Method

In reply to chr_sue:
I have changed something in your code.
class scaling;
int pclk;
function realtime pri(int scaledown,pclk);
$display("scaledown = %d ", scaledown);
pri = 0.00000006*pclk / scaledown;
$display("pri = %f ", pri);
return pri;
endfunction
endclass

module priyanka();
int scaledown = 1;
int pclk = 1;
int polling_cnt;
scaling s=new();
initial begin
scaledown = 1000;
pclk = 500000000;
repeat (3) begin
polling_cnt = s.pri(scaledown,pclk);
$display("%f ",polling_cnt);
pclk = 0.5 *pclk;

end

end
endmodule

-Now the question is there are 3 different values of pclk: 500000000, 250000000, 125000000. So for this, i wrote pclk = 0.5*pclk. But driver will use one value at a time, so how to code this?