Check in the pristine copy of ICU 4.6...

icu46/source/i18n/chnsecal.cpp

+/*
+ ******************************************************************************
+ * Copyright (C) 2007-2008, International Business Machines Corporation
+ * and others. All Rights Reserved.
+ ******************************************************************************
+ *
+ * File CHNSECAL.CPP
+ *
+ * Modification History:
+ *
+ *   Date        Name        Description
+ *   9/18/2007  ajmacher         ported from java ChineseCalendar
+ *****************************************************************************
+ */
+
+#include "chnsecal.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "umutex.h"
+#include <float.h>
+#include "gregoimp.h" // Math
+#include "astro.h" // CalendarAstronomer
+#include "uhash.h"
+#include "ucln_in.h"
+
+// Debugging
+#ifdef U_DEBUG_CHNSECAL
+# include <stdio.h>
+# include <stdarg.h>
+static void debug_chnsecal_loc(const char *f, int32_t l)
+{
+    fprintf(stderr, "%s:%d: ", f, l);
+}
+
+static void debug_chnsecal_msg(const char *pat, ...)
+{
+    va_list ap;
+    va_start(ap, pat);
+    vfprintf(stderr, pat, ap);
+    fflush(stderr);
+}
+// must use double parens, i.e.:  U_DEBUG_CHNSECAL_MSG(("four is: %d",4));
+#define U_DEBUG_CHNSECAL_MSG(x) {debug_chnsecal_loc(__FILE__,__LINE__);debug_chnsecal_msg x;}
+#else
+#define U_DEBUG_CHNSECAL_MSG(x)
+#endif
+
+
+// --- The cache --
+static UMTX astroLock = 0;  // pod bay door lock
+static U_NAMESPACE_QUALIFIER CalendarAstronomer *gChineseCalendarAstro = NULL;
+static U_NAMESPACE_QUALIFIER CalendarCache *gChineseCalendarWinterSolsticeCache = NULL;
+static U_NAMESPACE_QUALIFIER CalendarCache *gChineseCalendarNewYearCache = NULL;
+
+/**
+ * The start year of the Chinese calendar, the 61st year of the reign
+ * of Huang Di.  Some sources use the first year of his reign,
+ * resulting in EXTENDED_YEAR values 60 years greater and ERA (cycle)
+ * values one greater.
+ */
+static const int32_t CHINESE_EPOCH_YEAR = -2636; // Gregorian year
+
+/**
+ * The offset from GMT in milliseconds at which we perform astronomical
+ * computations.  Some sources use a different historically accurate
+ * offset of GMT+7:45:40 for years before 1929; we do not do this.
+ */
+static const double CHINA_OFFSET = 8 * kOneHour;
+
+/**
+ * Value to be added or subtracted from the local days of a new moon to
+ * get close to the next or prior new moon, but not cross it.  Must be
+ * >= 1 and < CalendarAstronomer.SYNODIC_MONTH.
+ */
+static const int32_t SYNODIC_GAP = 25;
+
+
+U_CDECL_BEGIN
+static UBool calendar_chinese_cleanup(void) {
+    if (gChineseCalendarAstro) {
+        delete gChineseCalendarAstro;
+        gChineseCalendarAstro = NULL;
+    }
+    if (gChineseCalendarWinterSolsticeCache) {
+        delete gChineseCalendarWinterSolsticeCache;
+        gChineseCalendarWinterSolsticeCache = NULL;
+    }
+    if (gChineseCalendarNewYearCache) {
+        delete gChineseCalendarNewYearCache;
+        gChineseCalendarNewYearCache = NULL;
+    }
+    umtx_destroy(&astroLock);
+    return TRUE;
+}
+U_CDECL_END
+
+U_NAMESPACE_BEGIN
+
+
+// Implementation of the ChineseCalendar class
+
+
+//-------------------------------------------------------------------------
+// Constructors...
