m3s041bo.v

another 8051 core porocesssor vhdl source code

//*******************************************************************       //
//IMPORTANT NOTICE                                                          //
//================                                                          //
//Copyright Mentor Graphics Corporation 1996 - 1999.  All rights reserved.  //
//This file and associated deliverables are the trade secrets,              //
//confidential information and copyrighted works of Mentor Graphics         //
//Corporation and its licensors and are subject to your license agreement   //
//with Mentor Graphics Corporation.                                         //
//                                                                          //
//Use of these deliverables for the purpose of making silicon from an IC    //
//design is limited to the terms and conditions of your license agreement   //
//with Mentor Graphics If you have further questions please contact Mentor  //
//Graphics Customer Support.                                                //
//                                                                          //
//This Mentor Graphics core (m8051 v1999.120) was extracted on              //
//workstation hostid _hostid_ Inventra                                      //
//M8051 ALU Carry Combiner Element
//Copyright Mentor Graphics Corporation and Licensors 1998. All Rights reserved.
//v1.001
////////////////////////////////////////////////////////////////////////////////
//
// Verilog file generated by X-HDL - Revision 3.0_11 Beta C April 24, 1998
// Thu Jul  9 22:06:23 1998
//
// Input file : m3s041bo.vhd
// Design name : m3s041bo
// Author : 
// Company : Mentor Graphics - Inventra
//
// Description : 
//
//
////////////////////////////////////////////////////////////////////////////////
//
//*********************************************************************
//%W% %G% SCCS Version Control
//File	        :       m3s041bo.vhd
//Created on    :       25th March 1997
//Purpose       :       Gate Level ALU Carry Combiner/Look Ahead Element
//Version       :       1.001
//Mod Date      :       2nd April 1998
//Mod History	:       1.001 _e suffix removed from entity names.
//
//*********************************************************************
//Hierarchy record      :
//Called by             :m3s004bo.vhd
//Calls to              :None
//*********************************************************************
//*********************************************************************
//Entity Definition
//*********************************************************************
module m3s041bo (S, P, G, C_IN, C_EN);
//*******************************************************************       //
//IMPORTANT NOTICE                                                          //
//================                                                          //
//Copyright Mentor Graphics Corporation 1996 - 1999.  All rights reserved.  //
//This file and associated deliverables are the trade secrets,              //
//confidential information and copyrighted works of Mentor Graphics         //
//Corporation and its licensors and are subject to your license agreement   //
//with Mentor Graphics Corporation.                                         //
//                                                                          //
//Use of these deliverables for the purpose of making silicon from an IC    //
//design is limited to the terms and conditions of your license agreement   //
//with Mentor Graphics If you have further questions please contact Mentor  //
//Graphics Customer Support.                                                //
//                                                                          //
//This Mentor Graphics core (m8051 v1999.120) was extracted on              //
//workstation hostid _hostid_ Inventra                                      //

  output[3:0] S;
  reg[3:0] S;
  input[3:0] P;
  input[2:0] G;
  input C_IN;
  input C_EN;

  //*********************************************************************
  // This module combines ALU product/propagate (P) and carry/generate (G)
  // bits to produce carry corrected result (S) of a 4-bit ALU operation
  // (a carry look ahead generator).  It is instantiated separately from
  // the ALU in order to prevent naive synthesis algorithms from producing
  // slow ripple carry implementations of this function.
  always @(P or G or C_IN or C_EN)
  begin
    S[0] <= P[0] ^ C_IN ; 
    S[1] <= P[1] ^ ((C_IN & P[0]) | (C_EN & G[0])) ; 
    S[2] <= P[2] ^ ((C_IN & P[0] & P[1]) | (C_EN & P[1] & G[0]) | (C_EN &
    G[1])) ; 
    S[3] <= P[3] ^ ((C_IN & P[0] & P[1] & P[2]) | (C_EN & P[1] & P[2] & G[
    0]) | (C_EN & P[2] & G[1]) | (C_EN & G[2])) ; 
  end 
  //*********************************************************************
endmodule