SimpleProcessorCore/src/MemoryMapper.vhd

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--! @file 
--! @brief Maps memory devices to a given memory space
--! @author Dominik Meyer
--! @email dmeyer@federationhq.de
--! @date 2010-06-03
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library ieee;
    use ieee.std_logic_1164.all;
    use ieee.std_logic_unsigned.all;


--! Maps memory devices to a given memory space
entity MemoryMapper is
    port(
        start   : in    std_logic_vector(15 downto 0);           --! start of memory space
        stop    : in    std_logic_vector(15 downto 0);           --! end of mempry space
        adr_in  : in    std_logic_vector(15 downto 0);
        req_in  : in    std_logic;                               --! ram request type
        req_out : out   std_logic;                               --! ram request type

        enable  : out   std_logic;

        adr_out : out   std_logic_vector(15 downto 0)

    );
end MemoryMapper;


--! architecture to map memory devices to memory space
architecture arch of MemoryMapper is

begin

    process(adr_in, req_in, start, stop)
    begin

        if (adr_in >= start and adr_in <= stop) then
            req_out <= req_in;
            adr_out <= adr_in-start;
            enable  <= '1';
        else
            req_out <= '0';
            enable  <= '0';
            adr_out <= (others => 'Z');
        end if;
    end process;

end arch;