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[openttd-joker.git] / src / saveload / saveload.cpp

/* $Id$ */

/*
 * 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 saveload.cpp
 * All actions handling saving and loading goes on in this file. The general actions
 * are as follows for saving a game (loading is analogous):
 * <ol>
 * <li>initialize the writer by creating a temporary memory-buffer for it
 * <li>go through all to-be saved elements, each 'chunk' (#ChunkHandler) prefixed by a label
 * <li>use their description array (#SaveLoad) to know what elements to save and in what version
 *    of the game it was active (used when loading)
 * <li>write all data byte-by-byte to the temporary buffer so it is endian-safe
 * <li>when the buffer is full; flush it to the output (eg save to file) (_sl.buf, _sl.bufp, _sl.bufe)
 * <li>repeat this until everything is done, and flush any remaining output to file
 * </ol>
 */
#include "../stdafx.h"
#include "../debug.h"
#include "../station_base.h"
#include "../dock_base.h"
#include "../thread/thread.h"
#include "../town.h"
#include "../network/network.h"
#include "../window_func.h"
#include "../strings_func.h"
#include "../core/endian_func.hpp"
#include "../vehicle_base.h"
#include "../company_func.h"
#include "../date_func.h"
#include "../autoreplace_base.h"
#include "../roadstop_base.h"
#include "../linkgraph/linkgraph.h"
#include "../linkgraph/linkgraphjob.h"
#include "../statusbar_gui.h"
#include "../fileio_func.h"
#include "../gamelog.h"
#include "../string_func.h"
#include "../string_func_extra.h"
#include "../fios.h"
#include "../error.h"

#include "../tbtr_template_vehicle.h"

#include "table/strings.h"

#include "saveload_internal.h"
#include "saveload_filter.h"

#include "../safeguards.h"

#include <deque>
#include <vector>

/*
 * Previous savegame versions, the trunk revision where they were
 * introduced and the released version that had that particular
 * savegame version.
 * Up to savegame version 18 there is a minor version as well.
 *
 *    1.0         0.1.x, 0.2.x
 *    2.0         0.3.0
 *    2.1         0.3.1, 0.3.2
 *    3.x         lost
 *    4.0     1
 *    4.1   122   0.3.3, 0.3.4
 *    4.2  1222   0.3.5
 *    4.3  1417
 *    4.4  1426
 *    5.0  1429
 *    5.1  1440
 *    5.2  1525   0.3.6
 *    6.0  1721
 *    6.1  1768
 *    7.0  1770
 *    8.0  1786
 *    9.0  1909
 *   10.0  2030
 *   11.0  2033
 *   11.1  2041
 *   12.1  2046
 *   13.1  2080   0.4.0, 0.4.0.1
 *   14.0  2441
 *   15.0  2499
 *   16.0  2817
 *   16.1  3155
 *   17.0  3212
 *   17.1  3218
 *   18    3227
 *   19    3396
 *   20    3403
 *   21    3472   0.4.x
 *   22    3726
 *   23    3915
 *   24    4150
 *   25    4259
 *   26    4466
 *   27    4757
 *   28    4987
 *   29    5070
 *   30    5946
 *   31    5999
 *   32    6001
 *   33    6440
 *   34    6455
 *   35    6602
 *   36    6624
 *   37    7182
 *   38    7195
 *   39    7269
 *   40    7326
 *   41    7348   0.5.x
 *   42    7573
 *   43    7642
 *   44    8144
 *   45    8501
 *   46    8705
 *   47    8735
 *   48    8935
 *   49    8969
 *   50    8973
 *   51    8978
 *   52    9066
 *   53    9316
 *   54    9613
 *   55    9638
 *   56    9667
 *   57    9691
 *   58    9762
 *   59    9779
 *   60    9874
 *   61    9892
 *   62    9905
 *   63    9956
 *   64   10006
 *   65   10210
 *   66   10211
 *   67   10236
 *   68   10266
 *   69   10319
 *   70   10541
 *   71   10567
 *   72   10601
 *   73   10903
 *   74   11030
 *   75   11107
 *   76   11139
 *   77   11172
 *   78   11176
 *   79   11188
 *   80   11228
 *   81   11244
 *   82   11410
 *   83   11589
 *   84   11822
 *   85   11874
 *   86   12042
 *   87   12129
 *   88   12134
 *   89   12160
 *   90   12293
 *   91   12347
 *   92   12381   0.6.x
 *   93   12648
 *   94   12816
 *   95   12924
 *   96   13226
 *   97   13256
 *   98   13375
 *   99   13838
 *  100   13952
 *  101   14233
 *  102   14332
 *  103   14598
 *  104   14735
 *  105   14803
 *  106   14919
 *  107   15027
 *  108   15045
 *  109   15075
 *  110   15148
 *  111   15190
 *  112   15290
 *  113   15340
 *  114   15601
 *  115   15695
 *  116   15893   0.7.x
 *  117   16037
 *  118   16129
 *  119   16242
 *  120   16439
 *  121   16694
 *  122   16855
 *  123   16909
 *  124   16993
 *  125   17113
 *  126   17433
 *  127   17439
 *  128   18281
 *  129   18292
 *  130   18404
 *  131   18481
 *  132   18522
 *  133   18674
 *  134   18703
 *  135   18719
 *  136   18764
 *  137   18912
 *  138   18942   1.0.x
 *  139   19346
 *  140   19382
 *  141   19799
 *  142   20003
 *  143   20048
 *  144   20334
 *  145   20376
 *  146   20446
 *  147   20621
 *  148   20659
 *  149   20832
 *  150   20857
 *  151   20918
 *  152   21171
 *  153   21263
 *  154   21426
 *  155   21453
 *  156   21728
 *  157   21862
 *  158   21933
 *  159   21962
 *  160   21974   1.1.x
 *  161   22567
 *  162   22713
 *  163   22767
 *  164   23290
 *  165   23304
 *  166   23415
 *  167   23504
 *  168   23637
 *  169   23816
 *  170   23826
 *  171   23835
 *  172   23947
 *  173   23967   1.2.0-RC1
 *  174   23973   1.2.x
 *  175   24136
 *  176   24446
 *  177   24619
 *  178   24789
 *  179   24810
 *  180   24998   1.3.x
 *  181   25012
 *  182   25296
 *  183   25363
 *  184   25508
 *  185   25620
 *  186   25833
 *  187   25899
 *  188   26169   1.4.x
 *  189   26450
 *  190   26547
 *  191   26646
 *  192   26700
 *  193   26802
 *  194   26881   1.5.x, 1.6.0
 *  195   27572   1.6.x
 *  196   27778   1.7.x
 *  197   27978   1.8.x
 *  198
 *  
 *  255   SL_PATCH_PACK
 *  256   SL_PATCH_PACK_DAYLENGTH
 *  257   SL_PATCH_PACK_TOWN_BUILDINGS
 *  258   SL_PATCH_PACK_MAP_FEATURES
 *  259   SL_PATCH_PACK_SAFE_WAITING_LOCATION
 *  260   SL_PATCH_PACK_1_2
 *  261   SL_PATCH_PACK_1_3
 *  262   SL_PATCH_PACK_1_4
 *  263   SL_PATCH_PACK_1_5
 *  264   SL_PATCH_PACK_1_6
 *  265   SL_PATCH_PACK_1_7
 *  266   SL_PATCH_PACK_1_8
 *  267   SL_PATCH_PACK_1_9
 *  268   SL_PATCH_PACK_1_10
 *  269   SL_PATCH_PACK_1_11
 *  270   SL_PATCH_PACK_1_12
 *  271   SL_PATCH_PACK_1_14
 *  272   SL_PATCH_PACK_1_15
 *  273   SL_PATCH_PACK_1_16
 *  274   SL_PATCH_PACK_1_18
 *  275   SL_PATCH_PACK_1_18_3
 *  276   SL_PATCH_PACK_1_18_4
 *  277   SL_PATCH_PACK_1_18_6
 *  278   SL_PATCH_PACK_1_19
 *  279   SL_PATCH_PACK_1_20
 *  280   SL_PATCH_PACK_1_21
 *  281   SL_PATCH_PACK_1_22
 *  282   SL_PATCH_PACK_1_23
 *  283   SL_PATCH_PACK_1_24
 *  284   SL_PATCH_PACK_1_25
 *  285   SL_PATCH_PACK_1_26
 *  286   SL_PATCH_PACK_1_27
 */
extern const uint16 SAVEGAME_VERSION = SL_PATCH_PACK_1_27; ///< Current savegame version of OpenTTD.

SavegameType _savegame_type; ///< type of savegame we are loading
FileToSaveLoad _file_to_saveload; ///< File to save or load in the openttd loop.

uint32 _ttdp_version;     ///< version of TTDP savegame (if applicable)
uint16 _sl_version;       ///< the major savegame version identifier
byte   _sl_minor_version; ///< the minor savegame version, DO NOT USE!
char _savegame_format[8]; ///< how to compress savegames
bool _do_autosave;        ///< are we doing an autosave at the moment?

/** What are we currently doing? */
enum SaveLoadAction {
        SLA_LOAD,        ///< loading
        SLA_SAVE,        ///< saving
        SLA_PTRS,        ///< fixing pointers
        SLA_NULL,        ///< null all pointers (on loading error)
        SLA_LOAD_CHECK,  ///< partial loading into #_load_check_data
};

enum NeedLength {
        NL_NONE = 0,       ///< not working in NeedLength mode
        NL_WANTLENGTH = 1, ///< writing length and data
        NL_CALCLENGTH = 2, ///< need to calculate the length
};

/** Save in chunks of 128 KiB. */
static const size_t MEMORY_CHUNK_SIZE = 128 * 1024;

/** A buffer for reading (and buffering) savegame data. */
struct ReadBuffer {
        byte buf[MEMORY_CHUNK_SIZE]; ///< Buffer we're going to read from.
        byte *bufp;                  ///< Location we're at reading the buffer.
        byte *bufe;                  ///< End of the buffer we can read from.
        LoadFilter *reader;          ///< The filter used to actually read.
        size_t read;                 ///< The amount of read bytes so far from the filter.

        /**
         * Initialise our variables.
         * @param reader The filter to actually read data.
         */
        ReadBuffer(LoadFilter *reader) : bufp(nullptr), bufe(nullptr), reader(reader), read(0)
        {
        }

        inline byte ReadByte()
        {
                if (this->bufp == this->bufe) {
                        size_t len = this->reader->Read(this->buf, lengthof(this->buf));
                        if (len == 0) SlErrorCorrupt("Unexpected end of chunk");

                        this->read += len;
                        this->bufp = this->buf;
                        this->bufe = this->buf + len;
                }

                return *this->bufp++;
        }

        /**
         * Get the size of the memory dump made so far.
         * @return The size.
         */
        size_t GetSize() const
        {
                return this->read - (this->bufe - this->bufp);
        }
};


/** Container for dumping the savegame (quickly) to memory. */
struct MemoryDumper {
        AutoFreeSmallVector<byte *, 16> blocks; ///< Buffer with blocks of allocated memory.
        byte *buf;                              ///< Buffer we're going to write to.
        byte *bufe;                             ///< End of the buffer we write to.

        /** Initialise our variables. */
        MemoryDumper() : buf(nullptr), bufe(nullptr)
        {
        }

        /**
         * Write a single byte into the dumper.
         * @param b The byte to write.
         */
        inline void WriteByte(byte b)
        {
                /* Are we at the end of this chunk? */
                if (this->buf == this->bufe) {
                        this->buf = CallocT<byte>(MEMORY_CHUNK_SIZE);
                        *this->blocks.Append() = this->buf;
                        this->bufe = this->buf + MEMORY_CHUNK_SIZE;
                }

                *this->buf++ = b;
        }

        /**
         * Flush this dumper into a writer.
         * @param writer The filter we want to use.
         */
        void Flush(SaveFilter *writer)
        {
                uint i = 0;
                size_t t = this->GetSize();

                while (t > 0) {
                        size_t to_write = min(MEMORY_CHUNK_SIZE, t);

                        writer->Write(this->blocks[i++], to_write);
                        t -= to_write;
                }

                writer->Finish();
        }

        /**
         * Get the size of the memory dump made so far.
         * @return The size.
         */
        size_t GetSize() const
        {
                return this->blocks.Length() * MEMORY_CHUNK_SIZE - (this->bufe - this->buf);
        }
};

/** The saveload struct, containing reader-writer functions, buffer, version, etc. */
struct SaveLoadParams {
        SaveLoadAction action;               ///< are we doing a save or a load atm.
        NeedLength need_length;              ///< working in NeedLength (Autolength) mode?
        byte block_mode;                     ///< ???
        bool error;                          ///< did an error occur or not

        size_t obj_len;                      ///< the length of the current object we are busy with
        int array_index, last_array_index;   ///< in the case of an array, the current and last positions

        MemoryDumper *dumper;                ///< Memory dumper to write the savegame to.
        SaveFilter *sf;                      ///< Filter to write the savegame to.

        ReadBuffer *reader;                  ///< Savegame reading buffer.
        LoadFilter *lf;                      ///< Filter to read the savegame from.

        StringID error_str;                  ///< the translatable error message to show
        char *extra_msg;                     ///< the error message

        byte ff_state;                       ///< The state of fast-forward when saving started.
        bool saveinprogress;                 ///< Whether there is currently a save in progress.
};

static SaveLoadParams _sl; ///< Parameters used for/at saveload.

/* these define the chunks */
extern const ChunkHandler _gamelog_chunk_handlers[];
extern const ChunkHandler _map_chunk_handlers[];
extern const ChunkHandler _misc_chunk_handlers[];
extern const ChunkHandler _name_chunk_handlers[];
extern const ChunkHandler _cheat_chunk_handlers[] ;
extern const ChunkHandler _setting_chunk_handlers[];
extern const ChunkHandler _company_chunk_handlers[];
extern const ChunkHandler _engine_chunk_handlers[];
extern const ChunkHandler _veh_chunk_handlers[];
extern const ChunkHandler _waypoint_chunk_handlers[];
extern const ChunkHandler _depot_chunk_handlers[];
extern const ChunkHandler _order_chunk_handlers[];
extern const ChunkHandler _town_chunk_handlers[];
extern const ChunkHandler _sign_chunk_handlers[];
extern const ChunkHandler _station_chunk_handlers[];
extern const ChunkHandler _industry_chunk_handlers[];
extern const ChunkHandler _economy_chunk_handlers[];
extern const ChunkHandler _subsidy_chunk_handlers[];
extern const ChunkHandler _cargomonitor_chunk_handlers[];
extern const ChunkHandler _goal_chunk_handlers[];
extern const ChunkHandler _story_page_chunk_handlers[];
extern const ChunkHandler _ai_chunk_handlers[];
extern const ChunkHandler _game_chunk_handlers[];
extern const ChunkHandler _animated_tile_chunk_handlers[];
extern const ChunkHandler _newgrf_chunk_handlers[];
extern const ChunkHandler _group_chunk_handlers[];
extern const ChunkHandler _cargopacket_chunk_handlers[];
extern const ChunkHandler _autoreplace_chunk_handlers[];
extern const ChunkHandler _labelmaps_chunk_handlers[];
extern const ChunkHandler _linkgraph_chunk_handlers[];
extern const ChunkHandler _airport_chunk_handlers[];
extern const ChunkHandler _object_chunk_handlers[];
extern const ChunkHandler _persistent_storage_chunk_handlers[];
extern const ChunkHandler _plan_chunk_handlers[];
extern const ChunkHandler _trace_restrict_chunk_handlers[];
extern const ChunkHandler _template_replacement_chunk_handlers[];
extern const ChunkHandler _template_vehicle_chunk_handlers[];
extern const ChunkHandler _logic_signal_handlers[];
extern const ChunkHandler _bridge_signal_chunk_handlers[];
extern const ChunkHandler _tunnel_chunk_handlers[];

/** Array of all chunks in a savegame, \c nullptr terminated. */
static const ChunkHandler * const _chunk_handlers[] = {
        _gamelog_chunk_handlers,
        _map_chunk_handlers,
        _misc_chunk_handlers,
        _name_chunk_handlers,
        _cheat_chunk_handlers,
        _setting_chunk_handlers,
        _veh_chunk_handlers,
        _waypoint_chunk_handlers,
        _depot_chunk_handlers,
        _order_chunk_handlers,
        _industry_chunk_handlers,
        _economy_chunk_handlers,
        _subsidy_chunk_handlers,
        _cargomonitor_chunk_handlers,
        _goal_chunk_handlers,
        _story_page_chunk_handlers,
        _engine_chunk_handlers,
        _town_chunk_handlers,
        _sign_chunk_handlers,
        _station_chunk_handlers,
        _company_chunk_handlers,
        _ai_chunk_handlers,
        _game_chunk_handlers,
        _animated_tile_chunk_handlers,
        _newgrf_chunk_handlers,
        _group_chunk_handlers,
        _cargopacket_chunk_handlers,
        _autoreplace_chunk_handlers,
        _labelmaps_chunk_handlers,
        _linkgraph_chunk_handlers,
        _airport_chunk_handlers,
        _object_chunk_handlers,
        _persistent_storage_chunk_handlers,
        _plan_chunk_handlers,
        _trace_restrict_chunk_handlers,
        _template_replacement_chunk_handlers,
        _template_vehicle_chunk_handlers,
        _logic_signal_handlers,
        _bridge_signal_chunk_handlers,
        _tunnel_chunk_handlers,
        nullptr,
};

/**
 * Iterate over all chunk handlers.
 * @param ch the chunk handler iterator
 */
#define FOR_ALL_CHUNK_HANDLERS(ch) \
        for (const ChunkHandler * const *chsc = _chunk_handlers; *chsc != nullptr; chsc++) \
                for (const ChunkHandler *ch = *chsc; ch != nullptr; ch = (ch->flags & CH_LAST) ? nullptr : ch + 1)

/** Null all pointers (convert index -> nullptr) */
static void SlNullPointers()
{
        _sl.action = SLA_NULL;

        /* We don't want any savegame conversion code to run
         * during NULLing; especially those that try to get
         * pointers from other pools. */
        _sl_version = SAVEGAME_VERSION;

        DEBUG(sl, 1, "Nulling pointers");

        FOR_ALL_CHUNK_HANDLERS(ch) {
                if (ch->ptrs_proc != nullptr) {
                        DEBUG(sl, 2, "Nulling pointers for %c%c%c%c", ch->id >> 24, ch->id >> 16, ch->id >> 8, ch->id);
                        ch->ptrs_proc();
                }
        }

        DEBUG(sl, 1, "All pointers nulled");

        assert(_sl.action == SLA_NULL);
}

/**
 * Error handler. Sets everything up to show an error message and to clean
 * up the mess of a partial savegame load.
 * @param string The translatable error message to show.
 * @param extra_msg An extra error message coming from one of the APIs.
 * @note This function does never return as it throws an exception to
 *       break out of all the saveload code.
 */
void NORETURN SlError(StringID string, const char *extra_msg)
{
        /* Distinguish between loading into _load_check_data vs. normal save/load. */
        if (_sl.action == SLA_LOAD_CHECK) {
                _load_check_data.error = string;
                free(_load_check_data.error_data);
                _load_check_data.error_data = (extra_msg == nullptr) ? nullptr : stredup(extra_msg);
        } else {
                _sl.error_str = string;
                free(_sl.extra_msg);
                _sl.extra_msg = (extra_msg == nullptr) ? nullptr : stredup(extra_msg);
        }

        /* We have to nullptr all pointers here; we might be in a state where
         * the pointers are actually filled with indices, which means that
         * when we access them during cleaning the pool dereferences of
         * those indices will be made with segmentation faults as result. */
        if (_sl.action == SLA_LOAD || _sl.action == SLA_PTRS) SlNullPointers();
        throw std::exception();
}

/**
 * Error handler for corrupt savegames. Sets everything up to show the
 * error message and to clean up the mess of a partial savegame load.
 * @param msg Location the corruption has been spotted.
 * @note This function does never return as it throws an exception to
 *       break out of all the saveload code.
 */
void NORETURN SlErrorCorrupt(const char *msg)
{
        SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_SAVEGAME, msg);
}


typedef void (*AsyncSaveFinishProc)();                ///< Callback for when the savegame loading is finished.
static AsyncSaveFinishProc _async_save_finish = nullptr; ///< Callback to call when the savegame loading is finished.
static ThreadObject *_save_thread;                    ///< The thread we're using to compress and write a savegame

/**
 * Called by save thread to tell we finished saving.
 * @param proc The callback to call when saving is done.
 */
static void SetAsyncSaveFinish(AsyncSaveFinishProc proc)
{
        if (_exit_game) return;
        while (_async_save_finish != nullptr) CSleep(10);

        _async_save_finish = proc;
}

/**
 * Handle async save finishes.
 */
void ProcessAsyncSaveFinish()
{
        if (_async_save_finish == nullptr) return;

        _async_save_finish();

        _async_save_finish = nullptr;

        if (_save_thread != nullptr) {
                _save_thread->Join();
                delete _save_thread;
                _save_thread = nullptr;
        }
}

/**
 * Wrapper for reading a byte from the buffer.
 * @return The read byte.
 */
byte SlReadByte()
{
        return _sl.reader->ReadByte();
}

/**
 * Wrapper for writing a byte to the dumper.
 * @param b The byte to write.
 */
void SlWriteByte(byte b)
{
        _sl.dumper->WriteByte(b);
}

static inline int SlReadUint16()
{
        int x = SlReadByte() << 8;
        return x | SlReadByte();
}

static inline uint32 SlReadUint32()
{
        uint32 x = SlReadUint16() << 16;
        return x | SlReadUint16();
}

static inline uint64 SlReadUint64()
{
        uint32 x = SlReadUint32();
        uint32 y = SlReadUint32();
        return (uint64)x << 32 | y;
}

static inline void SlWriteUint16(uint16 v)
{
        SlWriteByte(GB(v, 8, 8));
        SlWriteByte(GB(v, 0, 8));
}

static inline void SlWriteUint32(uint32 v)
{
        SlWriteUint16(GB(v, 16, 16));
        SlWriteUint16(GB(v,  0, 16));
}

static inline void SlWriteUint64(uint64 x)
{
        SlWriteUint32((uint32)(x >> 32));
        SlWriteUint32((uint32)x);
}

/**
 * Read in bytes from the file/data structure but don't do
 * anything with them, discarding them in effect
 * @param length The amount of bytes that is being treated this way
 */
static inline void SlSkipBytes(size_t length)
{
        for (; length != 0; length--) SlReadByte();
}

/**
 * Read in the header descriptor of an object or an array.
 * If the highest bit is set (7), then the index is bigger than 127
 * elements, so use the next byte to read in the real value.
 * The actual value is then both bytes added with the first shifted
 * 8 bits to the left, and dropping the highest bit (which only indicated a big index).
 * x = ((x & 0x7F) << 8) + SlReadByte();
 * @return Return the value of the index
 */
static uint SlReadSimpleGamma()
{
        uint i = SlReadByte();
        if (HasBit(i, 7)) {
                i &= ~0x80;
                if (HasBit(i, 6)) {
                        i &= ~0x40;
                        if (HasBit(i, 5)) {
                                i &= ~0x20;
                                if (HasBit(i, 4)) {
                                        i &= ~0x10;
                                        if (HasBit(i, 3)) {
                                                SlErrorCorrupt("Unsupported gamma");
                                        }
                                        i = SlReadByte(); // 32 bits only.
                                }
                                i = (i << 8) | SlReadByte();
                        }
                        i = (i << 8) | SlReadByte();
                }
                i = (i << 8) | SlReadByte();
        }
        return i;
}

/**
 * Write the header descriptor of an object or an array.
 * If the element is bigger than 127, use 2 bytes for saving
 * and use the highest byte of the first written one as a notice
 * that the length consists of 2 bytes, etc.. like this:
 * 0xxxxxxx
 * 10xxxxxx xxxxxxxx
 * 110xxxxx xxxxxxxx xxxxxxxx
 * 1110xxxx xxxxxxxx xxxxxxxx xxxxxxxx
 * 11110--- xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
 * We could extend the scheme ad infinum to support arbitrarily
 * large chunks, but as sizeof(size_t) == 4 is still very common
 * we don't support anything above 32 bits. That's why in the last
 * case the 3 most significant bits are unused.
 * @param i Index being written
 */

static void SlWriteSimpleGamma(size_t i)
{
        if (i >= (1 << 7)) {
                if (i >= (1 << 14)) {
                        if (i >= (1 << 21)) {
                                if (i >= (1 << 28)) {
                                        assert(i <= UINT32_MAX); // We can only support 32 bits for now.
                                        SlWriteByte((byte)(0xF0));
                                        SlWriteByte((byte)(i >> 24));
                                } else {
                                        SlWriteByte((byte)(0xE0 | (i >> 24)));
                                }
                                SlWriteByte((byte)(i >> 16));
                        } else {
                                SlWriteByte((byte)(0xC0 | (i >> 16)));
                        }
                        SlWriteByte((byte)(i >> 8));
                } else {
                        SlWriteByte((byte)(0x80 | (i >> 8)));
                }
        }
        SlWriteByte((byte)i);
}

/** Return how many bytes used to encode a gamma value */
static inline uint SlGetGammaLength(size_t i)
{
        return 1 + (i >= (1 << 7)) + (i >= (1 << 14)) + (i >= (1 << 21)) + (i >= (1 << 28));
}

static inline uint SlReadSparseIndex()
{
        return SlReadSimpleGamma();
}

static inline void SlWriteSparseIndex(uint index)
{
        SlWriteSimpleGamma(index);
}

static inline uint SlReadArrayLength()
{
        return SlReadSimpleGamma();
}

static inline void SlWriteArrayLength(size_t length)
{
        SlWriteSimpleGamma(length);
}

static inline uint SlGetArrayLength(size_t length)
{
        return SlGetGammaLength(length);
}

/**
 * Return the size in bytes of a certain type of normal/atomic variable
 * as it appears in memory. See VarTypes
 * @param conv VarType type of variable that is used for calculating the size
 * @return Return the size of this type in bytes
 */
static inline uint SlCalcConvMemLen(VarType conv)
{
        static const byte conv_mem_size[] = {1, 1, 1, 2, 2, 4, 4, 8, 8, 0};
        byte length = GB(conv, 4, 4);

        switch (length << 4) {
                case SLE_VAR_STRB:
                case SLE_VAR_STRBQ:
                case SLE_VAR_STR:
                case SLE_VAR_STRQ:
                        return SlReadArrayLength();

                default:
                        assert(length < lengthof(conv_mem_size));
                        return conv_mem_size[length];
        }
}

