// String of LEDs implemented as a series of flip-flops.
// Shifts the input from left-to-right.
// - SW[9] is the reset signal
// - SW[0] is the input signal
// - ~KEY[0] is the clock signal
module string_lights (output logic [9:0] LEDR,
                      input  logic [3:0] KEY,
                      input  logic [9:0] SW);

  logic clk, reset, in;
  assign clk   = ~KEY[0];
  assign reset = SW[9];
  assign in    = SW[0];

  always_ff @(posedge clk)
    if (reset)
      LEDR <= 10'd0;
    else
      LEDR <= {in, LEDR[9:1]};

endmodule  // string_lights