56 lines
1.5 KiB
C++
56 lines
1.5 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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#ifndef __UTIL_RAND_LCG_HPP
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#define __UTIL_RAND_LCG_HPP
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#include <cstdint>
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#include <type_traits>
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namespace util::rand {
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/// linear congruential generator
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///
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/// T: output/state type
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/// M: modulus
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/// A: multiplier
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/// C: increment
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template <typename T, T M, T A, T C>
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struct lcg {
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public:
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using result_type = T;
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static_assert (std::is_unsigned<T>::value,
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"LCG generates integer overflow which is undefined behaviour for signed types");
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explicit lcg (T seed);
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result_type operator() (void);
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static result_type min (void);
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static result_type max (void);
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void discard (unsigned);
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private:
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T m_x;
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};
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// glibc: typedef lcg<uint32_t, pow2(31), 1103515245, 12345> lcg_t;
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using lcg_t = lcg<uint64_t,0u,6364136223846793005ul, 1ul>;
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}
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#endif
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