/**
 * Return the size in bytes of a certain type of normal/atomic variable
 * as it appears in a saved game. See VarTypes
 * @param conv VarType type of variable that is used for calculating the size
 * @return Return the size of this type in bytes
 */
static inline byte SlCalcConvFileLen(VarType conv)
{
        static const byte conv_file_size[] = {1, 1, 2, 2, 4, 4, 8, 8, 2};
        byte length = GB(conv, 0, 4);
        assert(length < lengthof(conv_file_size));
        return conv_file_size[length];
}

/** Return the size in bytes of a reference (pointer) */
static inline size_t SlCalcRefLen()
{
        return IsSavegameVersionBefore(69) ? 2 : 4;
}

void SlSetArrayIndex(uint index)
{
        _sl.need_length = NL_WANTLENGTH;
        _sl.array_index = index;
}

static size_t _next_offs;

/**
 * Iterate through the elements of an array and read the whole thing
 * @return The index of the object, or -1 if we have reached the end of current block
 */
int SlIterateArray()
{
        int index;

        /* After reading in the whole array inside the loop
         * we must have read in all the data, so we must be at end of current block. */
        if (_next_offs != 0 && _sl.reader->GetSize() != _next_offs) SlErrorCorrupt("Invalid chunk size");

        for (;;) {
                uint length = SlReadArrayLength();
                if (length == 0) {
                        _next_offs = 0;
                        return -1;
                }

                _sl.obj_len = --length;
                _next_offs = _sl.reader->GetSize() + length;

                switch (_sl.block_mode) {
                        case CH_SPARSE_ARRAY: index = (int)SlReadSparseIndex(); break;
                        case CH_ARRAY:        index = _sl.array_index++; break;
                        default:
                                DEBUG(sl, 0, "SlIterateArray error");
                                return -1; // error
                }

                if (length != 0) return index;
        }
}

/**
 * Skip an array or sparse array
 */
void SlSkipArray()
{
        while (SlIterateArray() != -1) {
                SlSkipBytes(_next_offs - _sl.reader->GetSize());
        }
}

/**
 * Sets the length of either a RIFF object or the number of items in an array.
 * This lets us load an object or an array of arbitrary size
 * @param length The length of the sought object/array
 */
void SlSetLength(size_t length)
{
        assert(_sl.action == SLA_SAVE);

        switch (_sl.need_length) {
                case NL_WANTLENGTH:
                        _sl.need_length = NL_NONE;
                        switch (_sl.block_mode) {
                                case CH_RIFF:
                                        /* Ugly encoding of >16M RIFF chunks
                                         * The lower 24 bits are normal
                                         * The uppermost 4 bits are bits 24:27 */
                                        assert(length < (1 << 28));
                                        SlWriteUint32((uint32)((length & 0xFFFFFF) | ((length >> 24) << 28)));
                                        break;
                                case CH_ARRAY:
                                        assert(_sl.last_array_index <= _sl.array_index);
                                        while (++_sl.last_array_index <= _sl.array_index) {
                                                SlWriteArrayLength(1);
                                        }
                                        SlWriteArrayLength(length + 1);
                                        break;
                                case CH_SPARSE_ARRAY:
                                        SlWriteArrayLength(length + 1 + SlGetArrayLength(_sl.array_index)); // Also include length of sparse index.
                                        SlWriteSparseIndex(_sl.array_index);
                                        break;
                                default: NOT_REACHED();
                        }
                        break;

                case NL_CALCLENGTH:
                        _sl.obj_len += (int)length;
                        break;

                default: NOT_REACHED();
        }
}

/**
 * Save/Load bytes. These do not need to be converted to Little/Big Endian
 * so directly write them or read them to/from file
 * @param ptr The source or destination of the object being manipulated
 * @param length number of bytes this fast CopyBytes lasts
 */
static void SlCopyBytes(void *ptr, size_t length)
{
        byte *p = (byte *)ptr;

        switch (_sl.action) {
                case SLA_LOAD_CHECK:
                case SLA_LOAD:
                        for (; length != 0; length--) *p++ = SlReadByte();
                        break;
                case SLA_SAVE:
                        for (; length != 0; length--) SlWriteByte(*p++);
                        break;
                default: NOT_REACHED();
        }
}

/** Get the length of the current object */
size_t SlGetFieldLength()
{
        return _sl.obj_len;
}

/**
 * Return a signed-long version of the value of a setting
 * @param ptr pointer to the variable
 * @param conv type of variable, can be a non-clean
 * type, eg one with other flags because it is parsed
 * @return returns the value of the pointer-setting
 */
int64 ReadValue(const void *ptr, VarType conv)
{
        switch (GetVarMemType(conv)) {
                case SLE_VAR_BL:  return (*(const bool *)ptr != 0);
                case SLE_VAR_I8:  return *(const int8  *)ptr;
                case SLE_VAR_U8:  return *(const byte  *)ptr;
                case SLE_VAR_I16: return *(const int16 *)ptr;
                case SLE_VAR_U16: return *(const uint16*)ptr;
                case SLE_VAR_I32: return *(const int32 *)ptr;
                case SLE_VAR_U32: return *(const uint32*)ptr;
                case SLE_VAR_I64: return *(const int64 *)ptr;
                case SLE_VAR_U64: return *(const uint64*)ptr;
                case SLE_VAR_NULL:return 0;
                default: NOT_REACHED();
        }
}

/**
 * Write the value of a setting
 * @param ptr pointer to the variable
 * @param conv type of variable, can be a non-clean type, eg
 *             with other flags. It is parsed upon read
 * @param val the new value being given to the variable
 */
void WriteValue(void *ptr, VarType conv, int64 val)
{
        switch (GetVarMemType(conv)) {
                case SLE_VAR_BL:  *(bool  *)ptr = (val != 0);  break;
                case SLE_VAR_I8:  *(int8  *)ptr = val; break;
                case SLE_VAR_U8:  *(byte  *)ptr = val; break;
                case SLE_VAR_I16: *(int16 *)ptr = val; break;
                case SLE_VAR_U16: *(uint16*)ptr = val; break;
                case SLE_VAR_I32: *(int32 *)ptr = val; break;
                case SLE_VAR_U32: *(uint32*)ptr = val; break;
                case SLE_VAR_I64: *(int64 *)ptr = val; break;
                case SLE_VAR_U64: *(uint64*)ptr = val; break;
                case SLE_VAR_NAME: *(char**)ptr = CopyFromOldName(val); break;
                case SLE_VAR_NULL: break;
                default: NOT_REACHED();
        }
}

/**
 * Handle all conversion and typechecking of variables here.
 * In the case of saving, read in the actual value from the struct
 * and then write them to file, endian safely. Loading a value
 * goes exactly the opposite way
 * @param ptr The object being filled/read
 * @param conv VarType type of the current element of the struct
 */
static void SlSaveLoadConv(void *ptr, VarType conv)
{
        switch (_sl.action) {
                case SLA_SAVE: {
                        int64 x = ReadValue(ptr, conv);

                        /* Write the value to the file and check if its value is in the desired range */
                        switch (GetVarFileType(conv)) {
                                case SLE_FILE_I8: assert(x >= -128 && x <= 127);     SlWriteByte(x);break;
                                case SLE_FILE_U8: assert(x >= 0 && x <= 255);        SlWriteByte(x);break;
                                case SLE_FILE_I16:assert(x >= -32768 && x <= 32767); SlWriteUint16(x);break;
                                case SLE_FILE_STRINGID:
                                case SLE_FILE_U16:assert(x >= 0 && x <= 65535);      SlWriteUint16(x);break;
                                case SLE_FILE_I32:
                                case SLE_FILE_U32:                                   SlWriteUint32((uint32)x);break;
                                case SLE_FILE_I64:
                                case SLE_FILE_U64:                                   SlWriteUint64(x);break;
                                default: NOT_REACHED();
                        }
                        break;
                }
                case SLA_LOAD_CHECK:
                case SLA_LOAD: {
                        int64 x;
                        /* Read a value from the file */
                        switch (GetVarFileType(conv)) {
                                case SLE_FILE_I8:  x = (int8  )SlReadByte();   break;
                                case SLE_FILE_U8:  x = (byte  )SlReadByte();   break;
                                case SLE_FILE_I16: x = (int16 )SlReadUint16(); break;
                                case SLE_FILE_U16: x = (uint16)SlReadUint16(); break;
                                case SLE_FILE_I32: x = (int32 )SlReadUint32(); break;
                                case SLE_FILE_U32: x = (uint32)SlReadUint32(); break;
                                case SLE_FILE_I64: x = (int64 )SlReadUint64(); break;
                                case SLE_FILE_U64: x = (uint64)SlReadUint64(); break;
                                case SLE_FILE_STRINGID: x = RemapOldStringID((uint16)SlReadUint16()); break;
                                default: NOT_REACHED();
                        }

                        /* Write The value to the struct. These ARE endian safe. */
                        WriteValue(ptr, conv, x);
                        break;
                }
                case SLA_PTRS: break;
                case SLA_NULL: break;
                default: NOT_REACHED();
        }
}

/**
 * Calculate the net length of a string. This is in almost all cases
 * just strlen(), but if the string is not properly terminated, we'll
 * resort to the maximum length of the buffer.
 * @param ptr pointer to the stringbuffer
 * @param length maximum length of the string (buffer). If -1 we don't care
 * about a maximum length, but take string length as it is.
 * @return return the net length of the string
 */
static inline size_t SlCalcNetStringLen(const char *ptr, size_t length)
{
        if (ptr == nullptr) return 0;
        return min(strlen(ptr), length - 1);
}
 
/**
 * Calculate the gross length of the std::string that it
 * will occupy in the savegame. This includes the real length,
 * and the length that the index will occupy.
 * @param str reference to the std::string
 * @return return the gross length of the string
 */
static inline size_t SlCalcStdStrLen(const std::string &str)
{
        return str.size() + SlGetArrayLength(str.size()); // also include the length of the index
}

/**
 * Calculate the gross length of the string that it
 * will occupy in the savegame. This includes the real length, returned
 * by SlCalcNetStringLen and the length that the index will occupy.
 * @param ptr pointer to the stringbuffer
 * @param length maximum length of the string (buffer size, etc.)
 * @param conv type of data been used
 * @return return the gross length of the string
 */
static inline size_t SlCalcStringLen(const void *ptr, size_t length, VarType conv)
{
        size_t len;
        const char *str;

        switch (GetVarMemType(conv)) {
                default: NOT_REACHED();
                case SLE_VAR_STR:
                case SLE_VAR_STRQ:
                        str = *(const char * const *)ptr;
                        len = SIZE_MAX;
                        break;
                case SLE_VAR_STRB:
                case SLE_VAR_STRBQ:
                        str = (const char *)ptr;
                        len = length;
                        break;
        }

        len = SlCalcNetStringLen(str, len);
        return len + SlGetArrayLength(len); // also include the length of the index
}

/**
 * Save/Load a string.
 * @param ptr the string being manipulated
 * @param length of the string (full length)
 * @param conv must be SLE_FILE_STRING
 */
static void SlString(void *ptr, size_t length, VarType conv)
{
        switch (_sl.action) {
                case SLA_SAVE: {
                        size_t len;
                        switch (GetVarMemType(conv)) {
                                default: NOT_REACHED();
                                case SLE_VAR_STRB:
                                case SLE_VAR_STRBQ:
                                        len = SlCalcNetStringLen((char *)ptr, length);
                                        break;
                                case SLE_VAR_STR:
                                case SLE_VAR_STRQ:
                                        ptr = *(char **)ptr;
                                        len = SlCalcNetStringLen((char *)ptr, SIZE_MAX);
                                        break;
                        }

                        SlWriteArrayLength(len);
                        SlCopyBytes(ptr, len);
                        break;
                }
                case SLA_LOAD_CHECK:
                case SLA_LOAD: {
                        size_t len = SlReadArrayLength();

                        switch (GetVarMemType(conv)) {
                                default: NOT_REACHED();
                                case SLE_VAR_STRB:
                                case SLE_VAR_STRBQ:
                                        if (len >= length) {
                                                DEBUG(sl, 1, "String length in savegame is bigger than buffer, truncating");
                                                SlCopyBytes(ptr, length);
                                                SlSkipBytes(len - length);
                                                len = length - 1;
                                        } else {
                                                SlCopyBytes(ptr, len);
                                        }
                                        break;
                                case SLE_VAR_STR:
                                case SLE_VAR_STRQ: // Malloc'd string, free previous incarnation, and allocate
                                        free(*(char **)ptr);
                                        if (len == 0) {
                                                *(char **)ptr = nullptr;
                                                return;
                                        } else {
                                                *(char **)ptr = MallocT<char>(len + 1); // terminating '\0'
                                                ptr = *(char **)ptr;
                                                SlCopyBytes(ptr, len);
                                        }
                                        break;
                        }

                        ((char *)ptr)[len] = '\0'; // properly terminate the string
                        StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK;
                        if ((conv & SLF_ALLOW_CONTROL) != 0) {
                                settings = settings | SVS_ALLOW_CONTROL_CODE;
                                if (IsSavegameVersionBefore(169)) {
                                        str_fix_scc_encoded((char *)ptr, (char *)ptr + len);
                                }
                        }
                        if ((conv & SLF_ALLOW_NEWLINE) != 0) {
                                settings = settings | SVS_ALLOW_NEWLINE;
                        }
                        str_validate((char *)ptr, (char *)ptr + len, settings);
                        break;
                }
                case SLA_PTRS: break;
                case SLA_NULL: break;
                default: NOT_REACHED();
        }
}
 
