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RIOT/examples/riot_and_cpp/c_functions.c 2.38 KB
a752c7ab   elopes   add first test an...
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  /*
   * Copyright (C) 2014 Ho Chi Minh city University of Technology (HCMUT)
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     examples
   * @{
   *
   * @file
   * @brief       Some functions implementaion in C.
   *
   * @author      DangNhat Pham-Huu <51002279@hcmut.edu.vn>
   *
   * @}
   */
  
  #include "c_functions.h"
  
  #define IS_LEAP_YEAR(year) ((year%4 == 0) ? ((year%100 == 0) ? ((year%400 == 0) ? 1 : 0) : 1): 0)
  
  int hello(void)
  {
      puts("Hello world in a C function");
  
      return 0;
  }
  
  int day_of_week(int day, int month, int year)
  {
      int count, sum_of_days;
  
      /* 1/1/2000 is Saturday */
      int first_day = 6;
  
      /* check input date */
      if (year < 2000) {
          printf("Sorry buddy, your date should be >= 1/1/2000!\n");
          return -1;
      }
  
      if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
          if (day > 31 || day < 1) {
              printf("Sorry buddy, your date is not correct!\n");
              return -1;
          }
      }
      else if (month == 2) {
  
          if (IS_LEAP_YEAR(year)) {
              if (day > 29 || day < 1) {
                  printf("Sorry buddy, your date is not correct!\n");
                  return -1;
              }
          }
          else {
              if (day > 28 ||  day < 1) {
                  printf("Sorry buddy, your date is not correct!\n");
                  return -1;
              }
          }
      }
      else {
          if (day > 30 || day < 1) {
              printf("Sorry buddy, your date is not correct!\n");
              return -1;
          }
      }
  
      /* date is okay, convert... */
      sum_of_days = 0;
  
      for (count = 2000; count < year; count++) {
          sum_of_days += (((IS_LEAP_YEAR(count) == 1) ? 366 : 365)) % 7;
      }
  
      for (count = 1; count < month; count++) {
          if (count == 1 || count == 3 || count == 5 || count == 7 || count == 8 || count == 10 || count == 12) {
              sum_of_days += 31 % 7;
          }
          else if (count == 2) {
  
              if (IS_LEAP_YEAR(year)) {
                  sum_of_days += 29 % 7;
              }
              else {
                  sum_of_days += 28 % 7;
              }
          }
          else {
              sum_of_days += 30 % 7;
          }
      }
  
      sum_of_days += (day - 1) % 7;
  
      return (sum_of_days + first_day) % 7;
  }