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authorrubidium <rubidium@openttd.org>2010-10-27 16:42:20 +0000
committerrubidium <rubidium@openttd.org>2010-10-27 16:42:20 +0000
commit59519edd344b3e9fa7d8f9f768563e8533d3760b (patch)
tree3c68e8041adb9395345d0330e80b36686d0d8e02 /src/saveload
parent5ad2265c1d7f36d17ac157bd4e5e722a6a2355d3 (diff)
downloadopenttd-59519edd344b3e9fa7d8f9f768563e8533d3760b.tar.xz
(svn r21044) -Feature: XZ/LZMA2 savegame support. New default reduces savegame size by 10 to 30% with slightly more CPU usage. With maximum settings it reduces savegame size by 20 to 30%, but that takes 7 to 14 times longer. Map saving + downloading takes, on average, 5% less.
Diffstat (limited to 'src/saveload')
-rw-r--r--src/saveload/saveload.cpp116
1 files changed, 116 insertions, 0 deletions
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index 6f0bc055b..4e656c013 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -1944,6 +1944,106 @@ static void UninitWriteZlib()
#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, i.e.
+ * LZMA_STREAM_INIT can't be used to reset something. This var can.
+ */
+static const lzma_stream _lzma_init = LZMA_STREAM_INIT;
+/** The current LZMA stream we're processing. */
+static lzma_stream _lzma;
+
+static bool InitReadLZMA(byte compression)
+{
+ _lzma = _lzma_init;
+ /* Allow saves up to 256 MB uncompressed */
+ if (lzma_auto_decoder(&_lzma, 1 << 28, 0) != LZMA_OK) return false;
+
+ _sl.bufsize = MEMORY_CHUNK_SIZE;
+ _sl.buf = _sl.buf_ori = MallocT<byte>(MEMORY_CHUNK_SIZE + MEMORY_CHUNK_SIZE); // also contains fread buffer
+ return true;
+}
+
+static size_t ReadLZMA()
+{
+ _lzma.next_out = _sl.buf;
+ _lzma.avail_out = MEMORY_CHUNK_SIZE;
+
+ do {
+ /* read more bytes from the file? */
+ if (_lzma.avail_in == 0) {
+ _lzma.next_in = _sl.buf + MEMORY_CHUNK_SIZE;
+ _lzma.avail_in = fread(_sl.buf + MEMORY_CHUNK_SIZE, 1, MEMORY_CHUNK_SIZE, _sl.fh);
+ }
+
+ /* inflate the data */
+ lzma_ret r = lzma_code(&_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 (_lzma.avail_out != 0);
+
+ return MEMORY_CHUNK_SIZE - _lzma.avail_out;
+}
+
+static void UninitReadLZMA()
+{
+ lzma_end(&_lzma);
+ free(_sl.buf_ori);
+}
+
+static bool InitWriteLZMA(byte compression)
+{
+ _lzma = _lzma_init;
+ if (lzma_easy_encoder(&_lzma, compression, LZMA_CHECK_CRC32) != LZMA_OK) return false;
+
+ _sl.bufsize = MEMORY_CHUNK_SIZE;
+ _sl.buf = _sl.buf_ori = MallocT<byte>(MEMORY_CHUNK_SIZE);
+ return true;
+}
+
+static void WriteLZMALoop(lzma_stream *lzma, byte *p, size_t len, lzma_action action)
+{
+ byte buf[MEMORY_CHUNK_SIZE]; // output buffer
+ size_t n;
+ lzma->next_in = p;
+ lzma->avail_in = len;
+ do {
+ lzma->next_out = buf;
+ lzma->avail_out = sizeof(buf);
+
+ lzma_ret r = lzma_code(&_lzma, action);
+
+ /* bytes were emitted? */
+ if ((n = sizeof(buf) - lzma->avail_out) != 0) {
+ if (fwrite(buf, n, 1, _sl.fh) != 1) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE);
+ }
+ if (r == LZMA_STREAM_END) break;
+ if (r != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "liblzma returned error code");
+ } while (lzma->avail_in || !lzma->avail_out);
+}
+
+static void WriteLZMA(size_t len)
+{
+ WriteLZMALoop(&_lzma, _sl.buf, len, LZMA_RUN);
+}
+
+static void UninitWriteLZMA()
+{
+ /* flush any pending output. */
+ if (_sl.fh) WriteLZMALoop(&_lzma, NULL, 0, LZMA_FINISH);
+ lzma_end(&_lzma);
+ free(_sl.buf_ori);
+}
+
+#endif /* WITH_LZMA */
+
/*******************************************
************* END OF CODE *****************
*******************************************/
@@ -1966,18 +2066,34 @@ struct SaveLoadFormat {
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'), InitLZO, ReadLZO, UninitLZO, InitLZO, WriteLZO, UninitLZO, 0, 0, 0},
#else
{"lzo", TO_BE32X('OTTD'), NULL, NULL, NULL, NULL, NULL, NULL, 0, 0, 0},
#endif
+ /* Roughly 5 times larger at only 1% of the CPU usage over zlib level 6. */
{"none", TO_BE32X('OTTN'), InitNoComp, ReadNoComp, UninitNoComp, InitNoComp, WriteNoComp, UninitNoComp, 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'), InitReadZlib, ReadZlib, UninitReadZlib, InitWriteZlib, WriteZlib, UninitWriteZlib, 0, 6, 9},
#else
{"zlib", TO_BE32X('OTTZ'), NULL, NULL, NULL, NULL, NULL, NULL, 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 prefered over .tar.lzma. */
+ {"lzma", TO_BE32X('OTTX'), InitReadLZMA, ReadLZMA, UninitReadLZMA, InitWriteLZMA, WriteLZMA, UninitWriteLZMA, 0, 2, 9},
+#else
+ {"lzma", TO_BE32X('OTTX'), NULL, NULL, NULL, NULL, NULL, NULL, 0, 0, 0},
+#endif
};
/**