libcruft-util/rand/xorshift.hpp

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/*
2018-08-04 15:14:06 +10:00
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
*/
#pragma once
#include <limits>
namespace cruft::rand {
// implements a naive xorshift random generator.
//
// * users may not rely on identical output across executions or library
// updates. internal constants may change across releases
template <typename ValueT>
struct xorshift {
public:
using result_type = ValueT;
explicit xorshift (ValueT seed);
result_type operator() (void);
static constexpr result_type min (void) noexcept { return 1u; }
static constexpr auto max (void) noexcept { return std::numeric_limits<result_type>::max (); }
void discard (unsigned);
private:
ValueT m_state;
};
}