dcm

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

-- J.STELZNER
-- INFORMATIK-3 LABOR
-- 23.08.2006
-- File: COMM_FSM.VHD

library ieee;
use ieee.std_logic_1164.all;

entity COMM_FSM is
        port
        (
                PCI_CLOCK :in std_logic;
                PCI_RSTn :in std_logic;
                IO_READ :in std_logic;
                IO_WRITE :in std_logic;
                CONF_READ :in std_logic;
                CONF_WRITE :in std_logic;
                DEVSELn :in std_logic;

                IO_RD_COM : out std_logic;--> MUX_SEL(0)
                CF_RD_COM :out std_logic;
                IO_WR_COM :out std_logic;
                CF_WR_COM :out std_logic
        );
end entity COMM_FSM;

architecture COMM_FSM_DESIGN of COMM_FSM is


 --**********************************************************
 --*** COMMAND FSM CODIERUNG ***
 --**********************************************************
 --
 --
 -- |--------- IO_RD_COM
 -- ||-------- CF_RD_COM
 -- |||------- IO_WR_COM
 -- ||||------ CF_WR_COM
 -- ||||
        constant ST_IDLE_COMM :std_logic_vector (3 downto 0) := "0000";--
        constant ST_CONF_WRITE :std_logic_vector (3 downto 0) := "0001";--
        constant ST_IO_WRITE :std_logic_vector (3 downto 0) := "0010";--
        constant ST_CONF_READ :std_logic_vector (3 downto 0) := "0100";--
        constant ST_IO_READ :std_logic_vector (3 downto 0) := "1000";--

        signal COMM_STATE :std_logic_vector (3 downto 0);

 --************************************************************
 --*** FSM SPEICHER-AUTOMAT ***
 --************************************************************

        attribute syn_state_machine : boolean;
        attribute syn_state_machine of COMM_STATE : signal is false;

begin

 --**********************************************************
 --*** COMMAND FSM ***
 --**********************************************************

        process (PCI_CLOCK, PCI_RSTn)
        begin
        if PCI_RSTn = '0' then
                COMM_STATE <= "0000";

        elsif (rising_edge(PCI_CLOCK)) then
                case COMM_STATE is
                when ST_IDLE_COMM =>
                        if IO_READ = '1' then COMM_STATE <= ST_IO_READ;

                        elsif CONF_READ = '1' then
                                COMM_STATE <= ST_CONF_READ;

                        elsif IO_WRITE = '1' then
                                COMM_STATE <= ST_IO_WRITE;

                        elsif CONF_WRITE = '1' then
                                COMM_STATE <= ST_CONF_WRITE;

                        else
                                COMM_STATE <= ST_IDLE_COMM;
                        end if;

                when ST_IO_READ =>
                        if DEVSELn = '1' then
                                COMM_STATE <= ST_IDLE_COMM;
                        end if;

                when ST_CONF_READ =>
                        if DEVSELn = '1' then
                                COMM_STATE <= ST_IDLE_COMM;
                        end if;

                when ST_IO_WRITE =>
                        if DEVSELn = '1' then
                                COMM_STATE <= ST_IDLE_COMM;
                        end if;

                when ST_CONF_WRITE =>
                        if DEVSELn = '1' then
                                COMM_STATE <= ST_IDLE_COMM;
                        end if;

                when others =>
                        COMM_STATE <= ST_IDLE_COMM;

                end case; -- COMM_STATE
        end if; -- CLOCK
end process; -- PROCESS

 IO_RD_COM <= COMM_STATE(3);
 CF_RD_COM <= COMM_STATE(2);
 IO_WR_COM <= COMM_STATE(1);
 CF_WR_COM <= COMM_STATE(0);

end architecture COMM_FSM_DESIGN;