mirror of
https://github.com/libretro/scummvm.git
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119 lines
2.5 KiB
C++
119 lines
2.5 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (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, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#include "common/endian.h"
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#include "cine/unpack.h"
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namespace Cine {
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uint32 CineUnpacker::readSource() {
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uint32 value = READ_BE_UINT32(_src);
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_src -= 4;
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return value;
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}
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int CineUnpacker::rcr(int CF) {
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int rCF = (_chk & 1);
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_chk >>= 1;
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if (CF) {
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_chk |= 0x80000000;
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}
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return rCF;
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}
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int CineUnpacker::nextBit() {
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int CF = rcr(0);
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if (_chk == 0) {
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_chk = readSource();
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_crc ^= _chk;
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CF = rcr(1);
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}
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return CF;
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}
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uint16 CineUnpacker::getBits(byte numBits) {
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uint16 c = 0;
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while (numBits--) {
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c <<= 1;
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c |= nextBit();
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}
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return c;
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}
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void CineUnpacker::unpackHelper1(byte numBits, byte addCount) {
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uint16 count = getBits(numBits) + addCount + 1;
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_datasize -= count;
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while (count--) {
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*_dst = (byte)getBits(8);
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--_dst;
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}
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}
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void CineUnpacker::unpackHelper2(byte numBits) {
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uint16 i = getBits(numBits);
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uint16 count = _size + 1;
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_datasize -= count;
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while (count--) {
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*_dst = *(_dst + i);
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--_dst;
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}
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}
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bool CineUnpacker::unpack(byte *dst, const byte *src, int srcLen) {
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_src = src + srcLen - 4;
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_datasize = readSource();
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_dst = dst + _datasize - 1;
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_size = 0;
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_crc = readSource();
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_chk = readSource();
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_crc ^= _chk;
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do {
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if (!nextBit()) {
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_size = 1;
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if (!nextBit()) {
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unpackHelper1(3, 0);
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} else {
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unpackHelper2(8);
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}
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} else {
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uint16 c = getBits(2);
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if (c == 3) {
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unpackHelper1(8, 8);
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} else if (c < 2) {
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_size = c + 2;
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unpackHelper2(c + 9);
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} else {
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_size = getBits(8);
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unpackHelper2(12);
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}
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}
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} while (_datasize > 0 && _src >= src - 4);
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return _crc == 0;
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}
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} // End of namespace Cine
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