OpenTTD-patches/date.h

60 lines
1.7 KiB
C

/* $Id$ */
#ifndef DATE_H
#define DATE_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
*/
#define DAY_TICKS 74
/*
* 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 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 (365 * 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
/* Year and Date are defined elsewhere */
typedef uint8 Month;
typedef uint8 Day;
typedef uint16 DateFract;
typedef struct YearMonthDay {
Year year;
Month month;
Day day;
} YearMonthDay;
extern Year _cur_year;
extern Month _cur_month;
extern Date _date;
extern DateFract _date_fract;
void SetDate(Date date);
void ConvertDateToYMD(Date date, YearMonthDay *ymd);
Date ConvertYMDToDate(Year year, Month month, Day day);
#endif /* DATE_H */