EpochConverterJulian.h

/*
 * MIT License
 * Copyright (c) 2022 Brian T. Park
 */
 
#ifndef ACE_TIME_EPOCH_CONVERTER_JULIAN_H
#define ACE_TIME_EPOCH_CONVERTER_JULIAN_H
 
#include <stdint.h>
 
namespace ace_time {
 
class EpochConverterJulian {
  public:
    static const int16_t kInternalEpochYear = 2000;
 
    static const int32_t kDaysToInternalEpochFromUnixEpoch = 10957;
 
    static const int32_t kDaysToInternalEpochFromJulianEpoch = 1721060
        + (kInternalEpochYear / 400) * 146097; // 2451545
 
    static int32_t toEpochDays(int16_t year, uint8_t month, uint8_t day) {
      int8_t mm = (month - 14)/12;
      int32_t jdn = ((int32_t) 1461 * (year + 4800 + mm))/4
          + (367 * (month - 2 - 12 * mm))/12
          - (3 * ((year + 4900 + mm)/100))/4
          + day - 32075;
      return jdn - kDaysToInternalEpochFromJulianEpoch;
    }
 
    static void fromEpochDays(int32_t epochDays,
        int16_t& year, uint8_t& month, uint8_t& day) {
 
      uint32_t J = epochDays + kDaysToInternalEpochFromJulianEpoch;
      uint32_t f = J + 1401 + (((4 * J + 274277 ) / 146097) * 3) / 4 - 38;
      uint32_t e = 4 * f + 3;
      uint32_t g = e % 1461 / 4;
      uint32_t h = 5 * g + 2;
      day = (h % 153) / 5 + 1;
      month = (h / 153 + 2) % 12 + 1;
      year = (e / 1461) - 4716 + (12 + 2 - month) / 12;
 
      // 2000-01-01 is Saturday (7)
      //dayOfWeek = (epochDays + 6) % 7 + 1;
    }
};
 
}
 
#endif