题解 | #4bit超前进位加法器电路#

`timescale 1ns/1ns

module lca_4(
	input		[3:0]       A_in  ,
	input	    [3:0]		B_in  ,
    input                   C_1   ,
 
 	output	 wire			CO    ,
	output   wire [3:0]	    S
);
wire co1,co2,co3,co4;
add inst1(.a(A_in[0]), .b(B_in[0]), .cin(C_1), .co(co1), .s(S[0]));
add inst2(.a(A_in[1]), .b(B_in[1]), .cin(co1), .co(co2), .s(S[1]));
add inst3(.a(A_in[2]), .b(B_in[2]), .cin(co2), .co(co3), .s(S[2]));
add inst4(.a(A_in[3]), .b(B_in[3]), .cin(co3), .co(CO),  .s(S[3]));

endmodule

module add(
	input	a,
	input	b,
	input	cin,
	output	co,
	output	s 
);
	wire g;
	wire p;
	assign	g  = a&b;
	assign	p  = a^b;
	assign	s  = p^cin;
	assign	co = g | (p&cin); 
endmodule