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39
40#include "qglobal.h"
41#include "qmilankoviccalendar_p.h"
42#include "qcalendarmath_p.h"
43#include <QtCore/qmath.h>
44#include <QtCore/qlocale.h>
45#include <QtCore/qdatetime.h>
46
47QT_BEGIN_NAMESPACE
48
49using namespace QRoundingDown;
50
51/*!
52 \since 5.14
53
54 \class QMilankovicCalendar
55 \inmodule QtCore
56 \brief The QMilankovicCalendar class provides Milanković calendar system
57 implementation.
58
59 The Revised Julian calendar, also known as the Milanković calendar, or,
60 less formally, new calendar, is a calendar, developed and proposed by the
61 Serbian scientist Milutin Milanković in 1923, which effectively discontinued
62 the 340 years of divergence between the naming of dates sanctioned by those
63 Eastern Orthodox churches adopting it and the Gregorian calendar that has
64 come to predominate worldwide. This calendar was intended to replace the
65 ecclesiastical calendar based on the Julian calendar hitherto in use by all
66 of the Eastern Orthodox Church. The Revised Julian calendar temporarily
67 aligned its dates with the Gregorian calendar proclaimed in 1582 by Pope
68 Gregory XIII for adoption by the Christian world. The calendar has been
69 adopted by the Orthodox churches of Constantinople, Albania, Alexandria,
70 Antioch, Bulgaria, Cyprus, Greece, Poland, and Romania.
71
72 Source: \l {https://en.wikipedia.org/wiki/Revised_Julian_calendar}{Wikipedia
73 page on Milanković Calendar}
74 */
75
76QMilankovicCalendar::QMilankovicCalendar()
77 : QRomanCalendar(QStringLiteral("Milankovic"), QCalendar::System::Milankovic) {}
78
79QString QMilankovicCalendar::name() const
80{
81 return QStringLiteral("Milankovic");
82}
83
84QCalendar::System QMilankovicCalendar::calendarSystem() const
85{
86 return QCalendar::System::Milankovic;
87}
88
89bool QMilankovicCalendar::isLeapYear(int year) const
90{
91 if (year == QCalendar::Unspecified)
92 return false;
93 if (year <= 0)
94 ++year;
95 if (qMod(year, 4))
96 return false;
97 if (qMod(year, 100) == 0) {
98 const qint16 century = qMod(qDiv(year, 100), 9);
99 if (century != 2 && century != 6)
100 return false;
101 }
102 return true;
103}
104
105bool QMilankovicCalendar::dateToJulianDay(int year, int month, int day, qint64 *jd) const
106{
107 Q_ASSERT(jd);
108 if (!isDateValid(year, month, day))
109 return false;
110 if (year <= 0)
111 ++year;
112 const qint16 c0 = month < 3 ? -1 : 0;
113 const qint16 x1 = month - 12 * c0 - 3;
114 const qint16 x4 = year + c0;
115 const qint16 x3 = qDiv(x4, 100);
116 const qint16 x2 = qMod(x4, 100);
117 *jd = qDiv(328718 * x3 + 6, 9)
118 + qDiv(36525 * x2 , 100)
119 + qDiv(153 * x1 + 2 , 5)
120 + day + 1721119;
121 return true;
122}
123
124QCalendar::YearMonthDay QMilankovicCalendar::julianDayToDate(qint64 jd) const
125{
126 const qint64 k3 = 9 * (jd - 1721120) + 2;
127 const qint64 x3 = qDiv(k3, 328718);
128 const qint64 k2 = 100 * qDiv(qMod(k3, 328718), 9) + 99;
129 const qint64 k1 = qDiv(qMod(k2, 36525), 100) * 5 + 2;
130 const qint64 x2 = qDiv(k2, 36525);
131 const qint64 x1 = qDiv(5 * qDiv(qMod(k2, 36525), 100) + 2, 153);
132 const qint64 c0 = qDiv(x1 + 2, 12);
133 const int y = 100 * x3 + x2 + c0;
134 const int month = x1 - 12 * c0 + 3;
135 const int day = qDiv(qMod(k1, 153), 5) + 1;
136 return QCalendar::YearMonthDay(y > 0 ? y : y - 1, month, day);
137}
138
139QT_END_NAMESPACE
140