+//-------------------------------------------------------------------------
+
+
+Calendar* ChineseCalendar::clone() const {
+    return new ChineseCalendar(*this);
+}
+
+ChineseCalendar::ChineseCalendar(const Locale& aLocale, UErrorCode& success)
+:   Calendar(TimeZone::createDefault(), aLocale, success)
+{
+    isLeapYear = FALSE;
+    setTimeInMillis(getNow(), success); // Call this again now that the vtable is set up properly.
+}
+
+ChineseCalendar::ChineseCalendar(const ChineseCalendar& other) : Calendar(other) {
+    isLeapYear = other.isLeapYear;
+}
+
+ChineseCalendar::~ChineseCalendar()
+{
+}
+
+const char *ChineseCalendar::getType() const { 
+    return "chinese";
+}
+
+//-------------------------------------------------------------------------
+// Minimum / Maximum access functions
+//-------------------------------------------------------------------------
+
+
+static const int32_t LIMITS[UCAL_FIELD_COUNT][4] = {
+    // Minimum  Greatest     Least    Maximum
+    //           Minimum   Maximum
+    {        1,        1,    83333,    83333}, // ERA
+    {        1,        1,       60,       60}, // YEAR
+    {        0,        0,       11,       11}, // MONTH
+    {        1,        1,       50,       55}, // WEEK_OF_YEAR
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // WEEK_OF_MONTH
+    {        1,        1,       29,       30}, // DAY_OF_MONTH
+    {        1,        1,      353,      385}, // DAY_OF_YEAR
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // DAY_OF_WEEK
+    {       -1,       -1,        5,        5}, // DAY_OF_WEEK_IN_MONTH
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // AM_PM
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // HOUR
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // HOUR_OF_DAY
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // MINUTE
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // SECOND
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // MILLISECOND
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // ZONE_OFFSET
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // DST_OFFSET
+    { -5000000, -5000000,  5000000,  5000000}, // YEAR_WOY
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // DOW_LOCAL
+    { -5000000, -5000000,  5000000,  5000000}, // EXTENDED_YEAR
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // JULIAN_DAY
+    {/*N/A*/-1,/*N/A*/-1,/*N/A*/-1,/*N/A*/-1}, // MILLISECONDS_IN_DAY
+    {        0,        0,        1,        1}, // IS_LEAP_MONTH
+};
+
+
+/**
+* @draft ICU 2.4
+*/
+int32_t ChineseCalendar::handleGetLimit(UCalendarDateFields field, ELimitType limitType) const {
+    return LIMITS[field][limitType];
+}
+
+
+//----------------------------------------------------------------------
+// Calendar framework
+//----------------------------------------------------------------------
+
+/**
+ * Implement abstract Calendar method to return the extended year
+ * defined by the current fields.  This will use either the ERA and
+ * YEAR field as the cycle and year-of-cycle, or the EXTENDED_YEAR
+ * field as the continuous year count, depending on which is newer.
+ * @stable ICU 2.8
+ */
+int32_t ChineseCalendar::handleGetExtendedYear() {
+    int32_t year;
+    if (newestStamp(UCAL_ERA, UCAL_YEAR, kUnset) <= fStamp[UCAL_EXTENDED_YEAR]) {
+        year = internalGet(UCAL_EXTENDED_YEAR, 1); // Default to year 1
+    } else {
+        int32_t cycle = internalGet(UCAL_ERA, 1) - 1; // 0-based cycle
+        year = cycle * 60 + internalGet(UCAL_YEAR, 1);
+    }
+    return year;
+}
+
+/**
+ * Override Calendar method to return the number of days in the given
+ * extended year and month.
+ *
+ * <p>Note: This method also reads the IS_LEAP_MONTH field to determine
+ * whether or not the given month is a leap month.
+ * @stable ICU 2.8
+ */
+int32_t ChineseCalendar::handleGetMonthLength(int32_t extendedYear, int32_t month) const {
+    int32_t thisStart = handleComputeMonthStart(extendedYear, month, TRUE) -
+        kEpochStartAsJulianDay + 1; // Julian day -> local days
+    int32_t nextStart = newMoonNear(thisStart + SYNODIC_GAP, TRUE);
+    return nextStart - thisStart;
+}
+
+/**
+ * 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
+}
+
+/**
+ * Field resolution table that incorporates IS_LEAP_MONTH.
