library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.vhdl_verification.all;

entity tb_keypad_emu is
end tb_keypad_emu;

architecture behavior of tb_keypad_emu is

  -- DUT parameters
  constant VERBOSE        : boolean := true;

  -- DUT signals
  signal keypad_rows      : std_logic_vector(3 downto 0);
  signal keypad_columns   : std_logic_vector(3 downto 0);
  signal pressed_keys     : std_logic_vector(15 downto 0);

  -- Clock period and signal definition
  -- (we don't actually have a clock in this testbench, but it's nice to have
  -- some time magnitude, to wait for multiples of it)
  constant clk_period   : time      := 10 ns;
  signal clk            : std_logic := '0';

  -- Simulation control
  constant MAX_CYCLES   : integer   := 64;
  signal num_cycles     : integer   := 0;

begin

  -- Instantiate the Unit Under Test (UUT)
  uut : keypad_emu
    generic map (
      VERBOSE        => VERBOSE
    )
    port map (
      keypad_rows    => keypad_rows,
      keypad_columns => keypad_columns,
      pressed_keys   => pressed_keys
      );

  -- To stop the simulation without a failure message,
  -- stop the clock when we reach the desired number of cycles
  clk_process : process
  begin
    if(num_cycles < MAX_CYCLES) then
      clk <= '0';
      wait for clk_period/2;
      clk <= '1';
      wait for clk_period/2;
      num_cycles <= num_cycles + 1;
    else
      report "Ending simulation";
      wait;
    end if;
  end process;

  -- Stimulus process
  --
  -- Let's test this thing by sequentially pressing all keys!
  stim_proc : process
  begin
    wait for clk_period;
    pressed_keys <= (others => '0');
    wait for clk_period;
    for i in 0 to 15 loop
        pressed_keys <= (others => '0');
        pressed_keys(i) <= '1';
        wait for clk_period;
        for j in 0 to 3 loop
            keypad_columns <= (others => '1');
            keypad_columns(j) <= '0';
            wait for clk_period;
            --report "keypad_columns: " & slv2string(keypad_rows);
            --report "keypad_rows: " & slv2string(keypad_rows);
            for k in 0 to 3 loop
                if keypad_rows(k) = '0' then
                    report "Key pressed detected at column " & integer'image(j) & ", row " & integer'image(k);
                end if;
                end loop;
        end loop;
    end loop;
    pressed_keys <= (others => '0');
    wait;
  end process;

end;