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

// ArduinoJson - arduinojson.org
// Copyright Benoit Blanchon 2014-2020
// MIT License

#pragma once

#include <stddef.h>  // for size_t
#include <stdint.h>

#include <ArduinoJson/Configuration.hpp>
#include <ArduinoJson/Polyfills/alias_cast.hpp>
#include <ArduinoJson/Polyfills/math.hpp>

namespace ARDUINOJSON_NAMESPACE {

template <typename T, size_t = sizeof(T)>
struct FloatTraits {};

template <typename T>
struct FloatTraits<T, 8 /*64bits*/> {
  typedef uint64_t mantissa_type;
  static const short mantissa_bits = 52;
  static const mantissa_type mantissa_max =
      (mantissa_type(1) << mantissa_bits) - 1;

  typedef int16_t exponent_type;
  static const exponent_type exponent_max = 308;

  template <typename TExponent>
  static T make_float(T m, TExponent e) {
    if (e > 0) {
      for (uint8_t index = 0; e != 0; index++) {
        if (e & 1) m *= positiveBinaryPowerOfTen(index);
        e >>= 1;
      }
    } else {
      e = TExponent(-e);
      for (uint8_t index = 0; e != 0; index++) {
        if (e & 1) m *= negativeBinaryPowerOfTen(index);
        e >>= 1;
      }
    }
    return m;
  }

  static T positiveBinaryPowerOfTen(int index) {
    static T factors[] = {
        1e1,
        1e2,
        1e4,
        1e8,
        1e16,
        forge(0x4693B8B5, 0xB5056E17),  // 1e32
        forge(0x4D384F03, 0xE93FF9F5),  // 1e64
        forge(0x5A827748, 0xF9301D32),  // 1e128
        forge(0x75154FDD, 0x7F73BF3C)   // 1e256
    };
    return factors[index];
  }

  static T negativeBinaryPowerOfTen(int index) {
    static T factors[] = {
        forge(0x3FB99999, 0x9999999A),  // 1e-1
        forge(0x3F847AE1, 0x47AE147B),  // 1e-2
        forge(0x3F1A36E2, 0xEB1C432D),  // 1e-4
        forge(0x3E45798E, 0xE2308C3A),  // 1e-8
        forge(0x3C9CD2B2, 0x97D889BC),  // 1e-16
        forge(0x3949F623, 0xD5A8A733),  // 1e-32
        forge(0x32A50FFD, 0x44F4A73D),  // 1e-64
        forge(0x255BBA08, 0xCF8C979D),  // 1e-128
        forge(0x0AC80628, 0x64AC6F43)   // 1e-256
    };
    return factors[index];
  }

  static T negativeBinaryPowerOfTenPlusOne(int index) {
    static T factors[] = {
        1e0,
        forge(0x3FB99999, 0x9999999A),  // 1e-1
        forge(0x3F50624D, 0xD2F1A9FC),  // 1e-3
        forge(0x3E7AD7F2, 0x9ABCAF48),  // 1e-7
        forge(0x3CD203AF, 0x9EE75616),  // 1e-15
        forge(0x398039D6, 0x65896880),  // 1e-31
        forge(0x32DA53FC, 0x9631D10D),  // 1e-63
        forge(0x25915445, 0x81B7DEC2),  // 1e-127
        forge(0x0AFE07B2, 0x7DD78B14)   // 1e-255
    };
    return factors[index];
  }

  static T nan() {
    return forge(0x7ff80000, 0x00000000);
  }

  static T inf() {
    return forge(0x7ff00000, 0x00000000);
  }

  static T highest() {
    return forge(0x7FEFFFFF, 0xFFFFFFFF);
  }

  static T lowest() {
    return forge(0xFFEFFFFF, 0xFFFFFFFF);
  }

  // constructs a double floating point values from its binary representation
  // we use this function to workaround platforms with single precision literals
  // (for example, when -fsingle-precision-constant is passed to GCC)
  static T forge(uint32_t msb, uint32_t lsb) {
    return alias_cast<T>((uint64_t(msb) << 32) | lsb);
  }
};

template <typename T>
struct FloatTraits<T, 4 /*32bits*/> {
  typedef uint32_t mantissa_type;
  static const short mantissa_bits = 23;
  static const mantissa_type mantissa_max =
      (mantissa_type(1) << mantissa_bits) - 1;

  typedef int8_t exponent_type;
  static const exponent_type exponent_max = 38;

  template <typename TExponent>
  static T make_float(T m, TExponent e) {
    if (e > 0) {
      for (uint8_t index = 0; e != 0; index++) {
        if (e & 1) m *= positiveBinaryPowerOfTen(index);
        e >>= 1;
      }
    } else {
      e = -e;
      for (uint8_t index = 0; e != 0; index++) {
        if (e & 1) m *= negativeBinaryPowerOfTen(index);
        e >>= 1;
      }
    }
    return m;
  }

  static T positiveBinaryPowerOfTen(int index) {
    static T factors[] = {1e1f, 1e2f, 1e4f, 1e8f, 1e16f, 1e32f};
    return factors[index];
  }

  static T negativeBinaryPowerOfTen(int index) {
    static T factors[] = {1e-1f, 1e-2f, 1e-4f, 1e-8f, 1e-16f, 1e-32f};
    return factors[index];
  }

  static T negativeBinaryPowerOfTenPlusOne(int index) {
    static T factors[] = {1e0f, 1e-1f, 1e-3f, 1e-7f, 1e-15f, 1e-31f};
    return factors[index];
  }

  static T forge(uint32_t bits) {
    return alias_cast<T>(bits);
  }

  static T nan() {
    return forge(0x7fc00000);
  }

  static T inf() {
    return forge(0x7f800000);
  }

  static T highest() {
    return forge(0x7f7fffff);
  }

  static T lowest() {
    return forge(0xFf7fffff);
  }
};
}  // namespace ARDUINOJSON_NAMESPACE