mirror of https://github.com/OpenTTD/OpenTTD.git
60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
/* $Id$ */
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#ifndef DATE_H
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#define DATE_H
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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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#define DAY_TICKS 74
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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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#define ORIGINAL_BASE_YEAR 1920
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/** The maximum year of the original TTD */
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#define ORIGINAL_MAX_YEAR 2090
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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 (365 * ORIGINAL_BASE_YEAR + ORIGINAL_BASE_YEAR / 4 - ORIGINAL_BASE_YEAR / 100 + ORIGINAL_BASE_YEAR / 400)
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/* The absolute minimum & maximum years in OTTD */
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#define MIN_YEAR 0
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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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#define MAX_YEAR 5000000
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/* Year and Date are defined elsewhere */
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typedef uint8 Month;
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typedef uint8 Day;
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typedef uint16 DateFract;
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typedef struct YearMonthDay {
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Year year;
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Month month;
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Day day;
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} YearMonthDay;
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extern Year _cur_year;
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extern Month _cur_month;
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extern Date _date;
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extern DateFract _date_fract;
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void SetDate(Date date);
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void ConvertDateToYMD(Date date, YearMonthDay *ymd);
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Date ConvertYMDToDate(Year year, Month month, Day day);
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#endif /* DATE_H */
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