+ */
+const UFieldResolutionTable ChineseCalendar::CHINESE_DATE_PRECEDENCE[] =
+{
+    {
+        { UCAL_DAY_OF_MONTH, kResolveSTOP },
+        { UCAL_WEEK_OF_YEAR, UCAL_DAY_OF_WEEK, kResolveSTOP },
+        { UCAL_WEEK_OF_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
+        { UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
+        { UCAL_WEEK_OF_YEAR, UCAL_DOW_LOCAL, kResolveSTOP },
+        { UCAL_WEEK_OF_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
+        { UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
+        { UCAL_DAY_OF_YEAR, kResolveSTOP },
+        { kResolveRemap | UCAL_DAY_OF_MONTH, UCAL_IS_LEAP_MONTH, kResolveSTOP },
+        { kResolveSTOP }
+    },
+    {
+        { UCAL_WEEK_OF_YEAR, kResolveSTOP },
+        { UCAL_WEEK_OF_MONTH, kResolveSTOP },
+        { UCAL_DAY_OF_WEEK_IN_MONTH, kResolveSTOP },
+        { kResolveRemap | UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
+        { kResolveRemap | UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
+        { kResolveSTOP }
+    },
+    {{kResolveSTOP}}
+};
+
+/**
+ * Override Calendar to add IS_LEAP_MONTH to the field resolution
+ * table.
+ * @stable ICU 2.8
+ */
+const UFieldResolutionTable* ChineseCalendar::getFieldResolutionTable() const {
+    return CHINESE_DATE_PRECEDENCE;
+}
+
+/**
+ * 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 + CHINESE_EPOCH_YEAR - 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 handle leap months properly.
+ * @stable ICU 2.8
+ */
+void ChineseCalendar::add(UCalendarDateFields field, int32_t amount, UErrorCode& status) {
+    switch (field) {
+    case UCAL_MONTH:
+        if (amount != 0) {
+            int32_t dom = get(UCAL_DAY_OF_MONTH, status);
+            if (U_FAILURE(status)) break;
+            int32_t day = get(UCAL_JULIAN_DAY, status) - kEpochStartAsJulianDay; // Get local day
+            if (U_FAILURE(status)) break;
+            int32_t moon = day - dom + 1; // New moon 
+            offsetMonth(moon, dom, amount);
+        }
+        break;
+    default:
+        Calendar::add(field, amount, status);
+        break;
+    }
+}
+
+/**
+ * Override Calendar to handle leap months properly.
+ * @stable ICU 2.8
+ */
+void ChineseCalendar::add(EDateFields field, int32_t amount, UErrorCode& status) {
+    add((UCalendarDateFields)field, amount, status);
+}
+
+/**
+ * Override Calendar to handle leap months properly.
+ * @stable ICU 2.8
+ */
+void ChineseCalendar::roll(UCalendarDateFields field, int32_t amount, UErrorCode& status) {
+    switch (field) {
+    case UCAL_MONTH:
+        if (amount != 0) {
+            int32_t dom = get(UCAL_DAY_OF_MONTH, status);
+            if (U_FAILURE(status)) break;
+            int32_t day = get(UCAL_JULIAN_DAY, status) - kEpochStartAsJulianDay; // Get local day
+            if (U_FAILURE(status)) break;
+            int32_t moon = day - dom + 1; // New moon (start of this month)
+
+            // Note throughout the following:  Months 12 and 1 are never
+            // followed by a leap month (D&R p. 185).
+
+            // Compute the adjusted month number m.  This is zero-based
+            // value from 0..11 in a non-leap year, and from 0..12 in a
+            // leap year.
+            int32_t m = get(UCAL_MONTH, status); // 0-based month
+            if (U_FAILURE(status)) break;
+            if (isLeapYear) { // (member variable)
+                if (get(UCAL_IS_LEAP_MONTH, status) == 1) {
+                    ++m;
+                } else {
+                    // Check for a prior leap month.  (In the
+                    // following, month 0 is the first month of the
+                    // year.)  Month 0 is never followed by a leap
+                    // month, and we know month m is not a leap month.
