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-- register file model as a simple memory 

--

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library ieee;

use ieee.std_logic_1164.ALL;

use ieee.numeric_std.all;

entity regFileModel is

  port ( -- global signals

         clr        : in  std_logic;                     -- global reset input

         clk        : in  std_logic;                     -- global clock input

         -- internal bus to register file

         intAddress : in  std_logic_vector(7 downto 0);  -- address bus to register file

         intWrData  : in  std_logic_vector(7 downto 0);  -- write data to register file

         intWrite   : in  std_logic;                     -- write control to register file

         intRead    : in  std_logic;                     -- read control to register file

         intRdData  : out std_logic_vector(7 downto 0)); -- data read from register file

end regFileModel;

architecture Behavioral of regFileModel is

  type RAM is array (integer range <>)of std_logic_vector (7 downto 0);

  signal regFile : RAM (0 to 255);

  begin

    -- register file write

    process (clr, clk)

    begin

      if (clr = '1') then

        for index in 0 to 255 loop

          regFile(index) <= (others => '0');

        end loop;

      elsif (rising_edge(clk)) then

        if (intWrite = '1') then

          regFile(to_integer(unsigned(intAddress))) <= intWrData;

        end if;

      end if;

    end process;

    -- register file read

    process (clr, clk)

    begin

      if (clr = '1') then

        intRdData <= (others => '0');

      elsif (rising_edge(clk)) then

        if (intRead = '1') then

          intRdData <= regFile(to_integer(unsigned(intAddress)));

        end if;

      end if;

    end process;

  end Behavioral;