题解 | #超前进位加法器#

`timescale 1ns/1ns

module huawei8//四位超前进位加法器
(
	input wire [3:0]A,
	input wire [3:0]B,
	output wire [4:0]OUT
);

//*************code***********//
       wire [3:0] G;

       wire [3:0] P;

       wire [3:0] F;

       wire [4:1] C;



 Add1 u1

 (    .a(A[0]),

       .b(B[0]),

       .C_in(1'b0),

       .f(F[0]),

       .g(G[0]),

       .p(P[0])

 );

  Add1 u2

 (    .a(A[1]),

       .b(B[1]),

       .C_in(C[1]),

       .f(F[1]),

       .g(G[1]),

       .p(P[1])

 );

   Add1 u3

 (    .a(A[2]),

       .b(B[2]),

       .C_in(C[2]),

       .f(F[2]),

       .g(G[2]),

       .p(P[2])

 );

   Add1 u4

 (    .a(A[3]),

       .b(B[3]),

       .C_in(C[3]),

       .f(F[3]),

       .g(G[3]),

       .p(P[3])

 );

 CLA_4 uut

 (

       .P(P),

       .G(G),

       .C_in(1'b0),

       .Ci(C),

       .Gm(),

       .Pm()

 );

  assign OUT={C[4],F};

//*************code***********//
endmodule



//////////////下面是两个子模块////////

module Add1
(
		input a,
		input b,
		input C_in,
		output f,
		output g,
		output p
		);

assign f = a^b^C_in;
assign g = a & b;
assign p = a | b;
endmodule



module CLA_4(
		input [3:0]P,
		input [3:0]G,
		input C_in,
		output [4:1]Ci,
		output Gm,
		output Pm
	);

assign Ci[1]=G[0]|P[0]&C_in; 
assign Ci[2] = G[1]|P[1]&G[0]|P[1]&P[0]&C_in; 
assign Ci[3]=  G[2]|P[2]&G[1]|P[2]&P[1]&G[0]|P[2]&P[1]&P[0]&C_in;
assign Ci[4]=  G[3]|P[3]&G[2]|P[3]&P[2]&G[1]|P[3]&P[2]&P[1]&G[0]|P[3]&P[2]&P[1]&P[0]&C_in;




assign Gm=G[3]|P[3]&G[2]|P[3]&P[2]&G[1]|P[3]&P[2]&P[1]&G[0];
assign Pm=P[3]&P[2]&P[1]&P[0];





endmodule