/**
 * Save/Load a std::string.
 * @param ptr the std::string being manipulated
 * @param conv must be SLE_FILE_STRING
 */
static void SlStdString(std::string &str, VarType conv)
{
        switch (_sl.action) {
                case SLA_SAVE: {
                        SlWriteArrayLength(str.size());
                        SlCopyBytes(const_cast<char *>(str.data()), str.size());
                        break;
                }
                case SLA_LOAD_CHECK:
                case SLA_LOAD: {
                        size_t len = SlReadArrayLength();
                        str.resize(len);
                        SlCopyBytes(const_cast<char *>(str.c_str()), len);

                        StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK;
                        if ((conv & SLF_ALLOW_CONTROL) != 0) {
                                settings = settings | SVS_ALLOW_CONTROL_CODE;
                        }
                        if ((conv & SLF_ALLOW_NEWLINE) != 0) {
                                settings = settings | SVS_ALLOW_NEWLINE;
                        }
                        str_validate(str, settings);
                        break;
                }
                case SLA_PTRS: break;
                case SLA_NULL: break;
                default: NOT_REACHED();
        }
}

/**
 * Return the size in bytes of a certain type of atomic array
 * @param length The length of the array counted in elements
 * @param conv VarType type of the variable that is used in calculating the size
 */
static inline size_t SlCalcArrayLen(size_t length, VarType conv)
{
        return SlCalcConvFileLen(conv) * length;
}

/**
 * Save/Load an array.
 * @param array The array being manipulated
 * @param length The length of the array in elements
 * @param conv VarType type of the atomic array (int, byte, uint64, etc.)
 */
void SlArray(void *array, size_t length, VarType conv)
{
        if (_sl.action == SLA_PTRS || _sl.action == SLA_NULL) return;

        /* Automatically calculate the length? */
        if (_sl.need_length != NL_NONE) {
                SlSetLength(SlCalcArrayLen(length, conv));
                /* Determine length only? */
                if (_sl.need_length == NL_CALCLENGTH) return;
        }

        /* NOTICE - handle some buggy stuff, in really old versions everything was saved
         * as a byte-type. So detect this, and adjust array size accordingly */
        if (_sl.action != SLA_SAVE && _sl_version == 0) {
                /* all arrays except difficulty settings */
                if (conv == SLE_INT16 || conv == SLE_UINT16 || conv == SLE_STRINGID ||
                                conv == SLE_INT32 || conv == SLE_UINT32) {
                        SlCopyBytes(array, length * SlCalcConvFileLen(conv));
                        return;
                }
                /* used for conversion of Money 32bit->64bit */
                if (conv == (SLE_FILE_I32 | SLE_VAR_I64)) {
                        for (uint i = 0; i < length; i++) {
                                ((int64*)array)[i] = (int32)BSWAP32(SlReadUint32());
                        }
                        return;
                }
        }

        /* If the size of elements is 1 byte both in file and memory, no special
         * conversion is needed, use specialized copy-copy function to speed up things */
        if (conv == SLE_INT8 || conv == SLE_UINT8) {
                SlCopyBytes(array, length);
        } else {
                byte *a = (byte*)array;
                byte mem_size = SlCalcConvMemLen(conv);

                for (; length != 0; length --) {
                        SlSaveLoadConv(a, conv);
                        a += mem_size; // get size
                }
        }
}


/**
 * Pointers cannot be saved to a savegame, so this functions gets
 * the index of the item, and if not available, it hussles with
 * pointers (looks really bad :()
 * Remember that a nullptr item has value 0, and all
 * indices have +1, so vehicle 0 is saved as index 1.
 * @param obj The object that we want to get the index of
 * @param rt SLRefType type of the object the index is being sought of
 * @return Return the pointer converted to an index of the type pointed to
 */
static size_t ReferenceToInt(const void *obj, SLRefType rt)
{
        assert(_sl.action == SLA_SAVE);

        if (obj == nullptr) return 0;

        switch (rt) {
                case REF_VEHICLE_OLD: // Old vehicles we save as new ones
                case REF_VEHICLE:   return ((const  Vehicle*)obj)->index + 1;
                case REF_TEMPLATE_VEHICLE: return ((const TemplateVehicle*)obj)->index + 1;
                case REF_STATION:   return ((const  Station*)obj)->index + 1;
                case REF_TOWN:      return ((const     Town*)obj)->index + 1;
                case REF_ORDER:     return ((const    Order*)obj)->index + 1;
                case REF_ROADSTOPS: return ((const RoadStop*)obj)->index + 1;
                case REF_ENGINE_RENEWS:  return ((const       EngineRenew*)obj)->index + 1;
                case REF_CARGO_PACKET:   return ((const       CargoPacket*)obj)->index + 1;
                case REF_ORDERLIST:      return ((const         OrderList*)obj)->index + 1;
                case REF_STORAGE:        return ((const PersistentStorage*)obj)->index + 1;
                case REF_LINK_GRAPH:     return ((const         LinkGraph*)obj)->index + 1;
                case REF_LINK_GRAPH_JOB: return ((const      LinkGraphJob*)obj)->index + 1;
                case REF_DOCKS:          return ((const              Dock*)obj)->index + 1;
                default: NOT_REACHED();
        }
}

/**
 * Pointers cannot be loaded from a savegame, so this function
 * gets the index from the savegame and returns the appropriate
 * pointer from the already loaded base.
 * Remember that an index of 0 is a nullptr pointer so all indices
 * are +1 so vehicle 0 is saved as 1.
 * @param index The index that is being converted to a pointer
 * @param rt SLRefType type of the object the pointer is sought of
 * @return Return the index converted to a pointer of any type
 */
static void *IntToReference(size_t index, SLRefType rt)
{
        assert_compile(sizeof(size_t) <= sizeof(void *));

        assert(_sl.action == SLA_PTRS);

        /* After version 4.3 REF_VEHICLE_OLD is saved as REF_VEHICLE,
         * and should be loaded like that */
        if (rt == REF_VEHICLE_OLD && !IsSavegameVersionBefore(4, 4)) {
                rt = REF_VEHICLE;
        }

        /* No need to look up nullptr pointers, just return immediately */
        if (index == (rt == REF_VEHICLE_OLD ? 0xFFFF : 0)) return nullptr;

        /* Correct index. Old vehicles were saved differently:
         * invalid vehicle was 0xFFFF, now we use 0x0000 for everything invalid. */
        if (rt != REF_VEHICLE_OLD) index--;

        switch (rt) {
                case REF_ORDERLIST:
                        if (OrderList::IsValidID(index)) return OrderList::Get(index);
                        SlErrorCorrupt("Referencing invalid OrderList");

                case REF_ORDER:
                        if (Order::IsValidID(index)) return Order::Get(index);
                        /* in old versions, invalid order was used to mark end of order list */
                        if (IsSavegameVersionBefore(5, 2)) return nullptr;
                        SlErrorCorrupt("Referencing invalid Order");

                case REF_VEHICLE_OLD:
                case REF_VEHICLE:
                        if (Vehicle::IsValidID(index)) return Vehicle::Get(index);
                        SlErrorCorrupt("Referencing invalid Vehicle");

                case REF_TEMPLATE_VEHICLE:
                        if (TemplateVehicle::IsValidID(index)) return TemplateVehicle::Get(index);
                        SlErrorCorrupt("Referencing invalid TemplateVehicle");

                case REF_STATION:
                        if (Station::IsValidID(index)) return Station::Get(index);
                        SlErrorCorrupt("Referencing invalid Station");

                case REF_TOWN:
                        if (Town::IsValidID(index)) return Town::Get(index);
                        SlErrorCorrupt("Referencing invalid Town");

                case REF_ROADSTOPS:
                        if (RoadStop::IsValidID(index)) return RoadStop::Get(index);
                        SlErrorCorrupt("Referencing invalid RoadStop");

                case REF_DOCKS:
                        if (Dock::IsValidID(index)) return Dock::Get(index);
                        SlErrorCorrupt("Referencing invalid Dock");

                case REF_ENGINE_RENEWS:
                        if (EngineRenew::IsValidID(index)) return EngineRenew::Get(index);
                        SlErrorCorrupt("Referencing invalid EngineRenew");

                case REF_CARGO_PACKET:
                        if (CargoPacket::IsValidID(index)) return CargoPacket::Get(index);
                        SlErrorCorrupt("Referencing invalid CargoPacket");

                case REF_STORAGE:
                        if (PersistentStorage::IsValidID(index)) return PersistentStorage::Get(index);
                        SlErrorCorrupt("Referencing invalid PersistentStorage");

                case REF_LINK_GRAPH:
                        if (LinkGraph::IsValidID(index)) return LinkGraph::Get(index);
                        SlErrorCorrupt("Referencing invalid LinkGraph");

                case REF_LINK_GRAPH_JOB:
                        if (LinkGraphJob::IsValidID(index)) return LinkGraphJob::Get(index);
                        SlErrorCorrupt("Referencing invalid LinkGraphJob");

                default: NOT_REACHED();
        }
}

/**
 * Return the size in bytes of a list
 * @param list The std::list to find the size of
 */
template<typename PtrList>
static inline size_t SlCalcListLen(const void *list)
{
        const PtrList *l = (const PtrList *)list;

        int type_size = IsSavegameVersionBefore(69) ? 2 : 4;
        /* Each entry is saved as type_size bytes, plus type_size bytes are used for the length
         * of the list */
        return l->size() * type_size + type_size;
}
 
/**
 * Return the size in bytes of a list
 * @param list The std::list to find the size of
 */
 template<typename PtrList>
static inline size_t SlCalcVarListLen(const void *list, size_t item_size)
{
        const PtrList *l = (const PtrList *) list;
        /* Each entry is saved as item_size bytes, plus 4 bytes are used for the length
         * of the list */
        return l->size() * item_size + 4;
}


/**
 * Save/Load a list.
 * @param list The list being manipulated
 * @param conv SLRefType type of the list (Vehicle *, Station *, etc)
 */
template<typename PtrList>
static void SlList(void *list, SLRefType conv)
{
        /* Automatically calculate the length? */
        if (_sl.need_length != NL_NONE) {
                SlSetLength(SlCalcListLen<PtrList>(list));
                /* Determine length only? */
                if (_sl.need_length == NL_CALCLENGTH) return;
        }

        PtrList *l = (PtrList *)list;

        switch (_sl.action) {
                case SLA_SAVE: {
                        SlWriteUint32((uint32)l->size());

                        typename PtrList::iterator iter;
                        for (iter = l->begin(); iter != l->end(); ++iter) {
                                void *ptr = *iter;
                                SlWriteUint32((uint32)ReferenceToInt(ptr, conv));
                        }
                        break;
                }
                case SLA_LOAD_CHECK:
                case SLA_LOAD: {
                        size_t length = IsSavegameVersionBefore(69) ? SlReadUint16() : SlReadUint32();

                        /* Load each reference and push to the end of the list */
                        for (size_t i = 0; i < length; i++) {
                                size_t data = IsSavegameVersionBefore(69) ? SlReadUint16() : SlReadUint32();
                                l->push_back((void *)data);
                        }
                        break;
                }
                case SLA_PTRS: {
                        PtrList temp = *l;

                        l->clear();
                        typename PtrList::iterator iter;
                        for (iter = temp.begin(); iter != temp.end(); ++iter) {
                                void *ptr = IntToReference((size_t)*iter, conv);
                                l->push_back(ptr);
                        }
                        break;
                }
                case SLA_NULL:
                        l->clear();
                        break;
                default: NOT_REACHED();
        }
}
 
/**
 * Save/Load a list.
 * @param list The list being manipulated
 * @param conv VarType type of the list
 */
template<typename PtrList>
static void SlVarList(void *list, VarType conv)
{
        const size_t size_len = SlCalcConvMemLen(conv);
        /* Automatically calculate the length? */
        if (_sl.need_length != NL_NONE) {
                SlSetLength(SlCalcVarListLen<PtrList>(list, size_len));
                /* Determine length only? */
                if (_sl.need_length == NL_CALCLENGTH) return;
        }

        PtrList *l = (PtrList *)list;

        switch (_sl.action) {
                case SLA_SAVE: {
                        SlWriteUint32((uint32)l->size());

                        typename PtrList::iterator iter;
                        for (iter = l->begin(); iter != l->end(); ++iter) {
                                SlSaveLoadConv(&(*iter), conv);
                        }
                        break;
                }
                case SLA_LOAD_CHECK:
                case SLA_LOAD: {
                        size_t length = SlReadUint32();
                        l->resize(length);

                        typename PtrList::iterator iter;
                        iter = l->begin();

                        for (size_t i = 0; i < length; i++) {
                                SlSaveLoadConv(&(*iter), conv);
                                ++iter;
                        }
                        break;
                }
                case SLA_PTRS: break;
                case SLA_NULL:
                        l->clear();
                        break;
                default: NOT_REACHED();
        }
}


