154359Sroberto;# timelocal.pl 254359Sroberto;# 354359Sroberto;# Usage: 454359Sroberto;# $time = timelocal($sec,$min,$hours,$mday,$mon,$year,$junk,$junk,$isdst); 554359Sroberto;# $time = timegm($sec,$min,$hours,$mday,$mon,$year); 654359Sroberto 754359Sroberto;# These routines are quite efficient and yet are always guaranteed to agree 854359Sroberto;# with localtime() and gmtime(). We manage this by caching the start times 954359Sroberto;# of any months we've seen before. If we know the start time of the month, 1054359Sroberto;# we can always calculate any time within the month. The start times 1154359Sroberto;# themselves are guessed by successive approximation starting at the 1254359Sroberto;# current time, since most dates seen in practice are close to the 1354359Sroberto;# current date. Unlike algorithms that do a binary search (calling gmtime 1454359Sroberto;# once for each bit of the time value, resulting in 32 calls), this algorithm 1554359Sroberto;# calls it at most 6 times, and usually only once or twice. If you hit 1654359Sroberto;# the month cache, of course, it doesn't call it at all. 1754359Sroberto 1854359Sroberto;# timelocal is implemented using the same cache. We just assume that we're 1954359Sroberto;# translating a GMT time, and then fudge it when we're done for the timezone 2054359Sroberto;# and daylight savings arguments. The timezone is determined by examining 2154359Sroberto;# the result of localtime(0) when the package is initialized. The daylight 2254359Sroberto;# savings offset is currently assumed to be one hour. 2354359Sroberto 2454359SrobertoCONFIG: { 2554359Sroberto package timelocal; 2654359Sroberto 2754359Sroberto @epoch = localtime(0); 2854359Sroberto $tzmin = $epoch[2] * 60 + $epoch[1]; # minutes east of GMT 2954359Sroberto if ($tzmin > 0) { 3054359Sroberto $tzmin = 24 * 60 - $tzmin; # minutes west of GMT 3154359Sroberto $tzmin -= 24 * 60 if $epoch[5] == 70; # account for the date line 3254359Sroberto } 3354359Sroberto 3454359Sroberto $SEC = 1; 3554359Sroberto $MIN = 60 * $SEC; 3654359Sroberto $HR = 60 * $MIN; 3754359Sroberto $DAYS = 24 * $HR; 3854359Sroberto $YearFix = ((gmtime(946684800))[5] == 100) ? 100 : 0; 3954359Sroberto} 4054359Sroberto 4154359Srobertosub timegm { 4254359Sroberto package timelocal; 4354359Sroberto 4454359Sroberto $ym = pack(C2, @_[5,4]); 4554359Sroberto $cheat = $cheat{$ym} || &cheat; 4654359Sroberto $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS; 4754359Sroberto} 4854359Sroberto 4954359Srobertosub timelocal { 5054359Sroberto package timelocal; 5154359Sroberto 5254359Sroberto $ym = pack(C2, @_[5,4]); 5354359Sroberto $cheat = $cheat{$ym} || &cheat; 5454359Sroberto $cheat + $_[0] * $SEC + $_[1] * $MIN + $_[2] * $HR + ($_[3]-1) * $DAYS 5554359Sroberto + $tzmin * $MIN - 60 * 60 * ($_[8] != 0); 5654359Sroberto} 5754359Sroberto 5854359Srobertopackage timelocal; 5954359Sroberto 6054359Srobertosub cheat { 6154359Sroberto $year = $_[5]; 6254359Sroberto $month = $_[4]; 6354359Sroberto $guess = $^T; 6454359Sroberto @g = gmtime($guess); 6554359Sroberto $year += $YearFix if $year < $epoch[5]; 6654359Sroberto while ($diff = $year - $g[5]) { 6754359Sroberto $guess += $diff * (364 * $DAYS); 6854359Sroberto @g = gmtime($guess); 6954359Sroberto } 7054359Sroberto while ($diff = $month - $g[4]) { 7154359Sroberto $guess += $diff * (28 * $DAYS); 7254359Sroberto @g = gmtime($guess); 7354359Sroberto } 7454359Sroberto $g[3]--; 7554359Sroberto $guess -= $g[0] * $SEC + $g[1] * $MIN + $g[2] * $HR + $g[3] * $DAYS; 7654359Sroberto $cheat{$ym} = $guess; 7754359Sroberto} 78