library ieee;
use ieee.math_real.all;
use ieee.numeric_std.all;
use ieee.std_logic_1164.all;

entity ALU_tb is
end ALU_tb;

architecture Structurel of ALU_tb is

  --! ########   signals for component    ########
 
  	signal op1	: std_logic_vector(31 downto 0) := std_logic_vector(to_unsigned(32654, 32));
	signal op2	: std_logic_vector(31 downto 0) := std_logic_vector(to_unsigned(65877, 32));
	signal cin	: std_logic := '0';
	signal cmd	: std_logic_vector(1 downto 0) := "00";
	signal res	: std_logic_vector(31 downto 0) := (others => '0');
	signal cout	: std_logic;
	signal z	: std_logic;
	signal n	: std_logic;
	signal v	: std_logic;
	signal vdd	: bit := '1';
	signal vss	: bit := '0';

  --! ########         functions         ########
  function bit_to_integer (s : std_logic) return integer is
  begin
    if s = '1' then
      return 1;
    else
      return 0;
    end if;
  end function;

begin
  alu_0 : entity work.ALU
    port map(
      op1  => op1,
      op2  => op2,
      res  => res,
      cin  => cin,
      cout => cout,
      z    => z,
      n    => n,
      v    => v,
      cmd  => cmd,
      vdd  => vdd,
      vss  => vss
    );

  process

    variable vres : std_logic_vector(31 downto 0);

    variable vtempcin : natural;
    variable vtemp    : std_logic_vector(32 downto 0);

    variable vcarry_out : std_logic;
    variable vz         : std_logic;
    variable vv         : std_logic;

    -- variables for the random number
    variable seed1 : positive;
    variable seed2 : positive;
    variable x     : real;
    variable y     : integer;

  begin

    vdd <= '1';

    vss <= '0';

    -- seeds for random number
    seed1 := 1;
    seed2 := 1;

    cin <= '1';
    vtempcin := 0;
    wait for 1 ns;

    -- SUM
    cmd <= "00";
    wait for 1 ns;
    report "addition of 32 random numbers, range between (0 to 536870911)";
    
    la : for va in 0 to 31 loop

      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op1 <= std_logic_vector(to_unsigned(y, op1'length));


      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op2 <= std_logic_vector(to_unsigned(y, op2'length));
      wait for 1 ns;
      vtemp      := (std_logic_vector(unsigned("0" & op1) + unsigned("0" & op2) + to_unsigned(bit_to_integer(cin), 1)));
      vres       := vtemp(31 downto 0);
      vcarry_out := vtemp(32);
      if vres = x"0" then
        vz := '1';
      else
        vz := '0';
      end if;
      wait for 1 ns;
      assert (res = vres) report "[error] vres = " & integer'image(to_integer(unsigned(vres))) & " versus res = " & integer'image(to_integer(unsigned(res)))
      severity error;
      assert (bit_to_integer(n) = bit_to_integer(vtemp(31))) report "[error] negative. n = " & integer'image(bit_to_integer(n)) & " versus vn = " & integer'image(bit_to_integer(vtemp(31)))
      severity error;
      assert (bit_to_integer(cout) = bit_to_integer(vtemp(32))) report "[error] in carry out. cout = " & integer'image(bit_to_integer(cout)) & " versus vcout = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(z) = bit_to_integer(vz)) report "[error] z flag. z = " & integer'image(bit_to_integer(z)) & " versus vz = " & integer'image(bit_to_integer(vz))
      severity error;
    end loop la;


    cin <= '0';
    wait for 1 ns;
    report "addition of (7fff ffff) + (7fff ffff)";
    op1 <= x"7fffffff"; --(+)2147483647
    op2 <= x"7fffffff"; --(+)2147483647
    wait for 1 ns;
    assert (res = x"fffffffe") report "[error] res = " & integer'image(to_integer(unsigned(res))) severity error;
    assert (bit_to_integer(cout) = 0) report "cout = " & integer'image(bit_to_integer(cout)) severity error;
    assert (bit_to_integer(v) = 1) report "[error] v = " & integer'image(bit_to_integer(v)) severity error;



    wait for 1 ns;
    report "overflow, zero and carry in addition (ffff ffff) + (0000 0001)";
    op1 <= x"ffffffff";
    op2 <= x"00000001";
    wait for 1 ns;
    assert (res = x"00000000") report "[error] res = " & integer'image(to_integer(unsigned(res))) severity error;
    assert (bit_to_integer(z) = 1) report "[error] z = " & integer'image(bit_to_integer(z)) severity error;
    assert (bit_to_integer(cout) = 1) report "[error] cout = " & integer'image(bit_to_integer(cout)) severity error;
    assert (bit_to_integer(v) = 1) report "[error] v = " & integer'image(bit_to_integer(v)) severity error;
    

    wait for 1 ns;
    report "test addition negative number with negative result";
    op1 <= x"0000002a"; -- 42
    op2 <= x"ffffffd3"; -- -45
    wait for 1 ns;
    
    assert (res = x"fffffffd") report "[error] res = " & integer'image(to_integer(unsigned(res))) severity error;
    assert (bit_to_integer(n) = 1) report "[error] n = " & integer'image(bit_to_integer(n)) severity error;
    assert (bit_to_integer(z) = 0) report "[error] z = " & integer'image(bit_to_integer(z)) severity error;
    assert (bit_to_integer(cout) = 0) report "[error] cout = " & integer'image(bit_to_integer(cout)) severity error;
    assert (bit_to_integer(v) = 1) report "[error] v = " & integer'image(bit_to_integer(v)) severity error;


