| /* Look at first character in UTF-8 string. |
| Copyright (C) 1999-2000, 2002, 2006-2007, 2009-2020 Free Software |
| Foundation, Inc. |
| Written by Bruno Haible <bruno@clisp.org>, 2002. |
| |
| This program is free software: you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published |
| by the Free Software Foundation; either version 3 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| #include <config.h> |
| |
| /* Specification. */ |
| #include "unistr.h" |
| |
| int |
| u8_mblen (const uint8_t *s, size_t n) |
| { |
| if (n > 0) |
| { |
| /* Keep in sync with unistr.h and u8-mbtouc-aux.c. */ |
| uint8_t c = *s; |
| |
| if (c < 0x80) |
| return (c != 0 ? 1 : 0); |
| if (c >= 0xc2) |
| { |
| if (c < 0xe0) |
| { |
| if (n >= 2 |
| && (s[1] ^ 0x80) < 0x40) |
| return 2; |
| } |
| else if (c < 0xf0) |
| { |
| if (n >= 3 |
| && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40 |
| && (c >= 0xe1 || s[1] >= 0xa0) |
| && (c != 0xed || s[1] < 0xa0)) |
| return 3; |
| } |
| else if (c < 0xf8) |
| { |
| if (n >= 4 |
| && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40 |
| && (s[3] ^ 0x80) < 0x40 |
| && (c >= 0xf1 || s[1] >= 0x90) |
| && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90))) |
| return 4; |
| } |
| } |
| } |
| /* invalid or incomplete multibyte character */ |
| return -1; |
| } |