i am designing period-controlled-oscillator,but not getting the desired output from block.please suggest any changes to be made

module myosc(in,out,clk);
input in,clk;
output out;
electrical in,out,clk;

parameter real vh=1.5;
parameter real vl=0;


parameter real vtrans=0.6;
parameter real maxp=(1/5000000);
parameter real minp=(1/500);
integer comp;
integer n;
real period;
real step;



analog begin

@(initial_step)begin
period=(1/500000);

step=(1/5000) + $abstime;
end

@(timer(step))begin
n=!n;
step=step+(0.5*period);
end

@(cross(V(clk)-vtrans,1))
begin
if((V(in)-vtrans)>0)
comp=1;
else
comp=-1;
period = period +(comp*step);
end

if(period>maxp)
period=maxp;
if(period<minp)
period=minp;

V(out)<+transition(n?vh:vl,0,100p);
end


endmodule