`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date:    11:57:31 07/22/2018 
// Design Name: 
// Module Name:    Brent_kung_tree 
// Project Name: 
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
module Brent_kung_tree(a,b,s,cout,cin);
input [7:0] a,b;
output [7:0] s;
output cout;
input cin;
wire c1,c2,c3,c4,c5,c6,c7;
wire p0,p1,p2,p3,p4,p5,p6,p7,g0,g1,g2,g3,g4,g5,g6,g7;
wire p10,p20,p30,p40,p50,p60,p70,g10,g20,g30,g40,g50,g60,g70;
wire p32,p54,p76,p74,g32,g54,g76,g74;
node1 n1(a[0],b[0],g0,p0);
node1 n2(a[1],b[1],g1,p1);
node1 n3(a[2],b[2],g2,p2);
node1 n4(a[3],b[3],g3,p3);
node1 n5(a[4],b[4],g4,p4);
node1 n6(a[5],b[5],g5,p5);
node1 n7(a[6],b[6],g6,p6);
node1 n8(a[7],b[7],g7,p7);

node2 n9(p0,p1,g0,g1,p10,g10);
node2 n10(p2,p3,g2,g3,p32,g32);
node2 n11(p4,p5,g4,g5,p54,g54);
node2 n12(p6,p7,g6,g7,p76,g76);

node2 n13(p10,p32,g10,g32,p30,g30);
node2 n14(p54,p76,g54,g76,p74,g74);

node2 n15(p30,p74,g30,g74,p70,g70);

node2 n16(p10,p2,g10,g2,p20,g20);
node2 n17(p30,p4,g30,g4,p40,g40);
node2 n18(p30,p54,g30,g54,p50,g50);
node2 n19(p50,p6,g50,g6,p60,g60);

node3 n20(p0,g0,cin,c1,s[0]);
node3 n21(p1,g10,c1,c2,s[1]);
node3 n22(p2,g20,c2,c3,s[2]);
node3 n23(p3,g30,c3,c4,s[3]);
node3 n24(p4,g40,c4,c5,s[4]);
node3 n25(p5,g50,c5,c6,s[5]);
node3 n26(p6,g60,c6,c7,s[6]);
node3 n27(p7,g70,c7,cout,s[7]);
endmodule

module node1(
  input a,b,
  output g,p
    );
assign p = a^b;
assign g = a&b;
endmodule

module node2(p0,p1,g0,g1,p10,g10
    );
input p1,p0,g0,g1;
output p10,g10;
assign p10 = p1 & p0;
assign g10 = g1 | (p1 & g0);
endmodule

module node3(p,g,cin,cout,sum
    );
input p,g,cin;
output cout,sum;
assign cout = g | (g & cin);
assign sum = p ^ cin;
endmodule