library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.Numeric_Std.all;

architecture Behavioral of RAM is
    -- Die Länge der Adressen beträgt 6 Bit -> Länge/Größe des Vektors 64
    -- die Länge der einzelnen Speicherzellen 8 Bit
    type memory_type is array (0 to 127) of std_logic_vector(17 downto 0);
    -- Der anfängliche Inhalt des Speichers ist Null.
    signal memory : memory_type := (others => (others => '0'));
   --constant for high Z
    constant high_z : std_logic_vector(35 downto 0) := "ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ";

begin
    
    process (Clk) is
    variable addr1_int : INTEGER;
    variable addr2_int : INTEGER;
    begin
        if rising_edge(Clk) then
            
            output1 <= high_z;
            output2 <= high_z;
            
            addr1_int := to_integer(UNSIGNED(addr1));
            addr2_int := to_integer(UNSIGNED(addr2));
            
            if en_write = '0' then
                -- lesen
                if en_read1 = '1' then
                    output1 <= memory(addr1_int+1) & memory(addr1_int);
                end if;
                if en_read2 = '1' then
                    output2 <= memory(addr2_int+1) & memory(addr2_int);
                end if;
                
                --high Z wenn nur eins gelesen wird:
                if (en_read2 = '0') and (en_read1 = '1') then
                    output2 <= high_z;
                elsif (en_read1 = '0') and (en_read2 = '1') then
                    output1 <= high_z;
                end if;
            end if;
            
            -- schreiben
            if (en_write = '1') and (en_read1 = '0') and (en_read2 = '0') then
                memory(addr1_int) <= input;
                
            -- schreiben und lesen von addr2
            elsif (en_write = '1') and (en_read1 = '0') and (en_read2 = '1') then
                --kann nur ausgeführ werden wenn addr1 != addr2
                if not(addr1_int = addr2_int) and not(addr1_int = addr2_int+1) then
                    memory(addr1_int) <= input;
                    output2 <= memory(addr2_int+1) & memory(addr2_int);
                end if;

            end if;
        end if;
    end process;
end Behavioral;