题解 | #4bit超前进位加法器电路#
4bit超前进位加法器电路
https://www.nowcoder.com/practice/4d5b6dc4bb2848039da2ee40f9738363
`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;
assign G[0] = A_in[0] & B_in[0];
assign G[1] = A_in[1] & B_in[1];
assign G[2] = A_in[2] & B_in[2];
assign G[3] = A_in[3] & B_in[3];
assign P[0] = A_in[0] ^ B_in[0];
assign P[1] = A_in[1] ^ B_in[1];
assign P[2] = A_in[2] ^ B_in[2];
assign P[3] = A_in[3] ^ B_in[3];
wire [3:0] C;
assign S[0] = P[0] ^ C_1;
assign S[1] = P[1] ^ C[0];
assign S[2] = P[2] ^ C[1];
assign S[3] = P[3] ^ C[2];
assign CO = C[3];
assign C[0] = G[0] | P[0]&C_1;
assign C[1] = G[1] | P[1]&C[0];
assign C[2] = G[2] | P[2]&C[1];
assign C[3] = G[3] | P[3]&C[2];
endmodule
这种写法是最基础的写法。
尝试用别的方法来写:
`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;
genvar gi;
generate
for(gi=0;gi<4;gi=gi+1)begin:G_module
assign G[gi]=A_in[gi]&B_in[gi];
end
endgenerate
genvar pi;
generate
for(pi=0;pi<4;pi=pi+1)begin:P_module
assign P[pi]=A_in[pi]^B_in[pi];
end
endgenerate
wire [3:0] C;
assign S[0] = P[0] ^ C_1;
assign S[1] = P[1] ^ C[0];
assign S[2] = P[2] ^ C[1];
assign S[3] = P[3] ^ C[2];
assign CO = C[3];
assign C[0] = G[0] | P[0]&C_1;
assign C[1] = G[1] | P[1]&C[0];
assign C[2] = G[2] | P[2]&C[1];
assign C[3] = G[3] | P[3]&C[2];
endmodule
