MooseRandomPerturbation.h

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html
 
#pragma once
 
#include "DataIO.h"
#include "MooseError.h"
 
#include <cstdint>
 
class MooseRandomPerturbation
{
public:
  MooseRandomPerturbation(uint64_t seed, unsigned int n, unsigned int rounds = 8);
 
  uint32_t permute(uint32_t x) const;
 
  uint32_t invert(uint32_t y) const;
 
private:
  uint32_t permutePadded(uint32_t x) const;
 
  uint32_t invertPadded(uint32_t y) const;
 
  uint32_t roundFunction(uint32_t half, unsigned int round) const;
 
  static unsigned int ceilLog2(uint32_t n);
 
  static uint32_t mix32(uint32_t x);
 
  const uint32_t _k0;
  const uint32_t _k1;
  const unsigned int _n;
  const unsigned int _half_bits;
  const uint32_t _half_mask;
  const unsigned int _rounds;
 
  // for restart capability
  friend void dataStore<MooseRandomPerturbation>(std::ostream &, MooseRandomPerturbation &, void *);
};
 
template <>
inline void
dataStore(std::ostream & stream, MooseRandomPerturbation & v, void * context)
{
  uint64_t seed = (static_cast<uint64_t>(v._k1) << 32) | v._k0;
  dataStore(stream, seed, context);
  dataStore(stream, v._n, context);
  dataStore(stream, v._rounds, context);
}
 
template <>
inline void
dataStore(std::ostream & stream, std::unique_ptr<MooseRandomPerturbation> & v, void * context)
{
  dataStore(stream, *v, context);
}
 
template <>
inline void
dataLoad(std::istream & stream, std::unique_ptr<MooseRandomPerturbation> & v, void * context)
{
  uint64_t seed;
  unsigned int n, rounds;
  dataLoad(stream, seed, context);
  dataLoad(stream, n, context);
  dataLoad(stream, rounds, context);
  v = std::make_unique<MooseRandomPerturbation>(seed, n, rounds);
}