/* 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.
 *
 * $URL$
 * $Id$
 *
 */

/*
 * This code is based on Broken Sword 2.5 engine
 *
 * Copyright (c) Malte Thiesen, Daniel Queteschiner and Michael Elsdoerfer
 *
 * Licensed under GNU GPL v2
 *
 */

#ifndef SWORD25_PERSISTENCEBLOCK_H
#define SWORD25_PERSISTENCEBLOCK_H

#include "sword25/kernel/common.h"

namespace Sword25 {

class PersistenceBlock {
public:
	static uint getSInt32Size() {
		return sizeof(signed int) + sizeof(byte);
	}
	static uint getUInt32Size() {
		return sizeof(uint) + sizeof(byte);
	}
	static uint getFloat32Size() {
		return sizeof(float) + sizeof(byte);
	}
	static uint getBoolSize() {
		return sizeof(byte) + sizeof(byte);
	}
	static uint getStringSize(const Common::String &string) {
		return static_cast<uint>(sizeof(uint) + string.size() + sizeof(byte));
	}

protected:
	enum {
		SINT_MARKER,
		UINT_MARKER,
		FLOAT_MARKER,
		STRING_MARKER,
		BOOL_MARKER,
		BLOCK_MARKER
	};

	// -----------------------------------------------------------------------------
	// Endianess Conversions
	// -----------------------------------------------------------------------------
	//
	// Everything is stored in Little Endian
	// Big Endian Systems will need to be byte swapped during both saving and reading of saved values
	//

	template<typename T>
	static T convertEndianessFromSystemToStorage(T value) {
		if (isBigEndian())
			reverseByteOrder(&value);
		return value;
	}

	template<typename T>
	static T convertEndianessFromStorageToSystem(T value) {
		if (isBigEndian())
			reverseByteOrder(&value);
		return value;
	}

private:
	static bool isBigEndian() {
		uint dummy = 1;
		byte *dummyPtr = reinterpret_cast<byte *>(&dummy);
		return dummyPtr[0] == 0;
	}

	template<typename T>
	static void swap(T &one, T &two) {
		T temp = one;
		one = two;
		two = temp;
	}

	static void reverseByteOrder(void *ptr) {
		// Reverses the byte order of the 32-bit word pointed to by Ptr
		byte *charPtr = static_cast<byte *>(ptr);
		swap(charPtr[0], charPtr[3]);
		swap(charPtr[1], charPtr[2]);
	}
};

#define CTASSERT(ex) typedef char ctassert_type[(ex) ? 1 : -1]
CTASSERT(sizeof(byte) == 1);
CTASSERT(sizeof(signed int) == 4);
CTASSERT(sizeof(uint) == 4);
CTASSERT(sizeof(float) == 4);
#undef CTASSERT

} // End of namespace Sword25

#endif