1  /* Look at first character in UTF-16 string.
       2     Copyright (C) 1999-2002, 2006-2007, 2009-2023 Free Software Foundation, Inc.
       3     Written by Bruno Haible <bruno@clisp.org>, 2001.
       4  
       5     This file is free software.
       6     It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
       7     You can redistribute it and/or modify it under either
       8       - the terms of the GNU Lesser General Public License as published
       9         by the Free Software Foundation, either version 3, or (at your
      10         option) any later version, or
      11       - the terms of the GNU General Public License as published by the
      12         Free Software Foundation; either version 2, or (at your option)
      13         any later version, or
      14       - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".
      15  
      16     This file is distributed in the hope that it will be useful,
      17     but WITHOUT ANY WARRANTY; without even the implied warranty of
      18     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      19     Lesser General Public License and the GNU General Public License
      20     for more details.
      21  
      22     You should have received a copy of the GNU Lesser General Public
      23     License and of the GNU General Public License along with this
      24     program.  If not, see <https://www.gnu.org/licenses/>.  */
      25  
      26  #include <config.h>
      27  
      28  #if defined IN_LIBUNISTRING
      29  /* Tell unistr.h to declare u16_mbtouc as 'extern', not 'static inline'.  */
      30  # include "unistring-notinline.h"
      31  #endif
      32  
      33  /* Specification.  */
      34  #include "unistr.h"
      35  
      36  #if !HAVE_INLINE
      37  
      38  int
      39  u16_mbtouc (ucs4_t *puc, const uint16_t *s, size_t n)
      40  {
      41    uint16_t c = *s;
      42  
      43    if (c < 0xd800 || c >= 0xe000)
      44      {
      45        *puc = c;
      46        return 1;
      47      }
      48    if (c < 0xdc00)
      49      {
      50        if (n >= 2)
      51          {
      52            if (s[1] >= 0xdc00 && s[1] < 0xe000)
      53              {
      54                *puc = 0x10000 + ((c - 0xd800) << 10) + (s[1] - 0xdc00);
      55                return 2;
      56              }
      57            /* invalid multibyte character */
      58          }
      59        else
      60          {
      61            /* incomplete multibyte character */
      62          }
      63      }
      64    /* invalid multibyte character */
      65    *puc = 0xfffd;
      66    return 1;
      67  }
      68  
      69  #endif