library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity ram_cnt_cnt is
generic(N : Positive := 7);
 port(
    clk         : in    std_logic;
    srst        : in    std_logic;
    selected    : in    std_logic;
    cnt_ena     : in    std_logic;
    track       : in    std_logic;
    q_curr      : out   std_logic_vector(N-1 downto 0);
    cout        : out   std_logic;
    q_hold      : out   std_logic_vector(N-1 downto 0);
    cout_hold   : out   std_logic);
end ram_cnt_cnt;

architecture behav of ram_cnt_cnt is


signal q_curr_i  : std_logic_vector(N-1 downto 0);
signal q_next    : std_logic_vector(N-1 downto 0);
signal almost_f  : std_logic;
signal cout_i    : std_logic;
signal cout_next : std_logic;

constant cnt_max   : std_logic_vector(N-1 downto 0) := (others => '1');
--constant cnt_maxM1 : std_logic_vector(N-1 downto 0) := (0 => '0', others => '1');

begin

    process(clk)
    begin
        if rising_edge(clk) then
            cout_i   <= cout_next;
            q_curr_i <= q_next;
            if track = '1' then
                q_hold <= q_next;
                cout_hold <= cout_next;
            end if;
        end if;
    end process;

    q_curr <= q_curr_i;
    cout   <= cout_i;

    almost_f <= '1' when q_curr_i = cnt_max else '0';
    process(almost_f, cout_i, q_curr_i, selected, cnt_ena, srst)
    variable case_var : std_logic_vector(3 downto 0);
    begin
        if srst = '1' then
            cout_next <= '0';
            q_next <= (others => '0');
        else
            case_var := cnt_ena & selected & almost_f & cout_i;
            q_next    <= q_curr_i;
            cout_next <= cout_i;
            case case_var is
            when "0000" | "0001" | "0010" | "0011" | "0100" | "0110" =>
                NULL;
            when "1011" =>
                NULL; -- should not happen!!!
            when "0101" | "0111" =>
                cout_next <= '0';
            when "1001" | "1100" =>
                q_next <= q_curr_i + 1;
            when "1000" | "1010" | "1110" =>
                q_next <= q_curr_i + 1;
                cout_next <= almost_f;
            when "1101" =>
                q_next    <= q_curr_i + 1;
                cout_next <= '0';
            when "1111" =>
                q_next <= (others => '0');
                cout_next <= '1';
            when others =>
                q_next <= (others => '-');
                cout_next <= '-';
            end case;

        end if;
    end process;
end;