Change the signal direction in clocking block
As:
clocking cb@(posedge clk);
input out_put;
output a,b,sel;//output from tb n input to dut
endclocking
Change the signal direction in clocking block
As:
clocking cb@(posedge clk);
input out_put;
output a,b,sel;//output from tb n input to dut
endclocking