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/* $Id$ */
/*
* This file is part of OpenTTD.
* 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.
* 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.
* 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/>.
*/
/** @file date_type.h Types related to the dates in OpenTTD. */
#ifndef DATE_TYPE_H
#define DATE_TYPE_H
typedef int32 Date; ///< The type to store our dates in
typedef uint16 DateFract; ///< The fraction of a date we're in, i.e. the number of ticks since the last date changeover
typedef int32 Ticks; ///< The type to store ticks in
typedef int32 Year; ///< Type for the year, note: 0 based, i.e. starts at the year 0.
typedef uint8 Month; ///< Type for the month, note: 0 based, i.e. 0 = January, 11 = December.
typedef uint8 Day; ///< Type for the day of the month, note: 1 based, first day of a month is 1.
/**
* 1 day is 74 ticks; _date_fract used to be uint16 and incremented by 885. On
* an overflow the new day begun and 65535 / 885 = 74.
* 1 tick is approximately 30 ms.
* 1 day is thus about 2 seconds (74 * 30 = 2220) on a machine that can run OpenTTD normally
*/
static const int DAY_TICKS = 74; ///< ticks per day
static const int DAYS_IN_YEAR = 365; ///< days per year
static const int DAYS_IN_LEAP_YEAR = 366; ///< sometimes, you need one day more...
static const int STATION_RATING_TICKS = 185; ///< cycle duration for updating station rating
static const int STATION_ACCEPTANCE_TICKS = 250; ///< cycle duration for updating station acceptance
static const int CARGO_AGING_TICKS = 185; ///< cycle duration for aging cargo
static const int INDUSTRY_PRODUCE_TICKS = 256; ///< cycle duration for industry production
static const int TOWN_GROWTH_TICKS = 70; ///< cycle duration for towns trying to grow. (this originates from the size of the town array in TTD
static const int INDUSTRY_CUT_TREE_TICKS = INDUSTRY_PRODUCE_TICKS * 2; ///< cycle duration for lumber mill's extra action
/*
* ORIGINAL_BASE_YEAR, ORIGINAL_MAX_YEAR and DAYS_TILL_ORIGINAL_BASE_YEAR are
* primarily used for loading newgrf and savegame data and returning some
* newgrf (callback) functions that were in the original (TTD) inherited
* format, where '_date == 0' meant that it was 1920-01-01.
*/
/** The minimum starting year/base year of the original TTD */
static const Year ORIGINAL_BASE_YEAR = 1920;
/** The original ending year */
static const Year ORIGINAL_END_YEAR = 2051;
/** The maximum year of the original TTD */
static const Year ORIGINAL_MAX_YEAR = 2090;
/**
* Calculate the number of leap years till a given year.
*
* Each passed leap year adds one day to the 'day count'.
*
* A special case for the year 0 as no year has been passed,
* but '(year - 1) / 4' does not yield '-1' to counteract the
* '+1' at the end of the formula as divisions round to zero.
*
* @param year the year to get the leap years till.
* @return the number of leap years.
*/
#define LEAP_YEARS_TILL(year) ((year) == 0 ? 0 : ((year) - 1) / 4 - ((year) - 1) / 100 + ((year) - 1) / 400 + 1)
/**
* Calculate the date of the first day of a given year.
* @param year the year to get the first day of.
* @return the date.
*/
#define DAYS_TILL(year) (DAYS_IN_YEAR * (year) + LEAP_YEARS_TILL(year))
/**
* The offset in days from the '_date == 0' till
* 'ConvertYMDToDate(ORIGINAL_BASE_YEAR, 0, 1)'
*/
#define DAYS_TILL_ORIGINAL_BASE_YEAR DAYS_TILL(ORIGINAL_BASE_YEAR)
/** The absolute minimum & maximum years in OTTD */
static const Year MIN_YEAR = 0;
/** The default starting year */
static const Year DEF_START_YEAR = 1950;
/**
* MAX_YEAR, nicely rounded value of the number of years that can
* be encoded in a single 32 bits date, about 2^31 / 366 years.
*/
static const Year MAX_YEAR = 5000000;
/** The number of days till the last day */
#define MAX_DAY (DAYS_TILL(MAX_YEAR + 1) - 1)
/**
* Data structure to convert between Date and triplet (year, month, and day).
* @see ConvertDateToYMD(), ConvertYMDToDate()
*/
struct YearMonthDay {
Year year; ///< Year (0...)
Month month; ///< Month (0..11)
Day day; ///< Day (1..31)
};
static const Year INVALID_YEAR = -1; ///< Representation of an invalid year
static const Date INVALID_DATE = -1; ///< Representation of an invalid date
static const Ticks INVALID_TICKS = -1; ///< Representation of an invalid number of ticks
#endif /* DATE_TYPE_H */
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