diff options
Diffstat (limited to 'time')
| -rw-r--r-- | time/mktime.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/time/mktime.c b/time/mktime.c index 65168bf69d..1acad267ae 100644 --- a/time/mktime.c +++ b/time/mktime.c @@ -75,12 +75,17 @@ verify (right_shift_propagates_sign, -1 >> 1 == -1); #define TM_YEAR_BASE 1900 verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0); -#ifndef __isleap -/* Nonzero if YEAR is a leap year (every 4 years, - except every 100th isn't, and every 400th is). */ -# define __isleap(year) \ - ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0)) -#endif +/* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */ +static inline int +leapyear (int year) +{ + /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. + Also, work even if YEAR is negative. */ + return + ((year & 3) == 0 + && (year % 100 != 0 + || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); +} /* How many days come before each month (0-12). */ #ifndef _LIBC @@ -234,7 +239,7 @@ __mktime_internal (struct tm *tp, /* Calculate day of year from year, month, and day of month. The result need not be in range. */ - int yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)] + int yday = ((__mon_yday[leapyear (year)] [mon_remainder + 12 * negative_mon_remainder]) + mday - 1); |