Perl - Alguien entiende este codigo???

Hola tengo este codigo en perl y necesitaria que alguien comentase las lineas para yo entenderlo y asi poderlo pasar a javascript, ya que no se perl. GRACIAS:

# u'll need MIME::Base64 to get it to work aka C:\>echo install MIME-Base64|ppm

$nicething = '-'x60;
system('cls');
print "\t".$nicething."\n";
print "\t".' MDecode demo by Obscure for MDaemon'."\n";
print "\t".$nicething."\n";

if (@ARGV) {$passwd = $ARGV[0]} else {print "\t\t usage: MDecode.pl userlist.dat\n\n";exit;}

sub decode{
$decoded = '';
$f = '';
($y) = @_;
use MIME::Base64;
$decoded = decode_base64($y);
$a = unpack("H*",$decoded);

## this is the offset hex table
## this simple encryption just adds/subtracts a certain value
## for each character.
@off = (54,68,65,20,73,65,74,75,70,20,70,72,'6f',63,65,'9f');
$w = 0;
foreach $love (@off){
$h = substr($a,$w,2);
$d = hex $h;
$l = hex $love;
$letter = $d - $l;
$aa = pack("I*",$letter);
$q = substr($aa,0,1);
$f = $f.$q;
$w = $w + 2;
}
$f = substr($f,0,length($decoded));
return $f;
}

if (open (PASSF,$passwd)){
while (<PASSF>){
$dom = substr ($_,0,45);
$dom =~ s/ //g;
$user = substr ($_,45,30);
$user =~ s/ //g;
$enc = substr ($_,195,19);
$enc =~ s/ //g;
push(@enc,$enc);
push(@user,$user);
push(@dom,$dom);
}
close(PASSF);
$x = 0;
while ($x != $#enc+1){
print "\t\t".$user[$x].'@'.$dom[$x]."\t-->\t".&decode($enc[$x])."\n";
$x++;
}
} else {print "\t\t\tCould not open $passwd"};

no me plagies el nick xd