thirdparty-ArduinoJson/src/ArduinoJson/Numbers/FloatParts.hpp

// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License

#pragma once

#include <ArduinoJson/Configuration.hpp>
#include <ArduinoJson/Numbers/FloatTraits.hpp>
#include <ArduinoJson/Polyfills/math.hpp>

ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE

template <typename TFloat>
struct FloatParts {
  uint32_t integral;
  uint32_t decimal;
  int16_t exponent;
  int8_t decimalPlaces;

  FloatParts(TFloat value) {
    uint32_t maxDecimalPart = sizeof(TFloat) >= 8 ? 1000000000 : 1000000;
    decimalPlaces = sizeof(TFloat) >= 8 ? 9 : 6;

    exponent = normalize(value);

    integral = uint32_t(value);
    // reduce number of decimal places by the number of integral places
    for (uint32_t tmp = integral; tmp >= 10; tmp /= 10) {
      maxDecimalPart /= 10;
      decimalPlaces--;
    }

    TFloat remainder = (value - TFloat(integral)) * TFloat(maxDecimalPart);

    decimal = uint32_t(remainder);
    remainder = remainder - TFloat(decimal);

    // rounding:
    // increment by 1 if remainder >= 0.5
    decimal += uint32_t(remainder * 2);
    if (decimal >= maxDecimalPart) {
      decimal = 0;
      integral++;
      if (exponent && integral >= 10) {
        exponent++;
        integral = 1;
      }
    }

    // remove trailing zeros
    while (decimal % 10 == 0 && decimalPlaces > 0) {
      decimal /= 10;
      decimalPlaces--;
    }
  }

  static int16_t normalize(TFloat& value) {
    typedef FloatTraits<TFloat> traits;
    int16_t powersOf10 = 0;

    int8_t index = sizeof(TFloat) == 8 ? 8 : 5;
    int bit = 1 << index;

    if (value >= ARDUINOJSON_POSITIVE_EXPONENTIATION_THRESHOLD) {
      for (; index >= 0; index--) {
        if (value >= traits::positiveBinaryPowerOfTen(index)) {
          value *= traits::negativeBinaryPowerOfTen(index);
          powersOf10 = int16_t(powersOf10 + bit);
        }
        bit >>= 1;
      }
    }

    if (value > 0 && value <= ARDUINOJSON_NEGATIVE_EXPONENTIATION_THRESHOLD) {
      for (; index >= 0; index--) {
        if (value < traits::negativeBinaryPowerOfTenPlusOne(index)) {
          value *= traits::positiveBinaryPowerOfTen(index);
          powersOf10 = int16_t(powersOf10 - bit);
        }
        bit >>= 1;
      }
    }

    return powersOf10;
  }
};

ARDUINOJSON_END_PRIVATE_NAMESPACE