git.zerfleddert.de Git - raggedstone/blob - ethernet/source/pci/pci_out_reg.v

   1 //////////////////////////////////////////////////////////////////////
   2 ////                                                              ////
   3 ////  File name "out_reg.v"                                       ////
   4 ////                                                              ////
   5 ////  This file is part of the "PCI bridge" project               ////
   6 ////  http://www.opencores.org/cores/pci/                         ////
   7 ////                                                              ////
   8 ////  Author(s):                                                  ////
   9 ////      - Miha Dolenc (mihad@opencores.org)                     ////
  10 ////                                                              ////
  11 ////  All additional information is avaliable in the README       ////
  12 ////  file.                                                       ////
  13 ////                                                              ////
  14 ////                                                              ////
  15 //////////////////////////////////////////////////////////////////////
  16 ////                                                              ////
  17 //// Copyright (C) 2001 Miha Dolenc, mihad@opencores.org          ////
  18 ////                                                              ////
  19 //// This source file may be used and distributed without         ////
  20 //// restriction provided that this copyright statement is not    ////
  21 //// removed from the file and that any derivative work contains  ////
  22 //// the original copyright notice and the associated disclaimer. ////
  23 ////                                                              ////
  24 //// This source file is free software; you can redistribute it   ////
  25 //// and/or modify it under the terms of the GNU Lesser General   ////
  26 //// Public License as published by the Free Software Foundation; ////
  27 //// either version 2.1 of the License, or (at your option) any   ////
  28 //// later version.                                               ////
  29 ////                                                              ////
  30 //// This source is distributed in the hope that it will be       ////
  31 //// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
  32 //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
  33 //// PURPOSE.  See the GNU Lesser General Public License for more ////
  34 //// details.                                                     ////
  35 ////                                                              ////
  36 //// You should have received a copy of the GNU Lesser General    ////
  37 //// Public License along with this source; if not, download it   ////
  38 //// from http://www.opencores.org/lgpl.shtml                     ////
  39 ////                                                              ////
  40 //////////////////////////////////////////////////////////////////////
  41 //
  42 // CVS Revision History
  43 //
  44 // $Log: pci_out_reg.v,v $
  45 // Revision 1.1  2007-03-20 17:50:56  sithglan
  46 // add shit
  47 //
  48 // Revision 1.1  2003/01/27 16:49:31  mihad
  49 // Changed module and file names. Updated scripts accordingly. FIFO synchronizations changed.
  50 //
  51 // Revision 1.3  2002/02/01 15:25:12  mihad
  52 // Repaired a few bugs, updated specification, added test bench files and design document
  53 //
  54 // Revision 1.2  2001/10/05 08:14:28  mihad
  55 // Updated all files with inclusion of timescale file for simulation purposes.
  56 //
  57 // Revision 1.1.1.1  2001/10/02 15:33:46  mihad
  58 // New project directory structure
  59 //
  60 //
  61
  62 `include "pci_constants.v"
  63
  64 // synopsys translate_off
  65 `include "timescale.v"
  66 // synopsys translate_on
  67
  68 // module inferes a single IOB output block as known in FPGA architectures
  69 // It provides data flip flop with clock enable and output enable flip flop with clock enable
  70 // This is tested in Xilinx FPGA - active low output enable
  71 // Check polarity of output enable flip flop for specific architecure.
  72 module pci_out_reg
  73 (
  74     reset_in,
  75     clk_in,
  76     dat_en_in,
  77     en_en_in,
  78     dat_in,
  79     en_in,
  80     en_out,
  81     dat_out
  82 );
  83
  84 input   reset_in,
  85         clk_in,
  86         dat_en_in,
  87         en_en_in,
  88         dat_in,
  89         en_in ;
  90
  91 output dat_out ;
  92 output en_out ;
  93
  94 reg dat_out,
  95     en_out ;
  96
  97 `ifdef ACTIVE_LOW_OE
  98 wire en = ~en_in ;
  99 `else
 100 `ifdef ACTIVE_HIGH_OE
 101 wire en = en_in ;
 102 `endif
 103 `endif
 104
 105 always@(posedge reset_in or posedge clk_in)
 106 begin
 107     if ( reset_in )
 108         dat_out <= #`FF_DELAY 1'b0 ;
 109     else if ( dat_en_in )
 110         dat_out <= #`FF_DELAY dat_in ;
 111 end
 112
 113 always@(posedge reset_in or posedge clk_in)
 114 begin
 115     if ( reset_in )
 116         `ifdef ACTIVE_LOW_OE
 117         en_out <= #`FF_DELAY 1'b1 ;
 118         `else
 119         `ifdef ACTIVE_HIGH_OE
 120         en_out <= #`FF_DELAY 1'b0 ;
 121         `endif
 122         `endif
 123     else if ( en_en_in )
 124         en_out <= #`FF_DELAY en ;
 125 end
 126
 127 endmodule