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/*
This file is part of solidity.
solidity 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.
solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file SwarmHash.cpp
*/
#include <libdevcore/SwarmHash.h>
#include <libdevcore/Keccak256.h>
using namespace std;
using namespace dev;
namespace
{
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 swarmHashIntermediate(string const& _input, size_t _offset, size_t _length)
{
bytesConstRef ref;
bytes innerNodes;
if (_length <= 0x1000)
ref = bytesConstRef(_input).cropped(_offset, _length);
else
{
size_t maxRepresentedSize = 0x1000;
while (maxRepresentedSize * (0x1000 / 32) < _length)
maxRepresentedSize *= (0x1000 / 32);
for (size_t i = 0; i < _length; i += maxRepresentedSize)
{
size_t size = std::min(maxRepresentedSize, _length - i);
innerNodes += swarmHashIntermediate(_input, _offset + i, size).asBytes();
}
ref = bytesConstRef(&innerNodes);
}
return swarmHashSimple(ref, _length);
}
}
h256 dev::swarmHash(string const& _input)
{
return swarmHashIntermediate(_input, 0, _input.size());
}
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