use Benchmark qw( cmpthese );

our $data = '0:13:46:b:4:31';

cmpthese(-3, {
   ike_orig => 'my $mac = $data; $mac =~ s/(^|:)(?=[0-9a-fA-F](?::|$))/${1}0/g;               $mac;',
   ike_fast => 'my $mac = $data; $mac =~ s/(?<=:)(?=[0-9a-fA-F](?::|$))/0/g;
                                 $mac =~ s/^(?=[0-9a-fA-F](?::|$))/0/;                        $mac;',
   skeeve   => 'my $mac = $data; $mac = join ":", map substr("0$_",-2), split/:/, $mac;       $mac;',
   jwkrahn1 => 'my $mac = $data; $mac =~ s/([^:]+)/ sprintf "%02s", $1 /eg;                   $mac;',
   jwkrahn2 => 'my $mac = $data; $mac = join ":", map sprintf( "%02s", $_ ), split /:/, $mac; $mac;',
});