1

/* $Id$ */

     2

     3

#ifndef DATE_H

     4

#define DATE_H

     5

     6

#include "openttd.h"

     7

     8

/**

     9

 * 1 day is 74 ticks; _date_fract used to be uint16 and incremented by 885. On

    10

 *                    an overflow the new day begun and 65535 / 885 = 74.

    11

 * 1 tick is approximately 30 ms.

    12

 * 1 day is thus about 2 seconds (74 * 30 = 2220) on a machine that can run OpenTTD normally

    13

 */

    14

#define DAY_TICKS 74

    15

    16

/*

    17

 * ORIGINAL_BASE_YEAR, ORIGINAL_MAX_YEAR and DAYS_TILL_ORIGINAL_BASE_YEAR are

    18

 * primarily used for loading newgrf and savegame data and returning some

    19

 * newgrf (callback) functions that were in the original (TTD) inherited

    20

 * format, where '_date == 0' meant that it was 1920-01-01.

    21

 */

    22

    23

/** The minimum starting year/base year of the original TTD */

    24

#define ORIGINAL_BASE_YEAR 1920

    25

/** The maximum year of the original TTD */

    26

#define ORIGINAL_MAX_YEAR 2090

    27

    28

/**

    29

 * The offset in days from the '_date == 0' till

    30

 * 'ConvertYMDToDate(ORIGINAL_BASE_YEAR, 0, 1)'

    31

 */

    32

#define DAYS_TILL_ORIGINAL_BASE_YEAR (365 * ORIGINAL_BASE_YEAR + ORIGINAL_BASE_YEAR / 4 - ORIGINAL_BASE_YEAR / 100 + ORIGINAL_BASE_YEAR / 400)

    33

    34

/* The absolute minimum & maximum years in OTTD */

    35

#define MIN_YEAR 0

    36

/* MAX_YEAR, nicely rounded value of the number of years that can

    37

 * be encoded in a single 32 bits date, about 2^31 / 366 years. */

    38

#define MAX_YEAR 5000000

    39

    40

/* Year and Date are defined elsewhere */

    41

typedef uint8  Month;

    42

typedef uint8  Day;

    43

typedef uint16 DateFract;

    44

    45

typedef struct YearMonthDay {

    46

	Year  year;

    47

	Month month;

    48

	Day   day;

    49

} YearMonthDay;

    50

    51

extern Year      _cur_year;

    52

extern Month     _cur_month;

    53

extern Date      _date;

    54

extern DateFract _date_fract;

    55

    56

    57

void SetDate(Date date);

    58

void ConvertDateToYMD(Date date, YearMonthDay *ymd);

    59

Date ConvertYMDToDate(Year year, Month month, Day day);

    60

    61

#endif /* DATE_H */