first commit

timelocal.pl

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+;# timelocal.pl
+;#
+;# Usage:
+;#        $time = timelocal($sec,$min,$hours,$mday,$mon,$year);
+;#        $time = timegm($sec,$min,$hours,$mday,$mon,$year);
+
+;# These routines are quite efficient and yet are always guaranteed to agree
+;# with localtime() and gmtime().  We manage this by caching the start times
+;# of any months we've seen before.  If we know the start time of the month,
+;# we can always calculate any time within the month.  The start times
+;# themselves are guessed by successive approximation starting at the
+;# current time, since most dates seen in practice are close to the
+;# current date.  Unlike algorithms that do a binary search (calling gmtime
+;# once for each bit of the time value, resulting in 32 calls), this algorithm
+;# calls it at most 6 times, and usually only once or twice.  If you hit
+;# the month cache, of course, it doesn't call it at all.
+
+;# timelocal is implemented using the same cache.  We just assume that we're
+;# translating a GMT time, and then fudge it when we're done for the timezone
+;# and daylight savings arguments.  The timezone is determined by examining
+;# the result of localtime(0) when the package is initialized.  The daylight
+;# savings offset is currently assumed to be one hour.
+
+;# Both routines return -1 if the integer limit is hit. I.e. for dates
+;# after the 1st of January, 2038 on most machines.
+#
+#####   Peters TIP
+#
+#   Stunde Minute Sekunde sind unwichtig, also setzen auf 0 oder so
+#   Das Jahr ist 100 für 2000, 101 für 2001 usw
+#
+#############
+
+
+CONFIG: {
+    package timelocal;
+
+    local($[) = 0;
+    @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;
+    $YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0;
+    1;
+}
+
+sub timegm {
+    package timelocal;
+
+    local($[) = 0;
+    $ym = pack(C2, @_[5,4]);
+    $cheat = $cheat{$ym} || &cheat;
+    return -1 if $cheat<0;
+    $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS;
+}
+
+sub timelocal {
+    package timelocal;
+
+    local($[) = 0;
+    $time = &main'timegm + $tzmin*$MIN;
+    return -1 if $cheat<0;
+    @test = localtime($time);
+    $time -= $HR if $test[2] != $_[2];
+    $time;
+}
+
+package timelocal;
+
+sub cheat {
+    $year = $_[5];
+    $month = $_[4];
+    die "Month out of range 0..11 in timelocal.pl\n"
+        if $month > 11 || $month < 0;
+    die "Day out of range 1..31 in timelocal.pl\n"
+        if $_[3] > 31 || $_[3] < 1;
+    die "Hour out of range 0..23 in timelocal.pl\n"
+        if $_[2] > 23 || $_[2] < 0;
+    die "Minute out of range 0..59 in timelocal.pl\n"
+        if $_[1] > 59 || $_[1] < 0;
+    die "Second out of range 0..59 in timelocal.pl\n"
+        if $_[0] > 59 || $_[0] < 0;
+    $guess = $^T;
+    @g = gmtime($guess);
+    $year += $YearFix if $year < $epoch[5];
+    $lastguess = "";
+    while ($diff = $year - $g[5]) {
+        $guess += $diff * (363 * $DAYS);
+        @g = gmtime($guess);
+        if (($thisguess = "@g") eq $lastguess){
+            return -1; #date beyond this machine's integer limit
+        }
+        $lastguess = $thisguess;
+    }
+    while ($diff = $month - $g[4]) {
+        $guess += $diff * (27 * $DAYS);
+        @g = gmtime($guess);
+        if (($thisguess = "@g") eq $lastguess){
+            return -1; #date beyond this machine's integer limit
+        }
+        $lastguess = $thisguess;
+    }
+    @gfake = gmtime($guess-1); #still being sceptic
+    if ("@gfake" eq $lastguess){
+        return -1; #date beyond this machine's integer limit
+    }
+    $g[3]--;
+    $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS;
+    $cheat{$ym} = $guess;
+}