
}
if (ret == RET_ILUNI)
ret = big5_wctomb(conv,buf,wc,2);
if (ret != RET_ILUNI) {
if (ret != 2) abort();
if (!((buf[0] == 0xc6 && buf[1] >= 0xa1) || buf[0] == 0xc7)) {
if (n < 2)
return RET_TOOSMALL;
r[0] = buf[0];
r[1] = buf[1];
return 2;
}
}
ret = cp950ext_wctomb(conv,buf,wc,2);
if (ret != RET_ILUNI) {
if (ret != 2) abort();
if (n < 2)
return RET_TOOSMALL;
r[0] = buf[0];
r[1] = buf[1];
return 2;
}
return RET_ILUNI;
}