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libiconv

    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-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:         conv->istate = state;
   54:         return RET_SHIFT_ILSEQ(count);
   55:       }
   56:     }
   57:     s += 4; n -= 4;
   58:   }
   59:   conv->istate = state;
   60:   return RET_TOOFEW(count);
   61: }
   62: 
   63: /* We output UTF-32 in big-endian order, with byte-order mark. */
   64: /* The state is 0 at the beginning, 1 after the BOM has been written. */
   65: static int
   66: utf32_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
   67: {
   68:   if (wc < 0x110000 && !(wc >= 0xd800 && wc < 0xe000)) {
   69:     int count = 0;
   70:     if (!conv->ostate) {
   71:       if (n >= 4) {
   72:         r[0] = 0x00;
   73:         r[1] = 0x00;
   74:         r[2] = 0xFE;
   75:         r[3] = 0xFF;
   76:         r += 4; n -= 4; count += 4;
   77:       } else
   78:         return RET_TOOSMALL;
   79:     }
   80:     if (wc < 0x110000) {
   81:       if (n >= 4) {
   82:         r[0] = 0;
   83:         r[1] = (unsigned char) (wc >> 16);
   84:         r[2] = (unsigned char) (wc >> 8);
   85:         r[3] = (unsigned char) wc;
   86:         conv->ostate = 1;
   87:         return count+4;
   88:       } else
   89:         return RET_TOOSMALL;
   90:     }
   91:   }
   92:   return RET_ILUNI;
   93: }