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[raggedstone] / dhwk / source / pci / fifo_io_control.vhd

-- $Id: fifo_io_control.vhd,v 1.2 2007-03-11 09:14:58 sithglan Exp $

library IEEE;
use IEEE.std_logic_1164.all;

entity FIFO_IO_CONTROL is
        port
        (
                PCI_CLOCK :in std_logic;
                WRITE_XX1_0 :in std_logic; -- PCI Write
                FIFO_RDn :in std_logic; -- FIFO Read (low active)
                RESET :in std_logic;
                SYNC_FLAG_1 :in std_logic; -- Recv FIFO Empty (low active)
                SYNC_FLAG_7 :in std_logic; -- Send FIFO Full (low active)
                S_FIFO_RESETn :out std_logic; -- Send FIFO Reset (low active)
                R_FIFO_RESETn :out std_logic; -- Recv FIFO Reset (low active)
                S_FIFO_WRITEn :out std_logic; -- Send FIFO Write (low active)
                R_FIFO_READn :out std_logic; -- Recv FIFO Read (low active)
                S_FIFO_RETRANSMITn :out std_logic; -- Send FIFO Retransmit (low active)
                R_FIFO_RETRANSMITn :out std_logic; -- Recv FIFO Retransmit (low active)
                S_ERROR :out std_logic; -- Send ERROR
                R_ERROR :out std_logic; -- Recv ERROR
                SR_ERROR :out std_logic -- Send / Recv Error
        );
end entity FIFO_IO_CONTROL;

architecture FIFO_IO_CONTROL_DESIGN of FIFO_IO_CONTROL is

        signal SIG_S_ERROR :std_logic; -- Send Error
        signal SIG_R_ERROR :std_logic; -- Recv Error

begin

 -- FIFO Write

        process (PCI_CLOCK)
        begin
                if (rising_edge(PCI_CLOCK)) then
                        if (RESET = '1') then
                                S_FIFO_WRITEn <= '1';
                                SIG_S_ERROR <= '0';

                        elsif (WRITE_XX1_0 = '0') then
                                S_FIFO_WRITEn <= '1';

                        elsif (WRITE_XX1_0 = '1') then
                                if (SYNC_FLAG_7 = '0') then
                                        SIG_S_ERROR <= '1';

                                elsif (SYNC_FLAG_7 = '1') then
                                        S_FIFO_WRITEn <= '0';
                                        SIG_S_ERROR <= '0';
                                end if;
                        end if;
                end if;
        end process;

        S_ERROR <= SIG_S_ERROR;

 -- FIFO Read

        R_FIFO_READn <= FIFO_RDn;

-- Receive Error

        process (PCI_CLOCK)
        begin
                if (PCI_CLOCK'event and PCI_CLOCK ='1') then
                        if (RESET = '1') then
                                SIG_R_ERROR <= '0';

                        elsif (FIFO_RDn = '0' and SYNC_FLAG_1 = '0') then
                                SIG_R_ERROR <= '1';
                        end if;
                end if;
        end process;

        R_ERROR <= SIG_R_ERROR;

-- Send or Receive Error

        process (PCI_CLOCK)
        begin
                if (PCI_CLOCK'event and PCI_CLOCK ='1') then
                        SR_ERROR <= SIG_S_ERROR or SIG_R_ERROR;
                end if;
        end process;

-- FIFO Reset

        process (PCI_CLOCK)
        begin
                if (PCI_CLOCK'event and PCI_CLOCK ='1') then
                        S_FIFO_RESETn <= not RESET;
                        R_FIFO_RESETn <= not RESET;
                end if;
        end process;


-- FIFO Retransmit

        process (PCI_CLOCK)
        begin
                if (PCI_CLOCK'event and PCI_CLOCK ='1') then
                        S_FIFO_RETRANSMITn <= '1';
                        R_FIFO_RETRANSMITn <= '1';
                end if;
        end process;

end architecture FIFO_IO_CONTROL_DESIGN;