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/* Look at first character in UTF-8 string.
Copyright (C) 1999-2000, 2002, 2006-2007, 2009-2018 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 either:
* 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.
or
* 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.
or both in parallel, as here.
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;
}
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