
I would like you to implement a module named TopModule with the following
interface. All input and output ports are one bit unless otherwise
specified.

 - input  a ( 3 bits)
 - output q (16 bits)

The module should implement a combinational circuit. Read the simulation
waveforms to determine what the circuit does, then implement it.

  time  a     q
  0ns   x     x
  5ns   x     x
  10ns  x     x
  15ns  0  1232
  20ns  1  aee0
  25ns  2  27d4
  30ns  3  5a0e
  35ns  4  2066
  40ns  5  64ce
  45ns  6  c526
  50ns  7  2f19
  55ns  0  1232
  60ns  1  aee0
  65ns  2  27d4
  70ns  4  2066
  75ns  1  aee0
  80ns  1  aee0
  85ns  3  5a0e
  90ns  5  64ce

