sub sb2d{
    my $n=shift; 
    return undef unless $n =~ m[^[01]+$];
    my $s=ord( $n )==49;  
    $n=~tr[01][10] if $s; 
    $n = eval{ no warnings; eval '0b'.$n;};  
    $s ? -1 * ++$n : $n 
}