petern/OpenTTD
1
0
Fork 0
forked from mirror/OpenTTD
Code Pull Requests Activity

(svn r5999) -Feature: change the original date format to a 32 bits format based at the year 0.

Browse Source 
The game date subsystem now allows someone to start in the year 0 and continue
up to the year 5 000 000. However, you currently cannot build anything before 
1920 as there is no newgrf support for dates before 1920 or after 2090 yet.
This commit is contained in:
rubidium
2006-08-20 18:40:57 +00:00
parent 5e4667624e
commit 28a0843707
25 changed files with 160 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

77
date.c
View File

@@ -70,25 +70,47 @@ static const uint16 _accum_days_for_month[] = {
ACCUM_SEP, ACCUM_OCT, ACCUM_NOV, ACCUM_DEC,
};
static inline bool IsLeapYear(Year yr)
{
return yr % 4 == 0 && (yr % 100 != 0 || yr % 400 == 0);
}
/**
* Converts a Date to a Year, Month & Day.
* @param date the date to convert from
* @param ymd the year, month and day to write to
*/
void ConvertDateToYMD(Date date, YearMonthDay *ymd)
{
uint yr = date / (365 + 365 + 365 + 366);
uint rem = date % (365 + 365 + 365 + 366);
uint x;
/*
* Year determination in multiple steps to account for leap
* years. First do the large steps, then the smaller ones.
*/
yr *= 4;
/* There are 97 leap years in 400 years */
Year yr = 400 * (date / (365 * 400 + 97));
int rem = date % (365 * 400 + 97);
uint16 x;
if (rem >= 366) {
rem--;
do {
rem -= 365;
yr++;
} while (rem >= 365);
if (rem >= 31 + 28) rem++;
/* There are 24 leap years in 100 years */
yr += 100 * (rem / (365 * 100 + 24));
rem = rem % (365 * 100 + 24);
/* There is 1 leap year every 4 years */
yr += 4 * (rem / (365 * 4 + 1));
rem = rem % (365 * 4 + 1);
/* The last (max 3) years to account for; the first one
* can be, but is not necessarily a leap year */
while (rem >= (IsLeapYear(yr) ? 366 : 365)) {
rem -= IsLeapYear(yr) ? 366 : 365;
yr++;
}
ymd->year = BASE_YEAR + yr;
/* Skip the 29th of February in non-leap years */
if (!IsLeapYear(yr) && rem >= ACCUM_MAR - 1) rem++;
ymd->year = yr;
x = _month_date_from_year_day[rem];
ymd->month = x >> 5;
@@ -97,23 +119,28 @@ void ConvertDateToYMD(Date date, YearMonthDay *ymd)
/**
* Converts a tupe of Year, Month and Day to a Date.
* @param year is a number between 0..?
* @param year is a number between 0..MAX_YEAR
* @param month is a number between 0..11
* @param day is a number between 1..31
*/
Date ConvertYMDToDate(Year year, Month month, Day day)
{
uint rem;
uint yr = year - BASE_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.
*/
int nr_of_leap_years = (year == 0) ? 0 : ((year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + 1);
/* day in the year */
rem = _accum_days_for_month[month] + day - 1;
/* Day-offset in a leap year */
int days = _accum_days_for_month[month] + day - 1;
/* remove feb 29 from year 1,2,3 */
if (yr & 3) rem += (yr & 3) * 365 + (rem < 31 + 29);
/* Account for the missing of the 29th of February in non-leap years */
if (!IsLeapYear(year) && days >= ACCUM_MAR) days--;
/* base date. */
return (yr >> 2) * (365 + 365 + 365 + 366) + rem;
return year * 365 + nr_of_leap_years + days;
}
/** Functions used by the IncreaseDate function */
@@ -252,12 +279,12 @@ void IncreaseDate(void)
/* check if we reached the maximum year, decrement dates by a year */
} else if (_cur_year == MAX_YEAR + 1) {
Vehicle *v;
uint days_this_year;
_cur_year--;
_date -= 365;
FOR_ALL_VEHICLES(v) {
v->date_of_last_service -= 365;
}
days_this_year = IsLeapYear(_cur_year) ? 366 : 365;
_date -= days_this_year;
FOR_ALL_VEHICLES(v) v->date_of_last_service -= days_this_year;
/* Because the _date wraps here, and text-messages expire by game-days, we have to clean out
* all of them if the date is set back, else those messages will hang for ever */