stdlib/mbtowc.c

   1 /* Copyright (C) 1991 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <localeinfo.h>
  21 #include <ctype.h>
  22 #include <stddef.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27
  28 long int _mb_shift = 0;
  29
  30 /* Convert the multibyte character at S, which is no longer
  31    than N characters, to its `wchar_t' representation, placing
  32    this n *PWC and returning its length.  */
  33 int
  34 DEFUN(mbtowc, (pwc, s, n), wchar_t *pwc AND CONST char *s AND size_t n)
  35 {
  36   register CONST mb_char *mb;
  37   register wchar_t i;
  38
  39   if (s == NULL)
  40     return _mb_shift != 0;
  41
  42   if (_ctype_info->mbchar == NULL ||
  43       _ctype_info->mbchar->mb_chars == NULL)
  44     return -1;
  45   if (*s == '\0')
  46     return 0;
  47
  48   if (n > MB_CUR_MAX)
  49     n = MB_CUR_MAX;
  50
  51   for (i = 0; i < WCHAR_MAX; ++i)
  52     {
  53       mb = &_ctype_info->mbchar->mb_chars[i];
  54       /* EOF and NUL aren't MB chars.  */
  55       if (i == (wchar_t) EOF || i == (wchar_t) '\0')
  56         continue;
  57       /* Normal ASCII values can't start MB chars.  */
  58       else if (isascii(i))
  59         continue;
  60       else if (mb->string == NULL || mb->len == 0)
  61         continue;
  62       else if (mb->len > n)
  63         continue;
  64       else if (!strncmp(mb->string, s, mb->len))
  65         {
  66           _mb_shift += mb->shift;
  67           if (pwc != NULL)
  68             *pwc = i;
  69           return mb->len;
  70         }
  71     }
  72
  73   return -1;
  74 }