整理

include/boost/core/detail/splitmix64.hpp

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+#ifndef BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED
+
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+//
+// An implementation of splitmix64 for testing purposes,
+// derived from Sebastiano Vigna's public domain implementation
+// http://xorshift.di.unimi.it/splitmix64.c
+
+#include <boost/cstdint.hpp>
+
+namespace boost
+{
+namespace detail
+{
+
+class splitmix64
+{
+private:
+
+    boost::uint64_t x_;
+
+public:
+
+    splitmix64(): x_( 0 )
+    {
+    }
+
+    explicit splitmix64( boost::uint64_t seed ): x_( seed )
+    {
+    }
+
+    boost::uint64_t operator()()
+    {
+        x_ += ( boost::uint64_t(0x9e3779b9u) << 32 ) + 0x7f4a7c15u;
+
+        boost::uint64_t z = x_;
+
+        z ^= z >> 30;
+        z *= ( boost::uint64_t(0xbf58476du) << 32 ) + 0x1ce4e5b9u;
+        z ^= z >> 27;
+        z *= ( boost::uint64_t(0x94d049bbu) << 32 ) + 0x133111ebu;
+        z ^= z >> 31;
+
+        return z;
+    }
+};
+
+} // namespace detail
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED