scummvm/devtools/create_xeen/cc.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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

 // Disable symbol overrides so that we can use system headers.
#define FORBIDDEN_SYMBOL_ALLOW_ALL

#include "cc.h"
#include "common/endian.h"

uint16 CCArchive::convertNameToId(const Common::String &resourceName) {
	if (resourceName.empty())
		return 0xffff;

	Common::String name = resourceName;
	name.toUppercase();

	// Check if a resource number is being directly specified
	if (name.size() == 4) {
		char *endPtr;
		uint16 num = (uint16)strtol(name.c_str(), &endPtr, 16);
		if (!*endPtr)
			return num;
	}

	const byte *msgP = (const byte *)name.c_str();
	int total = *msgP++;
	for (; *msgP; total += *msgP++) {
		// Rotate the bits in 'total' right 7 places
		total = (total & 0x007F) << 9 | (total & 0xFF80) >> 7;
	}

	return total;
}

void CCArchive::loadIndex() {
	int count = _file.readUint16LE();
	long size = count * 8;

	// Read in the data for the archive's index
	byte *rawIndex = new byte[size];

	if (_file.read(rawIndex, size) != size) {
		delete[] rawIndex;
		error("Failed to read %ld bytes from CC archive", size);
	}

	// Decrypt the index
	int seed = 0xac;
	for (int i = 0; i < count * 8; ++i, seed += 0x67) {
		rawIndex[i] = (byte)((((rawIndex[i] << 2) | (rawIndex[i] >> 6)) + seed) & 0xff);
	}

	// Extract the index data into entry structures
	_index.resize(count);
	const byte *entryP = &rawIndex[0];
	for (int idx = 0; idx < count; ++idx, entryP += 8) {
		CCEntry &entry = _index[idx];
		entry._id = READ_LE_UINT16(entryP);
		entry._offset = READ_LE_UINT32(entryP + 2) & 0xffffff;
		entry._size = READ_LE_UINT16(entryP + 5);
		assert(!entryP[7]);
	}

	delete[] rawIndex;
}

void CCArchive::saveIndex() {
	// Fill up the data for the index entries into a raw data block
	byte *rawIndex = new byte[_index.size() * 8];
	byte b;

	byte *entryP = rawIndex;
	uint entryOffset = 8 * _index.size() + 2;
	for (uint i = 0; i < _index.size(); ++i, entryP += 8) {
		CCEntry &entry = _index[i];
		entry._offset = entryOffset;
		entryOffset += entry._size;

		WRITE_LE_UINT16(&entryP[0], entry._id);
		WRITE_LE_UINT32(&entryP[2], entry._offset);
		WRITE_LE_UINT16(&entryP[5], entry._size);
		entryP[7] = 0;
	}

	// Encrypt the index
	int seed = 0xac;
	for (uint i = 0; i < _index.size() * 8; ++i, seed += 0x67) {
		b = (rawIndex[i] - seed) & 0xff;
		b = (byte)((b >> 2) | (b << 6));

		assert(rawIndex[i] == (byte)((((b << 2) | (b >> 6)) + seed) & 0xff));
		rawIndex[i] = b;
	}

	// Write out the number of entries and the encrypted index data
	_file.writeWord(_index.size());
	_file.write(rawIndex, _index.size() * 8);

	delete[] rawIndex;
}

void CCArchive::saveEntries() {
	for (uint idx = 0; idx < _index.size(); ++idx) {
		CCEntry &ccEntry = _index[idx];

		// Encrypt the entry
		for (int i = 0; i < ccEntry._size; ++i)
			ccEntry._data[i] ^= 0x35;

		// Write out the entry
		_file.seek(ccEntry._offset);
		_file.write(ccEntry._data, ccEntry._size);
	}
}

void CCArchive::close() {
	if (_mode == kWrite) {
		saveIndex();
		saveEntries();
	}
}

void CCArchive::add(const Common::String &name, Common::MemFile &f) {
	assert(_mode == kWrite);
	_index.push_back(CCEntry(convertNameToId(name), f.getData(), f.size()));
}

Common::MemFile CCArchive::getMember(const Common::String &name) {
	uint16 id = convertNameToId(name);

	for (uint idx = 0; idx < _index.size(); ++idx) {
		CCEntry &entry = _index[idx];
		if (entry._id == id) {
			if (_file.seek(entry._offset) != 0)
				error("Failed to seek to %d for CC archive", entry._offset);

			if (_file.read(entry._data, entry._size) != entry._size)
				error("Failed to read %hu bytes from CC archive", entry._size);

			// Decrypt the entry
			for (int i = 0; i < entry._size; ++i)
				entry._data[i] ^= 0x35;

			return Common::MemFile(entry._data, entry._size);
		}
	}

	error("Failed to find %s", name.c_str());
}