+                    // moon1 will be the start of month 0 if there is
+                    // no leap month between month 0 and month m;
+                    // otherwise it will be the start of month 1.
+                    int moon1 = moon -
+                        (int) (CalendarAstronomer::SYNODIC_MONTH * (m - 0.5));
+                    moon1 = newMoonNear(moon1, TRUE);
+                    if (isLeapMonthBetween(moon1, moon)) {
+                        ++m;
+                    }
+                }
+                if (U_FAILURE(status)) break;
+            }
+
+            // Now do the standard roll computation on m, with the
+            // allowed range of 0..n-1, where n is 12 or 13.
+            int32_t n = isLeapYear ? 13 : 12; // Months in this year
+            int32_t newM = (m + amount) % n;
+            if (newM < 0) {
+                newM += n;
+            }
+
+            if (newM != m) {
+                offsetMonth(moon, dom, newM - m);
+            }
+        }
+        break;
+    default:
+        Calendar::roll(field, amount, status);
+        break;
+    }
+}
+
+void ChineseCalendar::roll(EDateFields field, int32_t amount, UErrorCode& status) {
+    roll((UCalendarDateFields)field, amount, status);
+}
+
+
+//------------------------------------------------------------------
+// Support methods and constants
+//------------------------------------------------------------------
+
+/**
+ * Convert local days to UTC epoch milliseconds.
+ * @param days days after January 1, 1970 0:00 Asia/Shanghai
+ * @return milliseconds after January 1, 1970 0:00 GMT
+ */
+double ChineseCalendar::daysToMillis(double days) {
+    return (days * kOneDay) - CHINA_OFFSET;
+}
+
+/**
+ * Convert UTC epoch milliseconds to local days.
+ * @param millis milliseconds after January 1, 1970 0:00 GMT
+ * @return days after January 1, 1970 0:00 Asia/Shanghai
+ */
+double ChineseCalendar::millisToDays(double millis) {
+    return ClockMath::floorDivide(millis + CHINA_OFFSET, kOneDay);
+}
+
+//------------------------------------------------------------------
+// Astronomical computations
+//------------------------------------------------------------------
+
+
+/**
+ * Return the major solar term on or after December 15 of the given
+ * Gregorian year, that is, the winter solstice of the given year.
+ * Computations are relative to Asia/Shanghai time zone.
+ * @param gyear a Gregorian year
+ * @return days after January 1, 1970 0:00 Asia/Shanghai of the
+ * winter solstice of the given year
+ */
+int32_t ChineseCalendar::winterSolstice(int32_t gyear) const {
+
+    UErrorCode status = U_ZERO_ERROR;
+    int32_t cacheValue = CalendarCache::get(&gChineseCalendarWinterSolsticeCache, gyear, status);
+
+    if (cacheValue == 0) {
+        // In books December 15 is used, but it fails for some years
+        // using our algorithms, e.g.: 1298 1391 1492 1553 1560.  That
+        // is, winterSolstice(1298) starts search at Dec 14 08:00:00
+        // PST 1298 with a final result of Dec 14 10:31:59 PST 1299.
+        double ms = daysToMillis(Grego::fieldsToDay(gyear, UCAL_DECEMBER, 1));
+
+        umtx_lock(&astroLock);
+        if(gChineseCalendarAstro == NULL) {
+            gChineseCalendarAstro = new CalendarAstronomer();
+            ucln_i18n_registerCleanup(UCLN_I18N_CHINESE_CALENDAR, calendar_chinese_cleanup);
+        }
+        gChineseCalendarAstro->setTime(ms);
+        UDate solarLong = gChineseCalendarAstro->getSunTime(CalendarAstronomer::WINTER_SOLSTICE(), TRUE);
+        umtx_unlock(&astroLock);
+
+        // Winter solstice is 270 degrees solar longitude aka Dongzhi
+        cacheValue = (int32_t)millisToDays(solarLong);
+        CalendarCache::put(&gChineseCalendarWinterSolsticeCache, gyear, cacheValue, status);
+    }
+    if(U_FAILURE(status)) {
+        cacheValue = 0;
+    }
+    return cacheValue;
+}
+
+/**
+ * Return the closest new moon to the given date, searching either
+ * forward or backward in time.
