lib/ucs2.h

   1 /*
   2  * Copyright (C) 1999-2001, 2008, 2011 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, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 /*
  21  * UCS-2
  22  */
  23
  24 /* Here we accept FFFE/FEFF marks as endianness indicators everywhere
  25    in the stream, not just at the beginning. The default is big-endian. */
  26 /* The state is 0 if big-endian, 1 if little-endian. */
  27 static int
  28 ucs2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
  29 {
  30   state_t state = conv->istate;
  31   int count = 0;
  32   for (; n >= 2;) {
  33     ucs4_t wc = (state ? s[0] + (s[1] << 8) : (s[0] << 8) + s[1]);
  34     if (wc == 0xfeff) {
  35     } else if (wc == 0xfffe) {
  36       state ^= 1;
  37     } else if (wc >= 0xd800 && wc < 0xe000) {
  38       conv->istate = state;
  39       return RET_SHIFT_ILSEQ(count);
  40     } else {
  41       *pwc = wc;
  42       conv->istate = state;
  43       return count+2;
  44     }
  45     s += 2; n -= 2; count += 2;
  46   }
  47   conv->istate = state;
  48   return RET_TOOFEW(count);
  49 }
  50
  51 /* But we output UCS-2 in big-endian order, without byte-order mark. */
  52 /* RFC 2152 says:
  53    "ISO/IEC 10646-1:1993(E) specifies that when characters the UCS-2 form are
  54     serialized as octets, that the most significant octet appear first." */
  55 static int
  56 ucs2_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
  57 {
  58   if (wc < 0x10000 && wc != 0xfffe && !(wc >= 0xd800 && wc < 0xe000)) {
  59     if (n >= 2) {
  60       r[0] = (unsigned char) (wc >> 8);
  61       r[1] = (unsigned char) wc;
  62       return 2;
  63     } else
  64       return RET_TOOSMALL;
  65   } else
  66     return RET_ILUNI;
  67 }