git.zerfleddert.de Git - raggedstone/blob - dhwk_old/source/pcipargen.vhd

   1 --+-------------------------------------------------------------------------------------------------+
   2 --|                                                                                                                                                                                                     |
   3 --|  File:              pcipargen.vhd                                                                                   |
   4 --|                                                                                                                                                                                                     |
   5 --|  Project:           pci32tlite_oc                                                                                                                                   |
   6 --|                                                                                                                                                                                                     |
   7 --|  Description:       PCI Parity Generator.                                                                                                                   |
   8 --|                                     PCI Target generates PAR in the data phase of a read cycle. The 1's sum on AD,  |
   9 --|                                     CBE and PAR is even.                                                                                    |
  10 --|                                                                                                                                                                                                     |
  11 --+-------------------------------------------------------------------------------------------------+
  12 --|                                                                                                                                                                                                     |
  13 --|  Revision history :                                                                                                                                                         |
  14 --|  Date                 Version       Author  Description                                                                                                             |
  15 --|  2005-05-13   R00A00        PAU             First alfa revision     (eng)                                                                           |
  16 --|                                                                                                                                                                                                     |
  17 --|  To do:                                                                                                                                                                                     |
  18 --|                                                                                                                                                                                                     |
  19 --+-------------------------------------------------------------------------------------------------+
  20 --+-----------------------------------------------------------------+
  21 --|                                                                                                                             |
  22 --|  Copyright (C) 2005 Peio Azkarate, peio@opencores.org               |
  23 --|                                                                                                                             |
  24 --|  This source file may be used and distributed without               |
  25 --|  restriction provided that this copyright statement is not          |
  26 --|  removed from the file and that any derivative work contains        |
  27 --|  the original copyright notice and the associated disclaimer.       |
  28 --|                                                                     |
  29 --|  This source file is free software; you can redistribute it     |
  30 --|  and/or modify it under the terms of the GNU Lesser General     |
  31 --|  Public License as published by the Free Software Foundation;   |
  32 --|  either version 2.1 of the License, or (at your option) any     |
  33 --|  later version.                                                 |
  34 --|                                                                                                                             |
  35 --|  This source is distributed in the hope that it will be         |
  36 --|  useful, but WITHOUT ANY WARRANTY; without even the implied     |
  37 --|  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR        |
  38 --|  PURPOSE.  See the GNU Lesser General Public License for more   |
  39 --|  details.                                                       |
  40 --|                                                                                                                             |
  41 --|  You should have received a copy of the GNU Lesser General      |
  42 --|  Public License along with this source; if not, download it     |
  43 --|  from http://www.opencores.org/lgpl.shtml                       |
  44 --|                                                                                                                             |
  45 --+-----------------------------------------------------------------+
  46
  47
  48 --+-----------------------------------------------------------------------------+
  49 --|                                                                     LIBRARIES                                                                       |
  50 --+-----------------------------------------------------------------------------+
  51
  52 library ieee;
  53 use ieee.std_logic_1164.all;
  54
  55
  56
  57 --+-----------------------------------------------------------------------------+
  58 --|                                                                     ENTITY                                                                          |
  59 --+-----------------------------------------------------------------------------+
  60
  61 entity pcipargen is
  62 port (
  63
  64         clk_i                   : in std_logic;
  65         pcidatout_i             : in std_logic_vector(31 downto 0);
  66         cbe_i                   : in std_logic_vector(3 downto 0);
  67         parOE_i                 : in std_logic;
  68         par_o                   : out std_logic
  69
  70 );
  71 end pcipargen;
  72
  73
  74 architecture rtl of pcipargen is
  75
  76
  77 --+-----------------------------------------------------------------------------+
  78 --|                                                                     COMPONENTS                                                                      |
  79 --+-----------------------------------------------------------------------------+
  80 --+-----------------------------------------------------------------------------+
  81 --|                                                                     CONSTANTS                                                                       |
  82 --+-----------------------------------------------------------------------------+
  83 --+-----------------------------------------------------------------------------+
  84 --|                                                                     SIGNALS                                                                         |
  85 --+-----------------------------------------------------------------------------+
  86
  87         signal d                        : std_logic_vector(31 downto 0);
  88         signal pardat           : std_logic;
  89         signal parcbe           : std_logic;
  90         signal par                      : std_logic;
  91         signal par_s            : std_logic;
  92
  93 component sync
  94 port (
  95     clk             : in std_logic;
  96     d           : in std_logic;
  97     q               : out std_logic
  98 );
  99 end component;
 100
 101 component sync2
 102 port (
 103     clk             : in std_logic;
 104     d           : in std_logic;
 105     q               : out std_logic
 106 );
 107 end component;
 108
 109 begin
 110
 111
 112         d <= pcidatout_i;
 113
 114
 115     --+-------------------------------------------------------------------------+
 116         --|  building parity                                                                                                            |
 117     --+-------------------------------------------------------------------------+
 118
 119         pardat  <= d(0)  xor d(1)  xor d(2)  xor d(3)  xor d(4)  xor d(5)  xor d(6)  xor d(7)  xor
 120                            d(8)  xor d(9)  xor d(10) xor d(11) xor d(12) xor d(13) xor d(14) xor d(15) xor
 121                            d(16) xor d(17) xor d(18) xor d(19) xor d(20) xor d(21) xor d(22) xor d(23) xor
 122                            d(24) xor d(25) xor d(26) xor d(27) xor d(28) xor d(29) xor d(30) xor d(31);
 123
 124         parcbe  <= cbe_i(0) xor cbe_i(1) xor cbe_i(2) xor cbe_i(3);
 125
 126         par <= pardat xor parcbe;
 127
 128     -- u1: sync port map ( clk => clk_i, d => par, q => par_s );
 129
 130     u1: sync2 port map (
 131                 clk => clk_i,
 132                 d => par,
 133                 q => par_s
 134         );
 135
 136
 137     --+-------------------------------------------------------------------------+
 138     --|  PAR                                                                                                                                    |
 139     --+-------------------------------------------------------------------------+
 140
 141         par_o <= par_s when ( parOE_i = '1' ) else 'Z';
 142
 143
 144 end rtl;