1/* Check UTF-16 string.
2   Copyright (C) 2002, 2006-2007, 2009-2010 Free Software Foundation, Inc.
3   Written by Bruno Haible <bruno@clisp.org>, 2002.
4
5   This program is free software: you can redistribute it and/or modify it
6   under the terms of the GNU Lesser General Public License as published
7   by the Free Software Foundation; either version 3 of the License, or
8   (at your option) any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public License
16   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
17
18#include <config.h>
19
20/* Specification.  */
21#include "unistr.h"
22
23const uint16_t *
24u16_check (const uint16_t *s, size_t n)
25{
26  const uint16_t *s_end = s + n;
27
28  while (s < s_end)
29    {
30      /* Keep in sync with unistr.h and utf16-ucs4.c.  */
31      uint16_t c = *s;
32
33      if (c < 0xd800 || c >= 0xe000)
34        {
35          s++;
36          continue;
37        }
38      if (c < 0xdc00)
39        {
40          if (s + 2 <= s_end
41              && s[1] >= 0xdc00 && s[1] < 0xe000)
42            {
43              s += 2;
44              continue;
45            }
46        }
47      /* invalid or incomplete multibyte character */
48      return s;
49    }
50  return NULL;
51}
52