diff options
Diffstat (limited to 'time/offtime.c')
| -rw-r--r-- | time/offtime.c | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/time/offtime.c b/time/offtime.c index 4b8ddb170b..4e062df0d3 100644 --- a/time/offtime.c +++ b/time/offtime.c @@ -19,7 +19,6 @@ Cambridge, MA 02139, USA. */ #include <ansidecl.h> #include <time.h> - /* Defined in mktime.c. */ extern CONST unsigned short int __mon_yday[2][13]; @@ -33,8 +32,7 @@ void DEFUN(__offtime, (t, offset, tp), CONST time_t *t AND long int offset AND struct tm *tp) { - register long int days, rem; - register int y; + register long int days, rem, y; register CONST unsigned short int *ip; days = *t / SECS_PER_DAY; @@ -59,15 +57,19 @@ DEFUN(__offtime, (t, offset, tp), if (tp->tm_wday < 0) tp->tm_wday += 7; y = 1970; - while (days >= (rem = __isleap(y) ? 366 : 365)) - { - ++y; - days -= rem; - } - while (days < 0) + +# define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400) + + while (days < 0 || days >= (__isleap (y) ? 366 : 365)) { - --y; - days += __isleap(y) ? 366 : 365; + /* Guess a corrected year, assuming 365 days per year. */ + int yg = y + days / 365 - (days % 365 < 0); + + /* Adjust DAYS and Y to match the guessed year. */ + days -= ((yg - y) * 365 + + LEAPS_THRU_END_OF (yg - 1) + - LEAPS_THRU_END_OF (y - 1)); + y = yg; } tp->tm_year = y - 1900; tp->tm_yday = days; |