//===-- rosa/support/math.hpp -----------------------------------*- C++ -*-===//
//
//                                 The RoSA Framework
//
//===----------------------------------------------------------------------===//
///
/// \file rosa/support/math.hpp
///
/// \author David Juhasz (david.juhasz@tuwien.ac.at)
///
/// \date 2017
///
/// \brief Math helpers.
///
//===----------------------------------------------------------------------===//

#ifndef ROSA_SUPPORT_MATH_HPP
#define ROSA_SUPPORT_MATH_HPP

#include <cmath>
#include <cstdlib>
#include <limits>
#include <type_traits>

namespace rosa {

/// Computes log base 2 of a number.
///
/// \param N the number to compute log base 2 for
///
/// \return log base 2 of \p N
constexpr size_t log2(const size_t N) {
  return ((N < 2) ? 1 : 1 + log2(N / 2));
}

/// Tells the next representable floating point value.
///
/// \tparam T type to operate on
///
/// \note The second type argument enforces \p T being a floating point type,
/// always use the default value!
///
/// \param V value to which find the next representable one
///
/// \return the next representable value of type \p T after value \p V
///
/// \pre Type \p T must be a floating point type, which is enforced by
/// `std::enable_if` in the second type argument.
template <typename T,
          typename = std::enable_if_t<std::is_floating_point<T>::value>>
T nextRepresentableFloatingPoint(const T V) {
  return std::nextafter(V, std::numeric_limits<T>::infinity());
}

} // End namespace rosa

#endif // ROSA_SUPPORT_MATH_HPP