cpp/openttd-patchpack/source Files · src/saveload/storage_sl.cpp

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Patric Stout

Feature: framework to make savegames self-descriptive

We won't be able to make it fully self-descriptive (looking at you
MAP-chunks), but anything else can. With this framework, we can
add headers for each chunk explaining how each chunk looks like
in detail.

They also will all be tables, making it a lot easier to read in
external tooling, and opening the way to consider a database
(like SQLite) to use as savegame format.

Lastly, with the headers in the savegame, you can freely add
fields without needing a savegame version bump; older versions
of OpenTTD will simply ignore the new field. This also means
we can remove all the SLE_CONDNULL, as they are irrelevant.

The next few commits will start using this framework.

/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file storage_sl.cpp Code handling saving and loading of persistent storages. */

#include "../stdafx.h"
#include "../newgrf_storage.h"
#include "saveload.h"

#include "../safeguards.h"

/** Description of the data to save and load in #PersistentStorage. */
static const SaveLoad _storage_desc[] = {
	 SLE_CONDVAR(PersistentStorage, grfid,    SLE_UINT32,                  SLV_6, SL_MAX_VERSION),
	 SLE_CONDARR(PersistentStorage, storage,  SLE_UINT32,  16,           SLV_161, SLV_EXTEND_PERSISTENT_STORAGE),
	 SLE_CONDARR(PersistentStorage, storage,  SLE_UINT32, 256,           SLV_EXTEND_PERSISTENT_STORAGE, SL_MAX_VERSION),
};

/** Load persistent storage data. */
static void Load_PSAC()
{
	int index;

	while ((index = SlIterateArray()) != -1) {
		assert(PersistentStorage::CanAllocateItem());
		PersistentStorage *ps = new (index) PersistentStorage(0, 0, 0);
		SlObject(ps, _storage_desc);
	}
}

/** Save persistent storage data. */
static void Save_PSAC()
{
	/* Write the industries */
	for (PersistentStorage *ps : PersistentStorage::Iterate()) {
		ps->ClearChanges();
		SlSetArrayIndex(ps->index);
		SlObject(ps, _storage_desc);
	}
}

/** Chunk handler for persistent storages. */
static const ChunkHandler persistent_storage_chunk_handlers[] = {
	{ 'PSAC', Save_PSAC, Load_PSAC, nullptr, nullptr, CH_ARRAY },
};

extern const ChunkHandlerTable _persistent_storage_chunk_handlers(persistent_storage_chunk_handlers);