49 lines
1.4 KiB
C++
49 lines
1.4 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2015 Danny Robson <danny@nerdcruft.net>
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*/
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#include "murmur1.hpp"
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#include "common.hpp"
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#include "../../debug.hpp"
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#include "../../endian.hpp"
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using util::hash::murmur1;
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///////////////////////////////////////////////////////////////////////////////
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uint32_t
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murmur1::operator() (util::view<const uint8_t*> data) const noexcept
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{
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static const uint32_t m = 0xc6a4a793;
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uint32_t h = m_seed ^ ((data.size () & 0xffffffff) * m);
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// mix the body
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auto cursor = data.begin ();
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for (auto last = data.end () - data.size () % sizeof (uint32_t); cursor < last; cursor += 4)
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h = mix (h, util::readhe<uint32_t> (cursor));
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// mix the tail
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if (data.size () % sizeof (uint32_t))
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h = mix (h, murmur::tail<uint32_t> (cursor, data.size ()));
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// finalise
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h *= m; h ^= h >> 10;
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h *= m; h ^= h >> 17;
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return h;
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}
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