LEFT SHIFT REGISTER

module fourBit_Reg(clk,d,pad,s,q);

input clk,pad,s;

input [3:0] d;

output q;

reg [3:0] temp;

always @ (posedge clk)

begin

if(s)

temp <= d;

else

temp <= {temp[2:0],pad};

end

assign q = temp[3];

endmodule

OUTPUT WAVEFORM