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 "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;
};