`timescale 1ns/10ps//===============================================================================//           TOP Level --->    8-bit RCA Source Code//                                     ---BAO Chaowei    Mar 3rd,2009//===============================================================================module  RCA_8bit(COUT,                 SUM,                 A,                 B,                 CIN                 );                   output         COUT;  output  [7:0]  SUM;  input   [7:0]  A;  input   [7:0]  B;  input          CIN;    wire   cout0,cout1,cout2,cout3,cout4,cout5,cout6,cout7;    RCA_CELL RCA_BIT0(.co     (cout0),                    .s      (SUM[0]),                    .a      (A[0]),                    .b      (B[0]),                    .ci     (CIN)                    );    RCA_CELL RCA_BIT1(.co     (cout1),                    .s      (SUM[1]),                    .a      (A[1]),                    .b      (B[1]),                    .ci     (cout0)                    );    RCA_CELL RCA_BIT2(.co     (cout2),                    .s      (SUM[2]),                    .a      (A[2]),                    .b      (B[2]),                    .ci     (cout1)                    );    RCA_CELL RCA_BIT3(.co     (cout3),                    .s      (SUM[3]),                    .a      (A[3]),                    .b      (B[3]),                    .ci     (cout2)                    );    RCA_CELL RCA_BIT4(.co     (cout4),                    .s      (SUM[4]),                    .a      (A[4]),                    .b      (B[4]),                    .ci     (cout3)                    );  RCA_CELL RCA_BIT5(.co     (cout5),                    .s      (SUM[5]),                    .a      (A[5]),                    .b      (B[5]),                    .ci     (cout4)                    );  RCA_CELL RCA_BIT6(.co     (cout6),                    .s      (SUM[6]),                    .a      (A[6]),                    .b      (B[6]),                    .ci     (cout5)                    );  RCA_CELL RCA_BIT7(.co     (cout7),                    .s      (SUM[7]),                    .a      (A[7]),                    .b      (B[7]),                    .ci     (cout6)                    );  assign   COUT  = cout7;endmodule//=======================1-bit cell for RCA(Ripple Carry Adder)=======================module  RCA_CELL(co,                 s,                 a,                 b,                 ci                 );                   output    co;  output    s;  input     a;  input     b;  input     ci;    assign   co = (a&&b) || (a&&ci) || (b&&ci);  assign   s  = a^b^ci;            endmodule