+ * @param days days after January 1, 1970 0:00 Asia/Shanghai
+ * @param after if true, search for a new moon on or after the given
+ * date; otherwise, search for a new moon before it
+ * @return days after January 1, 1970 0:00 Asia/Shanghai of the nearest
+ * new moon after or before <code>days</code>
+ */
+int32_t ChineseCalendar::newMoonNear(double days, UBool after) const {
+    
+    umtx_lock(&astroLock);
+    if(gChineseCalendarAstro == NULL) {
+        gChineseCalendarAstro = new CalendarAstronomer();
+        ucln_i18n_registerCleanup(UCLN_I18N_CHINESE_CALENDAR, calendar_chinese_cleanup);
+    }
+    gChineseCalendarAstro->setTime(daysToMillis(days));
+    UDate newMoon = gChineseCalendarAstro->getMoonTime(CalendarAstronomer::NEW_MOON(), after);
+    umtx_unlock(&astroLock);
+    
+    return (int32_t) millisToDays(newMoon);
+}
+
+/**
+ * Return the nearest integer number of synodic months between
+ * two dates.
+ * @param day1 days after January 1, 1970 0:00 Asia/Shanghai
+ * @param day2 days after January 1, 1970 0:00 Asia/Shanghai
+ * @return the nearest integer number of months between day1 and day2
+ */
+int32_t ChineseCalendar::synodicMonthsBetween(int32_t day1, int32_t day2) const {
+    double roundme = ((day2 - day1) / CalendarAstronomer::SYNODIC_MONTH);
+    return (int32_t) (roundme + (roundme >= 0 ? .5 : -.5));
+}
+
+/**
+ * Return the major solar term on or before a given date.  This
+ * will be an integer from 1..12, with 1 corresponding to 330 degrees,
+ * 2 to 0 degrees, 3 to 30 degrees,..., and 12 to 300 degrees.
+ * @param days days after January 1, 1970 0:00 Asia/Shanghai
+ */
+int32_t ChineseCalendar::majorSolarTerm(int32_t days) const {
+    
+    umtx_lock(&astroLock);
+    if(gChineseCalendarAstro == NULL) {
+        gChineseCalendarAstro = new CalendarAstronomer();
+        ucln_i18n_registerCleanup(UCLN_I18N_CHINESE_CALENDAR, calendar_chinese_cleanup);
+    }
+    gChineseCalendarAstro->setTime(daysToMillis(days));
+    UDate solarLongitude = gChineseCalendarAstro->getSunLongitude();
+    umtx_unlock(&astroLock);
+
+    // Compute (floor(solarLongitude / (pi/6)) + 2) % 12
+    int32_t term = ( ((int32_t)(6 * solarLongitude / CalendarAstronomer::PI)) + 2 ) % 12;
+    if (term < 1) {
+        term += 12;
+    }
+    return term;
+}
+
+/**
+ * Return true if the given month lacks a major solar term.
+ * @param newMoon days after January 1, 1970 0:00 Asia/Shanghai of a new
+ * moon
+ */
+UBool ChineseCalendar::hasNoMajorSolarTerm(int32_t newMoon) const {
+    return majorSolarTerm(newMoon) ==
+        majorSolarTerm(newMoonNear(newMoon + SYNODIC_GAP, TRUE));
+}
+
+
+//------------------------------------------------------------------
+// Time to fields
+//------------------------------------------------------------------
+
+/**
+ * Return true if there is a leap month on or after month newMoon1 and
+ * at or before month newMoon2.
+ * @param newMoon1 days after January 1, 1970 0:00 Asia/Shanghai of a
+ * new moon
+ * @param newMoon2 days after January 1, 1970 0:00 Asia/Shanghai of a
+ * new moon
+ */
+UBool ChineseCalendar::isLeapMonthBetween(int32_t newMoon1, int32_t newMoon2) const {
+
+#ifdef U_DEBUG_CHNSECAL
+    // This is only needed to debug the timeOfAngle divergence bug.
