libcruft-util/rand/mwc64x.cpp

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/*
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* 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/.
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*
* Copyright 2016 Danny Robson <danny@nerdcruft.net>
*/
#include "mwc64x.hpp"
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#include "../debug.hpp"
using cruft::rand::mwc64x;
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///////////////////////////////////////////////////////////////////////////////
mwc64x::mwc64x (seed_type _seed):
m_state (_seed)
{
CHECK_NEZ (m_state);
}
///////////////////////////////////////////////////////////////////////////////
mwc64x::value_type
mwc64x::operator() (void)
{
CHECK_NEZ (m_state);
uint32_t c = m_state >> 32u;
uint32_t x = m_state & 0xFFFFFFFFu;
m_state = x * 4294883355ULL + c;
return x ^ c;
}