lib/unistr/u16-mbtouc-unsafe.c

   1 /* Look at first character in UTF-16 string.
   2    Copyright (C) 1999-2002, 2006-2007, 2009-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2001.
   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 <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 #if defined IN_LIBUNISTRING
  21 /* Tell unistr.h to declare u16_mbtouc_unsafe as 'extern', not
  22    'static inline'.  */
  23 # include "unistring-notinline.h"
  24 #endif
  25
  26 /* Specification.  */
  27 #include "unistr.h"
  28
  29 #if !HAVE_INLINE
  30
  31 int
  32 u16_mbtouc_unsafe (ucs4_t *puc, const uint16_t *s, size_t n)
  33 {
  34   uint16_t c = *s;
  35
  36   if (c < 0xd800 || c >= 0xe000)
  37     {
  38       *puc = c;
  39       return 1;
  40     }
  41   if (c < 0xdc00)
  42     {
  43       if (n >= 2)
  44         {
  45           if (s[1] >= 0xdc00 && s[1] < 0xe000)
  46             {
  47               *puc = 0x10000 + ((c - 0xd800) << 10) + (s[1] - 0xdc00);
  48               return 2;
  49             }
  50           /* invalid multibyte character */
  51         }
  52       else
  53         {
  54           /* incomplete multibyte character */
  55         }
  56     }
  57   /* invalid multibyte character */
  58   *puc = 0xfffd;
  59   return 1;
  60 }
  61
  62 #endif