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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 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.
*
* $URL$
* $Id$
*
*/
#ifndef SCUMM_SAVELOAD_H
#define SCUMM_SAVELOAD_H
#include "common/scummsys.h"
#include <stddef.h> // for ptrdiff_t
namespace Common {
class SeekableReadStream;
class WriteStream;
}
namespace Scumm {
/**
* The current savegame format version.
* Our save/load system uses an elaborate scheme to allow us to modify the
* savegame while keeping full backward compatibility, in the sense that newer
* ScummVM versions always are able to load old savegames.
* In order to achieve that, we store a version in the savegame files, and whenever
* the savegame layout is modified, the version is incremented.
*
* This roughly works by marking each savegame entry with a range of versions
* for which it is valid; the save/load code iterates over all entries, but
* only saves/loads those which are valid for the version of the savegame
* which is being loaded/saved currently.
*/
#define CURRENT_VER 74
/**
* An auxillary macro, used to specify savegame versions. We use this instead
* of just writing the raw version, because this way they stand out more to
* the reading eye, making it a bit easier to navigate through the code.
*/
#define VER(x) x
/**
* The OFFS macro essentially provides the functionality of offsetof(), that
* is, it determines the offset of a struct/class member within instances of
* that class.
*
* This is a place where we cheat a bit and sacrifice some potential portability
* (although so far we haven't encountered any platform where this matters).
*
* To work around a warning in GCC 3.2 (and 3.1 ?) regarding non-POD types,
* we use a small trick: instead of 0 we use 42. Why? Well, it seems newer GCC
* versions have a heuristic built in to detect "offset-of" patterns - which is exactly
* what our OFFS macro does. Now, for non-POD types this is not really legal, because
* member need not be at a fixed offset relative to the variable, even if they are in
* current reality (many of our complex structs are non-POD; for an explanation of
* what POD means refer to <http://en.wikipedia.org/wiki/Plain_Old_Data_Structures> or
* to <http://www.informit.com/guides/content.asp?g=cplusplus&seqNum=32&rl=1>)
*/
#define OFFS(type,item) (((ptrdiff_t)(&((type*)42)->type::item))-42)
/**
* Similar to the OFFS macro, this macro computes the size (in bytes) of a
* member of a given struct/class type.
*/
#define SIZE(type,item) sizeof(((type*)42)->type::item)
// Any item that is still in use automatically gets a maxVersion equal to CURRENT_VER
#define MKLINE(type,item,saveas,minVer) {OFFS(type,item),saveas,SIZE(type,item),minVer,CURRENT_VER}
#define MKARRAY(type,item,saveas,dim,minVer) {OFFS(type,item),128|saveas,SIZE(type,item),minVer,CURRENT_VER}, {dim,1,0,0,0}
#define MKARRAY2(type,item,saveas,dim,dim2,rowlen,minVer) {OFFS(type,item),128|saveas,SIZE(type,item),minVer,CURRENT_VER}, {dim,dim2,rowlen,0,0}
// Use this if you have an entry that used to be smaller:
#define MKLINE_OLD(type,item,saveas,minVer,maxVer) {OFFS(type,item),saveas,SIZE(type,item),minVer,maxVer}
#define MKARRAY_OLD(type,item,saveas,dim,minVer,maxVer) {OFFS(type,item),128|saveas,SIZE(type,item),minVer,maxVer}, {dim,1,0,0,0}
#define MKARRAY2_OLD(type,item,saveas,dim,dim2,rowlen,minVer,maxVer) {OFFS(type,item),128|saveas,SIZE(type,item),minVer,maxVer}, {dim,dim2,rowlen,0,0}
// An obsolete item/array, to be ignored upon load. We retain the type/item params to make it easier to debug.
// Obsolete items have size == 0.
#define MK_OBSOLETE(type,item,saveas,minVer,maxVer) {0,saveas,0,minVer,maxVer}
#define MK_OBSOLETE_ARRAY(type,item,saveas,dim,minVer,maxVer) {0,128|saveas,0,minVer,maxVer}, {dim,1,0,0,0}
#define MK_OBSOLETE_ARRAY2(type,item,saveas,dim,dim2,rowlen,minVer,maxVer) {0,128|saveas,0,minVer,maxVer}, {dim,dim2,rowlen,0,0}
// End marker
#define MKEND() {0xFFFF,0xFF,0xFF,0,0}
enum {
sleByte = 1,
sleUint8 = 1,
sleInt8 = 1,
sleInt16 = 2,
sleUint16 = 3,
sleInt32 = 4,
sleUint32 = 5
};
struct SaveLoadEntry {
uint32 offs; // or: array dimension
uint16 type; // or: array dimension 2
uint16 size; // or: array row length
uint8 minVersion;
uint8 maxVersion;
};
class Serializer {
public:
Serializer(Common::SeekableReadStream *in, Common::WriteStream *out, uint32 savegameVersion)
: _loadStream(in), _saveStream(out),
_savegameVersion(savegameVersion)
{ }
void saveLoadArrayOf(void *b, int len, int datasize, byte filetype);
void saveLoadArrayOf(void *b, int num, int datasize, const SaveLoadEntry *sle);
void saveLoadEntries(void *d, const SaveLoadEntry *sle);
bool isSaving() { return (_saveStream != 0); }
bool isLoading() { return (_loadStream != 0); }
uint32 getVersion() { return _savegameVersion; }
void saveUint32(uint32 d);
void saveUint16(uint16 d);
void saveByte(byte b);
byte loadByte();
uint16 loadUint16();
uint32 loadUint32();
void saveBytes(void *b, int len);
void loadBytes(void *b, int len);
protected:
Common::SeekableReadStream *_loadStream;
Common::WriteStream *_saveStream;
uint32 _savegameVersion;
void saveArrayOf(void *b, int len, int datasize, byte filetype);
void loadArrayOf(void *b, int len, int datasize, byte filetype);
void saveEntries(void *d, const SaveLoadEntry *sle);
void loadEntries(void *d, const SaveLoadEntry *sle);
};
// Mixin class / interface. Maybe call it ISerializable or SerializableMixin ?
class Serializable {
public:
virtual ~Serializable() {}
virtual void saveLoadWithSerializer(Serializer *ser) = 0;
};
} // End of namespace Scumm
#endif
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