library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.all;


entity lab is
    Port ( clk,rst, rx : in  STD_LOGIC;    -- rst är tryckknappen i mitten under displayen
           seg: out  UNSIGNED(7 downto 0);
           an : out  UNSIGNED (3 downto 0));
end lab;

architecture Behavioral of lab is

  component leddriver
    Port ( clk,rst : in  STD_LOGIC;
           seg : out  UNSIGNED(7 downto 0);
           an : out  UNSIGNED (3 downto 0);
           value : in  UNSIGNED (15 downto 0));
  end component;

    signal sreg : UNSIGNED(9 downto 0) := B"0_00000000_0";  -- 10 bit skiftregister
    signal tal : UNSIGNED(15 downto 0) := X"0000";
    signal rx1,rx2 : std_logic;         -- vippor på insignalen
    signal sp : std_logic;              -- skiftpuls
    signal run : std_logic;             -- Bestäm om vi ska läsa in ett värde eller inte
    signal lp : std_logic;              -- laddpuls
    signal pos : UNSIGNED(1 downto 0) := "00";
    signal bit_counter : UNSIGNED(9 downto 0) := "0000000000";
    signal state_counter : UNSIGNED(3 downto 0) := "0000";
    alias nya_talet: unsigned(3 downto 0) is sreg(3 downto 0);
    alias pos0: unsigned(3 downto 0) is tal(15 downto 12);
    alias pos1: unsigned(3 downto 0) is tal(11 downto 8);
    alias pos2: unsigned(3 downto 0) is tal(7 downto 4);
    alias pos3: unsigned(3 downto 0) is tal(3 downto 0);


-- vippor
begin

process(clk) begin
    if rising_edge(clk) then
        if rst = '1' then
            rx1 <= '1';
            rx2 <= '1';
        else
            rx1 <= rx;
            rx2 <= rx1;
        end if;
    end if;
end process;

-- skiftregister
process(clk) begin
    if rising_edge(clk) then
        if rst = '1' then
            sreg <= "0000000000";
        elsif sp = '1' then
            sreg(9) <= rx2;
            sreg(8 downto 0) <= sreg(9 downto 1);
        else
            sreg <= sreg;
        end if;
    end if;
end process;


-- styrenhet
process(clk) begin
    if rising_edge then
        if rst = '1' then
            bit_counter <= "0000000000";
            state_counter <= "0000";
            run <= '0';
            lp <= '0';
            sp <= '0';
        elsif run = '1' then
            if state_counter = 10 then --när state_counter == 10 har vi fått in hela talet
                lp <= '1';
                sp <= '0';
                run <= '0';
                nya_talet <= sreg(4 downto 1); --Ger variabeln nya_talet värdet inläst
            elsif bit_counter < 0 then --bit_counter räknar ner från ett givet värde tills den blir negativ
                sp <= '1';
                bit_counter <= "1101100100"
                state_counter <= state_counter - 1;
            else  --Om inget av ovan ska den bara räkna ner bit_counter
                bit_counter <= bit_counter - 1;
                lp <= '0';
                sp <= '0';
            end if;
        elsif rx1 = 0 and rx2 = 1 then
            run <= '1';
            bit_counter <= "0110110010"; --Ger den värdet 434
            state_counter <= "1001"; --Ger den värdet 9
        else --Om inget av ovan ska programmet inte gör något
            run <= run;
            --Kanske sätta flera variabler till noll eller liknande
            --för att de inte ska ha konstiga värden
        end if;
    end if;
end process;


-- 2-bitsräknare
process(clk) begin
    if rising_edge(clk) then
        if rst = '1' then
            pos <= "00";
        elsif lp = '1' then
            pos <= pos + 1; --Den borde slå över till 0 från 3 eftersom pos är bara två bitar
        else
            pos <= pos;
        end if;
    end if;
end process;


-- 16- bitsregister
process(clk) begin
    if rising_edge(clk) then
        if rst = '1' then
            pos0 <= "0000";
            pos1 <= "0000";
            pos2 <= "0000";
            pos3 <= "0000";
        elsif lp = '1' then --Uppdatera tal bara då lp = 1
            if pos = "00" then
                pos0 <= nya_talet;
            elsif pos = "01" then
                pos1 <= nya_talet;
            elsif pos = "10" then
                pos2 <= nya_talet;
            elsif pos = "11" then
                pos3 <= nya_talet;
            else
                pos0 <= pos0;
                pos1 <= pos1;
                pos2 <= pos2;
                pos3 <= pos3;
        else
            pos0 <= pos0;
            pos1 <= pos1;
            pos2 <= pos2;
            pos3 <= pos3;
        end if;
    end if;
end process;

  -- *****************************
  -- * Multiplexad display       *
  -- *****************************
  -- Inkoppling av komponenten leddriver
  led: leddriver port map (clk, rst, seg, an, tal);

end Behavioral;