library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

library work;
use work.usefuls.ALL;

entity DividerN is
  generic (
      divide_value : positive := 8);
  port (
      clk, reset : in std_logic;
      clk_out, tc : out std_logic);
end DividerN;

architecture Behavioral of DividerN is
  constant required_bits : integer := min_bits(mod_even(divide_value) - 1);
  signal timer : std_logic_vector(required_bits - 1 downto 0) 
      := (others => '0');
  signal clk_n : std_logic;
begin
  clk_n <= not clk;
  
  gen_even: if (divide_value mod 2 = 0) generate
    process(clk, reset) begin
      if reset = '1' then
        timer <= (others => '0');
        tc <= '0';
      elsif clk'event and clk = '1' then
        if timer < conv_std_logic_vector(divide_value - 1, required_bits) then
          timer <= timer + 1;
          tc <= '0';
        else
          timer <= (others => '0');
          tc <= '1';
        end if;
      end if;
    end process;
    
    clk_out <= '1' when timer < conv_std_logic_vector(divide_value / 2, required_bits) 
        else '0';
  end generate;
  
  -- divide_value % 2 = 1のときは複雑(合成可能にするため)
  -- 例えば5のときはカウンタの動作が
  -- clk    ---___---___---___---___---___---___---___---___---
  -- timer   9  1  0  2  2  4  5  7  7  9  9  1  0  2  2  4  5
  -- clkout ___---------------_______________---------------___
  gen_odd: if (divide_value >= 3) and (divide_value mod 2 = 1) generate
    process(clk, clk_n, reset) begin
      if reset = '1' then
        timer <= (others => '0');
        tc <= '0';
      elsif (clk'event and clk = '1') then
        if timer >= conv_std_logic_vector(divide_value - 1, required_bits) then
          timer(0) <= '1';
        else
          timer(0) <= '0';
        end if;
      elsif (clk_n'event and clk_n = '1') then
        if timer < conv_std_logic_vector((divide_value * 2) - 1, required_bits) then
          timer(required_bits - 1 downto 1) <= timer(required_bits - 1 downto 1) + 1;
          tc <= '0';
        else
          timer(required_bits - 1 downto 1) <= (others => '0');
          tc <= '1';
        end if;
      end if;
    end process;
    
    clk_out <= '1' when timer < conv_std_logic_vector(divide_value, required_bits) 
        else '0';
  end generate;
  
  gen_unity: if (divide_value = 1) generate
    tc <= '0' when reset = '1' else clk;
    clk_out <= clk;
  end generate;
end Behavioral;