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/*
* Copyright (C) 2008, 2009
* Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* \author Yang Jianyu <xiaoyjy@hotmail.com>
*/
#include "unicode.h"
int utf8_char_width(const unsigned char* w)
{
if(w[0] < 0x80) return 1;
if(w[0] < 0xe0) return 2;
if(w[0] < 0xf0) return 3;
if(w[0] < 0xf8) return 4;
if(w[0] < 0xfc) return 5;
if(w[0] < 0xfe) return 6;
return -1;
}
int utf8_char_encode(const unsigned char* w, int* c)
{
/* 00000000-01111111 00-7F 0-127 US-ASCII (single byte) */
if(w[0] < 0x80) {
*c = (int)w[0];
return 1;
}
/* 10000000-10111111 80-BF 128-191 Second, third, or fourth byte of a multi-byte sequence */
/* 11000000-11000001 C0-C1 192-193 Overlong encoding: start of a 2-byte sequence, but code point <= 127*/
/* 11000010-11011111 C2-DF 194-223 Start of 2-byte sequence */
if(w[0] < 0xe0 && w[0] > 0xc1) {
*c = (int)(((w[0] - 0xc0) << 6) + w[1] - 0x80);
return 2;
}
/* 11100000-11101111 E0-EF 224-239 Start of 3-byte sequence */
if(w[0] < 0xf0 && w[0] > 0xdf)
{
*c = (int)(((w[0] - 0xe0) << 12) + ((w[1] - 0x80) << 6) + w[2] - 0x80);
return 3;
}
/* 11110000-11110100 F0-F4 240-244 Start of 4-byte sequence */
if(w[0] < 0xf8 && w[0] > 0xef)
{
*c = (int)(
((w[0] - 0xf0) << 18) +
((w[1] - 0x80) << 12) +
((w[2] - 0x80) << 6 ) + w[3] - 0x80);
return 4;
}
/* 11110101-11110111 F5-F7 245-247 Restricted by RFC 3629:
* start of 4-byte sequence for codepoint above 10FFFF
*/
/* 11111000-11111011 F8-FB 248-251 Restricted by RFC 3629: start of 5-byte sequence */
if(w[0] < 0xfc && w[0] > 0xf7)
{
*c = (int)(
((w[0] - 0xf8) << 24) +
((w[1] - 0x80) << 18) +
((w[2] - 0x80) << 12) +
((w[3] - 0x80) << 6 ) + w[4] - 0x80);
return 5;
}
/* 11111100-11111101 FC-FD 252-253 Restricted by RFC 3629: start of 6-byte sequence */
if(w[0] < 0xfe && w[0] > 0xfb)
{
*c = (int)(
((w[0] - 0xfc) << 30) +
((w[1] - 0x80) << 24) +
((w[2] - 0x80) << 18) +
((w[3] - 0x80) << 12) +
((w[4] - 0x80) << 6 ) + w[5] - 0x80);
return 6;
}
*c = 0;
return -1;
}
int utf8_char_decode(int unicode, unsigned char* utf)
{
int count = -1;
if(unicode < 0x80) /*0100,0000*/
count = 1;
else if (unicode < 0x800) /*0100,0000,0000*/
count = 2;
else if (unicode < 0x10000) /*0001,0000,0000,0000,000,*/
count = 3;
else if (unicode < 0x200000) /*0010,0000,0000,0000,0000,0000*/
count = 4;
else if (unicode < 0x4000000) /*0100,0000,0000,0000,0000,0000,0000*/
count = 5;
else if (unicode <= 0x7fffffff)/*0110,1111,1111,1111,1111,1111,1111,1111*/
count = 6;
else
return count;
switch (count) { /* note: code falls through cases! */
case 6: utf[5] = 0x80 | (unicode & 0x3f); unicode = unicode >> 6; unicode |= 0x4000000;
case 5: utf[4] = 0x80 | (unicode & 0x3f); unicode = unicode >> 6; unicode |= 0x200000;
case 4: utf[3] = 0x80 | (unicode & 0x3f); unicode = unicode >> 6; unicode |= 0x10000;
case 3: utf[2] = 0x80 | (unicode & 0x3f); unicode = unicode >> 6; unicode |= 0x800;
case 2: utf[1] = 0x80 | (unicode & 0x3f); unicode = unicode >> 6; unicode |= 0xc0;
case 1: utf[0] = (char)unicode;
}
return count;
}
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