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

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-- General counter which counter width and maximum value can be set by generic
-- attributes. When 'count' is equal to MAX value, 'event_ow' is high.
--------------------------------------------------------------------------------

entity counter is
  generic (
    WIDTH : integer;
    MAX   : integer);
  port (
    clk      : in  std_logic;
    clk_en   : in  std_logic;
    reset    : in  std_logic;
    count    : out std_logic_vector (WIDTH-1 downto 0);
    event_ow : out std_logic);
end counter;

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architecture behavioral of counter is

  signal eq_max : std_logic;            -- cnt is equal to MAX
  signal cnt    : std_logic_vector (WIDTH-1 downto 0) := (others => '0');

--------------------------------------------------------------------------------

begin

  assert MAX < 2**WIDTH
    report "MAX is bigger then counter max. value."
    severity error;

  
  count    <= cnt;
  event_ow <= eq_max and clk_en;

  
  COUTER : process (clk, reset) is
  begin
    if rising_edge(clk) then
      if reset = '1' then
        cnt <= (others => '0');
        
      else
        if clk_en = '1' then
          if eq_max = '1' then
            cnt <= (others => '0');
          else
            cnt <= cnt + 1;
          end if;
        end if;
      end if;
    end if;
  end process;

  
  CNT_EQ_MAX : process (cnt) is
  begin
    if cnt = CONV_STD_LOGIC_VECTOR(MAX, WIDTH) then
      eq_max <= '1';
    else
      eq_max <= '0';
    end if;
  end process;
  
end behavioral;