/** Are we going to save this object or not? */
static inline bool SlIsObjectValidInSavegame(const SaveLoad *sld)
{
        if (_sl_version < sld->version_from || _sl_version > sld->version_to) return false;
        if (sld->conv & SLF_NOT_IN_SAVE) return false;

        return true;
}

/**
 * Are we going to load this variable when loading a savegame or not?
 * @note If the variable is skipped it is skipped in the savegame
 * bytestream itself as well, so there is no need to skip it somewhere else
 */
static inline bool SlSkipVariableOnLoad(const SaveLoad *sld)
{
        if ((sld->conv & SLF_NO_NETWORK_SYNC) && _sl.action != SLA_SAVE && _networking && !_network_server) {
                SlSkipBytes(SlCalcConvMemLen(sld->conv) * sld->length);
                return true;
        }

        return false;
}

/**
 * Calculate the size of an object.
 * @param object to be measured
 * @param sld The SaveLoad description of the object so we know how to manipulate it
 * @return size of given object
 */
size_t SlCalcObjLength(const void *object, const SaveLoad *sld)
{
        size_t length = 0;

        /* Need to determine the length and write a length tag. */
        for (; sld->cmd != SL_END; sld++) {
                length += SlCalcObjMemberLength(object, sld);
        }
        return length;
}

size_t SlCalcObjMemberLength(const void *object, const SaveLoad *sld)
{
        assert(_sl.action == SLA_SAVE);

        switch (sld->cmd) {
                case SL_VAR:
                case SL_REF:
                case SL_ARR:
                case SL_STR:
                case SL_LST:
                case SL_DEQ:
                case SL_VEC:
                case SL_VARVEC:
                case SL_STDSTR:
                        /* CONDITIONAL saveload types depend on the savegame version */
                        if (!SlIsObjectValidInSavegame(sld)) break;

                        switch (sld->cmd) {
                                case SL_VAR: return SlCalcConvFileLen(sld->conv);
                                case SL_REF: return SlCalcRefLen();
                                case SL_ARR: return SlCalcArrayLen(sld->length, sld->conv);
                                case SL_STR: return SlCalcStringLen(GetVariableAddress(object, sld), sld->length, sld->conv);
                                case SL_LST: return SlCalcListLen<std::list<void *>>(GetVariableAddress(object, sld));
                                case SL_DEQ: return SlCalcListLen<std::deque<void *>>(GetVariableAddress(object, sld));
                                case SL_VEC: return SlCalcListLen<std::vector<void *>>(GetVariableAddress(object, sld));
                                case SL_VARVEC: {
                                        const size_t size_len = SlCalcConvMemLen(sld->conv);
                                        switch (size_len) {
                                                case 1: return SlCalcVarListLen<std::vector<byte>>(GetVariableAddress(object, sld), 1);
                                                case 2: return SlCalcVarListLen<std::vector<uint16>>(GetVariableAddress(object, sld), 2);
                                                case 4: return SlCalcVarListLen<std::vector<uint32>>(GetVariableAddress(object, sld), 4);
                                                case 8: return SlCalcVarListLen<std::vector<uint64>>(GetVariableAddress(object, sld), 8);
                                                default: NOT_REACHED();
                                        }
                                }
                                case SL_STDSTR: return SlCalcStdStrLen(*static_cast<std::string *>(GetVariableAddress(object, sld)));
                                default: NOT_REACHED();
                        }
                        break;
                case SL_WRITEBYTE: return 1; // a byte is logically of size 1
                case SL_VEH_INCLUDE: return SlCalcObjLength(object, GetVehicleDescription(VEH_END));
                case SL_ST_INCLUDE: return SlCalcObjLength(object, GetBaseStationDescription());
                default: NOT_REACHED();
        }
        return 0;
}

#ifdef OTTD_ASSERT

/**
 * Check whether the variable size of the variable in the saveload configuration
 * matches with the actual variable size.
 * @param sld The saveload configuration to test.
 */
static bool IsVariableSizeRight(const SaveLoad *sld)
{
        switch (sld->cmd) {
                case SL_VAR:
                        switch (GetVarMemType(sld->conv)) {
                                case SLE_VAR_BL:
                                        return sld->size == sizeof(bool);
                                case SLE_VAR_I8:
                                case SLE_VAR_U8:
                                        return sld->size == sizeof(int8);
                                case SLE_VAR_I16:
                                case SLE_VAR_U16:
                                        return sld->size == sizeof(int16);
                                case SLE_VAR_I32:
                                case SLE_VAR_U32:
                                        return sld->size == sizeof(int32);
                                case SLE_VAR_I64:
                                case SLE_VAR_U64:
                                        return sld->size == sizeof(int64);
                                default:
                                        return sld->size == sizeof(void *);
                        }
                case SL_REF:
                        /* These should all be pointer sized. */
                        return sld->size == sizeof(void *);

                case SL_STR:
                        /* These should be pointer sized, or fixed array. */
                        return sld->size == sizeof(void *) || sld->size == sld->length;
 
                case SL_STDSTR:
                        return sld->size == sizeof(std::string);

                default:
                        return true;
        }
}

#endif /* OTTD_ASSERT */

bool SlObjectMember(void *ptr, const SaveLoad *sld)
{
#ifdef OTTD_ASSERT
        assert(IsVariableSizeRight(sld));
#endif

        VarType conv = GB(sld->conv, 0, 8);
        switch (sld->cmd) {
                case SL_VAR:
                case SL_REF:
                case SL_ARR:
                case SL_STR:
                case SL_LST:
                case SL_DEQ:
                case SL_VEC:
                case SL_VARVEC:
                case SL_STDSTR:
                        /* CONDITIONAL saveload types depend on the savegame version */
                        if (!SlIsObjectValidInSavegame(sld)) return false;
                        if (SlSkipVariableOnLoad(sld)) return false;

                        switch (sld->cmd) {
                                case SL_VAR: SlSaveLoadConv(ptr, conv); break;
                                case SL_REF: // Reference variable, translate
                                        switch (_sl.action) {
                                                case SLA_SAVE:
                                                        SlWriteUint32((uint32)ReferenceToInt(*(void **)ptr, (SLRefType)conv));
                                                        break;
                                                case SLA_LOAD_CHECK:
                                                case SLA_LOAD:
                                                        *(size_t *)ptr = IsSavegameVersionBefore(69) ? SlReadUint16() : SlReadUint32();
                                                        break;
                                                case SLA_PTRS:
                                                        *(void **)ptr = IntToReference(*(size_t *)ptr, (SLRefType)conv);
                                                        break;
                                                case SLA_NULL:
                                                        *(void **)ptr = nullptr;
                                                        break;
                                                default: NOT_REACHED();
                                        }
                                        break;
                                case SL_ARR: SlArray(ptr, sld->length, conv); break;
                                case SL_STR: SlString(ptr, sld->length, sld->conv); break;
                                case SL_LST: SlList<std::list<void *>>(ptr, (SLRefType)conv); break;
                                case SL_DEQ: SlList<std::deque<void *>>(ptr, (SLRefType)conv); break;
                                case SL_VEC: SlList<std::vector<void *>>(ptr, (SLRefType)conv); break;
                                case SL_VARVEC: {
                                        const size_t size_len = SlCalcConvMemLen(sld->conv);
                                        switch (size_len) {
                                                case 1: SlVarList<std::vector<byte>>(ptr, conv); break;
                                                case 2: SlVarList<std::vector<uint16>>(ptr, conv); break;
                                                case 4: SlVarList<std::vector<uint32>>(ptr, conv); break;
                                                case 8: SlVarList<std::vector<uint64>>(ptr, conv); break;
                                                default: NOT_REACHED();
                                        }
                                        break;
                                }
                                case SL_STDSTR: SlStdString(*static_cast<std::string *>(ptr), sld->conv); break;
                                default: NOT_REACHED();
                        }
                        break;

                /* SL_WRITEBYTE translates a value of a variable to another one upon
                 * saving or loading.
                 * XXX - variable renaming abuse
                 * game_value: the value of the variable ingame is abused by sld->version_from
                 * file_value: the value of the variable in the savegame is abused by sld->version_to */
                case SL_WRITEBYTE:
                        switch (_sl.action) {
                                case SLA_SAVE: SlWriteByte(sld->version_to); break;
                                case SLA_LOAD_CHECK:
                                case SLA_LOAD: *(byte *)ptr = sld->version_from; break;
                                case SLA_PTRS: break;
                                case SLA_NULL: break;
                                default: NOT_REACHED();
                        }
                        break;

                /* SL_VEH_INCLUDE loads common code for vehicles */
                case SL_VEH_INCLUDE:
                        SlObject(ptr, GetVehicleDescription(VEH_END));
                        break;

                case SL_ST_INCLUDE:
                        SlObject(ptr, GetBaseStationDescription());
                        break;

                default: NOT_REACHED();
        }
        return true;
}

/**
 * Main SaveLoad function.
 * @param object The object that is being saved or loaded
 * @param sld The SaveLoad description of the object so we know how to manipulate it
 */
void SlObject(void *object, const SaveLoad *sld)
{
        /* Automatically calculate the length? */
        if (_sl.need_length != NL_NONE) {
                SlSetLength(SlCalcObjLength(object, sld));
                if (_sl.need_length == NL_CALCLENGTH) return;
        }

        for (; sld->cmd != SL_END; sld++) {
                void *ptr = sld->global ? sld->address : GetVariableAddress(object, sld);
                SlObjectMember(ptr, sld);
        }
}

/**
 * Save or Load (a list of) global variables
 * @param sldg The global variable that is being loaded or saved
 */
void SlGlobList(const SaveLoadGlobVarList *sldg)
{
        SlObject(nullptr, (const SaveLoad*)sldg);
}

/**
 * Do something of which I have no idea what it is :P
 * @param proc The callback procedure that is called
 * @param arg The variable that will be used for the callback procedure
 */
void SlAutolength(AutolengthProc *proc, void *arg)
{
        size_t offs;

        assert(_sl.action == SLA_SAVE);

        /* Tell it to calculate the length */
        _sl.need_length = NL_CALCLENGTH;
        _sl.obj_len = 0;
        proc(arg);

        /* Setup length */
        _sl.need_length = NL_WANTLENGTH;
        SlSetLength(_sl.obj_len);

        offs = _sl.dumper->GetSize() + _sl.obj_len;

        /* And write the stuff */
        proc(arg);

        if (offs != _sl.dumper->GetSize()) SlErrorCorrupt("Invalid chunk size");
}

/**
 * Load a chunk of data (eg vehicles, stations, etc.)
 * @param ch The chunkhandler that will be used for the operation
 */
static void SlLoadChunk(const ChunkHandler *ch)
{
        byte m = SlReadByte();
        size_t len;
        size_t endoffs;

        _sl.block_mode = m;
        _sl.obj_len = 0;

        switch (m) {
                case CH_ARRAY:
                        _sl.array_index = 0;
                        ch->load_proc();
                        if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
                        break;
                case CH_SPARSE_ARRAY:
                        ch->load_proc();
                        if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
                        break;
                default:
                        if ((m & 0xF) == CH_RIFF) {
                                /* Read length */
                                len = (SlReadByte() << 16) | ((m >> 4) << 24);
                                len += SlReadUint16();
                                _sl.obj_len = len;
                                endoffs = _sl.reader->GetSize() + len;
                                ch->load_proc();
                                if (_sl.reader->GetSize() != endoffs) SlErrorCorrupt("Invalid chunk size");
                        } else {
                                SlErrorCorrupt("Invalid chunk type");
                        }
                        break;
        }
}

/**
 * Load a chunk of data for checking savegames.
 * If the chunkhandler is nullptr, the chunk is skipped.
 * @param ch The chunkhandler that will be used for the operation
 */
static void SlLoadCheckChunk(const ChunkHandler *ch)
{
        byte m = SlReadByte();
        size_t len;
        size_t endoffs;

        _sl.block_mode = m;
        _sl.obj_len = 0;

        switch (m) {
                case CH_ARRAY:
                        _sl.array_index = 0;
                        if (ch->load_check_proc) {
                                ch->load_check_proc();
                        } else {
                                SlSkipArray();
                        }
                        break;
                case CH_SPARSE_ARRAY:
                        if (ch->load_check_proc) {
                                ch->load_check_proc();
                        } else {
                                SlSkipArray();
                        }
                        break;
                default:
                        if ((m & 0xF) == CH_RIFF) {
                                /* Read length */
                                len = (SlReadByte() << 16) | ((m >> 4) << 24);
                                len += SlReadUint16();
                                _sl.obj_len = len;
                                endoffs = _sl.reader->GetSize() + len;
                                if (ch->load_check_proc) {
                                        ch->load_check_proc();
                                } else {
                                        SlSkipBytes(len);
                                }
                                if (_sl.reader->GetSize() != endoffs) SlErrorCorrupt("Invalid chunk size");
                        } else {
                                SlErrorCorrupt("Invalid chunk type");
                        }
                        break;
        }
}

/**
 * Save a chunk of data (eg. vehicles, stations, etc.). Each chunk is
 * prefixed by an ID identifying it, followed by data, and terminator where appropriate
 * @param ch The chunkhandler that will be used for the operation
 */
static void SlSaveChunk(const ChunkHandler *ch)
{
        ChunkSaveLoadProc *proc = ch->save_proc;

        /* Don't save any chunk information if there is no save handler. */
        if (proc == nullptr) return;

