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amiro-os / core / src / aos_time.c @ 1678f270

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/*
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AMiRo-OS is an operating system designed for the Autonomous Mini Robot (AMiRo) platform.
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Copyright (C) 2016..2019  Thomas Schöpping et al.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program.  If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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 * @file    aos_time.c
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 * @brief   Time related function implementations.
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 *
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 * @addtogroup aos_time
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 * @{
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 */
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#include <aos_time.h>
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#include <aos_debug.h>
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#include <aos_system.h>
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/**
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 * @brief   Calculates the day of week from a specified date.
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 *
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 * @param[in] day     The day of the date.
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 * @param[in] month   The month of the daste.
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 * @param[in] year    The year of the date.
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 *
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 * @return    The day of week depending on the date represented in ISO format (1 = Monday to 7 = Sunday).
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 */
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uint8_t aosTimeDayOfWeekFromDate(const uint16_t day, const uint8_t month, const uint16_t year)
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{
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  aosDbgCheck(day >= 1 && day <= 31);
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  aosDbgCheck(month >= 1 && month <= 12);
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  /*
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   * Implementation of Zeller's congruence for Gregorian calender.
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   * See https://en.wikipedia.org/wiki/Zeller%27s_congruence for details.
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   */
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  const uint32_t q = day;
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  const uint32_t m = (month >= 3) ? month : month + 12;
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  const uint32_t K = year % 100;
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  const uint32_t J = year / 100;
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  const uint32_t h = (q + ((13 * (m + 1)) / 5) + K + (K / 4) + (J / 4) - (2 * J)) % 7;
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  return ((h + 5) % 7) + 1;
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}
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/** @} */