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RIOT/sys/timex/tm.c 2.48 KB
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  /*
   * Copyright (C) 2014  René Kijewski  <rene.kijewski@fu-berlin.de>
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  /**
   * @file
   * @author      René Kijewski <rene.kijewski@fu-berlin.de>
   */
  
  #include "tm.h"
  
  #include <stdint.h>
  
  const int8_t TM_MON_DAYS[12] = {
      31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  };
  
  const int16_t TM_MON_DAYS_ACCU[12] = {
      0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  };
  
  int tm_is_leap_year(unsigned year)
  {
      return ((year & 3) == 0) && ((year % 400 == 0) || (year % 100 != 0));
  }
  
  int tm_doomsday(int year)
  {
      int result;
      result  = TM_WDAY_TUE;
      result += year;
      result += year >>= 2;
      result -= year /= 25;
      result += year >>= 2;
      return result;
  }
  
  void tm_get_wyday(int year, int mon, int mday, int *wday, int *yday)
  {
      int is_leap_year = tm_is_leap_year(year);
      *yday = TM_MON_DAYS_ACCU[mon] + mday + (mon <= TM_MON_FEB ? 0 : is_leap_year) - 1;
      int jan1 = tm_doomsday(year) - 2 - is_leap_year;
      *wday = (jan1 + *yday) % 7;
  }
  
  void tm_fill_derived_values(struct tm *tm)
  {
      tm_get_wyday(tm->tm_year + 1900, tm->tm_mon, tm->tm_mday, &tm->tm_wday, &tm->tm_yday);
  }
  
  int tm_is_valid_date(int year, int mon, int mday)
  {
      if ((mon < TM_MON_JAN) || (mon > TM_MON_DEC)) {
          return 0;
      }
      if ((mday <= 0) || (mday > TM_MON_DAYS[mon])) {
          if ((mday != 29) || (mon != TM_MON_FEB) || !tm_is_leap_year(year)) {
              return 0;
          }
      }
      if (year <= 1582) {
          if (year < 1582) {
              return 0;
          }
          if ((mon < TM_MON_OCT) || ((mon == TM_MON_OCT) && (mday < 15))) {
              return 0;
          }
      }
  
      return 1;
  }
  
  int tm_is_valid_time(int hour, int min, int sec)
  {
      return (hour >= 0) && (hour < 24) &&
             (min >= 0) && (min < 60) &&
             (sec >= 0) && (sec <= 60);
  }