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1 // Copyright (C) 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4  **********************************************************************
5  * Copyright (c) 2003-2008, International Business Machines
6  * Corporation and others.  All Rights Reserved.
7  **********************************************************************
8  * Author: Alan Liu
9  * Created: September 2 2003
10  * Since: ICU 2.8
11  **********************************************************************
12  */
13 
14 #ifndef GREGOIMP_H
15 #define GREGOIMP_H
16 #include "unicode/utypes.h"
17 #if !UCONFIG_NO_FORMATTING
18 
19 #include "unicode/ures.h"
20 #include "unicode/locid.h"
21 #include "putilimp.h"
22 
23 U_NAMESPACE_BEGIN
24 
25 /**
26  * A utility class providing mathematical functions used by time zone
27  * and calendar code.  Do not instantiate.  Formerly just named 'Math'.
28  * @internal
29  */
30 class ClockMath {
31  public:
32     /**
33      * Divide two integers, returning the floor of the quotient.
34      * Unlike the built-in division, this is mathematically
35      * well-behaved.  E.g., <code>-1/4</code> => 0 but
36      * <code>floorDivide(-1,4)</code> => -1.
37      * @param numerator the numerator
38      * @param denominator a divisor which must be != 0
39      * @return the floor of the quotient
40      */
41     static int32_t floorDivide(int32_t numerator, int32_t denominator);
42 
43     /**
44      * Divide two numbers, returning the floor of the quotient.
45      * Unlike the built-in division, this is mathematically
46      * well-behaved.  E.g., <code>-1/4</code> => 0 but
47      * <code>floorDivide(-1,4)</code> => -1.
48      * @param numerator the numerator
49      * @param denominator a divisor which must be != 0
50      * @return the floor of the quotient
51      */
52     static inline double floorDivide(double numerator, double denominator);
53 
54     /**
55      * Divide two numbers, returning the floor of the quotient and
56      * the modulus remainder.  Unlike the built-in division, this is
57      * mathematically well-behaved.  E.g., <code>-1/4</code> => 0 and
58      * <code>-1%4</code> => -1, but <code>floorDivide(-1,4)</code> =>
59      * -1 with <code>remainder</code> => 3.  NOTE: If numerator is
60      * too large, the returned quotient may overflow.
61      * @param numerator the numerator
62      * @param denominator a divisor which must be != 0
63      * @param remainder output parameter to receive the
64      * remainder. Unlike <code>numerator % denominator</code>, this
65      * will always be non-negative, in the half-open range <code>[0,
66      * |denominator|)</code>.
67      * @return the floor of the quotient
68      */
69     static int32_t floorDivide(double numerator, int32_t denominator,
70                                int32_t& remainder);
71 
72     /**
73      * For a positive divisor, return the quotient and remainder
74      * such that dividend = quotient*divisor + remainder and
75      * 0 <= remainder < divisor.
76      *
77      * Works around edge-case bugs.  Handles pathological input
78      * (divident >> divisor) reasonably.
79      *
80      * Calling with a divisor <= 0 is disallowed.
81      */
82     static double floorDivide(double dividend, double divisor,
83                               double& remainder);
84 };
85 
86 // Useful millisecond constants
87 #define kOneDay    (1.0 * U_MILLIS_PER_DAY)       //  86,400,000
88 #define kOneHour   (60*60*1000)
89 #define kOneMinute 60000
90 #define kOneSecond 1000
91 #define kOneMillisecond  1
92 #define kOneWeek   (7.0 * kOneDay) // 604,800,000
93 
94 // Epoch constants
95 #define kJan1_1JulianDay  1721426 // January 1, year 1 (Gregorian)
96 
97 #define kEpochStartAsJulianDay  2440588 // January 1, 1970 (Gregorian)
98 
99 #define kEpochYear              1970
100 
101 
102 #define kEarliestViableMillis  -185331720384000000.0  // minimum representable by julian day  -1e17
103 
104 #define kLatestViableMillis     185753453990400000.0  // max representable by julian day      +1e17
105 
106 /**
107  * The minimum supported Julian day.  This value is equivalent to
108  * MIN_MILLIS.
