/* ********************************************************************** * Copyright (c) 2003, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * Author: Alan Liu * Created: September 2 2003 * Since: ICU 2.8 ********************************************************************** */ #ifndef GREGOIMP_H #define GREGOIMP_H #if !UCONFIG_NO_FORMATTING #include "unicode/utypes.h" U_NAMESPACE_BEGIN /** * A utility class providing mathematical functions used by time zone * and calendar code. Do not instantiate. */ class U_I18N_API Math { public: /** * Divide two integers, returning the floor of the quotient. * Unlike the built-in division, this is mathematically * well-behaved. E.g., -1/4 => 0 but * floorDivide(-1,4) => -1. * @param numerator the numerator * @param denominator a divisor which must be != 0 * @return the floor of the quotient */ static int32_t floorDivide(int32_t numerator, int32_t denominator); /** * Divide two numbers, returning the floor of the quotient. * Unlike the built-in division, this is mathematically * well-behaved. E.g., -1/4 => 0 but * floorDivide(-1,4) => -1. * @param numerator the numerator * @param denominator a divisor which must be != 0 * @return the floor of the quotient */ static inline double floorDivide(double numerator, double denominator); /** * Divide two numbers, returning the floor of the quotient and * the modulus remainder. Unlike the built-in division, this is * mathematically well-behaved. E.g., -1/4 => 0 and * -1%4 => -1, but floorDivide(-1,4) => * -1 with remainder => 3. NOTE: If numerator is * too large, the returned quotient may overflow. * @param numerator the numerator * @param denominator a divisor which must be != 0 * @param remainder output parameter to receive the * remainder. Unlike numerator % denominator, this * will always be non-negative, in the half-open range [0, * |denominator|). * @return the floor of the quotient */ static int32_t floorDivide(double numerator, int32_t denominator, int32_t& remainder); }; /** * A utility class providing proleptic Gregorian calendar functions * used by time zone and calendar code. Do not instantiate. * * Note: Unlike GregorianCalendar, all computations performed by this * class occur in the pure proleptic GregorianCalendar. */ class U_I18N_API Grego { public: /** * Return TRUE if the given year is a leap year. * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. * @return TRUE if the year is a leap year */ static inline UBool isLeapYear(int32_t year); /** * Return the number of days in the given month. * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. * @param month 0-based month, with 0==Jan * @return the number of days in the given month */ static inline int8_t monthLength(int32_t year, int32_t month); /** * Return the length of a previous month of the Gregorian calendar. * @param y the extended year * @param m the 0-based month number * @return the number of days in the month previous to the given month */ static inline int8_t previousMonthLength(int y, int m); /** * Convert a year, month, and day-of-month, given in the proleptic * Gregorian calendar, to 1970 epoch days. * @param year Gregorian year, with 0 == 1 BCE, -1 == 2 BCE, etc. * @param month 0-based month, with 0==Jan * @param dom 1-based day of month * @return the day number, with day 0 == Jan 1 1970 */ static double fieldsToDay(int32_t year, int32_t month, int32_t dom); /** * Convert a 1970-epoch day number to proleptic Gregorian year, * month, day-of-month, and day-of-week. * @param day 1970-epoch day (integral value) * @param year output parameter to receive year * @param month output parameter to receive month (0-based, 0==Jan) * @param dom output parameter to receive day-of-month (1-based) * @param dow output parameter to receive day-of-week (1-based, 1==Sun) * @param doy output parameter to receive day-of-year (1-based) */ static void dayToFields(double day, int32_t& year, int32_t& month, int32_t& dom, int32_t& dow, int32_t& doy); /** * Convert a 1970-epoch day number to proleptic Gregorian year, * month, day-of-month, and day-of-week. * @param day 1970-epoch day (integral value) * @param year output parameter to receive year * @param month output parameter to receive month (0-based, 0==Jan) * @param dom output parameter to receive day-of-month (1-based) * @param dow output parameter to receive day-of-week (1-based, 1==Sun) */ static inline void dayToFields(double day, int32_t& year, int32_t& month, int32_t& dom, int32_t& dow); /** * Converts Julian day to time as milliseconds. * @param julian the given Julian day number. * @return time as milliseconds. * @internal */ static inline double julianDayToMillis(int32_t julian); /** * Converts time as milliseconds to Julian day. * @param millis the given milliseconds. * @return the Julian day number. * @internal */ static inline int32_t millisToJulianDay(double millis); private: static const int16_t DAYS_BEFORE[24]; static const int8_t MONTH_LENGTH[24]; }; inline double Math::floorDivide(double numerator, double denominator) { return uprv_floor(numerator / denominator); } inline UBool Grego::isLeapYear(int32_t year) { // year&0x3 == year%4 return ((year&0x3) == 0) && ((year%100 != 0) || (year%400 == 0)); } inline int8_t Grego::monthLength(int32_t year, int32_t month) { return MONTH_LENGTH[month + isLeapYear(year)?12:0]; } inline int8_t Grego::previousMonthLength(int y, int m) { return (m > 0) ? monthLength(y, m-1) : 31; } inline void Grego::dayToFields(double day, int32_t& year, int32_t& month, int32_t& dom, int32_t& dow) { int32_t doy_unused; dayToFields(day,year,month,dom,dow,doy_unused); } // Useful millisecond constants static const double kOneDay = U_MILLIS_PER_DAY; // 86,400,000 static const int32_t kOneHour = 60*60*1000; #define kOneMinute 60000 #define kOneSecond 1000 #define kOneMillisecond 1 static const double kOneWeek = 7.0 * U_MILLIS_PER_DAY; // 604,800,000 static const int32_t kJan1_1JulianDay = 1721426; // January 1, year 1 (Gregorian) static const int32_t kEpochStartAsJulianDay = 2440588; // January 1, 1970 (Gregorian) static const int32_t kEpochYear = 1970; inline double Grego::julianDayToMillis(int32_t julian) { return (julian - kEpochStartAsJulianDay) * kOneDay; } inline int32_t Grego::millisToJulianDay(double millis) { return (int32_t) (kEpochStartAsJulianDay + Math::floorDivide(millis, kOneDay)); } static const double kEarliestViableMillis = -185331720384000000.0; // minimum representable by julian day -1e17 static const double kLatestViableMillis = 185753453990400000.0; // max representable by julian day +1e17 U_NAMESPACE_END #endif // !UCONFIG_NO_FORMATTING #endif // GREGOIMP_H //eof