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rand/xorshift: add trivial xorshift RNG

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This commit is contained in:
Danny Robson 2016-02-02 11:32:55 +11:00
parent c04c56ed32
commit 8841e9d055
3 changed files with 107 additions and 0 deletions
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3
Makefile.am
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@ -263,6 +263,8 @@ UTIL_FILES = \
quaternion.cpp \
quaternion.hpp \
raii.hpp \
rand/xorshift.cpp \
rand/xorshift.hpp \
random.cpp \
random.hpp \
random.ipp \
@ -421,6 +423,7 @@ TEST_BIN = \
test/point \
test/polynomial \
test/pool \
test/rand/xorshift \
test/random \
test/range \
test/rational \

66
rand/xorshift.cpp Normal file
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@ -0,0 +1,66 @@
/*
* 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>;

38
rand/xorshift.hpp Normal file
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@ -0,0 +1,38 @@
/*
* 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>
*/
#ifndef __UTIL_RAND_XORSHIFT_HPP
#define __UTIL_RAND_XORSHIFT_HPP
namespace util { namespace rand {
// implements a naive xorshift random generator.
//
// * does not comply with the c++11 rng class requirements
// * users may not rely on identical output across executions or library
// updates. internal constants may change across releases
template <typename T>
struct xorshift {
public:
xorshift (T seed);
T operator() (void);
private:
T m_state;
};
} }
#endif