lib/unistr/u32-prev.c

   1 /* Iterate over previous character in UTF-32 string.
   2    Copyright (C) 2002, 2006-2007, 2009-2021 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 <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "unistr.h"
  22
  23 const uint32_t *
  24 u32_prev (ucs4_t *puc, const uint32_t *s, const uint32_t *start)
  25 {
  26   if (s != start)
  27     {
  28       uint32_t c_1 = s[-1];
  29
  30       if (c_1 < 0xd800 || (c_1 >= 0xe000 && c_1 < 0x110000))
  31         {
  32           *puc = c_1;
  33           return s - 1;
  34         }
  35     }
  36   return NULL;
  37 }