scummvm/engines/tony/mpal/lzo.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
/* minilzo.c -- mini subset of the LZO real-time data compression library

   This file is part of the LZO real-time data compression library.

   Copyright (C) 2011 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2010 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2009 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer
   All Rights Reserved.

   The LZO library is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   The LZO library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the LZO library; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

   Markus F.X.J. Oberhumer
   <markus@oberhumer.com>
   http://www.oberhumer.com/opensource/lzo/
 */

#include "lzo.h"
#include "common/textconsole.h"

namespace Tony {

namespace MPAL {

#define pd(a, b)       ((uint32) ((a) - (b)))
#define TEST_IP        (ip < ip_end)

#define M2_MAX_OFFSET 0x0800

/**
 * Decompresses an LZO compressed resource
 */
int lzo1x_decompress(const byte *in, uint32 in_len, byte *out, uint32 *out_len) {
	register byte *op;
	register const byte *ip;
	register uint32 t = 0;
	register const byte *m_pos;

	const byte * const ip_end = in + in_len;

	*out_len = 0;

	op = out;
	ip = in;

	if (*ip > 17) {
		t = *ip++ - 17;
		if (t < 4)
			goto match_next;
		assert(t > 0);
		do
			*op++ = *ip++;
		while (--t > 0);
		goto first_literal_run;
	}

	while (TEST_IP) {
		t = *ip++;
		if (t >= 16)
			goto match;
		if (t == 0) {
			while (*ip == 0) {
				t += 255;
				ip++;
			}
			t += 15 + *ip++;
		}
		assert(t > 0);

		*op++ = *ip++;
		*op++ = *ip++;
		*op++ = *ip++;
		do
			*op++ = *ip++;
		while (--t > 0);

first_literal_run:
		t = *ip++;
		if (t >= 16)
			goto match;

		m_pos = op - (1 + M2_MAX_OFFSET);
		m_pos -= t >> 2;
		m_pos -= *ip++ << 2;

		*op++ = *m_pos++;
		*op++ = *m_pos++;
		*op++ = *m_pos;

		goto match_done;

		do {
match:
			if (t >= 64) {
				m_pos = op - 1;
				m_pos -= (t >> 2) & 7;
				m_pos -= *ip++ << 3;
				t = (t >> 5) - 1;
				assert(t > 0);
				goto copy_match;
			} else if (t >= 32) {
				t &= 31;
				if (t == 0) {
					while (*ip == 0) {
						t += 255;
						ip++;
					}
					t += 31 + *ip++;
				}
				m_pos = op - 1;
				m_pos -= (ip[0] >> 2) + (ip[1] << 6);
				ip += 2;
			} else if (t >= 16) {
				m_pos = op;
				m_pos -= (t & 8) << 11;
				t &= 7;
				if (t == 0) {
					while (*ip == 0) {
						t += 255;
						ip++;
					}
					t += 7 + *ip++;
				}
				m_pos -= (ip[0] >> 2) + (ip[1] << 6);
				ip += 2;
				if (m_pos == op)
					goto eof_found;
				m_pos -= 0x4000;
			} else {
				m_pos = op - 1;
				m_pos -= t >> 2;
				m_pos -= *ip++ << 2;
				*op++ = *m_pos++;
				*op++ = *m_pos;
				goto match_done;
			}

			assert(t > 0);
			{
copy_match:
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				do
					*op++ = *m_pos++;
				while (--t > 0);
			}

match_done:
			t = ip[-2] & 3;
			if (t == 0)
				break;

match_next:
			assert(t > 0);
			assert(t < 4);
			*op++ = *ip++;
			if (t > 1) {
				*op++ = *ip++;
				if (t > 2)
					*op++ = *ip++;
			}
			t = *ip++;
		} while (TEST_IP);
	}

eof_found:
	assert(t == 1);
	*out_len = pd(op, out);
	return (ip == ip_end ? LZO_E_OK :
	        (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));

}

} // end of namespace MPAL
} // end of namespace Tony