cla_8bit.v

IP core of adder,8-bit width, three design concerpts with different effect.

`timescale 1ns/10ps
//===============================================================================
//           TOP Level --->    8-bit CLA Source Code
//                                     ---BAO Chaowei    Mar 3rd,2009
//===============================================================================
module  CLA_8bit(COUT,
                 SUM,
                 A,
                 B,
                 CIN
                 );
                 
  output         COUT;
  output  [7:0]  SUM;
  input   [7:0]  A;
  input   [7:0]  B;
  input          CIN;
  
  wire   [7:0]  P;
  wire   [7:0]  G;
  wire   [7:0]  CO;
  
  PG_GENERATOR  PG_INST(.P   (P),
                        .G   (G),
                        .A   (A),
                        .B   (B)
                        );
  
  CY_GENERATOR  CY_INST(.CO  (CO),
                        .P   (P),
                        .G   (G),
                        .Ci  (CIN)
                        );
  
  assign   SUM[7:0]  = P[7:0] ^ {CO[6:0],CIN};  
  assign   COUT      = CO[7];
  
endmodule



//=======================PG Generator for 8-bit CLA=======================
module  PG_GENERATOR(P,
                     G,
                     A,
                     B
                     );
  
  output   [7:0]  P;
  output   [7:0]  G;
  input    [7:0]  A;
  input    [7:0]  B;
  
  assign   P  = A^B;
  assign   G  = A&B;
      
    
endmodule



//=======================Carry Generator for 8-bit CLA=======================
module  CY_GENERATOR(CO,
                     P,
                     G,
                     Ci
                     );
  output   [7:0]  CO;
  input    [7:0]  P;
  input    [7:0]  G;
  input           Ci;
  
  assign   CO[0]  = G[0] || (P[0]&&Ci);
  assign   CO[1]  = G[1] || (P[1]&&G[0]) || (P[1]&&P[0]&&Ci);
  assign   CO[2]  = G[2] || (P[2]&&G[1]) || (P[2]&&P[1]&&G[0]) || (P[2]&&P[1]&&P[0]&&Ci);
  assign   CO[3]  = 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]&&Ci); 
  assign   CO[4]  = G[4] || (P[4]&&G[3]) || (P[4]&&P[3]&&G[2]) || (P[4]&&P[3]&&P[2]&&G[1]) || (P[4]&&P[3]&&P[2]&&P[1]&&G[0]) || (P[4]&&P[3]&&P[2]&&P[1]&&P[0]&&Ci);
  assign   CO[5]  = G[5] || (P[5]&&G[4]) || (P[5]&&P[4]&&G[3]) || (P[5]&&P[4]&&P[3]&&G[2]) || (P[5]&&P[4]&&P[3]&&P[2]&&G[1]) || (P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&G[0]) || (P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&P[0]&&Ci);  
  assign   CO[6]  = G[6] || (P[6]&&G[5]) || (P[6]&&P[5]&&G[4]) || (P[6]&&P[5]&&P[4]&&G[3]) || (P[6]&&P[5]&&P[4]&&P[3]&&G[2]) || (P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&G[1]) || (P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&G[0]) || (P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&P[0]&&Ci);
  assign   CO[7]  = G[7] || (P[7]&&G[6]) || (P[7]&&P[6]&&G[5]) || (P[7]&&P[6]&&P[5]&&G[4]) || (P[7]&&P[6]&&P[5]&&P[4]&&G[3]) || (P[7]&&P[6]&&P[5]&&P[4]&&P[3]&&G[2]) || (P[7]&&P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&G[1]) || (P[7]&&P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&G[0]) || (P[7]&&P[6]&&P[5]&&P[4]&&P[3]&&P[2]&&P[1]&&P[0]&&Ci);
  
  
endmodule