/**
* Return the Julian day number of day before the first day of the
* given month in the given extended year.
*
* <p>Note: This method reads the IS_LEAP_MONTH field to determine
* whether the given month is a leap month.
* @param eyear the extended year
* @param month the zero-based month. The month is also determined
* by reading the IS_LEAP_MONTH field.
* @return the Julian day number of the day before the first
* day of the given month and year
* @stable ICU 2.8
*/
int32_t ChineseCalendar::handleComputeMonthStart(int32_t eyear, int32_t month, UBool useMonth) const {
ChineseCalendar *nonConstThis = (ChineseCalendar*)this; // cast away const
// If the month is out of range, adjust it into range, and
// modify the extended year value accordingly.
if (month < 0 || month > 11) {
double m = month;
eyear += (int32_t)ClockMath::floorDivide(m, 12.0, m);
month = (int32_t)m;
}
int32_t gyear = eyear + fEpochYear - 1; // Gregorian year
int32_t theNewYear = newYear(gyear);
int32_t newMoon = newMoonNear(theNewYear + month * 29, TRUE);
int32_t julianDay = newMoon + kEpochStartAsJulianDay;
// Save fields for later restoration
int32_t saveMonth = internalGet(UCAL_MONTH);
int32_t saveIsLeapMonth = internalGet(UCAL_IS_LEAP_MONTH);
// Ignore IS_LEAP_MONTH field if useMonth is false
int32_t isLeapMonth = useMonth ? saveIsLeapMonth : 0;
UErrorCode status = U_ZERO_ERROR;
nonConstThis->computeGregorianFields(julianDay, status);
if (U_FAILURE(status))
return 0;
// This will modify the MONTH and IS_LEAP_MONTH fields (only)
nonConstThis->computeChineseFields(newMoon, getGregorianYear(),
getGregorianMonth(), FALSE);
if (month != internalGet(UCAL_MONTH) ||
isLeapMonth != internalGet(UCAL_IS_LEAP_MONTH)) {
newMoon = newMoonNear(newMoon + SYNODIC_GAP, TRUE);
julianDay = newMoon + kEpochStartAsJulianDay;
}
nonConstThis->internalSet(UCAL_MONTH, saveMonth);
nonConstThis->internalSet(UCAL_IS_LEAP_MONTH, saveIsLeapMonth);
return julianDay - 1;
}
/**
* Override Calendar to compute several fields specific to the Chinese
* calendar system. These are:
*
* <ul><li>ERA
* <li>YEAR
* <li>MONTH
* <li>DAY_OF_MONTH
* <li>DAY_OF_YEAR
* <li>EXTENDED_YEAR</ul>
*
* The DAY_OF_WEEK and DOW_LOCAL fields are already set when this
* method is called. The getGregorianXxx() methods return Gregorian
* calendar equivalents for the given Julian day.
*
* <p>Compute the ChineseCalendar-specific field IS_LEAP_MONTH.
* @stable ICU 2.8
*/
void ChineseCalendar::handleComputeFields(int32_t julianDay, UErrorCode &/*status*/) {
computeChineseFields(julianDay - kEpochStartAsJulianDay, // local days
getGregorianYear(), getGregorianMonth(),
TRUE); // set all fields
}
void GregorianCalendar::handleComputeFields(int32_t julianDay, UErrorCode& status) {
int32_t eyear, month, dayOfMonth, dayOfYear, unusedRemainder;
if(U_FAILURE(status)) {
return;
}
#if defined (U_DEBUG_CAL)
fprintf(stderr, "%s:%d: jd%d- (greg's %d)- [cut=%d]\n",
__FILE__, __LINE__, julianDay, getGregorianDayOfYear(), fCutoverJulianDay);
#endif
if (julianDay >= fCutoverJulianDay) {
month = getGregorianMonth();
dayOfMonth = getGregorianDayOfMonth();
dayOfYear = getGregorianDayOfYear();
eyear = getGregorianYear();
} else {
// The Julian epoch day (not the same as Julian Day)
// is zero on Saturday December 30, 0 (Gregorian).
int32_t julianEpochDay = julianDay - (kJan1_1JulianDay - 2);
eyear = (int32_t) ClockMath::floorDivide((4.0*julianEpochDay) + 1464.0, (int32_t) 1461, unusedRemainder);
// Compute the Julian calendar day number for January 1, eyear
int32_t january1 = 365*(eyear-1) + ClockMath::floorDivide(eyear-1, (int32_t)4);
dayOfYear = (julianEpochDay - january1); // 0-based
// Julian leap years occurred historically every 4 years starting
// with 8 AD. Before 8 AD the spacing is irregular; every 3 years
// from 45 BC to 9 BC, and then none until 8 AD. However, we don't
// implement this historical detail; instead, we implement the
// computatinally cleaner proleptic calendar, which assumes
// consistent 4-year cycles throughout time.
UBool isLeap = ((eyear&0x3) == 0); // equiv. to (eyear%4 == 0)
// Common Julian/Gregorian calculation
int32_t correction = 0;
int32_t march1 = isLeap ? 60 : 59; // zero-based DOY for March 1
if (dayOfYear >= march1) {
correction = isLeap ? 1 : 2;
}
month = (12 * (dayOfYear + correction) + 6) / 367; // zero-based month
dayOfMonth = dayOfYear - (isLeap?kLeapNumDays[month]:kNumDays[month]) + 1; // one-based DOM
++dayOfYear;
#if defined (U_DEBUG_CAL)
// fprintf(stderr, "%d - %d[%d] + 1\n", dayOfYear, isLeap?kLeapNumDays[month]:kNumDays[month], month );
// fprintf(stderr, "%s:%d: greg's HCF %d -> %d/%d/%d not %d/%d/%d\n",
// __FILE__, __LINE__,julianDay,
// eyear,month,dayOfMonth,
// getGregorianYear(), getGregorianMonth(), getGregorianDayOfMonth() );
fprintf(stderr, "%s:%d: doy %d (greg's %d)- [cut=%d]\n",
__FILE__, __LINE__, dayOfYear, getGregorianDayOfYear(), fCutoverJulianDay);
#endif
}
// [j81] if we are after the cutover in its year, shift the day of the year
if((eyear == fGregorianCutoverYear) && (julianDay >= fCutoverJulianDay)) {
//from handleComputeMonthStart
int32_t gregShift = Grego::gregorianShift(eyear);
#if defined (U_DEBUG_CAL)
fprintf(stderr, "%s:%d: gregorian shift %d ::: doy%d => %d [cut=%d]\n",
__FILE__, __LINE__,gregShift, dayOfYear, dayOfYear+gregShift, fCutoverJulianDay);
#endif
dayOfYear += gregShift;
}
internalSet(UCAL_MONTH, month);
internalSet(UCAL_DAY_OF_MONTH, dayOfMonth);
internalSet(UCAL_DAY_OF_YEAR, dayOfYear);
internalSet(UCAL_EXTENDED_YEAR, eyear);
int32_t era = AD;
if (eyear < 1) {
era = BC;
eyear = 1 - eyear;
}
internalSet(UCAL_ERA, era);
internalSet(UCAL_YEAR, eyear);
}