        SlWriteUint32(ch->id);
        DEBUG(sl, 2, "Saving chunk %c%c%c%c", ch->id >> 24, ch->id >> 16, ch->id >> 8, ch->id);

        _sl.block_mode = ch->flags & CH_TYPE_MASK;
        switch (ch->flags & CH_TYPE_MASK) {
                case CH_RIFF:
                        _sl.need_length = NL_WANTLENGTH;
                        proc();
                        break;
                case CH_ARRAY:
                        _sl.last_array_index = 0;
                        SlWriteByte(CH_ARRAY);
                        proc();
                        SlWriteArrayLength(0); // Terminate arrays
                        break;
                case CH_SPARSE_ARRAY:
                        SlWriteByte(CH_SPARSE_ARRAY);
                        proc();
                        SlWriteArrayLength(0); // Terminate arrays
                        break;
                default: NOT_REACHED();
        }
}

/** Save all chunks */
static void SlSaveChunks()
{
        FOR_ALL_CHUNK_HANDLERS(ch) {
                SlSaveChunk(ch);
        }

        /* Terminator */
        SlWriteUint32(0);
}

/**
 * Find the ChunkHandler that will be used for processing the found
 * chunk in the savegame or in memory
 * @param id the chunk in question
 * @return returns the appropriate chunkhandler
 */
static const ChunkHandler *SlFindChunkHandler(uint32 id)
{
        FOR_ALL_CHUNK_HANDLERS(ch) if (ch->id == id) return ch;
        return nullptr;
}

/** Load all chunks */
static void SlLoadChunks()
{
        uint32 id;
        const ChunkHandler *ch;

        for (id = SlReadUint32(); id != 0; id = SlReadUint32()) {
                DEBUG(sl, 2, "Loading chunk %c%c%c%c", id >> 24, id >> 16, id >> 8, id);

                ch = SlFindChunkHandler(id);
                if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
                SlLoadChunk(ch);
        }
}

/** Load all chunks for savegame checking */
static void SlLoadCheckChunks()
{
        uint32 id;
        const ChunkHandler *ch;

        for (id = SlReadUint32(); id != 0; id = SlReadUint32()) {
                DEBUG(sl, 2, "Loading chunk %c%c%c%c", id >> 24, id >> 16, id >> 8, id);

                ch = SlFindChunkHandler(id);
                if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
                SlLoadCheckChunk(ch);
        }
}

/** Fix all pointers (convert index -> pointer) */
static void SlFixPointers()
{
        _sl.action = SLA_PTRS;

        DEBUG(sl, 1, "Fixing pointers");

        FOR_ALL_CHUNK_HANDLERS(ch) {
                if (ch->ptrs_proc != nullptr) {
                        DEBUG(sl, 2, "Fixing pointers for %c%c%c%c", ch->id >> 24, ch->id >> 16, ch->id >> 8, ch->id);
                        ch->ptrs_proc();
                }
        }

        DEBUG(sl, 1, "All pointers fixed");

        assert(_sl.action == SLA_PTRS);
}


/** Yes, simply reading from a file. */
struct FileReader : LoadFilter {
        FILE *file; ///< The file to read from.
        long begin; ///< The begin of the file.

        /**
         * Create the file reader, so it reads from a specific file.
         * @param file The file to read from.
         */
        FileReader(FILE *file) : LoadFilter(nullptr), file(file), begin(ftell(file))
        {
        }

        /** Make sure everything is cleaned up. */
        ~FileReader()
        {
                if (this->file != nullptr) fclose(this->file);
                this->file = nullptr;

                /* Make sure we don't double free. */
                _sl.sf = nullptr;
        }

        /* virtual */ size_t Read(byte *buf, size_t size)
        {
                /* We're in the process of shutting down, i.e. in "failure" mode. */
                if (this->file == nullptr) return 0;

                return fread(buf, 1, size, this->file);
        }

        /* virtual */ void Reset()
        {
                clearerr(this->file);
                if (fseek(this->file, this->begin, SEEK_SET)) {
                        DEBUG(sl, 1, "Could not reset the file reading");
                }
        }
};

/** Yes, simply writing to a file. */
struct FileWriter : SaveFilter {
        FILE *file; ///< The file to write to.

        /**
         * Create the file writer, so it writes to a specific file.
         * @param file The file to write to.
         */
        FileWriter(FILE *file) : SaveFilter(nullptr), file(file)
        {
        }

        /** Make sure everything is cleaned up. */
        ~FileWriter()
        {
                this->Finish();

                /* Make sure we don't double free. */
                _sl.sf = nullptr;
        }

        /* virtual */ void Write(byte *buf, size_t size)
        {
                /* We're in the process of shutting down, i.e. in "failure" mode. */
                if (this->file == nullptr) return;

                if (fwrite(buf, 1, size, this->file) != size) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE);
        }

        /* virtual */ void Finish()
        {
                if (this->file != nullptr) fclose(this->file);
                this->file = nullptr;
        }
};

/*******************************************
 ********** START OF LZO CODE **************
 *******************************************/

#ifdef WITH_LZO
#include <lzo/lzo1x.h>

/** Buffer size for the LZO compressor */
static const uint LZO_BUFFER_SIZE = 8192;

/** Filter using LZO compression. */
struct LZOLoadFilter : LoadFilter {
        /**
         * Initialise this filter.
         * @param chain The next filter in this chain.
         */
        LZOLoadFilter(LoadFilter *chain) : LoadFilter(chain)
        {
                if (lzo_init() != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
        }

        /* virtual */ size_t Read(byte *buf, size_t ssize)
        {
                assert(ssize >= LZO_BUFFER_SIZE);

                /* Buffer size is from the LZO docs plus the chunk header size. */
                byte out[LZO_BUFFER_SIZE + LZO_BUFFER_SIZE / 16 + 64 + 3 + sizeof(uint32) * 2];
                uint32 tmp[2];
                uint32 size;
                lzo_uint len = ssize;

                /* Read header*/
                if (this->chain->Read((byte*)tmp, sizeof(tmp)) != sizeof(tmp)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE, "File read failed");

                /* Check if size is bad */
                ((uint32*)out)[0] = size = tmp[1];

                if (_sl_version != 0) {
                        tmp[0] = TO_BE32(tmp[0]);
                        size = TO_BE32(size);
                }

                if (size >= sizeof(out)) SlErrorCorrupt("Inconsistent size");

                /* Read block */
                if (this->chain->Read(out + sizeof(uint32), size) != size) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);

                /* Verify checksum */
                if (tmp[0] != lzo_adler32(0, out, size + sizeof(uint32))) SlErrorCorrupt("Bad checksum");

                /* Decompress */
                int ret = lzo1x_decompress_safe(out + sizeof(uint32) * 1, size, buf, &len, nullptr);
                if (ret != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
                return len;
        }
};

/** Filter using LZO compression. */
struct LZOSaveFilter : SaveFilter {
        /**
         * Initialise this filter.
         * @param chain             The next filter in this chain.
         * @param compression_level The requested level of compression.
         */
        LZOSaveFilter(SaveFilter *chain, byte compression_level) : SaveFilter(chain)
        {
                if (lzo_init() != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
        }

        /* virtual */ void Write(byte *buf, size_t size)
        {
                const lzo_bytep in = buf;
                /* Buffer size is from the LZO docs plus the chunk header size. */
                byte out[LZO_BUFFER_SIZE + LZO_BUFFER_SIZE / 16 + 64 + 3 + sizeof(uint32) * 2];
                byte wrkmem[LZO1X_1_MEM_COMPRESS];
                lzo_uint outlen;

                do {
                        /* Compress up to LZO_BUFFER_SIZE bytes at once. */
                        lzo_uint len = size > LZO_BUFFER_SIZE ? LZO_BUFFER_SIZE : (lzo_uint)size;
                        lzo1x_1_compress(in, len, out + sizeof(uint32) * 2, &outlen, wrkmem);
                        ((uint32*)out)[1] = TO_BE32((uint32)outlen);
                        ((uint32*)out)[0] = TO_BE32(lzo_adler32(0, out + sizeof(uint32), outlen + sizeof(uint32)));
                        this->chain->Write(out, outlen + sizeof(uint32) * 2);

                        /* Move to next data chunk. */
                        size -= len;
                        in += len;
                } while (size > 0);
        }
};

#endif /* WITH_LZO */

/*********************************************
 ******** START OF NOCOMP CODE (uncompressed)*
 *********************************************/

/** Filter without any compression. */
struct NoCompLoadFilter : LoadFilter {
        /**
         * Initialise this filter.
         * @param chain The next filter in this chain.
         */
        NoCompLoadFilter(LoadFilter *chain) : LoadFilter(chain)
        {
        }

        /* virtual */ size_t Read(byte *buf, size_t size)
        {
                return this->chain->Read(buf, size);
        }
};

/** Filter without any compression. */
struct NoCompSaveFilter : SaveFilter {
        /**
         * Initialise this filter.
         * @param chain             The next filter in this chain.
         * @param compression_level The requested level of compression.
         */
        NoCompSaveFilter(SaveFilter *chain, byte compression_level) : SaveFilter(chain)
        {
        }

        /* virtual */ void Write(byte *buf, size_t size)
        {
                this->chain->Write(buf, size);
        }
};

/********************************************
 ********** START OF ZLIB CODE **************
 ********************************************/

#if defined(WITH_ZLIB)
#include <zlib.h>

/** Filter using Zlib compression. */
struct ZlibLoadFilter : LoadFilter {
        z_stream z;                        ///< Stream state we are reading from.
        byte fread_buf[MEMORY_CHUNK_SIZE]; ///< Buffer for reading from the file.

        /**
         * Initialise this filter.
         * @param chain The next filter in this chain.
         */
        ZlibLoadFilter(LoadFilter *chain) : LoadFilter(chain)
        {
                memset(&this->z, 0, sizeof(this->z));
                if (inflateInit(&this->z) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
        }

        /** Clean everything up. */
        ~ZlibLoadFilter()
        {
                inflateEnd(&this->z);
        }

        /* virtual */ size_t Read(byte *buf, size_t size)
        {
                this->z.next_out  = buf;
                this->z.avail_out = (uint)size;

                do {
                        /* read more bytes from the file? */
                        if (this->z.avail_in == 0) {
                                this->z.next_in = this->fread_buf;
                                this->z.avail_in = (uint)this->chain->Read(this->fread_buf, sizeof(this->fread_buf));
                        }

                        /* inflate the data */
                        int r = inflate(&this->z, 0);
                        if (r == Z_STREAM_END) break;

                        if (r != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "inflate() failed");
                } while (this->z.avail_out != 0);

                return size - this->z.avail_out;
        }
};

/** Filter using Zlib compression. */
struct ZlibSaveFilter : SaveFilter {
        z_stream z; ///< Stream state we are writing to.

        /**
         * Initialise this filter.
         * @param chain             The next filter in this chain.
         * @param compression_level The requested level of compression.
         */
        ZlibSaveFilter(SaveFilter *chain, byte compression_level) : SaveFilter(chain)
        {
                memset(&this->z, 0, sizeof(this->z));
                if (deflateInit(&this->z, compression_level) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
        }

        /** Clean up what we allocated. */
        ~ZlibSaveFilter()
        {
                deflateEnd(&this->z);
        }

        /**
         * Helper loop for writing the data.
         * @param p    The bytes to write.
         * @param len  Amount of bytes to write.
         * @param mode Mode for deflate.
         */
        void WriteLoop(byte *p, size_t len, int mode)
        {
                byte buf[MEMORY_CHUNK_SIZE]; // output buffer
                uint n;
                this->z.next_in = p;
                this->z.avail_in = (uInt)len;
                do {
                        this->z.next_out = buf;
                        this->z.avail_out = sizeof(buf);

                        /**
                         * For the poor next soul who sees many valgrind warnings of the
                         * "Conditional jump or move depends on uninitialised value(s)" kind:
                         * According to the author of zlib it is not a bug and it won't be fixed.
                         * http://groups.google.com/group/comp.compression/browse_thread/thread/b154b8def8c2a3ef/cdf9b8729ce17ee2
                         * [Mark Adler, Feb 24 2004, 'zlib-1.2.1 valgrind warnings' in the newsgroup comp.compression]
                         */
                        int r = deflate(&this->z, mode);

                        /* bytes were emitted? */
                        if ((n = sizeof(buf) - this->z.avail_out) != 0) {
                                this->chain->Write(buf, n);
                        }
                        if (r == Z_STREAM_END) break;

                        if (r != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "zlib returned error code");
                } while (this->z.avail_in || !this->z.avail_out);
        }

        /* virtual */ void Write(byte *buf, size_t size)
        {
                this->WriteLoop(buf, size, 0);
        }

        /* virtual */ void Finish()
        {
                this->WriteLoop(nullptr, 0, Z_FINISH);
                this->chain->Finish();
        }
};

#endif /* WITH_ZLIB */

/********************************************
 ********** START OF LZMA CODE **************
 ********************************************/

#if defined(WITH_LZMA)
#include <lzma.h>

/**
 * Have a copy of an initialised LZMA stream. We need this as it's
 * impossible to "re"-assign LZMA_STREAM_INIT to a variable in some
 * compilers, i.e. LZMA_STREAM_INIT can't be used to set something.
 * This var has to be used instead.
 */
static const lzma_stream _lzma_init = LZMA_STREAM_INIT;

/** Filter without any compression. */
struct LZMALoadFilter : LoadFilter {
        lzma_stream lzma;                  ///< Stream state that we are reading from.
        byte fread_buf[MEMORY_CHUNK_SIZE]; ///< Buffer for reading from the file.

