wcsmbs/wcrtomb.c

   1 /* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <wchar.h>
  22
  23 #ifndef EILSEQ
  24 #define EILSEQ EINVAL
  25 #endif
  26
  27 static const wchar_t encoding_mask[] =
  28 {
  29   ~0x7ff, ~0xffff, ~0x1fffff, ~0x3ffffff
  30 };
  31
  32 static const unsigned char encoding_byte[] =
  33 {
  34   0xc0, 0xe0, 0xf0, 0xf8, 0xfc
  35 };
  36
  37 /* The state is for this UTF8 encoding not used.  */
  38 static mbstate_t internal;
  39
  40 size_t
  41 __wcrtomb (char *s, wchar_t wc, mbstate_t *ps)
  42 {
  43   size_t written = 0;
  44
  45   if (ps == NULL)
  46     ps = &internal;
  47
  48   if (s == NULL)
  49     {
  50       /* This is equivalent to wcrtomb (<<internal>, L'\0', ps).  We
  51          only have to reset the state.  */
  52       ps->count = 0;
  53       return 1;
  54     }
  55
  56   /* Store the UTF8 representation of WC.  */
  57   if (wc < 0 || wc > 0x7fffffff)
  58     {
  59       /* This is no correct ISO 10646 character.  */
  60       __set_errno (EILSEQ);
  61       return (size_t) -1;
  62     }
  63
  64   if (wc < 0x80)
  65     {
  66       /* It's a one byte sequence.  */
  67       if (s != NULL)
  68         *s = (char) wc;
  69       ps->count = 0;
  70       return 1;
  71     }
  72
  73   for (written = 2; written < 6; ++written)
  74     if ((wc & encoding_mask[written - 2]) == 0)
  75       break;
  76
  77   if (s != NULL)
  78     {
  79       size_t cnt = written;
  80       s[0] = encoding_byte[cnt - 2];
  81
  82       --cnt;
  83       do
  84         {
  85           s[cnt] = 0x80 | (wc & 0x3f);
  86           wc >>= 6;
  87         }
  88       while (--cnt > 0);
  89       s[0] |= wc;
  90     }
  91
  92   return written;
  93 }
  94 weak_alias (__wcrtomb, wcrtomb)