wcsmbs/btowc.c

   1 /* Copyright (C) 1996-2000,2002,2005 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.org>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <ctype.h>
  21 #include <dlfcn.h>
  22 #include <gconv.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <wchar.h>
  26 #include <wcsmbsload.h>
  27 #include <limits.h>
  28
  29
  30 wint_t
  31 __btowc (c)
  32      int c;
  33 {
  34   const struct gconv_fcts *fcts;
  35
  36   /* If the parameter does not fit into one byte or it is the EOF value
  37      we can give the answer now.  */
  38   if (c < SCHAR_MIN || c > UCHAR_MAX || c == EOF)
  39     return WEOF;
  40
  41   /* We know that only ASCII compatible encodings are used for the
  42      locale and that the wide character encoding is ISO 10646.  */
  43   if (isascii (c))
  44     return (wint_t) c;
  45
  46   /* Get the conversion functions.  */
  47   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  48
  49   if (__builtin_expect (fcts->towc_nsteps == 1, 1)
  50       && __builtin_expect (fcts->towc->__btowc_fct != NULL, 1))
  51     {
  52       /* Use the shortcut function.  */
  53       return DL_CALL_FCT (fcts->towc->__btowc_fct,
  54                           (fcts->towc, (unsigned char) c));
  55     }
  56   else
  57     {
  58       /* Fall back to the slow but generic method.  */
  59       wchar_t result;
  60       struct __gconv_step_data data;
  61       unsigned char inbuf[1];
  62       const unsigned char *inptr = inbuf;
  63       size_t dummy;
  64       int status;
  65
  66       /* Tell where we want the result.  */
  67       data.__outbuf = (unsigned char *) &result;
  68       data.__outbufend = data.__outbuf + sizeof (wchar_t);
  69       data.__invocation_counter = 0;
  70       data.__internal_use = 1;
  71       data.__flags = __GCONV_IS_LAST;
  72       data.__statep = &data.__state;
  73       data.__trans = NULL;
  74
  75       /* Make sure we start in the initial state.  */
  76       memset (&data.__state, '\0', sizeof (mbstate_t));
  77
  78       /* Create the input string.  */
  79       inbuf[0] = c;
  80
  81       status = DL_CALL_FCT (fcts->towc->__fct,
  82                             (fcts->towc, &data, &inptr, inptr + 1,
  83                              NULL, &dummy, 0, 1));
  84
  85       if (status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
  86           && status != __GCONV_EMPTY_INPUT)
  87         /* The conversion failed.  */
  88         result = WEOF;
  89
  90       return result;
  91     }
  92 }
  93 weak_alias (__btowc, btowc)