How do you plan to solve it?
module dff_async_reset_preset ( input CLK, input RST, input PRE, input D, output reg Q ); always @(posedge CLK or posedge RST or posedge PRE) begin if(RST == 1'b1) Q <= 1'b0; else if(PRE == 1'b1) Q <= 1'b1; else Q <= D; end endmodule