library ieee;
library unisim;

use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;

entity keyboard is
    generic (
        input_clk: integer
    );
    port (
        clk: in std_logic;
        reset: in std_logic;

        bytes_received: out std_logic_vector(5 downto 0);

        ps2_scl: inout std_logic;
        ps2_sda: inout std_logic
    );
end keyboard;

architecture Behavioral of keyboard is
    signal ps2_reset_n: std_logic;
    signal ps2_clear_data_available: std_logic;
    signal ps2_data_available: std_logic;
    signal ps2_data_available_old: std_logic;

    signal byte_count: std_logic_vector(5 downto 0);
begin

    ps2_host: entity work.ps2 port map (
        clk_i => clk,
        rst_i => ps2_reset_n,

        data_o => open,
        data_i => "00000000",
        ibf_clr_i => ps2_clear_data_available,
        obf_set_i => '0', -- we don't want to write anything
        ibf_o => ps2_data_available,
        obf_o => open,

        frame_err_o => open, -- ignore errors for now
        parity_err_o => open,
        busy_o => open,
        err_clr_i => '0',

        wdt_o => open,

        ps2_clk_io => ps2_scl,
        ps2_data_io => ps2_sda
    );

    -- count bytes received
    main: process(clk, reset)
        constant max_delay: integer := input_clk / 200_000; -- 5µs
        variable delay: integer range 0 to max_delay := 0;
    begin
        if reset = '1' then
            delay := 0;
            byte_count <= "000000";
            -- reset component
            ps2_reset_n <= '0';
        elsif rising_edge(clk) then
            if delay = 5 then
                -- init component
                ps2_reset_n <= '1';
                delay := delay + 1;
            elsif delay = max_delay then
                ps2_clear_data_available <= '0';
                ps2_data_available_old <= ps2_data_available;
                if ps2_data_available_old = '0' and ps2_data_available = '1' then
                    -- count rising edges on ps2_data_available:
                    byte_count <= byte_count + 1;
                    ps2_clear_data_available <= '1';
                end if;
            else
                delay := delay + 1;
            end if;
        end if;
    end process main;

    bytes_received <= byte_count;

end Behavioral;