esp32displaytest/include/FixedPoint.h

template<int ScalingFactor>
class FixedPoint {
  int64_t val_;
 public:

  constexpr FixedPoint() : val_(0) {}

  constexpr FixedPoint(int64_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(int32_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(int16_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(int8_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(uint64_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(uint32_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(uint16_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(uint8_t v) : val_(v * ScalingFactor) {}

  constexpr FixedPoint(float v) : val_(static_cast<int64_t>(v * ScalingFactor)) {}

  constexpr FixedPoint(double v) : val_(static_cast<int64_t>(v * ScalingFactor)) {}

  constexpr FixedPoint(long double v) : val_(static_cast<int64_t>(v * ScalingFactor)) {}

  constexpr double toDouble() {
	return static_cast<double>(val_) / ScalingFactor;
  }

  constexpr int64_t toInt() {
	return val_ / ScalingFactor;
  }

  constexpr int GetScalingFactor() {
	return ScalingFactor;
  }

  constexpr int64_t GetUnderlyingValue() {
	return val_;
  }

  constexpr FixedPoint<ScalingFactor> abs() const {
	FixedPoint<ScalingFactor> res;
	res.val_ = std::abs(val_);
	return res;
  }

  constexpr FixedPoint<ScalingFactor> exp10(int exp) {
	FixedPoint<ScalingFactor> res = *this;
	while(exp > 0) {
	  res *= 10;
	  exp--;
	}
	while (exp < 0) {
	  res *= 10;
	  exp++;
	}
	return res;
  }

  String toString(int min_decimal_digits = 0, bool zero_prefix_if_less_than_one = true) {
	if (val_ == 0) {
	  return "0";
	}

	constexpr int max_len = std::numeric_limits<int64_t>::max_digits10 + 2; // max digits plus decimal point and sign
	char c[max_len];
	int len = 0;

	int64_t val = val_;

	bool negative = false;
	if (val < 0) {
	  negative = true;
	  val = -val;
	}
	int64_t decimal_part = val % ScalingFactor;
	if (decimal_part != 0) {
	  while (decimal_part % 10 == 0) {
		decimal_part /= 10;
	  }
	  do {
		len += 1;
		c[max_len - len] = '0' + decimal_part % 10;
		decimal_part /= 10;
	  } while (decimal_part > 0);
	  len += 1;
	  c[max_len - len] = '.';
	}

	val /= ScalingFactor;

	do {
	  len += 1;
	  c[max_len - len] = '0' + val % 10;
	  val /= 10;
	} while (val > 0);

	if (negative) {
	  len += 1;
	  c[max_len - len] = '-';
	}

	return String(&c[max_len - len], len);
  }

  constexpr FixedPoint<ScalingFactor> operator-() {
	FixedPoint<ScalingFactor> res;
	res.val_ = -val_;
	return res;
  }

  constexpr FixedPoint<ScalingFactor> &operator+=(const FixedPoint<ScalingFactor> &rhs) {
	val_ += rhs.val_;
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator+=(int rhs) {
	*this += FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator+=(double rhs) {
	*this += FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator-=(const FixedPoint<ScalingFactor> &rhs) {
	val_ -= rhs.val_;
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator-=(int rhs) {
	*this -= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator-=(double rhs) {
	*this -= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator*=(const FixedPoint<ScalingFactor> &rhs) {
	val_ = val_ * rhs.val_ / ScalingFactor;
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator*=(int rhs) {
	*this *= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator*=(double rhs) {
	*this *= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator/=(const FixedPoint<ScalingFactor> &rhs) {
	val_ = val_ * ScalingFactor / rhs.val_;
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator/=(int rhs) {
	*this /= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr FixedPoint<ScalingFactor> &operator/=(double rhs) {
	*this /= FixedPoint<ScalingFactor>(rhs);
	return *this;
  }

  constexpr friend FixedPoint<ScalingFactor> operator+(FixedPoint<ScalingFactor> lhs,
													   const FixedPoint<ScalingFactor> &rhs) {
	lhs += rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator-(FixedPoint<ScalingFactor> lhs,
													   const FixedPoint<ScalingFactor> &rhs) {
	lhs -= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator*(FixedPoint<ScalingFactor> lhs,
													   const FixedPoint<ScalingFactor> &rhs) {
	lhs *= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator/(FixedPoint<ScalingFactor> lhs,
													   const FixedPoint<ScalingFactor> &rhs) {
	lhs /= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator+(FixedPoint<ScalingFactor> lhs, int rhs) {
	lhs += rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator+(int lhs, FixedPoint<ScalingFactor> rhs) {
	rhs += lhs;
	return rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator+(FixedPoint<ScalingFactor> lhs, double rhs) {
	lhs += rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator+(double lhs, FixedPoint<ScalingFactor> rhs) {
	rhs += lhs;
	return rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator-(FixedPoint<ScalingFactor> lhs, int rhs) {
	lhs -= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator-(int lhs, FixedPoint<ScalingFactor> rhs) {
	return FixedPoint<ScalingFactor>(lhs) - rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator-(FixedPoint<ScalingFactor> lhs, double rhs) {
	lhs -= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator-(double lhs, FixedPoint<ScalingFactor> rhs) {
	return FixedPoint<ScalingFactor>(lhs) - rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator*(FixedPoint<ScalingFactor> lhs, int rhs) {
	lhs *= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator*(int lhs, FixedPoint<ScalingFactor> rhs) {
	rhs *= lhs;
	return rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator*(FixedPoint<ScalingFactor> lhs, double rhs) {
	lhs *= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator*(double lhs, FixedPoint<ScalingFactor> rhs) {
	rhs *= lhs;
	return rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator/(FixedPoint<ScalingFactor> lhs, int rhs) {
	lhs /= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator/(int lhs, FixedPoint<ScalingFactor> rhs) {
	return FixedPoint<ScalingFactor>(lhs) / rhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator/(FixedPoint<ScalingFactor> lhs, double rhs) {
	lhs /= rhs;
	return lhs;
  }

  constexpr friend FixedPoint<ScalingFactor> operator/(double lhs, FixedPoint<ScalingFactor> rhs) {
	return FixedPoint<ScalingFactor>(lhs) / rhs;
  }

  constexpr friend bool operator<(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return lhs.val_ < rhs.val_;
  }

  constexpr friend bool operator>(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return rhs < lhs;
  }

  constexpr friend bool operator<=(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return !(lhs > rhs);
  }

  constexpr friend bool operator>=(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return !(lhs < rhs);
  }

  constexpr friend bool operator==(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return lhs.val_ == rhs.val_;
  }

  constexpr friend bool operator!=(FixedPoint<ScalingFactor> lhs, const FixedPoint<ScalingFactor> &rhs) {
	return !(lhs == rhs);
  }

};