sub hexdump($data) {
   $data =~ s/\G(?|
       ( \0{16} )+ (?{ '*' })
     | ( .{1,16} ) (?{
            sprintf '%08X  %-50s|%-16s|', $-[1],
              join(' ', unpack('(H2)8a0(H2)8', $1)),
              $1 =~ tr{[\0-\x1F\x7F-\xFF]}{.}r
       }) 
   )/$^R\n/xgr;
}