module top;
system_clock #400 clock1(C);
system_clock #200 clock2(A);
system_clock #100 clock3(B);
adder1 M1(Cout, Sum, A, B, C);
endmodule
module adder1(Cout, Sum, A, B, C);
output Cout,Sum;
input A,B,C;
not I1(notA,A);
not I2(notB,B);
not I3(notC,C);
and I4(s1,A,B);
and I5(s2,B,C);
and I6(s3,A,C);
and I7(s4,notA,B,notC);
and I8(s5,A,notB,notC);
and I9(s6,notA,notB,C);
and I10(s7,A,B,C);
or I11(Cout,s1,s2,s3);
or I12(Sum,s4,s5,s6,s7);
endmodule
module system_clock(clk);
parameter PERIOD=100;
output clk;
reg clk;
initial clk=0;
always
begin
#(PERIOD/2) clk=~clk;
end
always@(posedge clk)
if($time>1000)$stop;
endmodule
