module alu_decoder (
input [1:0] opcode,
output reg [3:0] alu_op
);
always @* begin
case (opcode)
// Write solution here
2'd0: alu_op = 4'b0001;
2'd1: alu_op = 4'b0010;
2'd2: alu_op = 4'b0100;
2'd3: alu_op = 4'b1000;
default: alu_op = 4'd0;
endcase
end
endmodule