cpp/openttd-patchpack/source Changeset - r13756:5a0fce0c7ab0

Changeset - r13756:5a0fce0c7ab0

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rubidium - 15 years ago 2009-11-25 23:28:04
rubidium@openttd.org

(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

2 files changed with 32 insertions and 14 deletions:

src/date.cpp

src/date_type.h

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src/date.cpp

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@@ @@ -140,22 +140,13 @@ void ConvertDateToYMD(Date date, YearMon @@
  */
 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 */

src/date_type.h

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@@ @@ -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

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