math.h

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2021 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit.
 *
 * Major parts of the code are inspired from v1.1.8 of the Boost UT project,
 * released under the terms of the Boost Version 1.0 Software License,
 * which can be obtained from https://www.boost.org/LICENSE_1_0.txt.
 */
 
#ifndef MICRO_TEST_PLUS_MATH_H_
#define MICRO_TEST_PLUS_MATH_H_
 
// ----------------------------------------------------------------------------
 
#ifdef __cplusplus
 
// ----------------------------------------------------------------------------
 
#include <array>
 
// ----------------------------------------------------------------------------
 
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wconversion"
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#endif
#endif
 
namespace micro_os_plus::micro_test_plus
{
  // --------------------------------------------------------------------------

  namespace math
  {
    template <class T>
    [[nodiscard]] constexpr auto
    abs (const T t) -> T
    {
      return t < T{} ? -t : t;
    }

    template <class T>
    [[nodiscard]] constexpr auto
    min_value (const T& lhs, const T& rhs) -> const T&
    {
      return (rhs < lhs) ? rhs : lhs;
    }

    template <class T, class Exp_T>
    [[nodiscard]] constexpr auto
    pow (const T base, const Exp_T exp) -> T
    {
      // If the exponent is 0, return 1, otherwise recurse.
      return exp ? T (base * pow (base, exp - Exp_T (1))) : T (1);
    }

    template <class T, char... Cs>
    [[nodiscard]] constexpr auto
    num () -> T
    {
      // Assume all are digits or dot or apostrophe.
      static_assert (
          ((Cs == '.' or Cs == '\'' or (Cs >= '0' and Cs <= '9')) and ...));
      T result{};
      for (const char c : { Cs... })
        {
          if (c == '.')
            {
              break;
            }
          if (c >= '0' and c <= '9')
            {
              result = result * T (10) + T (c - '0');
            }
        }
      return result;
    }

    template <class T, char... Cs>
    [[nodiscard]] constexpr auto
    den () -> T
    {
      constexpr const std::array cs{ Cs... };
      T result{};
      auto i = 0u;
      while (cs[i++] != '.')
        {
        }
 
      for (auto j = i; j < sizeof...(Cs); ++j)
        {
          result += pow (T (10), sizeof...(Cs) - j) * T (cs[j] - '0');
        }
      return result;
    }

    template <class T, char... Cs>
    [[nodiscard]] constexpr auto
    den_size () -> T
    {
      constexpr const std::array cs{ Cs... };
      T i{};
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wconversion"
#endif
      while (cs[i++] != '.')
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
        {
        }
 
      return T (sizeof...(Cs)) - i + T (1);
    }

    template <class T, class Value_T>
    [[nodiscard]] constexpr auto
    den_size (Value_T value) -> T
    {
      constexpr auto precision = Value_T (1e-7);
      T result{};
      Value_T tmp{};
      do
        {
          value *= 10;
#if defined(__GNUC__)
#pragma GCC diagnostic push
#if !defined(__clang__) // GCC only
#pragma GCC diagnostic ignored "-Warith-conversion"
#endif
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wimplicit-int-float-conversion"
#endif
#endif
          tmp = value - T (value);
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
          ++result;
        }
      while (tmp > precision);
 
      return result;
    }
 
  } // namespace math
 
  // --------------------------------------------------------------------------
} // namespace micro_os_plus::micro_test_plus
 
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
 
// ----------------------------------------------------------------------------
 
#endif // __cplusplus
 
// ----------------------------------------------------------------------------
 
#endif // MICRO_TEST_PLUS_MATH_H_
 
// ----------------------------------------------------------------------------