109  */
110 #define MIN_JULIAN (-0x7F000000)
111 
112 /**
113  * The minimum supported epoch milliseconds.  This value is equivalent
114  * to MIN_JULIAN.
115  */
116 #define MIN_MILLIS ((MIN_JULIAN - kEpochStartAsJulianDay) * kOneDay)
117 
118 /**
119  * The maximum supported Julian day.  This value is equivalent to
120  * MAX_MILLIS.
121  */
122 #define MAX_JULIAN (+0x7F000000)
123 
124 /**
125  * The maximum supported epoch milliseconds.  This value is equivalent
126  * to MAX_JULIAN.
127  */
128 #define MAX_MILLIS ((MAX_JULIAN - kEpochStartAsJulianDay) * kOneDay)
129 
130 /**
131  * A utility class providing proleptic Gregorian calendar functions
132  * used by time zone and calendar code.  Do not instantiate.
133  *
134  * Note:  Unlike GregorianCalendar, all computations performed by this
135  * class occur in the pure proleptic GregorianCalendar.
136  */
137 class Grego {
138  public:
139     /**
140      * Return TRUE if the given year is a leap year.
141      * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc.
142      * @return TRUE if the year is a leap year
143      */
144     static inline UBool isLeapYear(int32_t year);
145 
146     /**
147      * Return the number of days in the given month.
148      * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc.
149      * @param month 0-based month, with 0==Jan
150      * @return the number of days in the given month
151      */
152     static inline int8_t monthLength(int32_t year, int32_t month);
153 
154     /**
155      * Return the length of a previous month of the Gregorian calendar.
156      * @param y the extended year
157      * @param m the 0-based month number
158      * @return the number of days in the month previous to the given month
159      */
160     static inline int8_t previousMonthLength(int y, int m);
161 
162     /**
163      * Convert a year, month, and day-of-month, given in the proleptic
164      * Gregorian calendar, to 1970 epoch days.
165      * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc.
166      * @param month 0-based month, with 0==Jan
167      * @param dom 1-based day of month
168      * @return the day number, with day 0 == Jan 1 1970
169      */
170     static double fieldsToDay(int32_t year, int32_t month, int32_t dom);
171 
172     /**
173      * Convert a 1970-epoch day number to proleptic Gregorian year,
174      * month, day-of-month, and day-of-week.
175      * @param day 1970-epoch day (integral value)
176      * @param year output parameter to receive year
177      * @param month output parameter to receive month (0-based, 0==Jan)
178      * @param dom output parameter to receive day-of-month (1-based)
179      * @param dow output parameter to receive day-of-week (1-based, 1==Sun)
180      * @param doy output parameter to receive day-of-year (1-based)
181      */
182     static void dayToFields(double day, int32_t& year, int32_t& month,
183                             int32_t& dom, int32_t& dow, int32_t& doy);
184 
185     /**
186      * Convert a 1970-epoch day number to proleptic Gregorian year,
187      * month, day-of-month, and day-of-week.
188      * @param day 1970-epoch day (integral value)
189      * @param year output parameter to receive year
190      * @param month output parameter to receive month (0-based, 0==Jan)
191      * @param dom output parameter to receive day-of-month (1-based)
192      * @param dow output parameter to receive day-of-week (1-based, 1==Sun)
193      */
194     static inline void dayToFields(double day, int32_t& year, int32_t& month,
195                                    int32_t& dom, int32_t& dow);
196 
197     /**
198      * Convert a 1970-epoch milliseconds to proleptic Gregorian year,
199      * month, day-of-month, and day-of-week, day of year and millis-in-day.