    -- AND
    wait for 1 ns;
    report "and of 32 random numbers in a range between (0 to 536870911)";
    cmd <= "01";
    wait for 1 ns;
    lb : for vb in 0 to 31 loop

      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op1 <= std_logic_vector(to_unsigned(y, op1'length));

      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op2 <= std_logic_vector(to_unsigned(y, op2'length));
      wait for 1 ns;
      vtemp      := (("0" & op1) and ("0" & op2));
      vres       := vtemp(31 downto 0);
      vcarry_out := vtemp(32);
      if vres = x"0" then
        vz := '1';
      else
        vz := '0';
      end if;
      wait for 1 ns;
      assert (res = vres) report "[error] or vres = " & integer'image(to_integer(unsigned(vres))) & " versus res = " & integer'image(to_integer(unsigned(res)))
      severity error;
      assert (bit_to_integer(n) = bit_to_integer(vtemp(31))) report "[error] negative. n = " & integer'image(bit_to_integer(n)) & " versus vn = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(cout) = bit_to_integer(vtemp(32))) report "[error] carry out. cout = " & integer'image(bit_to_integer(cout)) & " versus vcout = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(z) = bit_to_integer(vz)) report "[error] z flag. z = " & integer'image(bit_to_integer(z)) & " versus vz = " & integer'image(bit_to_integer(vz))
      severity error;
    end loop lb;


    -- OR
    wait for 1 ns;
    report "or of 32 random numbers in a range between (0 to 536870911)";
    cmd <= "10";
    wait for 1 ns;
    lc : for vc in 0 to 31 loop

      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op1 <= std_logic_vector(to_unsigned(y, op1'length));


      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op2 <= std_logic_vector(to_unsigned(y, op2'length));
      wait for 1 ns;
      vtemp      := (("0" & op1) or ("0" & op2));
      vres       := vtemp(31 downto 0);
      vcarry_out := vtemp(32);
      if vres = x"0" then
        vz := '1';
      else
        vz := '0';
      end if;
      wait for 1 ns;
      assert (res = vres) report "[error] or vres = " & integer'image(to_integer(unsigned(vres))) & " res = " & integer'image(to_integer(unsigned(res)))
      severity error;
      assert (bit_to_integer(n) = bit_to_integer(vtemp(31))) report "[error] negative. n = " & integer'image(bit_to_integer(n)) & " versus vn = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(cout) = bit_to_integer(vtemp(32))) report "[error] carry out. cout = " & integer'image(bit_to_integer(cout)) & " versus cout = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(z) = bit_to_integer(vz)) report "[error] z flag. z = " & integer'image(bit_to_integer(z)) & " versus vz = " & integer'image(bit_to_integer(vz))
      severity error;
    end loop lc;


    -- XOR
    wait for 1 ns;
    report "xor of 32 random numbers in a range between (0 to 536870911)";
    cmd <= "11";
    wait for 1 ns;
    ld : for vd in 0 to 31 loop

      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));

      op1 <= std_logic_vector(to_unsigned(y, op1'length));


      uniform(seed1, seed2, x);
      y := integer(floor(x * 536870911.0));
      -- assign the random number to op2
      op2 <= std_logic_vector(to_unsigned(y, op2'length));
      wait for 1 ns;
      vtemp      := (("0" & op1) xor ("0" & op2));
      vres       := vtemp(31 downto 0);
      vcarry_out := vtemp(32);
      if vres = x"0" then
        vz := '1';
      else
        vz := '0';
      end if;
      wait for 1 ns;
      assert (res = vres) report "[error] xor. vres = " & integer'image(to_integer(unsigned(vres))) & " versus res = " & integer'image(to_integer(unsigned(res)))
      severity error;
      assert (bit_to_integer(n) = bit_to_integer(vtemp(31))) report "[error]  negative. n = " & integer'image(bit_to_integer(n)) & " versus vn = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(cout) = bit_to_integer(vtemp(32))) report "[error]  carry out. cout = " & integer'image(bit_to_integer(cout)) & " versus vcout = " & integer'image(bit_to_integer(vtemp(32)))
      severity error;
      assert (bit_to_integer(z) = bit_to_integer(vz)) report "[error]  z flag. z = " & integer'image(bit_to_integer(z)) & " versus vz = " & integer'image(bit_to_integer(vz))
      severity error;
    end loop ld;

    
    
    wait for 1 ns;
    report "end_of_test" severity note;

    wait;
  end process;
end structurel;