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 // © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ********************************************************************** * Copyright (c) 2003-2008, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * Author: Alan Liu * Created: September 2 2003 * Since: ICU 2.8 ********************************************************************** */ #include "gregoimp.h" #if !UCONFIG_NO_FORMATTING #include "unicode/ucal.h" #include "uresimp.h" #include "cstring.h" #include "uassert.h" U_NAMESPACE_BEGIN int32_t ClockMath::floorDivide(int32_t numerator, int32_t denominator) { return (numerator >= 0) ? numerator / denominator : ((numerator + 1) / denominator) - 1; } int64_t ClockMath::floorDivide(int64_t numerator, int64_t denominator) { return (numerator >= 0) ? numerator / denominator : ((numerator + 1) / denominator) - 1; } int32_t ClockMath::floorDivide(double numerator, int32_t denominator, int32_t& remainder) { double quotient; quotient = uprv_floor(numerator / denominator); remainder = (int32_t) (numerator - (quotient * denominator)); return (int32_t) quotient; } double ClockMath::floorDivide(double dividend, double divisor, double& remainder) { // Only designed to work for positive divisors U_ASSERT(divisor > 0); double quotient = floorDivide(dividend, divisor); remainder = dividend - (quotient * divisor); // N.B. For certain large dividends, on certain platforms, there // is a bug such that the quotient is off by one. If you doubt // this to be true, set a breakpoint below and run cintltst. if (remainder < 0 || remainder >= divisor) { // E.g. 6.7317038241449352e+022 / 86400000.0 is wrong on my // machine (too high by one). 4.1792057231752762e+024 / // 86400000.0 is wrong the other way (too low). double q = quotient; quotient += (remainder < 0) ? -1 : +1; if (q == quotient) { // For quotients > ~2^53, we won't be able to add or // subtract one, since the LSB of the mantissa will be > // 2^0; that is, the exponent (base 2) will be larger than // the length, in bits, of the mantissa. In that case, we // can't give a correct answer, so we set the remainder to // zero. This has the desired effect of making extreme // values give back an approximate answer rather than // crashing. For example, UDate values above a ~10^25 // might all have a time of midnight. remainder = 0; } else { remainder = dividend - (quotient * divisor); } } U_ASSERT(0 <= remainder && remainder < divisor); return quotient; } const int32_t JULIAN_1_CE = 1721426; // January 1, 1 CE Gregorian const int32_t JULIAN_1970_CE = 2440588; // January 1, 1970 CE Gregorian const int16_t Grego::DAYS_BEFORE = {0,31,59,90,120,151,181,212,243,273,304,334, 0,31,60,91,121,152,182,213,244,274,305,335}; const int8_t Grego::MONTH_LENGTH = {31,28,31,30,31,30,31,31,30,31,30,31, 31,29,31,30,31,30,31,31,30,31,30,31}; double Grego::fieldsToDay(int32_t year, int32_t month, int32_t dom) { int32_t y = year - 1; double julian = 365 * y + ClockMath::floorDivide(y, 4) + (JULIAN_1_CE - 3) + // Julian cal ClockMath::floorDivide(y, 400) - ClockMath::floorDivide(y, 100) + 2 + // => Gregorian cal DAYS_BEFORE[month + (isLeapYear(year) ? 12 : 0)] + dom; // => month/dom return julian - JULIAN_1970_CE; // JD => epoch day } void Grego::dayToFields(double day, int32_t& year, int32_t& month, int32_t& dom, int32_t& dow, int32_t& doy) { // Convert from 1970 CE epoch to 1 CE epoch (Gregorian calendar) day += JULIAN_1970_CE - JULIAN_1_CE; // Convert from the day number to the multiple radix // representation. We use 400-year, 100-year, and 4-year cycles. // For example, the 4-year cycle has 4 years + 1 leap day; giving // 1461 == 365*4 + 1 days. int32_t n400 = ClockMath::floorDivide(day, 146097, doy); // 400-year cycle length int32_t n100 = ClockMath::floorDivide(doy, 36524, doy); // 100-year cycle length int32_t n4 = ClockMath::floorDivide(doy, 1461, doy); // 4-year cycle length int32_t n1 = ClockMath::floorDivide(doy, 365, doy); year = 400*n400 + 100*n100 + 4*n4 + n1; if (n100 == 4 || n1 == 4) { doy = 365; // Dec 31 at end of 4- or 400-year cycle } else { ++year; } UBool isLeap = isLeapYear(year); // Gregorian day zero is a Monday. dow = (int32_t) uprv_fmod(day + 1, 7); dow += (dow < 0) ? (UCAL_SUNDAY + 7) : UCAL_SUNDAY; // Common Julian/Gregorian calculation int32_t correction = 0; int32_t march1 = isLeap ? 60 : 59; // zero-based DOY for March 1 if (doy >= march1) { correction = isLeap ? 1 : 2; } month = (12 * (doy + correction) + 6) / 367; // zero-based month dom = doy - DAYS_BEFORE[month + (isLeap ? 12 : 0)] + 1; // one-based DOM doy++; // one-based doy } void Grego::timeToFields(UDate time, int32_t& year, int32_t& month, int32_t& dom, int32_t& dow, int32_t& doy, int32_t& mid) { double millisInDay; double day = ClockMath::floorDivide((double)time, (double)U_MILLIS_PER_DAY, millisInDay); mid = (int32_t)millisInDay; dayToFields(day, year, month, dom, dow, doy); } int32_t Grego::dayOfWeek(double day) { int32_t dow; ClockMath::floorDivide(day + UCAL_THURSDAY, 7, dow); return (dow == 0) ? UCAL_SATURDAY : dow; } int32_t Grego::dayOfWeekInMonth(int32_t year, int32_t month, int32_t dom) { int32_t weekInMonth = (dom + 6)/7; if (weekInMonth == 4) { if (dom + 7 > monthLength(year, month)) { weekInMonth = -1; } } else if (weekInMonth == 5) { weekInMonth = -1; } return weekInMonth; } U_NAMESPACE_END #endif //eof