200      * @param time 1970-epoch milliseconds
201      * @param year output parameter to receive year
202      * @param month output parameter to receive month (0-based, 0==Jan)
203      * @param dom output parameter to receive day-of-month (1-based)
204      * @param dow output parameter to receive day-of-week (1-based, 1==Sun)
205      * @param doy output parameter to receive day-of-year (1-based)
206      * @param mid output parameter to recieve millis-in-day
207      */
208     static void timeToFields(UDate time, int32_t& year, int32_t& month,
209                             int32_t& dom, int32_t& dow, int32_t& doy, int32_t& mid);
210 
211     /**
212      * Return the day of week on the 1970-epoch day
213      * @param day the 1970-epoch day (integral value)
214      * @return the day of week
215      */
216     static int32_t dayOfWeek(double day);
217 
218     /**
219      * Returns the ordinal number for the specified day of week within the month.
220      * The valid return value is 1, 2, 3, 4 or -1.
221      * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc.
222      * @param month 0-based month, with 0==Jan
223      * @param dom 1-based day of month
224      * @return The ordinal number for the specified day of week within the month
225      */
226     static int32_t dayOfWeekInMonth(int32_t year, int32_t month, int32_t dom);
227 
228     /**
229      * Converts Julian day to time as milliseconds.
230      * @param julian the given Julian day number.
231      * @return time as milliseconds.
232      * @internal
233      */
234     static inline double julianDayToMillis(int32_t julian);
235 
236     /**
237      * Converts time as milliseconds to Julian day.
238      * @param millis the given milliseconds.
239      * @return the Julian day number.
240      * @internal
241      */
242     static inline int32_t millisToJulianDay(double millis);
243 
244     /**
245      * Calculates the Gregorian day shift value for an extended year.
246      * @param eyear Extended year
247      * @returns number of days to ADD to Julian in order to convert from J->G
248      */
249     static inline int32_t gregorianShift(int32_t eyear);
250 
251  private:
252     static const int16_t DAYS_BEFORE[24];
253     static const int8_t MONTH_LENGTH[24];
254 };
255 
floorDivide(double numerator,double denominator)256 inline double ClockMath::floorDivide(double numerator, double denominator) {
257     return uprv_floor(numerator / denominator);
258 }
259 
isLeapYear(int32_t year)260 inline UBool Grego::isLeapYear(int32_t year) {
261     // year&0x3 == year%4
262     return ((year&0x3) == 0) && ((year%100 != 0) || (year%400 == 0));
263 }
264 
265 inline int8_t
monthLength(int32_t year,int32_t month)266 Grego::monthLength(int32_t year, int32_t month) {
267     return MONTH_LENGTH[month + (isLeapYear(year) ? 12 : 0)];
268 }
269 
270 inline int8_t
previousMonthLength(int y,int m)271 Grego::previousMonthLength(int y, int m) {
272   return (m > 0) ? monthLength(y, m-1) : 31;
273 }
274 
dayToFields(double day,int32_t & year,int32_t & month,int32_t & dom,int32_t & dow)275 inline void Grego::dayToFields(double day, int32_t& year, int32_t& month,
276                                int32_t& dom, int32_t& dow) {
277   int32_t doy_unused;
278   dayToFields(day,year,month,dom,dow,doy_unused);
279 }
280 
julianDayToMillis(int32_t julian)281 inline double Grego::julianDayToMillis(int32_t julian)
282 {
283   return (julian - kEpochStartAsJulianDay) * kOneDay;
284 }
285 
millisToJulianDay(double millis)286 inline int32_t Grego::millisToJulianDay(double millis) {
287   return (int32_t) (kEpochStartAsJulianDay + ClockMath::floorDivide(millis, (double)kOneDay));
288 }
289 
gregorianShift(int32_t eyear)290 inline int32_t Grego::gregorianShift(int32_t eyear) {
291   int32_t y = eyear-1;
292   int32_t gregShift = ClockMath::floorDivide(y, 400) - ClockMath::floorDivide(y, 100) + 2;
293   return gregShift;
294 }
295 
296 U_NAMESPACE_END
297 
298 #endif // !UCONFIG_NO_FORMATTING
299 #endif // GREGOIMP_H
300 
301 //eof
302