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/* $Id$ */
/** @file date_type.h Types related to the dates in OpenTTD. */
#ifndef DATE_TYPE_H
#define DATE_TYPE_H
/**
* 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
*/
enum {
DAY_TICKS = 74, ///< ticks per day
DAYS_IN_YEAR = 365, ///< days per year
DAYS_IN_LEAP_YEAR = 366, ///< sometimes, you need one day more...
};
/*
* 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 */
#define ORIGINAL_BASE_YEAR 1920
/** The original ending year */
#define ORIGINAL_END_YEAR 2051
/** The maximum year of the original TTD */
#define ORIGINAL_MAX_YEAR 2090
/**
* The offset in days from the '_date == 0' till
* 'ConvertYMDToDate(ORIGINAL_BASE_YEAR, 0, 1)'
*/
#define DAYS_TILL_ORIGINAL_BASE_YEAR (DAYS_IN_YEAR * ORIGINAL_BASE_YEAR + ORIGINAL_BASE_YEAR / 4 - ORIGINAL_BASE_YEAR / 100 + ORIGINAL_BASE_YEAR / 400)
/* The absolute minimum & maximum years in OTTD */
#define MIN_YEAR 0
/* 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. */
#define MAX_YEAR 5000000
typedef int32 Date;
typedef uint16 DateFract;
typedef int32 Year;
typedef uint8 Month;
typedef uint8 Day;
/**
* 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;
static const Date INVALID_DATE = -1;
#endif /* DATE_TYPE_H */
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