59 lines
1.2 KiB
C++
59 lines
1.2 KiB
C++
/*
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* Copyright 2015 - 2025 gary@drinkingtea.net
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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#pragma once
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#include "bit.hpp"
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#include "def.hpp"
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#include "stddef.hpp"
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#include "types.hpp"
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OX_CLANG_NOWARN_BEGIN(-Wunsafe-buffer-usage)
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namespace ox {
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using RandomSeed = uint64_t[2];
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// An implementation of the Xoroshiro128+ algorithm
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class OX_PACKED Random {
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private:
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RandomSeed m_seed = {540932923848, 540932540932};
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public:
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constexpr Random() noexcept = default;
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explicit constexpr Random(const RandomSeed &seed) noexcept;
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constexpr void seed(const RandomSeed &seed) noexcept;
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constexpr uint64_t gen() noexcept;
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};
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constexpr Random::Random(const RandomSeed &seed) noexcept: m_seed{seed[0], seed[1]} {
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}
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constexpr void Random::seed(const RandomSeed &seed) noexcept {
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m_seed[0] = seed[0];
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m_seed[1] = seed[1];
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}
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constexpr uint64_t Random::gen() noexcept {
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auto s0 = m_seed[0];
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auto s1 = m_seed[1];
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const auto retval = s0 + s1;
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// reseed for next number
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s1 ^= s0;
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m_seed[0] = rotl(s0, 55) ^ s1 ^ (s1 << 14);
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m_seed[1] = rotl(s1, 36);
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return retval;
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}
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}
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OX_CLANG_NOWARN_END
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