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diff --git a/intl/icu/source/i18n/dangical.cpp b/intl/icu/source/i18n/dangical.cpp
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+++ b/intl/icu/source/i18n/dangical.cpp
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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+ ******************************************************************************
+ * Copyright (C) 2013, International Business Machines Corporation
+ * and others. All Rights Reserved.
+ ******************************************************************************
+ *
+ * File DANGICAL.CPP
+ *****************************************************************************
+ */
+
+#include "chnsecal.h"
+#include "dangical.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "gregoimp.h" // Math
+#include "uassert.h"
+#include "ucln_in.h"
+#include "umutex.h"
+#include "unicode/rbtz.h"
+#include "unicode/tzrule.h"
+
+// --- The cache --
+static icu::TimeZone *gDangiCalendarZoneAstroCalc = nullptr;
+static icu::UInitOnce gDangiCalendarInitOnce {};
+
+/**
+ * The start year of the Korean traditional calendar (Dan-gi) is the inaugural
+ * year of Dan-gun (BC 2333).
+ */
+static const int32_t DANGI_EPOCH_YEAR = -2332; // Gregorian year
+
+U_CDECL_BEGIN
+static UBool calendar_dangi_cleanup() {
+    if (gDangiCalendarZoneAstroCalc) {
+        delete gDangiCalendarZoneAstroCalc;
+        gDangiCalendarZoneAstroCalc = nullptr;
+    }
+    gDangiCalendarInitOnce.reset();
+    return true;
+}
+U_CDECL_END
+
+U_NAMESPACE_BEGIN
+
+// Implementation of the DangiCalendar class
+
+//-------------------------------------------------------------------------
+// Constructors...
+//-------------------------------------------------------------------------
+
+DangiCalendar::DangiCalendar(const Locale& aLocale, UErrorCode& success)
+:   ChineseCalendar(aLocale, DANGI_EPOCH_YEAR, getDangiCalZoneAstroCalc(success), success)
+{
+}
+
+DangiCalendar::DangiCalendar (const DangiCalendar& other) 
+: ChineseCalendar(other)
+{
+}
+
+DangiCalendar::~DangiCalendar()
+{
+}
+
+DangiCalendar*
+DangiCalendar::clone() const
+{
+    return new DangiCalendar(*this);
+}
+
+const char *DangiCalendar::getType() const { 
+    return "dangi";
+}
+
+/**
+ * The time zone used for performing astronomical computations for
+ * Dangi calendar. In Korea various timezones have been used historically 
+ * (cf. http://www.math.snu.ac.kr/~kye/others/lunar.html): 
+ *  
+ *            - 1908/04/01: GMT+8 
+ * 1908/04/01 - 1911/12/31: GMT+8.5 
+ * 1912/01/01 - 1954/03/20: GMT+9 
+ * 1954/03/21 - 1961/08/09: GMT+8.5 
+ * 1961/08/10 -           : GMT+9 
+ *  
+ * Note that, in 1908-1911, the government did not apply the timezone change 
+ * but used GMT+8. In addition, 1954-1961's timezone change does not affect 
+ * the lunar date calculation. Therefore, the following simpler rule works: 
+ *   
+ * -1911: GMT+8 
+ * 1912-: GMT+9 
+ *  
+ * Unfortunately, our astronomer's approximation doesn't agree with the 
+ * references (http://www.math.snu.ac.kr/~kye/others/lunar.html and 
+ * http://astro.kasi.re.kr/Life/ConvertSolarLunarForm.aspx?MenuID=115) 
+ * in 1897/7/30. So the following ad hoc fix is used here: 
+ *  
+ *     -1896: GMT+8 
+ *      1897: GMT+7 
+ * 1898-1911: GMT+8 
+ * 1912-    : GMT+9 
+ */
+static void U_CALLCONV initDangiCalZoneAstroCalc(UErrorCode &status) {
+    U_ASSERT(gDangiCalendarZoneAstroCalc == nullptr);
+    const UDate millis1897[] = { (UDate)((1897 - 1970) * 365 * kOneDay) }; // some days of error is not a problem here
+    const UDate millis1898[] = { (UDate)((1898 - 1970) * 365 * kOneDay) }; // some days of error is not a problem here
+    const UDate millis1912[] = { (UDate)((1912 - 1970) * 365 * kOneDay) }; // this doesn't create an issue for 1911/12/20
+    LocalPointer<InitialTimeZoneRule> initialTimeZone(new InitialTimeZoneRule(
+        UnicodeString(u"GMT+8"), 8*kOneHour, 0), status);
+
+    LocalPointer<TimeZoneRule> rule1897(new TimeArrayTimeZoneRule(
+        UnicodeString(u"Korean 1897"), 7*kOneHour, 0, millis1897, 1, DateTimeRule::STANDARD_TIME), status);
+
+    LocalPointer<TimeZoneRule> rule1898to1911(new TimeArrayTimeZoneRule(
+        UnicodeString(u"Korean 1898-1911"), 8*kOneHour, 0, millis1898, 1, DateTimeRule::STANDARD_TIME), status);
+
+    LocalPointer<TimeZoneRule> ruleFrom1912(new TimeArrayTimeZoneRule(
+        UnicodeString(u"Korean 1912-"), 9*kOneHour, 0, millis1912, 1, DateTimeRule::STANDARD_TIME), status);
+
+    LocalPointer<RuleBasedTimeZone> dangiCalZoneAstroCalc(new RuleBasedTimeZone(
+        UnicodeString(u"KOREA_ZONE"), initialTimeZone.orphan()), status); // adopts initialTimeZone
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+    dangiCalZoneAstroCalc->addTransitionRule(rule1897.orphan(), status); // adopts rule1897
+    dangiCalZoneAstroCalc->addTransitionRule(rule1898to1911.orphan(), status);
+    dangiCalZoneAstroCalc->addTransitionRule(ruleFrom1912.orphan(), status);
+    dangiCalZoneAstroCalc->complete(status);
+    if (U_SUCCESS(status)) {
+        gDangiCalendarZoneAstroCalc = dangiCalZoneAstroCalc.orphan();
+    }
+    ucln_i18n_registerCleanup(UCLN_I18N_DANGI_CALENDAR, calendar_dangi_cleanup);
+}
+
+const TimeZone* DangiCalendar::getDangiCalZoneAstroCalc(UErrorCode &status) const {
+    umtx_initOnce(gDangiCalendarInitOnce, &initDangiCalZoneAstroCalc, status);
+    return gDangiCalendarZoneAstroCalc;
+}
+
+constexpr uint32_t kDangiRelatedYearDiff = -2333;
+
+int32_t DangiCalendar::getRelatedYear(UErrorCode &status) const
+{
+    int32_t year = get(UCAL_EXTENDED_YEAR, status);
+    if (U_FAILURE(status)) {
+        return 0;
+    }
+    return year + kDangiRelatedYearDiff;
+}
+
+void DangiCalendar::setRelatedYear(int32_t year)
+{
+    // set extended year
+    set(UCAL_EXTENDED_YEAR, year - kDangiRelatedYearDiff);
+}
+
+
+UOBJECT_DEFINE_RTTI_IMPLEMENTATION(DangiCalendar)
+
+U_NAMESPACE_END
+
+#endif
+