AMiRo-OS

/*

AMiRo-OS is an operating system designed for the Autonomous Mini Robot (AMiRo) platform.

Copyright (C) 2016..2019  Thomas Schöpping et al.

This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

/**

 * @file    aos_time.c

 * @brief   Time related function implementations.

 *

 * @addtogroup aos_time

 * @{

 */

#include <aos_time.h>

#include <aos_debug.h>

#include <aos_system.h>

/**

 * @brief   Calculates the day of week from a specified date.

 *

 * @param[in] day     The day of the date.

 * @param[in] month   The month of the daste.

 * @param[in] year    The year of the date.

 *

 * @return    The day of week depending on the date represented in ISO format (1 = Monday to 7 = Sunday).

 */

uint8_t aosTimeDayOfWeekFromDate(const uint16_t day, const uint8_t month, const uint16_t year)

{

  aosDbgCheck(day >= 1 && day <= 31);

  aosDbgCheck(month >= 1 && month <= 12);

  /*

   * Implementation of Zeller's congruence for Gregorian calender.

   * See https://en.wikipedia.org/wiki/Zeller%27s_congruence for details.

   */

  const uint32_t q = day;

  const uint32_t m = (month >= 3) ? month : month + 12;

  const uint32_t K = year % 100;

  const uint32_t J = year / 100;

  const uint32_t h = (q + ((13 * (m + 1)) / 5) + K + (K / 4) + (J / 4) - (2 * J)) % 7;

  return ((h + 5) % 7) + 1;

}

/** @} */