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authorUlrich Drepper <drepper@redhat.com>1999-09-06 17:03:16 +0000
committerUlrich Drepper <drepper@redhat.com>1999-09-06 17:03:16 +0000
commit7fcc87f4673c79e7dbcc7d972e646383b5e47ce3 (patch)
treebd6c2115b5d5edf9b8bbcc77737775f31461a444 /time/tzset.c
parent07c7a0552ab5031edb6af78197b5584a61d055eb (diff)
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Update.
1999-09-06 Andreas Schwab <schwab@suse.de> * time/tzset.c (compute_change): Replace slow loop to compute T by simple algorithm.
Diffstat (limited to 'time/tzset.c')
-rw-r--r--time/tzset.c17
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)
{