| 1,14 → 1,101 |
|---|
| /* |
| * gmtime_r.c |
| * Original Author: Adapted from tzcode maintained by Arthur David Olson. |
| * Modifications: |
| * - Changed to mktm_r and added __tzcalc_limits - 04/10/02, Jeff Johnston |
| * - Fixed bug in mday computations - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru> |
| * - Fixed bug in __tzcalc_limits - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru> |
| * - Move code from _mktm_r() to gmtime_r() - 05/09/14, Freddie Chopin <freddie_chopin@op.pl> |
| * - Fixed bug in calculations for dates after year 2069 or before year 1901. Ideas for |
| * solution taken from musl's __secs_to_tm() - 07/12/2014, Freddie Chopin |
| * <freddie_chopin@op.pl> |
| * - Use faster algorithm from civil_from_days() by Howard Hinnant - 12/06/2014, |
| * Freddie Chopin <freddie_chopin@op.pl> |
| * |
| * Converts the calendar time pointed to by tim_p into a broken-down time |
| * expressed as local time. Returns a pointer to a structure containing the |
| * broken-down time. |
| */ |
| |
| #include <time.h> |
| #include "local.h" |
| |
| /* Move epoch from 01.01.1970 to 01.03.0000 (yes, Year 0) - this is the first |
| * day of a 400-year long "era", right after additional day of leap year. |
| * This adjustment is required only for date calculation, so instead of |
| * modifying time_t value (which would require 64-bit operations to work |
| * correctly) it's enough to adjust the calculated number of days since epoch. |
| */ |
| #define EPOCH_ADJUSTMENT_DAYS 719468L |
| /* year to which the adjustment was made */ |
| #define ADJUSTED_EPOCH_YEAR 0 |
| /* 1st March of year 0 is Wednesday */ |
| #define ADJUSTED_EPOCH_WDAY 3 |
| /* there are 97 leap years in 400-year periods. ((400 - 97) * 365 + 97 * 366) */ |
| #define DAYS_PER_ERA 146097L |
| /* there are 24 leap years in 100-year periods. ((100 - 24) * 365 + 24 * 366) */ |
| #define DAYS_PER_CENTURY 36524L |
| /* there is one leap year every 4 years */ |
| #define DAYS_PER_4_YEARS (3 * 365 + 366) |
| /* number of days in a non-leap year */ |
| #define DAYS_PER_YEAR 365 |
| /* number of days in January */ |
| #define DAYS_IN_JANUARY 31 |
| /* number of days in non-leap February */ |
| #define DAYS_IN_FEBRUARY 28 |
| /* number of years per era */ |
| #define YEARS_PER_ERA 400 |
| |
| struct tm * |
| _DEFUN (gmtime_r, (tim_p, res), |
| _CONST time_t *__restrict tim_p _AND |
| struct tm *__restrict res) |
| { |
| return (_mktm_r (tim_p, res, 1)); |
| long days, rem; |
| _CONST time_t lcltime = *tim_p; |
| int era, weekday, year; |
| unsigned erayear, yearday, month, day; |
| unsigned long eraday; |
| |
| days = ((long)lcltime) / SECSPERDAY + EPOCH_ADJUSTMENT_DAYS; |
| rem = ((long)lcltime) % SECSPERDAY; |
| if (rem < 0) |
| { |
| rem += SECSPERDAY; |
| --days; |
| } |
| |
| /* compute hour, min, and sec */ |
| res->tm_hour = (int) (rem / SECSPERHOUR); |
| rem %= SECSPERHOUR; |
| res->tm_min = (int) (rem / SECSPERMIN); |
| res->tm_sec = (int) (rem % SECSPERMIN); |
| |
| /* compute day of week */ |
| if ((weekday = ((ADJUSTED_EPOCH_WDAY + days) % DAYSPERWEEK)) < 0) |
| weekday += DAYSPERWEEK; |
| res->tm_wday = weekday; |
| |
| /* compute year, month, day & day of year */ |
| /* for description of this algorithm see |
| * http://howardhinnant.github.io/date_algorithms.html#civil_from_days */ |
| era = (days >= 0 ? days : days - (DAYS_PER_ERA - 1)) / DAYS_PER_ERA; |
| eraday = days - era * DAYS_PER_ERA; /* [0, 146096] */ |
| erayear = (eraday - eraday / (DAYS_PER_4_YEARS - 1) + eraday / DAYS_PER_CENTURY - |
| eraday / (DAYS_PER_ERA - 1)) / 365; /* [0, 399] */ |
| yearday = eraday - (DAYS_PER_YEAR * erayear + erayear / 4 - erayear / 100); /* [0, 365] */ |
| month = (5 * yearday + 2) / 153; /* [0, 11] */ |
| day = yearday - (153 * month + 2) / 5 + 1; /* [1, 31] */ |
| month += month < 10 ? 2 : -10; |
| year = ADJUSTED_EPOCH_YEAR + erayear + era * YEARS_PER_ERA + (month <= 1); |
| |
| res->tm_yday = yearday >= DAYS_PER_YEAR - DAYS_IN_JANUARY - DAYS_IN_FEBRUARY ? |
| yearday - (DAYS_PER_YEAR - DAYS_IN_JANUARY - DAYS_IN_FEBRUARY) : |
| yearday + DAYS_IN_JANUARY + DAYS_IN_FEBRUARY + isleap(erayear); |
| res->tm_year = year - YEAR_BASE; |
| res->tm_mon = month; |
| res->tm_mday = day; |
| |
| res->tm_isdst = 0; |
| |
| return (res); |
| } |