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#include "gregoimp.h" 15 16#if !UCONFIG_NO_FORMATTING 17 18#include "unicode/ucal.h" 19#include "uresimp.h" 20#include "cstring.h" 21#include "uassert.h" 22 23U_NAMESPACE_BEGIN 24 25int32_t ClockMath::floorDivide(int32_t numerator, int32_t denominator) { 26 return (numerator >= 0) ? 27 numerator / denominator : ((numerator + 1) / denominator) - 1; 28} 29 30int32_t ClockMath::floorDivide(double numerator, int32_t denominator, 31 int32_t& remainder) { 32 double quotient; 33 quotient = uprv_floor(numerator / denominator); 34 remainder = (int32_t) (numerator - (quotient * denominator)); 35 return (int32_t) quotient; 36} 37 38double ClockMath::floorDivide(double dividend, double divisor, 39 double& remainder) { 40 // Only designed to work for positive divisors 41 U_ASSERT(divisor > 0); 42 double quotient = floorDivide(dividend, divisor); 43 remainder = dividend - (quotient * divisor); 44 // N.B. For certain large dividends, on certain platforms, there 45 // is a bug such that the quotient is off by one. If you doubt 46 // this to be true, set a breakpoint below and run cintltst. 47 if (remainder < 0 || remainder >= divisor) { 48 // E.g. 6.7317038241449352e+022 / 86400000.0 is wrong on my 49 // machine (too high by one). 4.1792057231752762e+024 / 50 // 86400000.0 is wrong the other way (too low). 51 double q = quotient; 52 quotient += (remainder < 0) ? -1 : +1; 53 if (q == quotient) { 54 // For quotients > ~2^53, we won't be able to add or 55 // subtract one, since the LSB of the mantissa will be > 56 // 2^0; that is, the exponent (base 2) will be larger than 57 // the length, in bits, of the mantissa. In that case, we 58 // can't give a correct answer, so we set the remainder to 59 // zero. This has the desired effect of making extreme 60 // values give back an approximate answer rather than 61 // crashing. For example, UDate values above a ~10^25 62 // might all have a time of midnight. 63 remainder = 0; 64 } else { 65 remainder = dividend - (quotient * divisor); 66 } 67 } 68 U_ASSERT(0 <= remainder && remainder < divisor); 69 return quotient; 70} 71 72const int32_t JULIAN_1_CE = 1721426; // January 1, 1 CE Gregorian 73const int32_t JULIAN_1970_CE = 2440588; // January 1, 1970 CE Gregorian 74 75const int16_t Grego::DAYS_BEFORE[24] = 76 {0,31,59,90,120,151,181,212,243,273,304,334, 77 0,31,60,91,121,152,182,213,244,274,305,335}; 78 79const int8_t Grego::MONTH_LENGTH[24] = 80 {31,28,31,30,31,30,31,31,30,31,30,31, 81 31,29,31,30,31,30,31,31,30,31,30,31}; 82 83double Grego::fieldsToDay(int32_t year, int32_t month, int32_t dom) { 84 85 int32_t y = year - 1; 86 87 double julian = 365 * y + ClockMath::floorDivide(y, 4) + (JULIAN_1_CE - 3) + // Julian cal 88 ClockMath::floorDivide(y, 400) - ClockMath::floorDivide(y, 100) + 2 + // => Gregorian cal 89 DAYS_BEFORE[month + (isLeapYear(year) ? 12 : 0)] + dom; // => month/dom 90 91 return julian - JULIAN_1970_CE; // JD => epoch day 92} 93 94void Grego::dayToFields(double day, int32_t& year, int32_t& month, 95 int32_t& dom, int32_t& dow, int32_t& doy) { 96 97 // Convert from 1970 CE epoch to 1 CE epoch (Gregorian calendar) 98 day += JULIAN_1970_CE - JULIAN_1_CE; 99 100 // Convert from the day number to the multiple radix 101 // representation. We use 400-year, 100-year, and 4-year cycles. 102 // For example, the 4-year cycle has 4 years + 1 leap day; giving 103 // 1461 == 365*4 + 1 days. 104 int32_t n400 = ClockMath::floorDivide(day, 146097, doy); // 400-year cycle length 105 int32_t n100 = ClockMath::floorDivide(doy, 36524, doy); // 100-year cycle length 106 int32_t n4 = ClockMath::floorDivide(doy, 1461, doy); // 4-year cycle length 107 int32_t n1 = ClockMath::floorDivide(doy, 365, doy); 108 year = 400*n400 + 100*n100 + 4*n4 + n1; 109 if (n100 == 4 || n1 == 4) { 110 doy = 365; // Dec 31 at end of 4- or 400-year cycle 111 } else { 112 ++year; 113 } 114 115 UBool isLeap = isLeapYear(year); 116 117 // Gregorian day zero is a Monday. 118 dow = (int32_t) uprv_fmod(day + 1, 7); 119 dow += (dow < 0) ? (UCAL_SUNDAY + 7) : UCAL_SUNDAY; 120 121 // Common Julian/Gregorian calculation 122 int32_t correction = 0; 123 int32_t march1 = isLeap ? 60 : 59; // zero-based DOY for March 1 124 if (doy >= march1) { 125 correction = isLeap ? 1 : 2; 126 } 127 month = (12 * (doy + correction) + 6) / 367; // zero-based month 128 dom = doy - DAYS_BEFORE[month + (isLeap ? 12 : 0)] + 1; // one-based DOM 129 doy++; // one-based doy 130} 131 132void Grego::timeToFields(UDate time, int32_t& year, int32_t& month, 133 int32_t& dom, int32_t& dow, int32_t& doy, int32_t& mid) { 134 double millisInDay; 135 double day = ClockMath::floorDivide((double)time, (double)U_MILLIS_PER_DAY, millisInDay); 136 mid = (int32_t)millisInDay; 137 dayToFields(day, year, month, dom, dow, doy); 138} 139 140int32_t Grego::dayOfWeek(double day) { 141 int32_t dow; 142 ClockMath::floorDivide(day + UCAL_THURSDAY, 7, dow); 143 return (dow == 0) ? UCAL_SATURDAY : dow; 144} 145 146int32_t Grego::dayOfWeekInMonth(int32_t year, int32_t month, int32_t dom) { 147 int32_t weekInMonth = (dom + 6)/7; 148 if (weekInMonth == 4) { 149 if (dom + 7 > monthLength(year, month)) { 150 weekInMonth = -1; 151 } 152 } else if (weekInMonth == 5) { 153 weekInMonth = -1; 154 } 155 return weekInMonth; 156} 157 158U_NAMESPACE_END 159 160#endif 161//eof 162