wcsmbs/wcrtomb.c

   1 /* Copyright (C) 1996 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
  17 not, 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   char fake[1];
  44   size_t written = 0;
  45
  46   if (ps == NULL)
  47     ps = &internal;
  48
  49   if (s == NULL)
  50     {
  51       s = fake;
  52       wc = L'\0';
  53     }
  54
  55   /* Store the UTF8 representation of WC.  */
  56   if (wc < 0 || wc > 0x7fffffff)
  57     {
  58       /* This is no correct ISO 10646 character.  */
  59       errno = EILSEQ;
  60       return (size_t) -1;
  61     }
  62
  63   if (wc < 0x80)
  64     {
  65       /* It's a one byte sequence.  */
  66       if (s != NULL)
  67         *s = (char) wc;
  68       return 1;
  69     }
  70
  71   for (written = 2; written < 6; ++written)
  72     if ((wc & encoding_mask[written - 2]) == 0)
  73       break;
  74
  75   if (s != NULL)
  76     {
  77       size_t cnt = written;
  78       s[0] = encoding_byte[cnt - 2];
  79
  80       --cnt;
  81       do
  82         {
  83           s[cnt] = 0x80 | (wc & 0x3f);
  84           wc >>= 6;
  85         }
  86       while (--cnt > 0);
  87       s[0] |= wc;
  88     }
  89
  90   return written;
  91 }