+    // Remove this later. Liu 11/9/00
+    if (synodicMonthsBetween(newMoon1, newMoon2) >= 50) {
+        U_DEBUG_CHNSECAL_MSG((
+            "isLeapMonthBetween(%d, %d): Invalid parameters", newMoon1, newMoon2
+            ));
+    }
+#endif
+
+    return (newMoon2 >= newMoon1) &&
+        (isLeapMonthBetween(newMoon1, newMoonNear(newMoon2 - SYNODIC_GAP, FALSE)) ||
+         hasNoMajorSolarTerm(newMoon2));
+}
+
+/**
+ * Compute fields for the Chinese calendar system.  This method can
+ * either set all relevant fields, as required by
+ * <code>handleComputeFields()</code>, or it can just set the MONTH and
+ * IS_LEAP_MONTH fields, as required by
+ * <code>handleComputeMonthStart()</code>.
+ *
+ * <p>As a side effect, this method sets {@link #isLeapYear}.
+ * @param days days after January 1, 1970 0:00 Asia/Shanghai of the
+ * date to compute fields for
+ * @param gyear the Gregorian year of the given date
+ * @param gmonth the Gregorian month of the given date
+ * @param setAllFields if true, set the EXTENDED_YEAR, ERA, YEAR,
+ * DAY_OF_MONTH, and DAY_OF_YEAR fields.  In either case set the MONTH
+ * and IS_LEAP_MONTH fields.
+ */
+void ChineseCalendar::computeChineseFields(int32_t days, int32_t gyear, int32_t gmonth,
+                                  UBool setAllFields) {
+
+    // Find the winter solstices before and after the target date.
+    // These define the boundaries of this Chinese year, specifically,
+    // the position of month 11, which always contains the solstice.
+    // We want solsticeBefore <= date < solsticeAfter.
+    int32_t solsticeBefore;
+    int32_t solsticeAfter = winterSolstice(gyear);
+    if (days < solsticeAfter) {
+        solsticeBefore = winterSolstice(gyear - 1);
+    } else {
+        solsticeBefore = solsticeAfter;
+        solsticeAfter = winterSolstice(gyear + 1);
+    }
+
+    // Find the start of the month after month 11.  This will be either
+    // the prior month 12 or leap month 11 (very rare).  Also find the
+    // start of the following month 11.
+    int32_t firstMoon = newMoonNear(solsticeBefore + 1, TRUE);
+    int32_t lastMoon = newMoonNear(solsticeAfter + 1, FALSE);
+    int32_t thisMoon = newMoonNear(days + 1, FALSE); // Start of this month
+    // Note: isLeapYear is a member variable
+    isLeapYear = synodicMonthsBetween(firstMoon, lastMoon) == 12;
+
+    int32_t month = synodicMonthsBetween(firstMoon, thisMoon);
+    if (isLeapYear && isLeapMonthBetween(firstMoon, thisMoon)) {
+        month--;
+    }
+    if (month < 1) {
+        month += 12;
+    }
+
+    UBool isLeapMonth = isLeapYear &&
+        hasNoMajorSolarTerm(thisMoon) &&
+        !isLeapMonthBetween(firstMoon, newMoonNear(thisMoon - SYNODIC_GAP, FALSE));
+
+    internalSet(UCAL_MONTH, month-1); // Convert from 1-based to 0-based
+    internalSet(UCAL_IS_LEAP_MONTH, isLeapMonth?1:0);
+
+    if (setAllFields) {
+
+        int32_t year = gyear - CHINESE_EPOCH_YEAR;
+        if (month < 11 ||
+            gmonth >= UCAL_JULY) {
+            year++;
+        }
+        int32_t dayOfMonth = days - thisMoon + 1;
+
+        internalSet(UCAL_EXTENDED_YEAR, year);
+
+        // 0->0,60  1->1,1  60->1,60  61->2,1  etc.
