ref: fdb6b0f31f5ff2d14d44689eb477a54d5f65157e
dir: /textscreen/txt_utf8.c/
// // Copyright(C) 2005-2014 Simon Howard // // 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 // of the License, or (at your option) any later version. // // This program 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 General Public License for more details. // #include <stdio.h> #include <stdlib.h> #include <string.h> #include "txt_utf8.h" // Encode a Unicode character as UTF-8, storing it in the buffer 'p' // and returning the new, incremented position. char *TXT_EncodeUTF8(char *p, unsigned int c) { if (c < 0x80) // 1 character (ASCII): { p[0] = c; return p + 1; } else if (c < 0x800) // 2 character: { p[0] = 0xc0 | (c >> 6); p[1] = 0x80 | (c & 0x3f); return p + 2; } else if (c < 0x10000) // 3 chacater: { p[0] = 0xe0 | (c >> 12); p[1] = 0x80 | ((c >> 6) & 0x3f); p[2] = 0x80 | (c & 0x3f); return p + 3; } else if (c < 0x200000) // 4 character: { p[0] = 0xf0 | (c >> 18); p[1] = 0x80 | ((c >> 12) & 0x3f); p[2] = 0x80 | ((c >> 6) & 0x3f); p[3] = 0x80 | (c & 0x3f); return p + 4; } else { // Too big! return p; } } // Decode UTF-8 character, incrementing *ptr over the decoded bytes. unsigned int TXT_DecodeUTF8(const char **ptr) { const char *p = *ptr; unsigned int c; // UTF-8 decode. if ((*p & 0x80) == 0) // 1 character (ASCII): { c = *p; *ptr += 1; } else if ((p[0] & 0xe0) == 0xc0 // 2 character: && (p[1] & 0xc0) == 0x80) { c = ((p[0] & 0x1f) << 6) | (p[1] & 0x3f); *ptr += 2; } else if ((p[0] & 0xf0) == 0xe0 // 3 character: && (p[1] & 0xc0) == 0x80 && (p[2] & 0xc0) == 0x80) { c = ((p[0] & 0x0f) << 12) | ((p[1] & 0x3f) << 6) | (p[2] & 0x3f); *ptr += 3; } else if ((p[0] & 0xf8) == 0xf0 // 4 character: && (p[1] & 0xc0) == 0x80 && (p[2] & 0xc0) == 0x80 && (p[3] & 0xc0) == 0x80) { c = ((p[0] & 0x07) << 18) | ((p[1] & 0x3f) << 12) | ((p[2] & 0x3f) << 6) | (p[3] & 0x3f); *ptr += 4; } else { // Decode failure. // Don't bother with 5/6 byte sequences. c = 0; } return c; } // Count the number of characters in a UTF-8 string. unsigned int TXT_UTF8_Strlen(const char *s) { const char *p; unsigned int result = 0; unsigned int c; for (p = s; *p != '\0';) { c = TXT_DecodeUTF8(&p); if (c == 0) { break; } ++result; } return result; } // Skip past the first n characters in a UTF-8 string. char *TXT_UTF8_SkipChars(const char *s, unsigned int n) { unsigned int i; const char *p; p = s; for (i = 0; i < n; ++i) { if (TXT_DecodeUTF8(&p) == 0) { break; } } return (char *) p; }