1 files changed, 113 insertions, 0 deletions
diff --git a/src/liblzma/common/memory_usage.c b/src/liblzma/common/memory_usage.c
new file mode 100644
index 00000000..b6f27957
--- /dev/null
+++ b/src/liblzma/common/memory_usage.c
@@ -0,0 +1,113 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       memory_usage.c
+/// \brief      Calculate rough amount of memory required by filters
+//
+//  Copyright (C) 2007 Lasse Collin
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2.1 of the License, or (at your option) any later version.
+//
+//  This library 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
+//  Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+#include "lz_encoder.h"
+#include "lzma_literal.h"
+
+
+static uint64_t
+get_usage(const lzma_options_filter *filter, bool is_encoder)
+{
+	uint64_t ret;
+
+	switch (filter->id) {
+	case LZMA_FILTER_COPY:
+	case LZMA_FILTER_X86:
+	case LZMA_FILTER_POWERPC:
+	case LZMA_FILTER_IA64:
+	case LZMA_FILTER_ARM:
+	case LZMA_FILTER_ARMTHUMB:
+	case LZMA_FILTER_SPARC:
+	case LZMA_FILTER_DELTA:
+		// These don't require any significant amount of memory.
+		ret = 0;
+		break;
+
+	case LZMA_FILTER_SUBBLOCK:
+		if (is_encoder) {
+			const lzma_options_subblock *options = filter->options;
+			ret = options->subblock_data_size;
+		} else {
+			ret = 0;
+		}
+		break;
+
+#ifdef HAVE_FILTER_LZMA
+	case LZMA_FILTER_LZMA: {
+		const lzma_options_lzma *options = filter->options;
+
+		// Literal coder - this can be signficant if both values are
+		// big, or if sizeof(probability) is big.
+		ret = literal_states(options->literal_context_bits,
+				options->literal_pos_bits) * LIT_SIZE
+				* sizeof(probability);
+
+		// Dictionary base size
+		ret += options->dictionary_size;
+
+		if (is_encoder) {
+#	ifdef HAVE_ENCODER
+			// This is rough, but should be accurate enough
+			// in practice.
+			ret += options->dictionary_size / 2;
+
+			uint32_t dummy1;
+			uint32_t dummy2;
+			uint32_t num_items;
+			if (lzma_lz_encoder_hash_properties(
+					options->match_finder,
+					options->dictionary_size,
+					&dummy1, &dummy2, &num_items))
+				return UINT64_MAX;
+
+			ret += (uint64_t)(num_items) * sizeof(uint32_t);
+#	else
+			return UINT64_MAX;
+#	endif
+		}
+
+		break;
+	}
+#endif
+
+	default:
+		return UINT64_MAX;
+	}
+
+	return ret;
+}
+
+
+extern LZMA_API uint32_t
+lzma_memory_usage(const lzma_options_filter *filters, lzma_bool is_encoder)
+{
+	uint64_t usage = 0;
+
+	for (size_t i = 0; filters[i].id != UINT64_MAX; ++i) {
+		const uint64_t ret = get_usage(filters + i, is_encoder);
+		if (ret == UINT64_MAX)
+			return UINT32_MAX;
+
+		usage += ret;
+	}
+
+	// Convert to mebibytes with rounding.
+	return usage / (1024 * 1024) + (usage % (1024 * 1024) >= 512 ? 1 : 0);
+}