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author | rubidium <rubidium@openttd.org> | 2009-11-25 23:28:04 +0000 |
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committer | rubidium <rubidium@openttd.org> | 2009-11-25 23:28:04 +0000 |
commit | 1a8c203d6ec29cf200b37fd995e865821c8ce888 (patch) | |
tree | 6fead8ca2f9912f460132eb58edd610343685ebf | |
parent | d3a925af42e8e5ce01a63a57dfd57c0ed99a6c96 (diff) | |
download | openttd-1a8c203d6ec29cf200b37fd995e865821c8ce888.tar.xz |
(svn r18291) -Codechange: rework the calculation of the 'days till year' macro a bit so it can be properly reused and add a MAX_DAY
-rw-r--r-- | src/date.cpp | 11 | ||||
-rw-r--r-- | src/date_type.h | 35 |
2 files changed, 32 insertions, 14 deletions
diff --git a/src/date.cpp b/src/date.cpp index 51ff6e426..e1b6d1943 100644 --- a/src/date.cpp +++ b/src/date.cpp @@ -140,22 +140,13 @@ void ConvertDateToYMD(Date date, YearMonthDay *ymd) */ Date ConvertYMDToDate(Year year, Month month, Day day) { - /* - * Each passed leap year adds one day to the 'day count'. - * - * A special case for the year 0 as no year has been passed, - * but '(year - 1) / 4' does not yield '-1' to counteract the - * '+1' at the end of the formula as divisions round to zero. - */ - int nr_of_leap_years = (year == 0) ? 0 : ((year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + 1); - /* Day-offset in a leap year */ int days = _accum_days_for_month[month] + day - 1; /* Account for the missing of the 29th of February in non-leap years */ if (!IsLeapYear(year) && days >= ACCUM_MAR) days--; - return year * DAYS_IN_YEAR + nr_of_leap_years + days; + return DAYS_TILL(year) + days; } /** Functions used by the IncreaseDate function */ diff --git a/src/date_type.h b/src/date_type.h index 9817e1e2f..ae92b1d27 100644 --- a/src/date_type.h +++ b/src/date_type.h @@ -39,17 +39,44 @@ enum { #define ORIGINAL_MAX_YEAR 2090 /** + * Calculate the number of leap years till a given year. + * + * Each passed leap year adds one day to the 'day count'. + * + * A special case for the year 0 as no year has been passed, + * but '(year - 1) / 4' does not yield '-1' to counteract the + * '+1' at the end of the formula as divisions round to zero. + * + * @param year the year to get the leap years till. + * @return the number of leap years. + */ +#define LEAP_YEARS_TILL(year) ((year) == 0 ? 0 : ((year) - 1) / 4 - ((year) - 1) / 100 + ((year) - 1) / 400 + 1) + +/** + * Calculate the date of the first day of a given year. + * @param year the year to get the first day of. + * @return the date. + */ +#define DAYS_TILL(year) (DAYS_IN_YEAR * (year) + LEAP_YEARS_TILL(year)) + +/** * 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) +#define DAYS_TILL_ORIGINAL_BASE_YEAR DAYS_TILL(ORIGINAL_BASE_YEAR) -/* The absolute minimum & maximum years in OTTD */ +/** 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. */ + +/** + * 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 +/** The number of days till the last day */ +#define MAX_DAY DAYS_TILL(MAX_YEAR + 1) - 1 + typedef int32 Date; ///< The type to store our dates in typedef uint16 DateFract; ///< The fraction of a date we're in, i.e. the number of ticks since the last date changeover typedef int32 Ticks; ///< The type to store ticks in |