LIBRARY IEEE;
     USE IEEE.STD_LOGIC_1164.all;
     USE IEEE.NUMERIC_STD.all;
     USE IEEE.STD_LOGIC_SIGNED.all;


    ENTITY Lab6 IS
     PORT ( in_num                  :       in   STD_LOGIC_VECTOR(7 downto 0);                  --8-bit input
            HEX0,HEX1,HEX2,HEX3     :       out  STD_LOGIC_VECTOR(6 downto 0));

     End ENTITY Lab6;


     ARCHITECTURE behavior OF Lab6 IS

     SIGNAL Hundreds_Digit, Tens_Digit, Ones_Digit  : STD_LOGIC_VECTOR(7 DOWNTO 0);
     SIGNAL Abs_num                                 : STD_LOGIC_VECTOR(7 DOWNTO 0);


     CONSTANT BLANK  : STD_LOGIC_VECTOR(6 DOWNTO 0) := "1111111";
     CONSTANT ZERO   : STD_LOGIC_VECTOR(6 DOWNTO 0) := "1000000";--g, f, e, d, c, b, a
     CONSTANT ONE    : STD_LOGIC_VECTOR(6 DOWNTO 0) := "1111001";
     CONSTANT TWO    : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0100100";
     CONSTANT THREE  : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0110000";
     CONSTANT FOUR   : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0011001";
     CONSTANT FIVE   : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0010010";
     CONSTANT SIX    : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0000010";
     CONSTANT SEVEN  : STD_LOGIC_VECTOR(6 DOWNTO 0) := "1111000";
     CONSTANT EIGHT  : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0000000";
     CONSTANT NINE   : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0011000";
     CONSTANT a      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0001000";
     CONSTANT b      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0000011";
     CONSTANT C      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "1000110";
     CONSTANT d      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0100001";
     CONSTANT E      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0000110";
     CONSTANT F      : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0001110";
     CONSTANT DASH   : STD_LOGIC_VECTOR(6 DOWNTO 0) := "0111111";


     BEGIN


      P1: PROCESS(in_num)

        BEGIN

    IF (in_num(7) = '1') THEN

            HEX3 <= DASH;

    ELSE
            HEX3 <= BLANK;

    END IF;
            END PROCESS;

    ----------------------------------------------------------------------------------------------------
     P2: PROCESS(in_num, Abs_num)

        BEGIN

        IF(in_num(7) = '0') THEN
                    Abs_num <= in_num;
        ELSE
                    Abs_num <= (NOT(in_num)) + 1;
        END IF;
            END PROCESS;

     ------------------------------------------------------------------------------------------------------
     Hundreds_Digit <= STD_LOGIC_VECTOR(UNSIGNED(Abs_num)/100);

     Tens_Digit <= STD_LOGIC_VECTOR(UNSIGNED(Abs_num)/10);

     Ones_Digit <= STD_LOGIC_VECTOR(UNSIGNED(Abs_num)REM 10);
     ------------------------------------------------------------------------------------------------------

     P3: PROCESS(Hundreds_Digit)

     BEGIN

     CASE Hundreds_Digit IS


            WHEN "00000001" => HEX2 <= ONE;
            WHEN "00000010" => HEX2 <= TWO;
            WHEN "00000011" => HEX2 <= THREE;
            WHEN "00000100" => HEX2 <= FOUR;
            WHEN "00000101" => HEX2 <= FIVE;
            WHEN "00000110" => HEX2 <= SIX;
            WHEN "00000111" => HEX2 <= SEVEN;
            WHEN "00001000" => HEX2 <= EIGHT;
            WHEN "00001001" => HEX2 <= NINE;
            WHEN OTHERS      => HEX2 <= ZERO;

            END CASE;
            END PROCESS;
     ----------------------------------------------------------------------------------------------------------

     P4: PROCESS(Tens_Digit)

     BEGIN

     CASE Tens_Digit IS


            WHEN "00000001" => HEX1 <= ONE;
            WHEN "00000010" => HEX1 <= TWO;
            WHEN "00000011" => HEX1 <= THREE;
            WHEN "00000100" => HEX1 <= FOUR;
            WHEN "00000101" => HEX1 <= FIVE;
            WHEN "00000110" => HEX1 <= SIX;
            WHEN "00000111" => HEX1 <= SEVEN;
            WHEN "00001000" => HEX1 <= EIGHT;
            WHEN "00001001" => HEX1 <= NINE;
            WHEN OTHERS      => HEX1 <= ZERO;

            END CASE;
            END PROCESS;
     ----------------------------------------------------------------------------------------------------------

    P5: PROCESS(Ones_Digit)

     BEGIN

     CASE Ones_Digit IS


            WHEN "00000001" => HEX0 <= ONE;
            WHEN "00000010" => HEX0 <= TWO;
            WHEN "00000011" => HEX0 <= THREE;
            WHEN "00000100" => HEX0 <= FOUR;
            WHEN "00000101" => HEX0 <= FIVE;
            WHEN "00000110" => HEX0 <= SIX;
            WHEN "00000111" => HEX0 <= SEVEN;
            WHEN "00001000" => HEX0 <= EIGHT;
            WHEN "00001001" => HEX0 <= NINE;
            WHEN OTHERS      => HEX0 <= ZERO;

            END CASE;
            END PROCESS;


       END ARCHITECTURE behavior;