git.zerfleddert.de Git - raggedstone/blob - dhwk/source/parity_out.vhd

   1 -- J.STELZNER
   2 -- INFORMATIK-3 LABOR
   3 -- 23.08.2006
   4 -- File: PARITY_OUT.VHD
   5
   6 library ieee;
   7 use ieee.std_logic_1164.all;
   8
   9 entity PARITY_OUT is
  10         port(
  11                 PCI_CLOCK               :in             std_logic;
  12                 PCI_RSTn                :in             std_logic;
  13                 PAR_IN                  :in             std_logic_vector ( 2 downto 0);
  14                 PAR_REG                 :in             std_logic;
  15                 SERR_CHECK      :in             std_logic;
  16                 PERR_CHECK      :in             std_logic;
  17                 OE_PCI_PAR      :in             std_logic;
  18                 OE_PCI_PERR     :in             std_logic;
  19                 PA_ER_RE                :in             std_logic;
  20                 SERR_ENA                :in             std_logic;
  21                 PCI_PAR_IN      :in             std_logic;
  22                 PERR                            :out    std_logic;
  23                 SERR                            :out    std_logic;
  24                 PCI_PERRn               :out    std_logic;      --      s/t/s
  25                 PCI_SERRn               :out    std_logic;      --      o/d
  26                 PCI_PAR                 :out    std_logic               --      t/s
  27                 );
  28 end entity PARITY_OUT;
  29
  30 architecture PARITY_OUT_DESIGN of PARITY_OUT is
  31
  32         signal PAR                      :std_logic;
  33         signal PAR_FF           :std_logic;
  34         signal SERR_FF  :std_logic;
  35         signal PERR_FF  :std_logic;
  36
  37 begin
  38
  39         PAR             <= ( PAR_IN(2) xor PAR_IN(1) xor PAR_IN(0) );
  40
  41         process (PCI_CLOCK, PCI_RSTn)
  42         begin
  43                 if      PCI_RSTn = '0'  then    PAR_FF  <= '0';
  44                                                                                                                         PERR_FF <= '0';
  45                                                                                                                         SERR_FF <= '0';
  46
  47                 elsif (PCI_CLOCK'event and PCI_CLOCK = '1') then
  48
  49                         PAR_FF  <=      PAR;
  50                         SERR_FF <=      ((PCI_PAR_IN xor PAR) and SERR_CHECK) and PA_ER_RE and SERR_ENA and (not SERR_FF);
  51                         PERR_FF <=      ((PCI_PAR_IN xor PAR) and PERR_CHECK) and (not PERR_FF);
  52
  53                 end if;
  54         end process;
  55
  56         SERR                    <=  SERR_FF;
  57         PERR                    <=  PERR_FF;
  58
  59         PCI_PAR         <= PAR_FF                               when    OE_PCI_PAR      = '1' else 'Z' ;
  60         PCI_SERRn       <= '0'                                  when    SERR_FF                 = '1' else 'Z' ;
  61         PCI_PERRn       <= not PERR_FF  when    OE_PCI_PERR     = '1' and PA_ER_RE = '1' else 'Z' ;
  62
  63 end architecture PARITY_OUT_DESIGN;
  64
  65
  66