diff options
Diffstat (limited to 'time')
| -rw-r--r-- | time/tzset.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/time/tzset.c b/time/tzset.c index 24624fa188..6af2fbaf00 100644 --- a/time/tzset.c +++ b/time/tzset.c @@ -418,16 +418,23 @@ compute_change (rule, year) int year; { register time_t t; - int y; if (year != -1 && rule->computed_for == year) - /* Operations on times in 1969 will be slower. Oh well. */ + /* Operations on times in 2 BC will be slower. Oh well. */ return 1; /* First set T to January 1st, 0:00:00 GMT in YEAR. */ - t = 0; - for (y = 1970; y < year; ++y) - t += SECSPERDAY * (__isleap (y) ? 366 : 365); + if (year > 1970) + t = ((year - 1970) * 365 + + /* Compute the number of leapdays between 1970 and YEAR + (exclusive). There is a leapday every 4th year ... */ + + ((year - 1) / 4 - 1970 / 4) + /* ... except every 100th year ... */ + - ((year - 1) / 100 - 1970 / 100) + /* ... but still every 400th year. */ + + ((year - 1) / 400 - 1970 / 400)) * SECSPERDAY; + else + t = 0; switch (rule->type) { |