        /**
         * Initialise this filter.
         * @param chain The next filter in this chain.
         */
        LZMALoadFilter(LoadFilter *chain) : LoadFilter(chain), lzma(_lzma_init)
        {
                /* Allow saves up to 256 MB uncompressed */
                if (lzma_auto_decoder(&this->lzma, 1 << 28, 0) != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
        }

        /** Clean everything up. */
        ~LZMALoadFilter()
        {
                lzma_end(&this->lzma);
        }

        /* virtual */ size_t Read(byte *buf, size_t size)
        {
                this->lzma.next_out  = buf;
                this->lzma.avail_out = size;

                do {
                        /* read more bytes from the file? */
                        if (this->lzma.avail_in == 0) {
                                this->lzma.next_in  = this->fread_buf;
                                this->lzma.avail_in = this->chain->Read(this->fread_buf, sizeof(this->fread_buf));
                        }

                        /* inflate the data */
                        lzma_ret r = lzma_code(&this->lzma, LZMA_RUN);
                        if (r == LZMA_STREAM_END) break;
                        if (r != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "liblzma returned error code");
                } while (this->lzma.avail_out != 0);

                return size - this->lzma.avail_out;
        }
};

/** Filter using LZMA compression. */
struct LZMASaveFilter : SaveFilter {
        lzma_stream lzma; ///< Stream state that we are writing to.

        /**
         * Initialise this filter.
         * @param chain             The next filter in this chain.
         * @param compression_level The requested level of compression.
         */
        LZMASaveFilter(SaveFilter *chain, byte compression_level) : SaveFilter(chain), lzma(_lzma_init)
        {
                if (lzma_easy_encoder(&this->lzma, compression_level, LZMA_CHECK_CRC32) != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
        }

        /** Clean up what we allocated. */
        ~LZMASaveFilter()
        {
                lzma_end(&this->lzma);
        }

        /**
         * Helper loop for writing the data.
         * @param p      The bytes to write.
         * @param len    Amount of bytes to write.
         * @param action Action for lzma_code.
         */
        void WriteLoop(byte *p, size_t len, lzma_action action)
        {
                byte buf[MEMORY_CHUNK_SIZE]; // output buffer
                size_t n;
                this->lzma.next_in = p;
                this->lzma.avail_in = len;
                do {
                        this->lzma.next_out = buf;
                        this->lzma.avail_out = sizeof(buf);

                        lzma_ret r = lzma_code(&this->lzma, action);

                        /* bytes were emitted? */
                        if ((n = sizeof(buf) - this->lzma.avail_out) != 0) {
                                this->chain->Write(buf, n);
                        }
                        if (r == LZMA_STREAM_END) break;
                        if (r != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "liblzma returned error code");
                } while (this->lzma.avail_in || !this->lzma.avail_out);
        }

        /* virtual */ void Write(byte *buf, size_t size)
        {
                this->WriteLoop(buf, size, LZMA_RUN);
        }

        /* virtual */ void Finish()
        {
                this->WriteLoop(nullptr, 0, LZMA_FINISH);
                this->chain->Finish();
        }
};

#endif /* WITH_LZMA */

/*******************************************
 ************* END OF CODE *****************
 *******************************************/

/** The format for a reader/writer type of a savegame */
struct SaveLoadFormat {
        const char *name;                     ///< name of the compressor/decompressor (debug-only)
        uint32 tag;                           ///< the 4-letter tag by which it is identified in the savegame

        LoadFilter *(*init_load)(LoadFilter *chain);                    ///< Constructor for the load filter.
        SaveFilter *(*init_write)(SaveFilter *chain, byte compression); ///< Constructor for the save filter.

        byte min_compression;                 ///< the minimum compression level of this format
        byte default_compression;             ///< the default compression level of this format
        byte max_compression;                 ///< the maximum compression level of this format
};

/** The different saveload formats known/understood by OpenTTD. */
static const SaveLoadFormat _saveload_formats[] = {
#if defined(WITH_LZO)
        /* Roughly 75% larger than zlib level 6 at only ~7% of the CPU usage. */
        {"lzo",    TO_BE32X('OTTD'), CreateLoadFilter<LZOLoadFilter>,    CreateSaveFilter<LZOSaveFilter>,    0, 0, 0},
#else
        {"lzo",    TO_BE32X('OTTD'), nullptr,                               nullptr,                               0, 0, 0},
#endif
        /* Roughly 5 times larger at only 1% of the CPU usage over zlib level 6. */
        {"none",   TO_BE32X('OTTN'), CreateLoadFilter<NoCompLoadFilter>, CreateSaveFilter<NoCompSaveFilter>, 0, 0, 0},
#if defined(WITH_ZLIB)
        /* After level 6 the speed reduction is significant (1.5x to 2.5x slower per level), but the reduction in filesize is
         * fairly insignificant (~1% for each step). Lower levels become ~5-10% bigger by each level than level 6 while level
         * 1 is "only" 3 times as fast. Level 0 results in uncompressed savegames at about 8 times the cost of "none". */
        {"zlib",   TO_BE32X('OTTZ'), CreateLoadFilter<ZlibLoadFilter>,   CreateSaveFilter<ZlibSaveFilter>,   0, 6, 9},
#else
        {"zlib",   TO_BE32X('OTTZ'), nullptr,                               nullptr,                               0, 0, 0},
#endif
#if defined(WITH_LZMA)
        /* Level 2 compression is speed wise as fast as zlib level 6 compression (old default), but results in ~10% smaller saves.
         * Higher compression levels are possible, and might improve savegame size by up to 25%, but are also up to 10 times slower.
         * The next significant reduction in file size is at level 4, but that is already 4 times slower. Level 3 is primarily 50%
         * slower while not improving the filesize, while level 0 and 1 are faster, but don't reduce savegame size much.
         * It's OTTX and not e.g. OTTL because liblzma is part of xz-utils and .tar.xz is preferred over .tar.lzma. */
        {"lzma",   TO_BE32X('OTTX'), CreateLoadFilter<LZMALoadFilter>,   CreateSaveFilter<LZMASaveFilter>,   0, 2, 9},
#else
        {"lzma",   TO_BE32X('OTTX'), nullptr,                               nullptr,                               0, 0, 0},
#endif
};

/**
 * Return the savegameformat of the game. Whether it was created with ZLIB compression
 * uncompressed, or another type
 * @param s Name of the savegame format. If nullptr it picks the first available one
 * @param compression_level Output for telling what compression level we want.
 * @return Pointer to SaveLoadFormat struct giving all characteristics of this type of savegame
 */
static const SaveLoadFormat *GetSavegameFormat(char *s, byte *compression_level)
{
        const SaveLoadFormat *def = lastof(_saveload_formats);

        /* find default savegame format, the highest one with which files can be written */
        while (!def->init_write) def--;

        if (!StrEmpty(s)) {
                /* Get the ":..." of the compression level out of the way */
                char *complevel = strrchr(s, ':');
                if (complevel != nullptr) *complevel = '\0';

                for (const SaveLoadFormat *slf = &_saveload_formats[0]; slf != endof(_saveload_formats); slf++) {
                        if (slf->init_write != nullptr && strcmp(s, slf->name) == 0) {
                                *compression_level = slf->default_compression;
                                if (complevel != nullptr) {
                                        /* There is a compression level in the string.
                                         * First restore the : we removed to do proper name matching,
                                         * then move the the begin of the actual version. */
                                        *complevel = ':';
                                        complevel++;

                                        /* Get the version and determine whether all went fine. */
                                        char *end;
                                        long level = strtol(complevel, &end, 10);
                                        if (end == complevel || level != Clamp(level, slf->min_compression, slf->max_compression)) {
                                                SetDParamStr(0, complevel);
                                                ShowErrorMessage(STR_CONFIG_ERROR, STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_LEVEL, WL_CRITICAL);
                                        } else {
                                                *compression_level = level;
                                        }
                                }
                                return slf;
                        }
                }

                SetDParamStr(0, s);
                SetDParamStr(1, def->name);
                ShowErrorMessage(STR_CONFIG_ERROR, STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_ALGORITHM, WL_CRITICAL);

                /* Restore the string by adding the : back */
                if (complevel != nullptr) *complevel = ':';
        }
        *compression_level = def->default_compression;
        return def;
}

/* actual loader/saver function */
void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settings);
extern bool AfterLoadGame();
extern bool LoadOldSaveGame(const char *file);

/**
 * Clear/free saveload state.
 */
static inline void ClearSaveLoadState()
{
        delete _sl.dumper;
        _sl.dumper = nullptr;

        delete _sl.sf;
        _sl.sf = nullptr;

        delete _sl.reader;
        _sl.reader = nullptr;

        delete _sl.lf;
        _sl.lf = nullptr;
}

/**
 * Update the gui accordingly when starting saving
 * and set locks on saveload. Also turn off fast-forward cause with that
 * saving takes Aaaaages
 */
static void SaveFileStart()
{
        _sl.ff_state = _fast_forward;
        _fast_forward = 0;
        SetMouseCursorBusy(true);

        InvalidateWindowData(WC_STATUS_BAR, 0, SBI_SAVELOAD_START);
        _sl.saveinprogress = true;
}

/** Update the gui accordingly when saving is done and release locks on saveload. */
static void SaveFileDone()
{
        if (_game_mode != GM_MENU) _fast_forward = _sl.ff_state;
        SetMouseCursorBusy(false);

        InvalidateWindowData(WC_STATUS_BAR, 0, SBI_SAVELOAD_FINISH);
        _sl.saveinprogress = false;
}

/** Set the error message from outside of the actual loading/saving of the game (AfterLoadGame and friends) */
void SetSaveLoadError(StringID str)
{
        _sl.error_str = str;
}

/** Get the string representation of the error message */
const char *GetSaveLoadErrorString()
{
        SetDParam(0, _sl.error_str);
        SetDParamStr(1, _sl.extra_msg);

        static char err_str[512];
        GetString(err_str, _sl.action == SLA_SAVE ? STR_ERROR_GAME_SAVE_FAILED : STR_ERROR_GAME_LOAD_FAILED, lastof(err_str));
        return err_str;
}

/** Show a gui message when saving has failed */
static void SaveFileError()
{
        SetDParamStr(0, GetSaveLoadErrorString());
        ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_ERROR);
        SaveFileDone();
}

/**
 * We have written the whole game into memory, _memory_savegame, now find
 * and appropriate compressor and start writing to file.
 */
static SaveOrLoadResult SaveFileToDisk(bool threaded)
{
        try {
                byte compression;
                const SaveLoadFormat *fmt = GetSavegameFormat(_savegame_format, &compression);

                /* We have written our stuff to memory, now write it to file! */
                uint32 hdr[2] = { fmt->tag, TO_BE32(SAVEGAME_VERSION << 16) };
                _sl.sf->Write((byte*)hdr, sizeof(hdr));

                _sl.sf = fmt->init_write(_sl.sf, compression);
                _sl.dumper->Flush(_sl.sf);

                ClearSaveLoadState();

                if (threaded) SetAsyncSaveFinish(SaveFileDone);

                return SL_OK;
        } catch (...) {
                ClearSaveLoadState();

                AsyncSaveFinishProc asfp = SaveFileDone;

                /* We don't want to shout when saving is just
                 * cancelled due to a client disconnecting. */
                if (_sl.error_str != STR_NETWORK_ERROR_LOSTCONNECTION) {
                        /* Skip the "colour" character */
                        DEBUG(sl, 0, "%s", GetSaveLoadErrorString() + 3);
                        asfp = SaveFileError;
                }

                if (threaded) {
                        SetAsyncSaveFinish(asfp);
                } else {
                        asfp();
                }
                return SL_ERROR;
        }
}

/** Thread run function for saving the file to disk. */
static void SaveFileToDiskThread(void *arg)
{
        SaveFileToDisk(true);
}

void WaitTillSaved()
{
        if (_save_thread == nullptr) return;

        _save_thread->Join();
        delete _save_thread;
        _save_thread = nullptr;

        /* Make sure every other state is handled properly as well. */
        ProcessAsyncSaveFinish();
}

/**
 * Actually perform the saving of the savegame.
 * General tactics is to first save the game to memory, then write it to file
 * using the writer, either in threaded mode if possible, or single-threaded.
 * @param writer   The filter to write the savegame to.
 * @param threaded Whether to try to perform the saving asynchronously.
 * @return Return the result of the action. #SL_OK or #SL_ERROR
 */
static SaveOrLoadResult DoSave(SaveFilter *writer, bool threaded)
{
        assert(!_sl.saveinprogress);

        _sl.dumper = new MemoryDumper();
        _sl.sf = writer;

        _sl_version = SAVEGAME_VERSION;

        SaveViewportBeforeSaveGame();
        SlSaveChunks();

        SaveFileStart();
        if (!threaded || !ThreadObject::New(&SaveFileToDiskThread, nullptr, &_save_thread, "ottd:savegame")) {
                if (threaded) DEBUG(sl, 1, "Cannot create savegame thread, reverting to single-threaded mode...");

