41 lines
1.2 KiB
C++
41 lines
1.2 KiB
C++
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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 http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2019 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include "../posix/fd.hpp"
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namespace cruft::rand {
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/// Models std::random_device and is suitable as a drop-in replacement.
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///
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/// This implementation assumes that the CPU supports the `rdrand`
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/// instruction, and does not check that this is the case.
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///
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/// It is safe to instantiatate the object even if the instructions are
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/// not supported, but it is the users responsibility to prevent calls to
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/// the object if this is not the case.
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class rdrand {
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public:
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using result_type = unsigned;
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rdrand ();
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rdrand (std::string const&);
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rdrand (rdrand const &) = delete;
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rdrand& operator= (rdrand const&) = delete;
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result_type operator() (void);
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double entropy (void) const noexcept;
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static constexpr result_type min (void) { return std::numeric_limits<result_type>::min (); }
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static constexpr result_type max (void) { return std::numeric_limits<result_type>::max (); }
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};
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}
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