uniform.hpp

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/*
 * Copyright (C) 2018-2026 The ESPResSo project
 *
 * ESPResSo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include "utils/device_qualifier.hpp"
 
#include <cinttypes>
#include <limits>
 
namespace Utils {
/**
 * @brief Uniformly map unsigned integer to double.
 *
 * This maps a unsigned integer to the double interval
 * (0., 1.], where 0 is mapped to the smallest representable
 * value larger than 0., and the maximal integer value is
 * mapped to 1.
 *
 * @param in Unsigned integer value
 * @return Mapped floating point value.
 */
constexpr DEVICE_QUALIFIER inline double uniform(uint64_t in) {
  auto constexpr const max = std::numeric_limits<uint64_t>::max();
  auto constexpr const fac = 1. / (static_cast<double>(max) + 1.);
 
  return fac * static_cast<double>(in) + 0.5 * fac;
}
 
} // namespace Utils