90 lines
2.2 KiB
C++
90 lines
2.2 KiB
C++
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/*
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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 "murmur2.hpp"
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#include "../../debug.hpp"
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#include "common.hpp"
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///////////////////////////////////////////////////////////////////////////////
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uint32_t
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util::hash::murmur2::hash_32 (const void *restrict key,
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size_t len,
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uint32_t seed)
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{
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CHECK (key);
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// setup
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constexpr auto m = detail::constants<uint32_t>::m;
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uint32_t h = seed ^ uint32_t (len);
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// body
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auto cursor = reinterpret_cast<const uint32_t*> (key);
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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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// tail
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if (len % sizeof (uint32_t)) {
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h ^= murmur::tail (cursor, len);
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h *= m;
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}
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// finalise
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h ^= h >> 13;
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h *= m;
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h ^= h >> 15;
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return h;
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}
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//-----------------------------------------------------------------------------
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uint64_t
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util::hash::murmur2::hash_64 (const void *restrict key,
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size_t len,
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uint64_t seed)
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{
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// setup
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constexpr auto m = detail::constants<uint64_t>::m;
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constexpr auto r = detail::constants<uint64_t>::r;
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uint64_t h = seed ^ (len * m);
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// body
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auto cursor = reinterpret_cast<const uint64_t*> (key);
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auto last = cursor + len / sizeof (uint64_t);
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for (; cursor < last; ++cursor)
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h = mix (h, *cursor);
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// tail
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if (len % sizeof (uint64_t)) {
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h ^= murmur::tail (cursor, len);
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h *= m;
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}
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// finalise
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h ^= h >> r;
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h *= m;
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h ^= h >> r;
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return h;
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}
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