src/time.h

   1 ///
   2 /// \file       time.h
   3 ///             Conversion between time_t and cenmin_t and back.
   4 ///             time_t is the POSIX time.
   5 ///             min1900_t is the minutes from Jan 1, 1900
   6 ///
   7
   8 /*
   9     Copyright (C) 2005-2006, Net Direct Inc. (http://www.netdirect.ca/)
  10
  11     This program is free software; you can redistribute it and/or modify
  12     it under the terms of the GNU General Public License as published by
  13     the Free Software Foundation; either version 2 of the License, or
  14     (at your option) any later version.
  15
  16     This program is distributed in the hope that it will be useful,
  17     but WITHOUT ANY WARRANTY; without even the implied warranty of
  18     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  19
  20     See the GNU General Public License in the COPYING file at the
  21     root directory of this project for more details.
  22 */
  23
  24 #ifndef __BARRY_TIME_H__
  25 #define __BARRY_TIME_H__
  26
  27 #include <time.h>
  28
  29 //
  30 // Calculate the number of minutes between Jan 01, 1900 and Jan 01, 1970
  31 //
  32 // There are 17 leap years between 1900 and 1970
  33 //    (1969-1900) / 4 = 17.25
  34 //
  35 // 1900 itself is not a leap year (not divisible by 400)
  36 //
  37 #define DAY_MINUTES (24 * 60)
  38 #define YEAR_MINUTES (365 * DAY_MINUTES)
  39 #define LEAP_YEAR_COUNT ((1970-1901) / 4)
  40 #define YEAR_COUNT (1970 - 1900)
  41
  42 // therefore, the difference between standard C's time and min1900_t's
  43 // time in minutes:
  44 #define STDC_MIN1900_DIFF (YEAR_COUNT * YEAR_MINUTES + LEAP_YEAR_COUNT * DAY_MINUTES)
  45
  46 namespace Barry {
  47
  48 typedef long min1900_t;
  49
  50 inline min1900_t time2min(time_t t)
  51 {
  52         return t / 60 + STDC_MIN1900_DIFF;
  53 }
  54
  55 inline time_t min2time(min1900_t m)
  56 {
  57         return (m - STDC_MIN1900_DIFF) * 60;
  58 }
  59
  60
  61 } // namespace Barry
  62
  63 #endif
  64