component top 
  word_length : generic integer = 8
  T_IO        : generic type = bitvector(word_length)
  data_in     : in T_IO
  data_out    : out T_IO

register
  storage: T_IO = 0

begin
  storage[0] = storage[word_length-1]
  storage[1:word_length-1] = data_in[0:word_length-2]
  data_out = storage
end