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 /* ********************************************************************** * Copyright (c) 2003, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * Author: Alan Liu * Created: September 2 2003 * Since: ICU 2.8 ********************************************************************** */ #include "gregoimp.h" #include "unicode/ucal.h" int32_t Math::floorDivide(int32_t numerator, int32_t denominator) { return (numerator >= 0) ? numerator / denominator : ((numerator + 1) / denominator) - 1; } int32_t Math::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; } 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[24] = {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[24] = {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 + Math::floorDivide(y, 4) + (JULIAN_1_CE - 3) + // Julian cal Math::floorDivide(y, 400) - Math::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 = Math::floorDivide(day, 146097, doy); // 400-year cycle length int32_t n100 = Math::floorDivide(doy, 36524, doy); // 100-year cycle length int32_t n4 = Math::floorDivide(doy, 1461, doy); // 4-year cycle length int32_t n1 = Math::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 } //eof