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Initial revision

    1: /*
    2:  * Copyright (C) 1999-2001, 2008 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., 51 Franklin Street,
   18:  * Fifth Floor, Boston, MA 02110-1301, USA.
   19:  */
   20: 
   21: /*
   22:  * UTF-16
   23:  */
   24: 
   25: /* Specification: RFC 2781 */
   26: 
   27: /* Here we accept FFFE/FEFF marks as endianness indicators everywhere
   28:    in the stream, not just at the beginning. (This is contrary to what
   29:    RFC 2781 section 3.2 specifies, but it allows concatenation of byte
   30:    sequences to work flawlessly, while disagreeing with the RFC 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: utf16_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 >= 2;) {
   40:     ucs4_t wc = (state ? s[0] + (s[1] << 8) : (s[0] << 8) + s[1]);
   41:     if (wc == 0xfeff) {
   42:     } else if (wc == 0xfffe) {
   43:       state ^= 1;
   44:     } else if (wc >= 0xd800 && wc < 0xdc00) {
   45:       if (n >= 4) {
   46:         ucs4_t wc2 = (state ? s[2] + (s[3] << 8) : (s[2] << 8) + s[3]);
   47:         if (!(wc2 >= 0xdc00 && wc2 < 0xe000))
   48:           goto ilseq;
   49:         *pwc = 0x10000 + ((wc - 0xd800) << 10) + (wc2 - 0xdc00);
   50:         conv->istate = state;
   51:         return count+4;
   52:       } else
   53:         break;
   54:     } else if (wc >= 0xdc00 && wc < 0xe000) {
   55:       goto ilseq;
   56:     } else {
   57:       *pwc = wc;
   58:       conv->istate = state;
   59:       return count+2;
   60:     }
   61:     s += 2; n -= 2; count += 2;
   62:   }
   63:   conv->istate = state;
   64:   return RET_TOOFEW(count);
   65: 
   66: ilseq:
   67:   conv->istate = state;
   68:   return RET_SHIFT_ILSEQ(count);
   69: }
   70: 
   71: /* We output UTF-16 in big-endian order, with byte-order mark.
   72:    See RFC 2781 section 3.3 for a rationale: Some document formats
   73:    mandate a BOM; the file concatenation issue is not so severe as
   74:    long as the above utf16_mbtowc function is used. */
   75: /* The state is 0 at the beginning, 1 after the BOM has been written. */
   76: static int
   77: utf16_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
   78: {
   79:   if (wc != 0xfffe && !(wc >= 0xd800 && wc < 0xe000)) {
   80:     int count = 0;
   81:     if (!conv->ostate) {
   82:       if (n >= 2) {
   83:         r[0] = 0xFE;
   84:         r[1] = 0xFF;
   85:         r += 2; n -= 2; count += 2;
   86:       } else
   87:         return RET_TOOSMALL;
   88:     }
   89:     if (wc < 0x10000) {
   90:       if (n >= 2) {
   91:         r[0] = (unsigned char) (wc >> 8);
   92:         r[1] = (unsigned char) wc;
   93:         conv->ostate = 1;
   94:         return count+2;
   95:       } else
   96:         return RET_TOOSMALL;
   97:     }
   98:     else if (wc < 0x110000) {
   99:       if (n >= 4) {
  100:         ucs4_t wc1 = 0xd800 + ((wc - 0x10000) >> 10);
  101:         ucs4_t wc2 = 0xdc00 + ((wc - 0x10000) & 0x3ff);
  102:         r[0] = (unsigned char) (wc1 >> 8);
  103:         r[1] = (unsigned char) wc1;
  104:         r[2] = (unsigned char) (wc2 >> 8);
  105:         r[3] = (unsigned char) wc2;
  106:         conv->ostate = 1;
  107:         return count+4;
  108:       } else
  109:         return RET_TOOSMALL;
  110:     }
  111:   }
  112:   return RET_ILUNI;
  113: }