1 // 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 integers, 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 int64_t floorDivide(int64_t numerator, int64_t denominator); 53 54 /** 55 * Divide two numbers, returning the floor of the quotient. 56 * Unlike the built-in division, this is mathematically 57 * well-behaved. E.g., <code>-1/4</code> => 0 but 58 * <code>floorDivide(-1,4)</code> => -1. 59 * @param numerator the numerator 60 * @param denominator a divisor which must be != 0 61 * @return the floor of the quotient 62 */ 63 static inline double floorDivide(double numerator, double denominator); 64 65 /** 66 * Divide two numbers, returning the floor of the quotient and 67 * the modulus remainder. Unlike the built-in division, this is 68 * mathematically well-behaved. E.g., <code>-1/4</code> => 0 and 69 * <code>-1%4</code> => -1, but <code>floorDivide(-1,4)</code> => 70 * -1 with <code>remainder</code> => 3. NOTE: If numerator is 71 * too large, the returned quotient may overflow. 72 * @param numerator the numerator 73 * @param denominator a divisor which must be != 0 74 * @param remainder output parameter to receive the 75 * remainder. Unlike <code>numerator % denominator</code>, this 76 * will always be non-negative, in the half-open range <code>[0, 77 * |denominator|)</code>. 78 * @return the floor of the quotient 79 */ 80 static int32_t floorDivide(double numerator, int32_t denominator, 81 int32_t& remainder); 82 83 /** 84 * For a positive divisor, return the quotient and remainder 85 * such that dividend = quotient*divisor + remainder and 86 * 0 <= remainder < divisor. 87 * 88 * Works around edge-case bugs. Handles pathological input 89 * (divident >> divisor) reasonably. 90 * 91 * Calling with a divisor <= 0 is disallowed. 92 */ 93 static double floorDivide(double dividend, double divisor, 94 double& remainder); 95 }; 96 97 // Useful millisecond constants 98 #define kOneDay (1.0 * U_MILLIS_PER_DAY) // 86,400,000 99 #define kOneHour (60*60*1000) 100 #define kOneMinute 60000 101 #define kOneSecond 1000 102 #define kOneMillisecond 1 103 #define kOneWeek (7.0 * kOneDay) // 604,800,000 104 105 // Epoch constants 106 #define kJan1_1JulianDay 1721426 // January 1, year 1 (Gregorian) 107 108 #define kEpochStartAsJulianDay 2440588 // January 1, 1970 (Gregorian) 109 110 #define kEpochYear 1970 111 112 113 #define kEarliestViableMillis -185331720384000000.0 // minimum representable by julian day -1e17 114 115 #define kLatestViableMillis 185753453990400000.0 // max representable by julian day +1e17 116 117 /** 118 * The minimum supported Julian day. This value is equivalent to 119 * MIN_MILLIS. 120 */ 121 #define MIN_JULIAN (-0x7F000000) 122 123 /** 124 * The minimum supported epoch milliseconds. This value is equivalent 125 * to MIN_JULIAN. 126 */ 127 #define MIN_MILLIS ((MIN_JULIAN - kEpochStartAsJulianDay) * kOneDay) 128 129 /** 130 * The maximum supported Julian day. This value is equivalent to 131 * MAX_MILLIS. 132 */ 133 #define MAX_JULIAN (+0x7F000000) 134 135 /** 136 * The maximum supported epoch milliseconds. This value is equivalent 137 * to MAX_JULIAN. 138 */ 139 #define MAX_MILLIS ((MAX_JULIAN - kEpochStartAsJulianDay) * kOneDay) 140 141 /** 142 * A utility class providing proleptic Gregorian calendar functions 143 * used by time zone and calendar code. Do not instantiate. 144 * 145 * Note: Unlike GregorianCalendar, all computations performed by this 146 * class occur in the pure proleptic GregorianCalendar. 147 */ 148 class Grego { 149 public: 150 /** 151 * Return TRUE if the given year is a leap year. 152 * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. 153 * @return TRUE if the year is a leap year 154 */ 155 static inline UBool isLeapYear(int32_t year); 156 157 /** 158 * Return the number of days in the given month. 159 * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. 160 * @param month 0-based month, with 0==Jan 161 * @return the number of days in the given month 162 */ 163 static inline int8_t monthLength(int32_t year, int32_t month); 164 165 /** 166 * Return the length of a previous month of the Gregorian calendar. 167 * @param y the extended year 168 * @param m the 0-based month number 169 * @return the number of days in the month previous to the given month 170 */ 171 static inline int8_t previousMonthLength(int y, int m); 172 173 /** 174 * Convert a year, month, and day-of-month, given in the proleptic 175 * Gregorian calendar, to 1970 epoch days. 176 * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. 