1 files changed, 69 insertions, 0 deletions
diff --git a/libdevcore/SwarmHash.cpp b/libdevcore/SwarmHash.cpp
new file mode 100644
index 00000000..583d84b1
--- /dev/null
+++ b/libdevcore/SwarmHash.cpp
@@ -0,0 +1,69 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum 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, either version 3 of the License, or
+	(at your option) any later version.
+
+	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file SwarmHash.cpp
+ */
+
+#include <libdevcore/SwarmHash.h>
+
+#include <libdevcore/SHA3.h>
+
+using namespace std;
+using namespace dev;
+
+
+bytes toLittleEndian(size_t _size)
+{
+	bytes encoded(8);
+	for (size_t i = 0; i < 8; ++i)
+		encoded[i] = (_size >> (8 * i)) & 0xff;
+	return encoded;
+}
+
+h256 swarmHashSimple(bytesConstRef _data, size_t _size)
+{
+	return keccak256(toLittleEndian(_size) + _data.toBytes());
+}
+
+h256 dev::swarmHash(bytes const& _input)
+{
+	bytes data = _input;
+	size_t lastChunkSize = 0;
+	size_t level = 0;
+	do
+	{
+		bytes innerNodes;
+		size_t i = 0;
+		do
+		{
+			size_t bytes = std::min<size_t>(0x1000, data.size() - i);
+			size_t size = bytes << (7 * level);
+			if (i + 0x1000 >= data.size())
+			{
+				// last node
+				size = level == 0 ? bytes : ((bytes - 32) << (7 * level)) + lastChunkSize;
+				lastChunkSize = size;
+			}
+			innerNodes += swarmHashSimple(bytesConstRef(_input.data() + i, bytes), size).asBytes();
+			i += 0x1000;
+		}
+		while (i < data.size());
+		data = std::move(innerNodes);
+		level++;
+	}
+	while (data.size() > 32);
+	return h256(data);
+}