78 lines
2.5 KiB
Perl
78 lines
2.5 KiB
Perl
|
;# timelocal.pl
|
||
|
|
;#
|
||
|
|
;# Usage:
|
||
|
|
;# $time = timelocal($sec,$min,$hours,$mday,$mon,$year,$junk,$junk,$isdst);
|
||
|
|
;# $time = timegm($sec,$min,$hours,$mday,$mon,$year);
|
||
|
|
|
||
|
|
;# These routines are quite efficient and yet are always guaranteed to agree
|
||
|
|
;# with localtime() and gmtime(). We manage this by caching the start times
|
||
|
|
;# of any months we've seen before. If we know the start time of the month,
|
||
|
|
;# we can always calculate any time within the month. The start times
|
||
|
|
;# themselves are guessed by successive approximation starting at the
|
||
|
|
;# current time, since most dates seen in practice are close to the
|
||
|
|
;# current date. Unlike algorithms that do a binary search (calling gmtime
|
||
|
|
;# once for each bit of the time value, resulting in 32 calls), this algorithm
|
||
|
|
;# calls it at most 6 times, and usually only once or twice. If you hit
|
||
|
|
;# the month cache, of course, it doesn't call it at all.
|
||
|
|
|
||
|
|
;# timelocal is implemented using the same cache. We just assume that we're
|
||
|
|
;# translating a GMT time, and then fudge it when we're done for the timezone
|
||
|
|
;# and daylight savings arguments. The timezone is determined by examining
|
||
|
|
;# the result of localtime(0) when the package is initialized. The daylight
|
||
|
|
;# savings offset is currently assumed to be one hour.
|
||
|
|
|
||
|
|
CONFIG: {
|
||
|
|
package timelocal;
|
||
|
|
|
||
|
|
@epoch = localtime(0);
|
||
|
|
$tzmin = $epoch[2] * 60 + $epoch[1]; # minutes east of GMT
|
||
|
|
if ($tzmin > 0) {
|
||
|
|
$tzmin = 24 * 60 - $tzmin; # minutes west of GMT
|
||
|
|
$tzmin -= 24 * 60 if $epoch[5] == 70; # account for the date line
|
||
|
|
}
|
||
|
|
|
||
|
|
$SEC = 1;
|
||
|
|
$MIN = 60 * $SEC;
|
||
|
|
$HR = 60 * $MIN;
|
||
|
|
$DAYS = 24 * $HR;
|
||
|
|
$YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
sub timegm {
|
||
|
|
package timelocal;
|
||
|
|
|
||
|
|
$ym = pack(C2, @_[5,4]);
|
||
|
|
$cheat = $cheat{$ym} || &cheat;
|
||
|
|
$cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS;
|
||
|
|
}
|
||
|
|
|
||
|
|
sub timelocal {
|
||
|
|
package timelocal;
|
||
|
|
|
||
|
|
$ym = pack(C2, @_[5,4]);
|
||
|
|
$cheat = $cheat{$ym} || &cheat;
|
||
|
|
$cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS
|
||
|
|
+ $tzmin * $MIN - 60 * 60 * ($_[8] != 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
package timelocal;
|
||
|
|
|
||
|
|
sub cheat {
|
||
|
|
$year = $_[5];
|
||
|
|
$month = $_[4];
|
||
|
|
$guess = $^T;
|
||
|
|
@g = gmtime($guess);
|
||
|
|
$year += $YearFix if $year < $epoch[5];
|
||
|
|
while ($diff = $year - $g[5]) {
|
||
|
|
$guess += $diff * (364 * $DAYS);
|
||
|
|
@g = gmtime($guess);
|
||
|
|
}
|
||
|
|
while ($diff = $month - $g[4]) {
|
||
|
|
$guess += $diff * (28 * $DAYS);
|
||
|
|
@g = gmtime($guess);
|
||
|
|
}
|
||
|
|
$g[3]--;
|
||
|
|
$guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS;
|
||
|
|
$cheat{$ym} = $guess;
|
||
|
|
}
|