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 [3:0] G;
wire [3:0] P;
wire [3:0] C;

assign C[0] = C_1;

assign G[3] = A_in[3] & B_in[3];
assign G[2] = A_in[2] & B_in[2];
assign G[1] = A_in[1] & B_in[1];
assign G[0] = A_in[0] & B_in[0];

assign P[3] = A_in[3] ^ B_in[3];
assign P[2] = A_in[2] ^ B_in[2];
assign P[1] = A_in[1] ^ B_in[1];
assign P[0] = A_in[0] ^ B_in[0];

assign CO   = G[3] + P[3]*C[3];
assign C[3] = G[2] + P[2]*C[2];
assign C[2] = G[1] + P[1]*C[1];
assign C[1] = G[0] + P[0]*C[0];

assign S[3] = P[3]^C[3];
assign S[2] = P[2]^C[2];
assign S[1] = P[1]^C[1];
assign S[0] = P[0]^C[0];

    
endmodule