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Codechange: use C++ algorithms to determine the SaveLoadFormat

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Rubidium 2024-04-09 22:57:39 +02:00 committed by rubidium42
parent 77f27e0804
commit df8eeb1b10
1 changed files with 56 additions and 47 deletions
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103
src/saveload/saveload.cpp
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@ -2628,23 +2628,28 @@ struct SaveLoadFormat {
uint8_t max_compression; ///< the maximum compression level of this format
};
static const uint32_t SAVEGAME_TAG_LZO = TO_BE32X('OTTD');
static const uint32_t SAVEGAME_TAG_NONE = TO_BE32X('OTTN');
static const uint32_t SAVEGAME_TAG_ZLIB = TO_BE32X('OTTZ');
static const uint32_t SAVEGAME_TAG_LZMA = TO_BE32X('OTTX');
/** 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},
{"lzo", SAVEGAME_TAG_LZO, CreateLoadFilter<LZOLoadFilter>, CreateSaveFilter<LZOSaveFilter>, 0, 0, 0},
#else
{"lzo", TO_BE32X('OTTD'), nullptr, nullptr, 0, 0, 0},
{"lzo", SAVEGAME_TAG_LZO, 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},
{"none", SAVEGAME_TAG_NONE, 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},
{"zlib", SAVEGAME_TAG_ZLIB, CreateLoadFilter<ZlibLoadFilter>, CreateSaveFilter<ZlibSaveFilter>, 0, 6, 9},
#else
{"zlib", TO_BE32X('OTTZ'), nullptr, nullptr, 0, 0, 0},
{"zlib", SAVEGAME_TAG_ZLIB, nullptr, nullptr, 0, 0, 0},
#endif
#if defined(WITH_LIBLZMA)
/* Level 2 compression is speed wise as fast as zlib level 6 compression (old default), but results in ~10% smaller saves.
@ -2652,9 +2657,9 @@ static const SaveLoadFormat _saveload_formats[] = {
* 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},
{"lzma", SAVEGAME_TAG_LZMA, CreateLoadFilter<LZMALoadFilter>, CreateSaveFilter<LZMASaveFilter>, 0, 2, 9},
#else
{"lzma", TO_BE32X('OTTX'), nullptr, nullptr, 0, 0, 0},
{"lzma", SAVEGAME_TAG_LZMA, nullptr, nullptr, 0, 0, 0},
#endif
};
@ -2885,6 +2890,49 @@ SaveOrLoadResult SaveWithFilter(std::shared_ptr<SaveFilter> writer, bool threade
}
}
/**
* Determines the SaveLoadFormat that is connected to the given tag.
* When the given tag is known, that format is chosen and a check on the validity of the version is performed.
* Otherwise a fallback to an ancient buggy format using LZO is chosen.
* @param tag The tag from the header describing the savegame compression/format.
* @param raw_version The raw version from the savegame header.
* @return The SaveLoadFormat to use for attempting to open the savegame.
*/
static const SaveLoadFormat *DetermineSaveLoadFormat(uint32_t tag, uint32_t raw_version)
{
auto fmt = std::find_if(std::begin(_saveload_formats), std::end(_saveload_formats), [tag](const auto &fmt) { return fmt.tag == tag; });
if (fmt != std::end(_saveload_formats)) {
/* Check version number */
_sl_version = (SaveLoadVersion)(TO_BE32(raw_version) >> 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(raw_version) >> 8) & 0xFF;
Debug(sl, 1, "Loading savegame version {}", _sl_version);
/* Is the version higher than the current? */
if (_sl_version > SAVEGAME_VERSION) SlError(STR_GAME_SAVELOAD_ERROR_TOO_NEW_SAVEGAME);
if (_sl_version >= SLV_START_PATCHPACKS && _sl_version <= SLV_END_PATCHPACKS) SlError(STR_GAME_SAVELOAD_ERROR_PATCHPACK);
return fmt;
}
Debug(sl, 0, "Unknown savegame type, trying to load it as the buggy format");
_sl.lf->Reset();
_sl_version = SL_MIN_VERSION;
_sl_minor_version = 0;
/* Try to find the LZO savegame format; it uses 'OTTD' as tag. */
fmt = std::find_if(std::begin(_saveload_formats), std::end(_saveload_formats), [](const auto &fmt) { return fmt.tag == SAVEGAME_TAG_LZO; });
if (fmt == std::end(_saveload_formats)) {
/* Who removed the LZO savegame format definition? When built without LZO support,
* the formats must still list it just without a method to read the file.
* The caller of this function has to check for the existence of load function. */
NOT_REACHED();
}
return fmt;
}
/**
* Actually perform the loading of a "non-old" savegame.
* @param reader The filter to read the savegame from.
@ -2906,46 +2954,7 @@ static SaveOrLoadResult DoLoad(std::shared_ptr<LoadFilter> reader, bool load_che
if (_sl.lf->Read((uint8_t*)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 = SL_MIN_VERSION;
_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? */
NOT_REACHED();
}
if (fmt->tag == TO_BE32X('OTTD')) break;
fmt++;
}
break;
}
if (fmt->tag == hdr[0]) {
/* check version number */
_sl_version = (SaveLoadVersion)(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 {}", _sl_version);
/* Is the version higher than the current? */
if (_sl_version > SAVEGAME_VERSION) SlError(STR_GAME_SAVELOAD_ERROR_TOO_NEW_SAVEGAME);
if (_sl_version >= SLV_START_PATCHPACKS && _sl_version <= SLV_END_PATCHPACKS) SlError(STR_GAME_SAVELOAD_ERROR_PATCHPACK);
break;
}
fmt++;
}
const SaveLoadFormat *fmt = DetermineSaveLoadFormat(hdr[0], hdr[1]);
/* loader for this savegame type is not implemented? */
if (fmt->init_load == nullptr) {