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