+        int32_t yearOfCycle;
+        int32_t cycle = ClockMath::floorDivide(year - 1, 60, yearOfCycle);
+        internalSet(UCAL_ERA, cycle + 1);
+        internalSet(UCAL_YEAR, yearOfCycle + 1);
+
+        internalSet(UCAL_DAY_OF_MONTH, dayOfMonth);
+
+        // Days will be before the first new year we compute if this
+        // date is in month 11, leap 11, 12.  There is never a leap 12.
+        // New year computations are cached so this should be cheap in
+        // the long run.
+        int32_t theNewYear = newYear(gyear);
+        if (days < theNewYear) {
+            theNewYear = newYear(gyear-1);
+        }
+        internalSet(UCAL_DAY_OF_YEAR, days - theNewYear + 1);
+    }
+}
+
+
+//------------------------------------------------------------------
+// Fields to time
+//------------------------------------------------------------------
+
+/**
+ * Return the Chinese new year of the given Gregorian year.
+ * @param gyear a Gregorian year
+ * @return days after January 1, 1970 0:00 Asia/Shanghai of the
+ * Chinese new year of the given year (this will be a new moon)
+ */
+int32_t ChineseCalendar::newYear(int32_t gyear) const {
+    UErrorCode status = U_ZERO_ERROR;
+    int32_t cacheValue = CalendarCache::get(&gChineseCalendarNewYearCache, gyear, status);
+
+    if (cacheValue == 0) {
+
+        int32_t solsticeBefore= winterSolstice(gyear - 1);
+        int32_t solsticeAfter = winterSolstice(gyear);
+        int32_t newMoon1 = newMoonNear(solsticeBefore + 1, TRUE);
+        int32_t newMoon2 = newMoonNear(newMoon1 + SYNODIC_GAP, TRUE);
+        int32_t newMoon11 = newMoonNear(solsticeAfter + 1, FALSE);
+        
+        if (synodicMonthsBetween(newMoon1, newMoon11) == 12 &&
+            (hasNoMajorSolarTerm(newMoon1) || hasNoMajorSolarTerm(newMoon2))) {
+            cacheValue = newMoonNear(newMoon2 + SYNODIC_GAP, TRUE);
+        } else {
+            cacheValue = newMoon2;
+        }
+
+        CalendarCache::put(&gChineseCalendarNewYearCache, gyear, cacheValue, status);
+    }
+    if(U_FAILURE(status)) {
+        cacheValue = 0;
+    }
+    return cacheValue;
+}
+
+/**
+ * Adjust this calendar to be delta months before or after a given
+ * start position, pinning the day of month if necessary.  The start
+ * position is given as a local days number for the start of the month
+ * and a day-of-month.  Used by add() and roll().
+ * @param newMoon the local days of the first day of the month of the
+ * start position (days after January 1, 1970 0:00 Asia/Shanghai)
+ * @param dom the 1-based day-of-month of the start position
+ * @param delta the number of months to move forward or backward from
+ * the start position
+ */
+void ChineseCalendar::offsetMonth(int32_t newMoon, int32_t dom, int32_t delta) {
+    UErrorCode status = U_ZERO_ERROR;
+
+    // Move to the middle of the month before our target month.
+    newMoon += (int32_t) (CalendarAstronomer::SYNODIC_MONTH * (delta - 0.5));
+
+    // Search forward to the target month's new moon
+    newMoon = newMoonNear(newMoon, TRUE);
+
+    // Find the target dom
+    int32_t jd = newMoon + kEpochStartAsJulianDay - 1 + dom;
+
+    // Pin the dom.  In this calendar all months are 29 or 30 days
+    // so pinning just means handling dom 30.
+    if (dom > 29) {
+        set(UCAL_JULIAN_DAY, jd-1);
+        // TODO Fix this.  We really shouldn't ever have to
+        // explicitly call complete().  This is either a bug in
+        // this method, in ChineseCalendar, or in
+        // Calendar.getActualMaximum().  I suspect the last.
