93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
// Copyright 2005-2014 Daniel James.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Based on Peter Dimov's proposal
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// http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
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// issue 6.18.
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//
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// This also contains public domain code from MurmurHash. From the
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// MurmurHash header:
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//
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// MurmurHash3 was written by Austin Appleby, and is placed in the public
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// domain. The author hereby disclaims copyright to this source code.
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//
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// Copyright 2021 Ion Gaztanaga
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// Refactored the original boost/container_hash/hash.hpp to avoid
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// any heavy std header dependencies to just combine two hash
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// values represented in a std::size_t type.
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#ifndef BOOST_INTRUSIVE_DETAIL_HASH_COMBINE_HPP
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#define BOOST_INTRUSIVE_DETAIL_HASH_COMBINE_HPP
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#ifndef BOOST_CONFIG_HPP
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# include <boost/config.hpp>
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#endif
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#if defined(BOOST_HAS_PRAGMA_ONCE)
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# pragma once
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#endif
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#include <boost/cstdint.hpp>
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#if defined(_MSC_VER)
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# include <stdlib.h>
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# define BOOST_INTRUSIVE_HASH_ROTL32(x, r) _rotl(x,r)
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#else
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# define BOOST_INTRUSIVE_HASH_ROTL32(x, r) (x << r) | (x >> (32 - r))
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#endif
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namespace boost {
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namespace intrusive {
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namespace detail {
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template <typename SizeT>
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inline void hash_combine_size_t(SizeT& seed, SizeT value)
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{
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seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
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}
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inline void hash_combine_size_t(boost::uint32_t& h1, boost::uint32_t k1)
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{
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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k1 *= c1;
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k1 = BOOST_INTRUSIVE_HASH_ROTL32(k1,15);
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k1 *= c2;
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h1 ^= k1;
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h1 = BOOST_INTRUSIVE_HASH_ROTL32(h1,13);
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h1 = h1*5+0xe6546b64;
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}
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// Don't define 64-bit hash combine on platforms without 64 bit integers,
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// and also not for 32-bit gcc as it warns about the 64-bit constant.
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#if !defined(BOOST_NO_INT64_T) && \
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!(defined(__GNUC__) && ULONG_MAX == 0xffffffff)
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inline void hash_combine_size_t(boost::uint64_t& h, boost::uint64_t k)
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{
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const boost::uint64_t m = UINT64_C(0xc6a4a7935bd1e995);
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const int r = 47;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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// Completely arbitrary number, to prevent 0's
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// from hashing to 0.
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h += 0xe6546b64;
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}
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#endif // BOOST_NO_INT64_T
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} //namespace detail {
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} //namespace intrusive {
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} //namespace boost {
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#endif //BOOST_INTRUSIVE_DETAIL_HASH_COMBINE_HPP
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