lib/utf32.h

   1 /*
   2  * Copyright (C) 1999-2001 Free Software Foundation, Inc.
   3  * This file is part of the GNU LIBICONV Library.
   4  *
   5  * The GNU LIBICONV Library is free software; you can redistribute it
   6  * and/or modify it under the terms of the GNU Library General Public
   7  * License as published by the Free Software Foundation; either version 2
   8  * of the License, or (at your option) any later version.
   9  *
  10  * The GNU LIBICONV Library is distributed in the hope that it will be
  11  * useful, 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 LIBICONV Library; see the file COPYING.LIB.
  17  * If not, write to the Free Software Foundation, Inc., 59 Temple Place -
  18  * Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 /*
  22  * UTF-32
  23  */
  24
  25 /* Specification: Unicode 3.1 Standard Annex #19 */
  26
  27 /* Here we accept FFFE0000/0000FEFF marks as endianness indicators
  28    everywhere in the stream, not just at the beginning. (This is contrary
  29    to what #19 D36c specifies, but it allows concatenation of byte
  30    sequences to work flawlessly, while disagreeing with #19 behaviour
  31    only for strings containing U+FEFF characters, which is quite rare.)
  32    The default is big-endian. */
  33 /* The state is 0 if big-endian, 1 if little-endian. */
  34 static int
  35 utf32_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
  36 {
  37   state_t state = conv->istate;
  38   int count = 0;
  39   for (; n >= 4;) {
  40     ucs4_t wc = (state
  41                   ? s[0] + (s[1] << 8) + (s[2] << 16) + (s[3] << 24)
  42                   : (s[0] << 24) + (s[1] << 16) + (s[2] << 8) + s[3]);
  43     count += 4;
  44     if (wc == 0x0000feff) {
  45     } else if (wc == 0xfffe0000u) {
  46       state ^= 1;
  47     } else {
  48       if (wc < 0x110000 && !(wc >= 0xd800 && wc < 0xe000)) {
  49         *pwc = wc;
  50         conv->istate = state;
  51         return count;
  52       } else
  53         return RET_ILSEQ;
  54     }
  55     s += 4; n -= 4;
  56   }
  57   conv->istate = state;
  58   return RET_TOOFEW(count);
  59 }
  60
  61 /* We output UTF-32 in big-endian order, with byte-order mark. */
  62 /* The state is 0 at the beginning, 1 after the BOM has been written. */
  63 static int
  64 utf32_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
  65 {
  66   if (wc < 0x110000 && !(wc >= 0xd800 && wc < 0xe000)) {
  67     int count = 0;
  68     if (!conv->ostate) {
  69       if (n >= 4) {
  70         r[0] = 0x00;
  71         r[1] = 0x00;
  72         r[2] = 0xFE;
  73         r[3] = 0xFF;
  74         r += 4; n -= 4; count += 4;
  75       } else
  76         return RET_TOOSMALL;
  77     }
  78     if (wc < 0x110000) {
  79       if (n >= 4) {
  80         r[0] = 0;
  81         r[1] = (unsigned char) (wc >> 16);
  82         r[2] = (unsigned char) (wc >> 8);
  83         r[3] = (unsigned char) wc;
  84         conv->ostate = 1;
  85         return count+4;
  86       } else
  87         return RET_TOOSMALL;
  88     }
  89   }
  90   return RET_ILSEQ;
  91 }