library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;

architecture behavioral of cache is
    -- Cache parameters
    constant CACHE_SIZE : integer := 16;
    constant TAG_WIDTH : integer := 4;
    constant DATA_WIDTH : integer := 7;
    constant INDEX_WIDTH : integer := 4;

    -- Cache memory
    type cache_array is array (0 to CACHE_SIZE-1) of std_logic_vector(TAG_WIDTH+DATA_WIDTH-1 downto 0);
    constant cache_content : cache_array := (
        "10001100010", "10000111101", "00111010011", "11001000110",
        "10001101111", "10001110110", "11011100001", "10111101011",
        "11101101110", "10001111110", "11010001110", "11011000011",
        "11111100000", "10101001001", "10000101011", "11101010100"
    );

    -- Signals
    signal data_next : std_logic_vector(6 downto 0);
    signal hit_next : std_logic;
    
begin
    process(clk)
    begin
        if falling_edge(clk) then
            if en_read = '1' then
                data <= data_next;
                ch_cm <= hit_next;
            else
                data <= "ZZZZZZZ";
                ch_cm <= '0';
            end if;
        end if;
    end process;
    
    process(addr,clk)
    
    variable index : integer range 0 to CACHE_SIZE-1;
    variable tag : std_logic_vector(TAG_WIDTH-1 downto 0);
    variable cache_tag : std_logic_vector(TAG_WIDTH-1 downto 0);
    variable cache_data : std_logic_vector(DATA_WIDTH-1 downto 0);
    
    begin
        -- Extract index and tag from address
        index := to_integer(unsigned(addr(INDEX_WIDTH-1 downto 0)));
        tag := addr(addr'length-1 downto INDEX_WIDTH);
        
        cache_tag := cache_content(index)(TAG_WIDTH+DATA_WIDTH-1 downto DATA_WIDTH);
        cache_data := cache_content(index)(DATA_WIDTH-1 downto 0);

        if tag = cache_tag then
            hit_next <= '1'; -- Cache hit
            data_next <= cache_data;
        else
            hit_next <= '0';
            data_next <= (others => 'Z'); -- Cache miss
        end if;
    end process;
    
end architecture behavioral;