                SaveOrLoadResult result = SaveFileToDisk(false);
                SaveFileDone();

                return result;
        }

        return SL_OK;
}

/**
 * Save the game using a (writer) filter.
 * @param writer   The filter to write the savegame to.
 * @param threaded Whether to try to perform the saving asynchronously.
 * @return Return the result of the action. #SL_OK or #SL_ERROR
 */
SaveOrLoadResult SaveWithFilter(SaveFilter *writer, bool threaded)
{
        try {
                _sl.action = SLA_SAVE;
                return DoSave(writer, threaded);
        } catch (...) {
                ClearSaveLoadState();
                return SL_ERROR;
        }
}

/**
 * Actually perform the loading of a "non-old" savegame.
 * @param reader     The filter to read the savegame from.
 * @param load_check Whether to perform the checking ("preview") or actually load the game.
 * @return Return the result of the action. #SL_OK or #SL_REINIT ("unload" the game)
 */
static SaveOrLoadResult DoLoad(LoadFilter *reader, bool load_check)
{
        _sl.lf = reader;

        if (load_check) {
                /* Clear previous check data */
                _load_check_data.Clear();
                /* Mark SL_LOAD_CHECK as supported for this savegame. */
                _load_check_data.checkable = true;
        }

        uint32 hdr[2];
        if (_sl.lf->Read((byte*)hdr, sizeof(hdr)) != sizeof(hdr)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);

        /* see if we have any loader for this type. */
        const SaveLoadFormat *fmt = _saveload_formats;
        for (;;) {
                /* No loader found, treat as version 0 and use LZO format */
                if (fmt == endof(_saveload_formats)) {
                        DEBUG(sl, 0, "Unknown savegame type, trying to load it as the buggy format");
                        _sl.lf->Reset();
                        _sl_version = 0;
                        _sl_minor_version = 0;

                        /* Try to find the LZO savegame format; it uses 'OTTD' as tag. */
                        fmt = _saveload_formats;
                        for (;;) {
                                if (fmt == endof(_saveload_formats)) {
                                        /* Who removed LZO support? Bad bad boy! */
                                        NOT_REACHED();
                                }
                                if (fmt->tag == TO_BE32X('OTTD')) break;
                                fmt++;
                        }
                        break;
                }

                if (fmt->tag == hdr[0]) {
                        /* check version number */
                        _sl_version = TO_BE32(hdr[1]) >> 16;
                        /* Minor is not used anymore from version 18.0, but it is still needed
                         * in versions before that (4 cases) which can't be removed easy.
                         * Therefore it is loaded, but never saved (or, it saves a 0 in any scenario). */
                        _sl_minor_version = (TO_BE32(hdr[1]) >> 8) & 0xFF;

                        DEBUG(sl, 1, "Loading savegame version %d", _sl_version);

                        /* Is the version higher than the current? */
                        if (_sl_version > SAVEGAME_VERSION) SlError(STR_GAME_SAVELOAD_ERROR_TOO_NEW_SAVEGAME);
                        break;
                }

                fmt++;
        }

        /* loader for this savegame type is not implemented? */
        if (fmt->init_load == nullptr) {
                char err_str[64];
                seprintf(err_str, lastof(err_str), "Loader for '%s' is not available.", fmt->name);
                SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, err_str);
        }

        _sl.lf = fmt->init_load(_sl.lf);
        _sl.reader = new ReadBuffer(_sl.lf);
        _next_offs = 0;

        if (!load_check) {
                /* Old maps were hardcoded to 256x256 and thus did not contain
                 * any mapsize information. Pre-initialize to 256x256 to not to
                 * confuse old games */
                InitializeGame(256, 256, true, true);

                GamelogReset();

                if (IsSavegameVersionBefore(4)) {
                        /*
                         * NewGRFs were introduced between 0.3,4 and 0.3.5, which both
                         * shared savegame version 4. Anything before that 'obviously'
                         * does not have any NewGRFs. Between the introduction and
                         * savegame version 41 (just before 0.5) the NewGRF settings
                         * were not stored in the savegame and they were loaded by
                         * using the settings from the main menu.
                         * So, to recap:
                         * - savegame version  <  4:  do not load any NewGRFs.
                         * - savegame version >= 41:  load NewGRFs from savegame, which is
                         *                            already done at this stage by
                         *                            overwriting the main menu settings.
                         * - other savegame versions: use main menu settings.
                         *
                         * This means that users *can* crash savegame version 4..40
                         * savegames if they set incompatible NewGRFs in the main menu,
                         * but can't crash anymore for savegame version < 4 savegames.
                         *
                         * Note: this is done here because AfterLoadGame is also called
                         * for TTO/TTD/TTDP savegames which have their own NewGRF logic.
                         */
                        ClearGRFConfigList(&_grfconfig);
                }
        }

        if (load_check) {
                /* Load chunks into _load_check_data.
                 * No pools are loaded. References are not possible, and thus do not need resolving. */
                SlLoadCheckChunks();
        } else {
                /* Load chunks and resolve references */
                SlLoadChunks();
                SlFixPointers();
        }

        ClearSaveLoadState();

        _savegame_type = SGT_OTTD;

        if (load_check) {
                /* The only part from AfterLoadGame() we need */
                _load_check_data.grf_compatibility = IsGoodGRFConfigList(_load_check_data.grfconfig);
        } else {
                GamelogStartAction(GLAT_LOAD);

                /* After loading fix up savegame for any internal changes that
                 * might have occurred since then. If it fails, load back the old game. */
                if (!AfterLoadGame()) {
                        GamelogStopAction();
                        return SL_REINIT;
                }

                GamelogStopAction();
        }

        return SL_OK;
}

/**
 * Load the game using a (reader) filter.
 * @param reader   The filter to read the savegame from.
 * @return Return the result of the action. #SL_OK or #SL_REINIT ("unload" the game)
 */
SaveOrLoadResult LoadWithFilter(LoadFilter *reader)
{
        try {
                _sl.action = SLA_LOAD;
                return DoLoad(reader, false);
        } catch (...) {
                ClearSaveLoadState();
                return SL_REINIT;
        }
}

/**
 * Main Save or Load function where the high-level saveload functions are
 * handled. It opens the savegame, selects format and checks versions
 * @param filename The name of the savegame being created/loaded
 * @param mode Save or load mode. Load can also be a TTD(Patch) game. Use #SL_LOAD, #SL_OLD_LOAD, #SL_LOAD_CHECK, or #SL_SAVE.
 * @param sb The sub directory to save the savegame in
 * @param threaded True when threaded saving is allowed
 * @return Return the result of the action. #SL_OK, #SL_ERROR, or #SL_REINIT ("unload" the game)
 */
SaveOrLoadResult SaveOrLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded)
{
        /* An instance of saving is already active, so don't go saving again */
        if (_sl.saveinprogress && fop == SLO_SAVE && dft == DFT_GAME_FILE && threaded) {
                /* if not an autosave, but a user action, show error message */
                if (!_do_autosave) ShowErrorMessage(STR_ERROR_SAVE_STILL_IN_PROGRESS, INVALID_STRING_ID, WL_ERROR);
                return SL_OK;
        }
        WaitTillSaved();

        try {
                /* Load a TTDLX or TTDPatch game */
                if (fop == SLO_LOAD && dft == DFT_OLD_GAME_FILE) {
                        InitializeGame(256, 256, true, true); // set a mapsize of 256x256 for TTDPatch games or it might get confused

                        /* TTD/TTO savegames have no NewGRFs, TTDP savegame have them
                         * and if so a new NewGRF list will be made in LoadOldSaveGame.
                         * Note: this is done here because AfterLoadGame is also called
                         * for OTTD savegames which have their own NewGRF logic. */
                        ClearGRFConfigList(&_grfconfig);
                        GamelogReset();
                        if (!LoadOldSaveGame(filename)) return SL_REINIT;
                        _sl_version = 0;
                        _sl_minor_version = 0;
                        GamelogStartAction(GLAT_LOAD);
                        if (!AfterLoadGame()) {
                                GamelogStopAction();
                                return SL_REINIT;
                        }
                        GamelogStopAction();
                        return SL_OK;
                }

                assert(dft == DFT_GAME_FILE);
                switch (fop) {
                        case SLO_CHECK:
                                _sl.action = SLA_LOAD_CHECK;
                                break;

                        case SLO_LOAD:
                                _sl.action = SLA_LOAD;
                                break;

                        case SLO_SAVE:
                                _sl.action = SLA_SAVE;
                                break;

                        default: NOT_REACHED();
                }

                FILE *fh = (fop == SLO_SAVE) ? FioFOpenFile(filename, "wb", sb) : FioFOpenFile(filename, "rb", sb);

                /* Make it a little easier to load savegames from the console */
                if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
                if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", BASE_DIR);
                if (fh == nullptr && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);

                if (fh == nullptr) {
                        SlError(fop == SLO_SAVE ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
                }

                if (fop == SLO_SAVE) { // SAVE game
                        DEBUG(desync, 1, "save: %08x; %02x; %s", _date, _date_fract, filename);
                        if (_network_server || !_settings_client.gui.threaded_saves) threaded = false;

                        return DoSave(new FileWriter(fh), threaded);
                }

                /* LOAD game */
                assert(fop == SLO_LOAD || fop == SLO_CHECK);
                DEBUG(desync, 1, "load: %s", filename);
                return DoLoad(new FileReader(fh), fop == SLO_CHECK);
        } catch (...) {
                /* This code may be executed both for old and new save games. */
                ClearSaveLoadState();

                /* Skip the "colour" character */
                if (fop != SLO_CHECK) DEBUG(sl, 0, "%s", GetSaveLoadErrorString() + 3);

                /* A saver/loader exception!! reinitialize all variables to prevent crash! */
                return (fop == SLO_LOAD) ? SL_REINIT : SL_ERROR;
        }
}

/** Do a save when exiting the game (_settings_client.gui.autosave_on_exit) */
void DoExitSave()
{
        SaveOrLoad("exit.sav", SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR);
}

/**
 * Fill the buffer with the default name for a savegame *or* screenshot.
 * @param buf the buffer to write to.
 * @param last the last element in the buffer.
 */
void GenerateDefaultSaveName(char *buf, const char *last)
{
        /* Check if we have a name for this map, which is the name of the first
         * available company. When there's no company available we'll use
         * 'Spectator' as "company" name. */
        CompanyID cid = _local_company;
        if (!Company::IsValidID(cid)) {
                const Company *c;
                FOR_ALL_COMPANIES(c) {
                        cid = c->index;
                        break;
                }
        }

        SetDParam(0, cid);

        /* Insert current date */
        switch (_settings_client.gui.date_format_in_default_names) {
                case 0: SetDParam(1, STR_JUST_DATE_LONG); break;
                case 1: SetDParam(1, STR_JUST_DATE); break;
                case 2: SetDParam(1, STR_JUST_DATE_ISO); break;
                default: NOT_REACHED();
        }
        SetDParam(2, _date);

        /* Get the correct string (special string for when there's not company) */
        GetString(buf, !Company::IsValidID(cid) ? STR_SAVEGAME_NAME_SPECTATOR : STR_SAVEGAME_NAME_DEFAULT, last);
        SanitizeFilename(buf);
}

/**
 * Set the mode and file type of the file to save or load based on the type of file entry at the file system.
 * @param ft Type of file entry of the file system.
 */
void FileToSaveLoad::SetMode(FiosType ft)
{
        this->SetMode(SLO_LOAD, GetAbstractFileType(ft), GetDetailedFileType(ft));
}

/**
 * Set the mode and file type of the file to save or load.
 * @param fop File operation being performed.
 * @param aft Abstract file type.
 * @param dft Detailed file type.
 */
void FileToSaveLoad::SetMode(SaveLoadOperation fop, AbstractFileType aft, DetailedFileType dft)
{
        if (aft == FT_INVALID || aft == FT_NONE) {
                this->file_op = SLO_INVALID;
                this->detail_ftype = DFT_INVALID;
                this->abstract_ftype = FT_INVALID;
                return;
        }

        this->file_op = fop;
        this->detail_ftype = dft;
        this->abstract_ftype = aft;
}

/**
 * Set the name of the file.
 * @param name Name of the file.
 */
void FileToSaveLoad::SetName(const char *name)
{
        strecpy(this->name, name, lastof(this->name));
}

/**
 * Set the title of the file.
 * @param title Title of the file.
 */
void FileToSaveLoad::SetTitle(const char *title)
{
        strecpy(this->title, title, lastof(this->title));
}

#if 0
/**
 * Function to get the type of the savegame by looking at the file header.
 * NOTICE: Not used right now, but could be used if extensions of savegames are garbled
 * @param file Savegame to be checked
 * @return SL_OLD_LOAD or SL_LOAD of the file
 */
int GetSavegameType(char *file)
{
        const SaveLoadFormat *fmt;
        uint32 hdr;
        FILE *f;
        int mode = SL_OLD_LOAD;

        f = fopen(file, "rb");
        if (fread(&hdr, sizeof(hdr), 1, f) != 1) {
                DEBUG(sl, 0, "Savegame is obsolete or invalid format");
                mode = SL_LOAD; // don't try to get filename, just show name as it is written
        } else {
                /* see if we have any loader for this type. */
                for (fmt = _saveload_formats; fmt != endof(_saveload_formats); fmt++) {
                        if (fmt->tag == hdr) {
                                mode = SL_LOAD; // new type of savegame
                                break;
                        }
                }
        }

        fclose(f);
        return mode;
}
#endif