git.zerfleddert.de Git - raggedstone/blob - dhwk/source/pci/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                 SERR_FF <= ((PCI_PAR_IN xor PAR) and SERR_CHECK) and PA_ER_RE and SERR_ENA and (not SERR_FF);
  49                 PERR_FF <= ((PCI_PAR_IN xor PAR) and PERR_CHECK) and (not PERR_FF);
  50         end if;
  51 end process;
  52
  53 SERR <= SERR_FF;
  54 PERR <= PERR_FF;
  55
  56 PCI_PAR <= PAR_FF when OE_PCI_PAR = '1' else 'Z';
  57 PCI_SERRn <= '0' when SERR_FF = '1' else 'Z';
  58 PCI_PERRn <= not PERR_FF when OE_PCI_PERR = '1' and PA_ER_RE = '1' else 'Z';
  59
  60 end architecture PARITY_OUT_DESIGN;