
Build a priority encoder for 8-bit inputs. Given an 8-bit vector, the
output should report the first (least significant) bit in the vector that
is 1. Report zero if the input vector has no bits that are high. For
example, the input 8'b10010000 should output 3'd4, because bit[4] is
first bit that is high.

module TopModule (
  input [7:0] in,
  output reg [2:0] pos
);

