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engines/ultima/ultima8/filesys/flex_file.cpp

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+/* 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/>.
+ *
+ */
+
+#include "common/memstream.h"
+
+#include "ultima/ultima8/misc/debugger.h"
+#include "ultima/ultima8/filesys/flex_file.h"
+
+namespace Ultima {
+namespace Ultima8 {
+
+static const int FLEX_TABLE_OFFSET = 0x80;
+static const int FLEX_HDR_SIZE = 0x52;
+static const char FLEX_HDR_PAD = 0x1A;
+
+FlexFile::FlexFile(Common::SeekableReadStream *rs) : _rs(rs) {
+	_valid = isFlexFile(_rs);
+
+	if (_valid)
+		_valid = readMetadata();
+}
+
+FlexFile::~FlexFile() {
+	delete _rs;
+}
+
+//static
+bool FlexFile::isFlexFile(Common::SeekableReadStream *rs) {
+	rs->seek(0);
+	int i;
+	char buf[FLEX_HDR_SIZE];
+	rs->read(buf, FLEX_HDR_SIZE);
+
+	for (i = 0; i < FLEX_HDR_SIZE; ++i) {
+		if (buf[i] == FLEX_HDR_PAD) break;
+	}
+
+	if (i < FLEX_HDR_SIZE) {
+		for (++i; i < FLEX_HDR_SIZE; ++i) {
+			if (buf[i] != FLEX_HDR_PAD) return false;
+		}
+		return true;
+	}
+	return false;
+}
+
+bool FlexFile::readMetadata() {
+	_rs->seek(FLEX_HDR_SIZE + 2);
+	uint32 count = _rs->readUint32LE();
+
+	if (count > 4095) {
+		// In practice the largest flex in either Crusader or U8 games has
+		// 3074 entries, so this seems invalid.
+		warning("Flex invalid: improbable number of entries %d", count);
+		return false;
+	}
+
+	if (_rs->size() < FLEX_TABLE_OFFSET + 8 * count) {
+		warning("Flex invalid: stream not long enough for offset table");
+		return false;
+	}
+
+	_entries.reserve(count);
+	_rs->seek(FLEX_TABLE_OFFSET);
+	for (unsigned int i = 0; i < count; ++i) {
+		FileEntry fe;
+		fe._offset = _rs->readUint32LE();
+		fe._size = _rs->readUint32LE();
+
+		_entries.push_back(fe);
+	}
+
+	return true;
+}
+
+Common::SeekableReadStream *FlexFile::getDataSource(uint32 index, bool is_text) {
+	uint32 size;
+	uint8 *buf = getObject(index, &size);
+
+	if (!buf)
+		return nullptr;
+
+	return new Common::MemoryReadStream(buf, size, DisposeAfterUse::YES);
+}
+
+uint8 *FlexFile::getObject(uint32 index, uint32 *sizep) {
+	if (index >= _entries.size())
+		return nullptr;
+
+	uint32 size = _entries[index]._size;
+	if (size == 0)
+		return nullptr;
+
+	uint8 *object = new uint8[size];
+	uint32 offset = _entries[index]._offset;
+
+	_rs->seek(offset);
+	_rs->read(object, size);
+
+	if (sizep)
+		*sizep = size;
+
+	return object;
+}
+
+uint32 FlexFile::getSize(uint32 index) const {
+	if (index >= _entries.size())
+		return 0;
+
+	return _entries[index]._size;
+}
+
+} // End of namespace Ultima8
+} // End of namespace Ultima