[WIP] First test of liblzma executable filters

- See issue #75
- Filter maximum is 4, so up to 3 filters + LZMA2 can be used
- X86+PPC+ARM could be a good default
- TODO: Command line parameter so set or disable filters

- Changed VS settings, so unfortunately there are some tab/space changes in here, too.

contrib/liblzma/compress_easy_mt.cpp

@@ -45,17 +45,24 @@ bool init_decoder(lzma_stream *strm)
 	return check(ret);
 }
 
+lzma_filter get_filter(lzma_vli filter_id) {
+	lzma_filter result;
+	result.id = filter_id;
+	result.options = NULL;
+	return result;
+}
+
 bool init_encoder_mt(lzma_stream *strm, int threads, uint64_t max_memory, uint64_t &memory_usage, uint64_t &block_size)
 {
 	// The threaded encoder takes the options as pointer to
 	// a lzma_mt structure.
 	lzma_mt mt;
 
 	// No flags are needed.
-	mt	.flags = 0;
+	mt.flags = 0;
 
 	// Let liblzma determine a sane block size.
-	mt	.block_size = 0;
+	mt.block_size = 0;
 
 	// Use no timeout for lzma_code() calls by setting timeout
 	// to zero. That is, sometimes lzma_code() might block for
@@ -64,32 +71,67 @@ bool init_encoder_mt(lzma_stream *strm, int threads, uint64_t max_memory, uint64
 	// needing updates, specify a timeout in milliseconds here.
 	// See the documentation of lzma_mt in lzma/container.h for
 	// information how to choose a reasonable timeout.
-	mt	.timeout = 110;
-
-	// To use a preset, filters must be set to NULL.
-	mt.filters = NULL;
-
+	mt.timeout = 110;
 	mt.check = LZMA_CHECK_CRC32;
 
 	mt.threads = threads;
 
-    uint64_t preset_memory_usage;
-    int preset_to_use = 1; // Always use at least preset 1, even if it exceeds the given memory limit
-    for (int preset = 2; preset <= 9; preset++) {
-        mt.preset = preset;
-        preset_memory_usage = lzma_stream_encoder_mt_memusage(&mt, &block_size);
-        if (preset_memory_usage > max_memory) break;
-        memory_usage = preset_memory_usage;
-        preset_to_use = preset;
-    }
-
-    mt.preset = preset_to_use;
-
+	uint64_t preset_memory_usage;
+  int preset_to_use = 1; // Always use at least preset 1, even if it exceeds the given memory limit
+  for (int preset = 2; preset <= 9; preset++) {
+		lzma_options_lzma opt_lzma2;
+		if (lzma_lzma_preset(&opt_lzma2, preset)) {
+			fprintf(stderr, "Unsupported preset, possibly a bug\n");
+			return false;
+		}
+
+		lzma_filter filterLzma2;
+		filterLzma2.id = LZMA_FILTER_LZMA2;
+		filterLzma2.options = &opt_lzma2;
+
+		// the executable filters we use don't change memory usage, so we just ignore them here
+		// and set them below
+		const lzma_filter filters[] = {
+			filterLzma2,
+			get_filter(LZMA_VLI_UNKNOWN)
+		};
+
+		mt.filters = filters;
+
+    preset_memory_usage = lzma_stream_encoder_mt_memusage(&mt, &block_size);
+    if (preset_memory_usage > max_memory) break;
+    memory_usage = preset_memory_usage;
+    preset_to_use = preset;
+  }
+
+	lzma_options_lzma opt_lzma2;
+	if (lzma_lzma_preset(&opt_lzma2, preset_to_use)) {
+		fprintf(stderr, "Unsupported preset, possibly a bug\n");
+		return false;
+	}
+
+	lzma_filter filterLzma2;
+	filterLzma2.id = LZMA_FILTER_LZMA2;
+	filterLzma2.options = &opt_lzma2;
+
+	const lzma_filter filters[] = {
+		get_filter(LZMA_FILTER_X86),
+		get_filter(LZMA_FILTER_POWERPC),
+		//get_filter(LZMA_FILTER_IA64),
+		get_filter(LZMA_FILTER_ARM),
+		//get_filter(LZMA_FILTER_ARMTHUMB),
+		//get_filter(LZMA_FILTER_SPARC),
+		filterLzma2,
+		get_filter(LZMA_VLI_UNKNOWN)
+	};
+
+	mt.filters = filters;
+
 	// Initialize the threaded encoder.
 	lzma_ret ret = lzma_stream_encoder_mt(strm, &mt);
 
-    // Determine memory usage and block size
-    memory_usage = lzma_stream_encoder_mt_memusage(&mt, &block_size);
+  // Determine memory usage and block size
+  memory_usage = lzma_stream_encoder_mt_memusage(&mt, &block_size);
 
-    return check(ret);
+  return check(ret);
 }