177 * @param month 0-based month, with 0==Jan 178 * @param dom 1-based day of month 179 * @return the day number, with day 0 == Jan 1 1970 180 */ 181 static double fieldsToDay(int32_t year, int32_t month, int32_t dom); 182 183 /** 184 * Convert a 1970-epoch day number to proleptic Gregorian year, 185 * month, day-of-month, and day-of-week. 186 * @param day 1970-epoch day (integral value) 187 * @param year output parameter to receive year 188 * @param month output parameter to receive month (0-based, 0==Jan) 189 * @param dom output parameter to receive day-of-month (1-based) 190 * @param dow output parameter to receive day-of-week (1-based, 1==Sun) 191 * @param doy output parameter to receive day-of-year (1-based) 192 */ 193 static void dayToFields(double day, int32_t& year, int32_t& month, 194 int32_t& dom, int32_t& dow, int32_t& doy); 195 196 /** 197 * Convert a 1970-epoch day number to proleptic Gregorian year, 198 * month, day-of-month, and day-of-week. 199 * @param day 1970-epoch day (integral value) 200 * @param year output parameter to receive year 201 * @param month output parameter to receive month (0-based, 0==Jan) 202 * @param dom output parameter to receive day-of-month (1-based) 203 * @param dow output parameter to receive day-of-week (1-based, 1==Sun) 204 */ 205 static inline void dayToFields(double day, int32_t& year, int32_t& month, 206 int32_t& dom, int32_t& dow); 207 208 /** 209 * Convert a 1970-epoch milliseconds to proleptic Gregorian year, 210 * month, day-of-month, and day-of-week, day of year and millis-in-day. 211 * @param time 1970-epoch milliseconds 212 * @param year output parameter to receive year 213 * @param month output parameter to receive month (0-based, 0==Jan) 214 * @param dom output parameter to receive day-of-month (1-based) 215 * @param dow output parameter to receive day-of-week (1-based, 1==Sun) 216 * @param doy output parameter to receive day-of-year (1-based) 217 * @param mid output parameter to recieve millis-in-day 218 */ 219 static void timeToFields(UDate time, int32_t& year, int32_t& month, 220 int32_t& dom, int32_t& dow, int32_t& doy, int32_t& mid); 221 222 /** 223 * Return the day of week on the 1970-epoch day 224 * @param day the 1970-epoch day (integral value) 225 * @return the day of week 226 */ 227 static int32_t dayOfWeek(double day); 228 229 /** 230 * Returns the ordinal number for the specified day of week within the month. 231 * The valid return value is 1, 2, 3, 4 or -1. 232 * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. 233 * @param month 0-based month, with 0==Jan 234 * @param dom 1-based day of month 235 * @return The ordinal number for the specified day of week within the month 236 */ 237 static int32_t dayOfWeekInMonth(int32_t year, int32_t month, int32_t dom); 238 239 /** 240 * Converts Julian day to time as milliseconds. 241 * @param julian the given Julian day number. 242 * @return time as milliseconds. 243 * @internal 244 */ 245 static inline double julianDayToMillis(int32_t julian); 246 247 /** 248 * Converts time as milliseconds to Julian day. 249 * @param millis the given milliseconds. 250 * @return the Julian day number. 251 * @internal 252 */ 253 static inline int32_t millisToJulianDay(double millis); 254 255 /** 256 * Calculates the Gregorian day shift value for an extended year. 257 * @param eyear Extended year 258 * @returns number of days to ADD to Julian in order to convert from J->G 259 */ 260 static inline int32_t gregorianShift(int32_t eyear); 261 262 private: 263 static const int16_t DAYS_BEFORE[24]; 264 static const int8_t MONTH_LENGTH[24]; 265 }; 266 267 inline double ClockMath::floorDivide(double numerator, double denominator) { 268 return uprv_floor(numerator / denominator); 269 } 270 271 inline UBool Grego::isLeapYear(int32_t year) { 272 // year&0x3 == year%4 273 return ((year&0x3) == 0) && ((year%100 != 0) || (year%400 == 0)); 274 } 275 276 inline int8_t 277 Grego::monthLength(int32_t year, int32_t month) { 278 return MONTH_LENGTH[month + (isLeapYear(year) ? 12 : 0)]; 279 } 280 281 inline int8_t 282 Grego::previousMonthLength(int y, int m) { 283 return (m > 0) ? monthLength(y, m-1) : 31; 284 } 285 286 inline void Grego::dayToFields(double day, int32_t& year, int32_t& month, 287 int32_t& dom, int32_t& dow) { 288 int32_t doy_unused; 289 dayToFields(day,year,month,dom,dow,doy_unused); 290 } 291 292 inline double Grego::julianDayToMillis(int32_t julian) 293 { 294 return (julian - kEpochStartAsJulianDay) * kOneDay; 295 } 296 297 inline int32_t Grego::millisToJulianDay(double millis) { 298 return (int32_t) (kEpochStartAsJulianDay + ClockMath::floorDivide(millis, (double)kOneDay)); 299 } 300 301 inline int32_t Grego::gregorianShift(int32_t eyear) { 302 int32_t y = eyear-1; 303 int32_t gregShift = ClockMath::floorDivide(y, 400) - ClockMath::floorDivide(y, 100) + 2; 304 return gregShift; 305 } 306 307 U_NAMESPACE_END 308 309 #endif // !UCONFIG_NO_FORMATTING 310 #endif // GREGOIMP_H 311 312 //eof 313
