libcruft-util/rand/mwc64x.cpp
Danny Robson 34788756d2 build: don't use './' as an include prefix
GCC produces ODR error when including paths of the form './foo' and
'foo' in the same binary. Rather than managing duplication we just
universally pick the absolute form over the relative form.
2017-11-22 16:49:37 +11:00

46 lines
1.1 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 2016 Danny Robson <danny@nerdcruft.net>
*/
#include "mwc64x.hpp"
#include "../debug.hpp"
using util::rand::mwc64x;
///////////////////////////////////////////////////////////////////////////////
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;
}