sub xlat {
  my ($octets) = @_ ;
  return pack('B*', unpack('b*', $octets)) ;
} ;

my $test = '0x4000040000000200800000000000000000000002'
            .'0000000000c004000108008000000000000000000'
            .'00000000000000000000000000000000000000000'
            .'00000000000000000000000000000000000000000'
            .'00000000000000000000000000000000000000000'
            .'00000000000000000000000000000000000000000'
            .'00000000000';
my $bits;

$bits = showbits($test);

my @s = ranges($bits);
print "Ranges: ", join(', ', @s);

$bits = showbits(xlat($test));
@s = ranges($bits);
print join(',',@s);

$bits = showbits(xlat(xlat($test)));
@s = ranges($bits);
print join(',',@s);

sub ranges{
my $test = shift;
my $r = undef ;
my @s = () ;
for my $vn (1..length($test) * 8) {
  if (vec($test, $vn, 1)) {
    if (!defined($r)) { push @s, "$vn-" ; } ;
    $r = $vn ;
  }
  else {
    if (defined($r))  { $s[-1] .= "$r" ;  $r = undef ; } ;
  } ;
} ;
return @s;
}

sub showbits {
  my ($octets) = @_ ;
  my $s = unpack('B*', $octets) ;
  $s =~ s/([01]{8})(?=[01])/$1/g ;
  ranges($s) ;
} ;