I have written a module in verilog implementing D flip-flop, like following:-
module d_flip_flop(q,d,clk,reset);
Now, I want to implement 4-bit shift register using this module. So I have to execute four d flip flops in parallel inside always @(negedge clk) block. I don't know how to parallel execute four user defined modules inside always(or how to instantiate). I don't want a direct behavioral implementation of 4-bit shift register.