四位全加器verilog代码

`timescale 1ns/1ns module fulladd_4(sum,c_out,a,b,c_in); output [3:0] sum; output c_out; input [3:0] a,b; input c_in; wire p0,g0,p1,g1,p2,g2,p3,g3; wire c4,c3,c2,c1; ............ ............