lib/unistr/u16-mbtouc.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 as 'extern', not 'static inline'.  */
  22 # include "unistring-notinline.h"
  23 #endif
  24
  25 /* Specification.  */
  26 #include "unistr.h"
  27
  28 #if !HAVE_INLINE
  29
  30 int
  31 u16_mbtouc (ucs4_t *puc, const uint16_t *s, size_t n)
  32 {
  33   uint16_t c = *s;
  34
  35   if (c < 0xd800 || c >= 0xe000)
  36     {
  37       *puc = c;
  38       return 1;
  39     }
  40   if (c < 0xdc00)
  41     {
  42       if (n >= 2)
  43         {
  44           if (s[1] >= 0xdc00 && s[1] < 0xe000)
  45             {
  46               *puc = 0x10000 + ((c - 0xd800) << 10) + (s[1] - 0xdc00);
  47               return 2;
  48             }
  49           /* invalid multibyte character */
  50         }
  51       else
  52         {
  53           /* incomplete multibyte character */
  54         }
  55     }
  56   /* invalid multibyte character */
  57   *puc = 0xfffd;
  58   return 1;
  59 }
  60
  61 #endif