$begin = /BEGIN MAC REGISTER DUMP/
$end = /END MAC REGISTER DUMP/
def name
  base = ARGF.path
  i = 0
  loop do
    name = "#{base}.#{i}"
    return name unless File.exists? name
    i += 1
  end
end

f = nil
while gets
  (f.close; f = nil) if ~$end
  f << $_ if f
  f = File.open name, 'w' if ~$begin
end