64 lines
1.6 KiB
C++
64 lines
1.6 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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//-----------------------------------------------------------------------------
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uint32_t
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util::hash::murmur1::mix (uint32_t h, uint32_t k)
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{
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static const uint32_t m = 0xc6a4a793;
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h += k;
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h *= m;
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h ^= h >> 16;
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return h;
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}
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//-----------------------------------------------------------------------------
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uint32_t
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util::hash::murmur1::hash_32 (const void *restrict data,
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size_t len,
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uint32_t seed)
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{
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CHECK (data);
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static const uint32_t m = 0xc6a4a793;
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uint32_t h = seed ^ (len * m);
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// mix the body
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auto cursor = reinterpret_cast<const uint32_t*> (data);
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auto last = cursor + len / sizeof (uint32_t);
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for (; cursor < last; ++cursor)
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h = mix (h, *cursor);
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// mix the tail
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if (len % sizeof (uint32_t))
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h = mix (h, murmur::tail (cursor, len));
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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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