sub select
{
 shift
   if defined $_[0] && !ref($_[0]);

 my($r,$w,$e,$t) = @_;
 my @result = ();

 my $rb = defined $r ? $r->[VEC_BITS] : undef;
 my $wb = defined $w ? $w->[VEC_BITS] : undef;
 my $eb = defined $e ? $e->[VEC_BITS] : undef;

 if(select($rb,$wb,$eb,$t) > 0)
  {
   my @r = ();
   my @w = ();
   my @e = ();
   my $i = _max(defined $r ? scalar(@$r)-1 : 0,
                defined $w ? scalar(@$w)-1 : 0,
                defined $e ? scalar(@$e)-1 : 0);

   for( ; $i >= FIRST_FD ; $i--)
    {
     my $j = $i - FIRST_FD;
     push(@r, $r->[$i])
        if defined $rb && defined $r->[$i] && vec($rb, $j, 1);
     push(@w, $w->[$i])
        if defined $wb && defined $w->[$i] && vec($wb, $j, 1);
     push(@e, $e->[$i])
        if defined $eb && defined $e->[$i] && vec($eb, $j, 1);
    }

   @result = (\@r, \@w, \@e);
  }
 @result;
}