module Accumulator (
    input  logic        clk,
    input  logic        direction,
    input  logic [15:0] increment,
    output logic [15:0] result
);
    logic [15:0] next;

    always_comb begin
        if (direction)
            next = result + increment;
        else
            next = result - increment;
    end

    always_ff @(posedge clk)
        result <= next;
endmodule