/* Conversion UTF-16 to UCS-4.
   Copyright (C) 2001-2002, 2006-2007, 2009-2021 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2001.

   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"

#if defined IN_LIBUNISTRING || HAVE_INLINE

int
u16_mbtouc_aux (ucs4_t *puc, const uint16_t *s, size_t n)
{
  uint16_t c = *s;

  if (c < 0xdc00)
    {
      if (n >= 2)
        {
          if (s[1] >= 0xdc00 && s[1] < 0xe000)
            {
              *puc = 0x10000 + ((c - 0xd800) << 10) + (s[1] - 0xdc00);
              return 2;
            }
          /* invalid multibyte character */
        }
      else
        {
          /* incomplete multibyte character */
        }
    }
  /* invalid multibyte character */
  *puc = 0xfffd;
  return 1;
}

#endif
