313 lines
6.4 KiB
C
313 lines
6.4 KiB
C
/* -*- c-basic-offset: 8 -*-
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rdesktop: A Remote Desktop Protocol client.
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Protocol services - RDP decompression
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Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <string.h>
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#include "rdesktop.h"
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/* MPPC decompression based on RFC 2118 */
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/* Licensing: */
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/* Decompression is allowed as long as we */
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/* don't compress data */
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/* The algorithm is LZS and is patented for another couple of years. */
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/* More information: */
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/* http://www.ietf.org/ietf/IPR/hifn-ipr-draft-friend-tls-lzs-compression.txt */
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RDPCOMP g_mppc_dict;
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int mppc_expand(uint8 *data, uint32 clen, uint8 ctype, uint32 *roff, uint32 *rlen)
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{
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int k, walker_len = 0, walker;
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uint32 i = 0;
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int next_offset, match_off;
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int match_len;
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int old_offset, match_bits;
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RD_BOOL big = ctype & RDP_MPPC_BIG ? True : False;
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uint8 *dict = g_mppc_dict.hist;
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if ((ctype & RDP_MPPC_COMPRESSED) == 0)
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{
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*roff = 0;
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*rlen = clen;
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return 0;
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}
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if ((ctype & RDP_MPPC_RESET) != 0)
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{
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g_mppc_dict.roff = 0;
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}
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if ((ctype & RDP_MPPC_FLUSH) != 0)
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{
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memset(dict, 0, RDP_MPPC_DICT_SIZE);
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g_mppc_dict.roff = 0;
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}
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*roff = 0;
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*rlen = 0;
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walker = g_mppc_dict.roff;
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next_offset = walker;
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old_offset = next_offset;
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*roff = old_offset;
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if (clen == 0)
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return 0;
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clen += i;
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do
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{
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if (walker_len == 0)
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{
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if (i >= clen)
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break;
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walker = data[i++] << 24;
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walker_len = 8;
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}
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if (walker >= 0)
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{
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if (walker_len < 8)
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{
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if (i >= clen)
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{
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if (walker != 0)
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return -1;
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break;
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}
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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walker_len += 8;
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}
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if (next_offset >= RDP_MPPC_DICT_SIZE)
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return -1;
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dict[next_offset++] = (uint8)((uint32)walker >> 24);
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walker <<= 8;
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walker_len -= 8;
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continue;
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}
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walker <<= 1;
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if (--walker_len == 0)
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{
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if (i >= clen)
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return -1;
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walker = data[i++] << 24;
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walker_len = 8;
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}
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if (walker >= 0)
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{
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if (walker_len < 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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walker_len += 8;
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}
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if (next_offset >= RDP_MPPC_DICT_SIZE)
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return -1;
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dict[next_offset++] = (uint8)(walker >> 24 | 0x80);
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walker <<= 8;
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walker_len -= 8;
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continue;
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}
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walker <<= 1;
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if (--walker_len < (big ? 3 : 2))
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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walker_len += 8;
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}
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if (big)
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{
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switch (((uint32)walker) >> 29)
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{
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case 7:
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for (; walker_len < 9; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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walker <<= 3;
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match_off = ((uint32)walker) >> 26;
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walker <<= 6;
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walker_len -= 9;
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break;
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case 6:
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for (; walker_len < 11; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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walker <<= 3;
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match_off = (((uint32)walker) >> 24) + 64;
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walker <<= 8;
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walker_len -= 11;
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break;
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case 5:
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case 4:
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for (; walker_len < 13; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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walker <<= 2;
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match_off = (((uint32)walker) >> 21) + 320;
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walker <<= 11;
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walker_len -= 13;
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break;
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default:
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for (; walker_len < 17; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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walker <<= 1;
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match_off = (((uint32)walker) >> 16) + 2368;
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walker <<= 16;
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walker_len -= 17;
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break;
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}
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}
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else
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{
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switch (((uint32)walker) >> 30)
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{
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case 3:
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if (walker_len < 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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walker_len += 8;
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}
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walker <<= 2;
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match_off = ((uint32)walker) >> 26;
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walker <<= 6;
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walker_len -= 8;
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break;
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case 2:
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for (; walker_len < 10; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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walker <<= 2;
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match_off = (((uint32)walker) >> 24) + 64;
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walker <<= 8;
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walker_len -= 10;
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break;
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default:
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for (; walker_len < 14; walker_len += 8)
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{
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if (i >= clen)
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return -1;
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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match_off = (walker >> 18) + 320;
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walker <<= 14;
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walker_len -= 14;
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break;
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}
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}
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if (walker_len == 0)
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{
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if (i >= clen)
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return -1;
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walker = data[i++] << 24;
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walker_len = 8;
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}
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match_len = 0;
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if (walker >= 0)
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{
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match_len = 3;
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walker <<= 1;
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walker_len--;
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}
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else
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{
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match_bits = big ? 14 : 11;
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do
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{
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walker <<= 1;
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if (--walker_len == 0)
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{
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if (i >= clen)
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return -1;
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walker = data[i++] << 24;
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walker_len = 8;
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}
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if (walker >= 0)
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break;
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if (--match_bits == 0)
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{
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return -1;
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}
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} while (1);
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match_len = (big ? 16 : 13) - match_bits;
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walker <<= 1;
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if (--walker_len < match_len)
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{
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for (; walker_len < match_len; walker_len += 8)
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{
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if (i >= clen)
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{
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return -1;
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}
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walker |= (data[i++] & 0xff) << (24 - walker_len);
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}
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}
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match_bits = match_len;
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match_len = (walker >> (32 - match_bits));
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match_len &= ((1 << match_bits) - 1);
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match_len |= (1 << match_bits);
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walker <<= match_bits;
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walker_len -= match_bits;
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}
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if (next_offset + match_len >= RDP_MPPC_DICT_SIZE)
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{
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return -1;
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}
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k = (next_offset - match_off) & (big ? 65535 : 8191);
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do
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{
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dict[next_offset++] = dict[k++];
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} while (--match_len != 0);
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} while (1);
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g_mppc_dict.roff = next_offset;
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*roff = old_offset;
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*rlen = next_offset - old_offset;
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return 0;
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}
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