Benchmark: timing 10000 iterations of regex-em, split-em...
  regex-em:  2 wallclock secs ( 3.64 usr +  0.00 sys =  3.64 CPU)
  split-em:  3 wallclock secs ( 3.13 usr +  0.00 sys =  3.13 CPU)
bash-2.04$ perl pack_ip.pl
Benchmark: timing 10000 iterations of regex-em, split-em...
  regex-em:  3 wallclock secs ( 4.03 usr +  0.00 sys =  4.03 CPU)
  split-em:  3 wallclock secs ( 3.76 usr +  0.00 sys =  3.76 CPU)