80 lines
1.8 KiB
C++
80 lines
1.8 KiB
C++
// Copyright 2022, 2023 Peter Dimov
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// Distributed under the Boost Software License, Version 1.0.
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// https://www.boost.org/LICENSE_1_0.txt
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#ifndef BOOST_HASH_DETAIL_MULX_HPP
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#define BOOST_HASH_DETAIL_MULX_HPP
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#include <boost/cstdint.hpp>
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#if defined(_MSC_VER)
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# include <intrin.h>
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#endif
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namespace boost
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{
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namespace hash_detail
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{
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#if defined(_MSC_VER) && defined(_M_X64) && !defined(__clang__)
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__forceinline boost::uint64_t mulx( boost::uint64_t x, boost::uint64_t y )
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{
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boost::uint64_t r2;
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boost::uint64_t r = _umul128( x, y, &r2 );
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return r ^ r2;
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}
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#elif defined(_MSC_VER) && defined(_M_ARM64) && !defined(__clang__)
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__forceinline boost::uint64_t mulx( boost::uint64_t x, boost::uint64_t y )
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{
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boost::uint64_t r = x * y;
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boost::uint64_t r2 = __umulh( x, y );
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return r ^ r2;
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}
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#elif defined(__SIZEOF_INT128__)
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inline boost::uint64_t mulx( boost::uint64_t x, boost::uint64_t y )
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{
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__uint128_t r = static_cast<__uint128_t>( x ) * y;
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return static_cast<boost::uint64_t>( r ) ^ static_cast<boost::uint64_t>( r >> 64 );
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}
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#else
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inline boost::uint64_t mulx( boost::uint64_t x, boost::uint64_t y )
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{
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boost::uint64_t x1 = static_cast<boost::uint32_t>( x );
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boost::uint64_t x2 = x >> 32;
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boost::uint64_t y1 = static_cast<boost::uint32_t>( y );
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boost::uint64_t y2 = y >> 32;
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boost::uint64_t r3 = x2 * y2;
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boost::uint64_t r2a = x1 * y2;
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r3 += r2a >> 32;
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boost::uint64_t r2b = x2 * y1;
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r3 += r2b >> 32;
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boost::uint64_t r1 = x1 * y1;
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boost::uint64_t r2 = (r1 >> 32) + static_cast<boost::uint32_t>( r2a ) + static_cast<boost::uint32_t>( r2b );
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r1 = (r2 << 32) + static_cast<boost::uint32_t>( r1 );
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r3 += r2 >> 32;
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return r1 ^ r3;
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}
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#endif
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} // namespace hash_detail
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} // namespace boost
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#endif // #ifndef BOOST_HASH_DETAIL_MULX_HPP
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