pci_parity_check.v

这是用pci-wishbone核和16450串口核在xilinx的fpga上实现的串口程序

//////////////////////////////////////////////////////////////////////
////                                                              ////
////  File name "pci_parity_check.v"                              ////
////                                                              ////
////  This file is part of the "PCI bridge" project               ////
////  http://www.opencores.org/cores/pci/                         ////
////                                                              ////
////  Author(s):                                                  ////
////      - Miha Dolenc ([e-mail])                     ////
////                                                              ////
////  All additional information is avaliable in the README       ////
////  file.                                                       ////
////                                                              ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2001 Miha Dolenc, [e-mail]          ////
////                                                              ////
//// This source file may be used and distributed without         ////
//// restriction provided that this copyright statement is not    ////
//// removed from the file and that any derivative work contains  ////
//// the original copyright notice and the associated disclaimer. ////
////                                                              ////
//// This source file is free software; you can redistribute it   ////
//// and/or modify it under the terms of the GNU Lesser General   ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any   ////
//// later version.                                               ////
////                                                              ////
//// This source is distributed in the hope that it will be       ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
//// PURPOSE.  See the GNU Lesser General Public License for more ////
//// details.                                                     ////
////                                                              ////
//// You should have received a copy of the GNU Lesser General    ////
//// Public License along with this source; if not, download it   ////
//// from http://www.opencores.org/lgpl.shtml                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: pci_parity_check.v,v $
// Revision 1.6  2003/02/13 18:26:33  mihad
// Cleaned up the code. No functional changes.
//
// Revision 1.5  2003/01/27 16:49:31  mihad
// Changed module and file names. Updated scripts accordingly. FIFO synchronizations changed.
//
// Revision 1.4  2002/08/13 11:03:53  mihad
// Added a few testcases. Repaired wrong reset value for PCI_AM5 register. Repaired Parity Error Detected bit setting. Changed PCI_AM0 to always enabled(regardles of PCI_AM0 define), if image 0 is used as configuration image
//
// Revision 1.3  2002/02/01 15:25:12  mihad
// Repaired a few bugs, updated specification, added test bench files and design document
//
// Revision 1.2  2001/10/05 08:14:30  mihad
// Updated all files with inclusion of timescale file for simulation purposes.
//
// Revision 1.1.1.1  2001/10/02 15:33:47  mihad
// New project directory structure
//
//

// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
`include "pci_constants.v"
`include "bus_commands.v"

module pci_parity_check
(
    reset_in,
    clk_in,
    pci_par_in,
    pci_par_out,
    pci_par_en_out,
    pci_perr_in,
    pci_perr_out,
    pci_perr_out_in,
    pci_perr_en_out,
    pci_serr_en_in,
    pci_serr_out,
    pci_serr_out_in,
    pci_serr_en_out,
    pci_frame_reg_in,
    pci_frame_en_in,
    pci_irdy_en_in,
    pci_irdy_reg_in,
    pci_trdy_reg_in,
    pci_trdy_en_in,
    pci_par_en_in,
    pci_ad_out_in,
    pci_ad_reg_in,
    pci_cbe_in_in,
    pci_cbe_reg_in,
    pci_cbe_out_in,
    pci_cbe_en_in,
    pci_ad_en_in,
    par_err_response_in,
    par_err_detect_out,
    perr_mas_detect_out,

    serr_enable_in,
    sig_serr_out

);

// system inputs
input       reset_in ;
input       clk_in ;

// pci signals that are monitored or generated by parity error checker
input           pci_par_in ;            // pci PAR input
output          pci_par_out ;           // pci_PAR output
output          pci_par_en_out ;        // pci PAR enable output
input           pci_perr_in ;           // PERR# input
output          pci_perr_out ;          // PERR# output
output          pci_perr_en_out ;       // PERR# buffer enable output
input           pci_serr_en_in ;        // SERR enable input
output          pci_serr_out ;          // SERR# output
input           pci_serr_out_in ;       // SERR# output value input
input           pci_perr_out_in ;       // PERR# output value input
output          pci_serr_en_out ;       // SERR# buffer enable output
input           pci_frame_reg_in ;       // frame from pci bus input
input           pci_frame_en_in ;       // frame enable driven by master state machine
input           pci_irdy_en_in ;        // irdy enable input from PCI master
input           pci_irdy_reg_in ;        // irdy from PCI bus
input           pci_trdy_reg_in ;        // target ready from PCI bus
input           pci_trdy_en_in ;        // target ready output enable
input           pci_par_en_in ;         // par enable input
input [31:0]    pci_ad_out_in ;         // data driven by bridge to PCI
input [31:0]    pci_ad_reg_in ;          // data driven by other agents on PCI
input [3:0]     pci_cbe_in_in ;         // cbe driven by outside agents
input [3:0]     pci_cbe_reg_in ;        // registered cbe driven by outside agents
input [3:0]     pci_cbe_out_in ;        // cbe driven by pci master state machine
input           pci_ad_en_in ;          // ad enable input
input           par_err_response_in ;   // parity error response bit from conf.space
output          par_err_detect_out ;    // parity error detected signal out
output          perr_mas_detect_out ;   // master asserted PERR or sampled PERR asserted
input           serr_enable_in ;        // system error enable bit from conf.space
output          sig_serr_out ;          // signalled system error output for configuration space
input           pci_cbe_en_in ;

// FFs for frame input - used for determining whether PAR is sampled for address phase or for data phase
reg     frame_dec2 ;
reg check_perr ;

/*=======================================================================================================================
CBE lines' parity is needed for overall parity calculation
=======================================================================================================================*/
wire par_cbe_out = pci_cbe_out_in[3] ^ pci_cbe_out_in[2] ^ pci_cbe_out_in[1] ^ pci_cbe_out_in[0] ;
wire par_cbe_in  = pci_cbe_reg_in[3] ^ pci_cbe_reg_in[2] ^ pci_cbe_reg_in[1] ^ pci_cbe_reg_in[0] ;

/*=======================================================================================================================
Parity generator - parity is generated and assigned to output on every clock edge. PAR output enable is active
one clock cycle after data output enable. Depending on whether master is performing access or target is responding,
apropriate cbe data is included in parity generation. Non - registered CBE is used during reads through target SM
=======================================================================================================================*/

// generate appropriate par signal
wire data_par = (pci_ad_out_in[31] ^ pci_ad_out_in[30] ^ pci_ad_out_in[29] ^ pci_ad_out_in[28]) ^
                (pci_ad_out_in[27] ^ pci_ad_out_in[26] ^ pci_ad_out_in[25] ^ pci_ad_out_in[24]) ^
                (pci_ad_out_in[23] ^ pci_ad_out_in[22] ^ pci_ad_out_in[21] ^ pci_ad_out_in[20]) ^
                (pci_ad_out_in[19] ^ pci_ad_out_in[18] ^ pci_ad_out_in[17] ^ pci_ad_out_in[16]) ^
                (pci_ad_out_in[15] ^ pci_ad_out_in[14] ^ pci_ad_out_in[13] ^ pci_ad_out_in[12]) ^
                (pci_ad_out_in[11] ^ pci_ad_out_in[10] ^ pci_ad_out_in[9]  ^ pci_ad_out_in[8])  ^
                (pci_ad_out_in[7]  ^ pci_ad_out_in[6]  ^ pci_ad_out_in[5]  ^ pci_ad_out_in[4])  ^
                (pci_ad_out_in[3]  ^ pci_ad_out_in[2]  ^ pci_ad_out_in[1]  ^ pci_ad_out_in[0]) ;