+        complete(status);
+        if (U_FAILURE(status)) return;
+        if (getActualMaximum(UCAL_DAY_OF_MONTH, status) >= dom) {
+            if (U_FAILURE(status)) return;
+            set(UCAL_JULIAN_DAY, jd);
+        }
+    } else {
+        set(UCAL_JULIAN_DAY, jd);
+    }
+}
+
+
+UBool
+ChineseCalendar::inDaylightTime(UErrorCode& status) const
+{
+    // copied from GregorianCalendar
+    if (U_FAILURE(status) || !getTimeZone().useDaylightTime()) 
+        return FALSE;
+
+    // Force an update of the state of the Calendar.
+    ((ChineseCalendar*)this)->complete(status); // cast away const
+
+    return (UBool)(U_SUCCESS(status) ? (internalGet(UCAL_DST_OFFSET) != 0) : FALSE);
+}
+
+// default century
+const UDate     ChineseCalendar::fgSystemDefaultCentury        = DBL_MIN;
+const int32_t   ChineseCalendar::fgSystemDefaultCenturyYear    = -1;
+
+UDate           ChineseCalendar::fgSystemDefaultCenturyStart       = DBL_MIN;
+int32_t         ChineseCalendar::fgSystemDefaultCenturyStartYear   = -1;
+
+
+UBool ChineseCalendar::haveDefaultCentury() const
+{
+    return TRUE;
+}
+
+UDate ChineseCalendar::defaultCenturyStart() const
+{
+    return internalGetDefaultCenturyStart();
+}
+
+int32_t ChineseCalendar::defaultCenturyStartYear() const
+{
+    return internalGetDefaultCenturyStartYear();
+}
+
+UDate
+ChineseCalendar::internalGetDefaultCenturyStart() const
+{
+    // lazy-evaluate systemDefaultCenturyStart
+    UBool needsUpdate;
+    UMTX_CHECK(NULL, (fgSystemDefaultCenturyStart == fgSystemDefaultCentury), needsUpdate);
+
+    if (needsUpdate) {
+        initializeSystemDefaultCentury();
+    }
+
+    // use defaultCenturyStart unless it's the flag value;
+    // then use systemDefaultCenturyStart
+
+    return fgSystemDefaultCenturyStart;
+}
+
+int32_t
+ChineseCalendar::internalGetDefaultCenturyStartYear() const
+{
+    // lazy-evaluate systemDefaultCenturyStartYear
+    UBool needsUpdate;
+    UMTX_CHECK(NULL, (fgSystemDefaultCenturyStart == fgSystemDefaultCentury), needsUpdate);
+
+    if (needsUpdate) {
+        initializeSystemDefaultCentury();
+    }
+
+    // use defaultCenturyStart unless it's the flag value;
+    // then use systemDefaultCenturyStartYear
+
+    return    fgSystemDefaultCenturyStartYear;
+}
+
+void
+ChineseCalendar::initializeSystemDefaultCentury()
+{
+    // initialize systemDefaultCentury and systemDefaultCenturyYear based
+    // on the current time.  They'll be set to 80 years before
+    // the current time.
+    UErrorCode status = U_ZERO_ERROR;
+    ChineseCalendar calendar(Locale("@calendar=chinese"),status);
+    if (U_SUCCESS(status))
+    {
+        calendar.setTime(Calendar::getNow(), status);
+        calendar.add(UCAL_YEAR, -80, status);
+        UDate    newStart =  calendar.getTime(status);
+        int32_t  newYear  =  calendar.get(UCAL_YEAR, status);
+        umtx_lock(NULL);
+        if (fgSystemDefaultCenturyStart == fgSystemDefaultCentury)
+        {
+            fgSystemDefaultCenturyStartYear = newYear;
+            fgSystemDefaultCenturyStart = newStart;
+        }
+        umtx_unlock(NULL);
+    }
+    // We have no recourse upon failure unless we want to propagate the failure
+    // out.
+}
+
+UOBJECT_DEFINE_RTTI_IMPLEMENTATION(ChineseCalendar)
+
+U_NAMESPACE_END
+
+#endif
+