libcruft-util/rand/xorshift.cpp

67 lines
1.7 KiB
C++

/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2015-2016 Danny Robson <danny@nerdcruft.net>
*/
#include "./xorshift.hpp"
#include "../debug.hpp"
#include <cstdint>
using util::rand::xorshift;
///////////////////////////////////////////////////////////////////////////////
template <typename T>
xorshift<T>::xorshift (T seed):
m_state (seed)
{
// state must not be zero, or the period will be zero.
CHECK_NEZ (m_state);
}
///////////////////////////////////////////////////////////////////////////////
namespace util { namespace rand {
template <>
uint32_t
xorshift<uint32_t>::operator() (void)
{
m_state ^= m_state << 13u;
m_state ^= m_state >> 17u;
m_state ^= m_state << 5u;
return m_state;
}
//-----------------------------------------------------------------------------
template <>
uint64_t
xorshift<uint64_t>::operator() (void)
{
m_state ^= m_state << 13u;
m_state ^= m_state >> 7u;
m_state ^= m_state << 17u;
return m_state;
}
} }
///////////////////////////////////////////////////////////////////////////////
template struct util::rand::xorshift<uint32_t>;
template struct util::rand::xorshift<uint64_t>;