Return to timelocal.pl CVS log

Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / ntp / scripts / monitoring

Annotation of embedaddon/ntp/scripts/monitoring/timelocal.pl, revision 1.1

1.1     ! misho       1: ;# timelocal.pl
        !             2: ;#
        !             3: ;# Usage:
        !             4: ;#     $time = timelocal($sec,$min,$hours,$mday,$mon,$year,$junk,$junk,$isdst);
        !             5: ;#     $time = timegm($sec,$min,$hours,$mday,$mon,$year);
        !             6: 
        !             7: ;# These routines are quite efficient and yet are always guaranteed to agree
        !             8: ;# with localtime() and gmtime().  We manage this by caching the start times
        !             9: ;# of any months we've seen before.  If we know the start time of the month,
        !            10: ;# we can always calculate any time within the month.  The start times
        !            11: ;# themselves are guessed by successive approximation starting at the
        !            12: ;# current time, since most dates seen in practice are close to the
        !            13: ;# current date.  Unlike algorithms that do a binary search (calling gmtime
        !            14: ;# once for each bit of the time value, resulting in 32 calls), this algorithm
        !            15: ;# calls it at most 6 times, and usually only once or twice.  If you hit
        !            16: ;# the month cache, of course, it doesn't call it at all.
        !            17: 
        !            18: ;# timelocal is implemented using the same cache.  We just assume that we're
        !            19: ;# translating a GMT time, and then fudge it when we're done for the timezone
        !            20: ;# and daylight savings arguments.  The timezone is determined by examining
        !            21: ;# the result of localtime(0) when the package is initialized.  The daylight
        !            22: ;# savings offset is currently assumed to be one hour.
        !            23: 
        !            24: CONFIG: {
        !            25:     package timelocal;
        !            26:     
        !            27:     @epoch = localtime(0);
        !            28:     $tzmin = $epoch[2] * 60 + $epoch[1];       # minutes east of GMT
        !            29:     if ($tzmin > 0) {
        !            30:        $tzmin = 24 * 60 - $tzmin;              # minutes west of GMT
        !            31:        $tzmin -= 24 * 60 if $epoch[5] == 70;   # account for the date line
        !            32:     }
        !            33: 
        !            34:     $SEC = 1;
        !            35:     $MIN = 60 * $SEC;
        !            36:     $HR = 60 * $MIN;
        !            37:     $DAYS = 24 * $HR;
        !            38:     $YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
        !            39: }
        !            40: 
        !            41: sub timegm {
        !            42:     package timelocal;
        !            43: 
        !            44:     $ym = pack(C2, @_[5,4]);
        !            45:     $cheat = $cheat{$ym} || &cheat;
        !            46:     $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS;
        !            47: }
        !            48: 
        !            49: sub timelocal {
        !            50:     package timelocal;
        !            51: 
        !            52:     $ym = pack(C2, @_[5,4]);
        !            53:     $cheat = $cheat{$ym} || &cheat;
        !            54:     $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS
        !            55:        + $tzmin * $MIN - 60 * 60 * ($_[8] != 0);
        !            56: }
        !            57: 
        !            58: package timelocal;
        !            59: 
        !            60: sub cheat {
        !            61:     $year = $_[5];
        !            62:     $month = $_[4];
        !            63:     $guess = $^T;
        !            64:     @g = gmtime($guess);
        !            65:     $year += $YearFix if $year < $epoch[5];
        !            66:     while ($diff = $year - $g[5]) {
        !            67:        $guess += $diff * (364 * $DAYS);
        !            68:        @g = gmtime($guess);
        !            69:     }
        !            70:     while ($diff = $month - $g[4]) {
        !            71:        $guess += $diff * (28 * $DAYS);
        !            72:        @g = gmtime($guess);
        !            73:     }
        !            74:     $g[3]--;
        !            75:     $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS;
        !            76:     $cheat{$ym} = $guess;
        !            77: }