src/date_type.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD 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, version 2.
   6  * OpenTTD 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.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file date_type.h Types related to the dates in OpenTTD. */
  11
  12 #ifndef DATE_TYPE_H
  13 #define DATE_TYPE_H
  14
  15 typedef int32  Date;      ///< The type to store our dates in
  16 typedef uint16 DateFract; ///< The fraction of a date we're in, i.e. the number of ticks since the last date changeover
  17 typedef int32  Ticks;     ///< The type to store ticks in
  18
  19 typedef int32  Year;  ///< Type for the year, note: 0 based, i.e. starts at the year 0.
  20 typedef uint8  Month; ///< Type for the month, note: 0 based, i.e. 0 = January, 11 = December.
  21 typedef uint8  Day;   ///< Type for the day of the month, note: 1 based, first day of a month is 1.
  22
  23 /**
  24  * 1 day is 74 ticks; _date_fract used to be uint16 and incremented by 885. On
  25  *                    an overflow the new day begun and 65535 / 885 = 74.
  26  * 1 tick is approximately 30 ms.
  27  * 1 day is thus about 2 seconds (74 * 30 = 2220) on a machine that can run OpenTTD normally
  28  */
  29
  30 static const int DEFAULT_DAY_TICKS          = 74;                         ///< ticks per day
  31 static const int TICKS_PER_MINUTE           = DEFAULT_DAY_TICKS / 5;      ///< one default day == 5 minutes
  32 static const int DAYS_IN_YEAR               = 365;                        ///< days per year
  33 static const int DAYS_IN_LEAP_YEAR          = 366;                        ///< sometimes, you need one day more...
  34
  35 static const int STATION_RATING_TICKS       = 185;                        ///< cycle duration for updating station rating
  36 static const int STATION_ACCEPTANCE_TICKS   = 250;                        ///< cycle duration for updating station acceptance
  37 static const int STATION_LINKGRAPH_TICKS    = 504;                                            ///< cycle duration for cleaning dead links
  38 static const int CARGO_AGING_TICKS          = 185;                                                ///< cycle duration for aging cargo
  39 static const int INDUSTRY_PRODUCE_TICKS     = 256;                                                ///< cycle duration for industry production
  40 static const int DEFAULT_TOWN_GROWTH_TICKS  = 70 ;                        ///< cycle duration for towns trying to grow. (this originates from the size of the town array in TTD
  41 static const int INDUSTRY_CUT_TREE_TICKS    = INDUSTRY_PRODUCE_TICKS * 2; ///< cycle duration for lumber mill's extra action
  42
  43
  44 /*
  45  * ORIGINAL_BASE_YEAR, ORIGINAL_MAX_YEAR and DAYS_TILL_ORIGINAL_BASE_YEAR are
  46  * primarily used for loading newgrf and savegame data and returning some
  47  * newgrf (callback) functions that were in the original (TTD) inherited
  48  * format, where '_date == 0' meant that it was 1920-01-01.
  49  */
  50
  51 /** The minimum starting year/base year of the original TTD */
  52 static const Year ORIGINAL_BASE_YEAR = 1920;
  53 /** The original ending year */
  54 static const Year ORIGINAL_END_YEAR  = 2051;
  55 /** The maximum year of the original TTD */
  56 static const Year ORIGINAL_MAX_YEAR  = 2090;
  57
  58 /**
  59  * Calculate the number of leap years till a given year.
  60  *
  61  * Each passed leap year adds one day to the 'day count'.
  62  *
  63  * A special case for the year 0 as no year has been passed,
  64  * but '(year - 1) / 4' does not yield '-1' to counteract the
  65  * '+1' at the end of the formula as divisions round to zero.
  66  *
  67  * @param year the year to get the leap years till.
  68  * @return the number of leap years.
  69  */
  70 #define LEAP_YEARS_TILL(year) ((year) == 0 ? 0 : ((year) - 1) / 4 - ((year) - 1) / 100 + ((year) - 1) / 400 + 1)
  71
  72 /**
  73  * Calculate the date of the first day of a given year.
  74  * @param year the year to get the first day of.
  75  * @return the date.
  76  */
  77 #define DAYS_TILL(year) (DAYS_IN_YEAR * (year) + LEAP_YEARS_TILL(year))
  78
  79 /**
  80  * The offset in days from the '_date == 0' till
  81  * 'ConvertYMDToDate(ORIGINAL_BASE_YEAR, 0, 1)'
  82  */
  83 #define DAYS_TILL_ORIGINAL_BASE_YEAR DAYS_TILL(ORIGINAL_BASE_YEAR)
  84
  85 /** The absolute minimum & maximum years in OTTD */
  86 static const Year MIN_YEAR = 0;
  87
  88 /** The default starting year */
  89 static const Year DEF_START_YEAR = 1950;
  90
  91 /**
  92  * MAX_YEAR, nicely rounded value of the number of years that can
  93  * be encoded in a single 32 bits date, about 2^31 / 366 years.
  94  */
  95 static const Year MAX_YEAR  = 5000000;
  96
  97 /** The number of days till the last day */
  98 #define MAX_DAY (DAYS_TILL(MAX_YEAR + 1) - 1)
  99
 100 /**
 101  * Data structure to convert between Date and triplet (year, month, and day).
 102  * @see ConvertDateToYMD(), ConvertYMDToDate()
 103  */
 104 struct YearMonthDay {
 105         Year  year;   ///< Year (0...)
 106         Month month;  ///< Month (0..11)
 107         Day   day;    ///< Day (1..31)
 108 };
 109
 110 static const Year  INVALID_YEAR  = -1; ///< Representation of an invalid year
 111 static const Date  INVALID_DATE  = -1; ///< Representation of an invalid date
 112 static const Ticks INVALID_TICKS = -1; ///< Representation of an invalid number of ticks
 113
 114 #endif /* DATE_TYPE_H */