LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY Calculadora IS
  port (
    -- Clocks

    CLOCK_24,                                      -- 24 MHz
    CLOCK_27,                                      -- 27 MHz
    CLOCK_50,                                      -- 50 MHz
    EXT_CLOCK : in std_logic;                      -- External Clock

    -- Buttons and switches

    KEY : in std_logic_vector(3 downto 0);         -- Push buttons
    SW  : in std_logic_vector(9 downto 0);         -- DPDT switches

    -- LED displays

    HEX0, HEX1, HEX2, HEX3             -- 7-segment displays
       : out std_logic_vector(6 downto 0);
    LEDG : out std_logic_vector(7 downto 0);       -- Green LEDs
    LEDR : out std_logic_vector(9 downto 0);      -- Red LEDs

    -- RS-232 interface

    UART_TXD : out std_logic;                      -- UART transmitter
    UART_RXD : in std_logic;                       -- UART receiver

    -- SDRAM

    DRAM_DQ : inout std_logic_vector(15 downto 0); -- Data Bus
    DRAM_ADDR : out std_logic_vector(11 downto 0); -- Address Bus
    DRAM_LDQM,                                     -- Low-byte Data Mask
    DRAM_UDQM,                                     -- High-byte Data Mask
    DRAM_WE_N,                                     -- Write Enable
    DRAM_CAS_N,                                    -- Column Address Strobe
    DRAM_RAS_N,                                    -- Row Address Strobe
    DRAM_CS_N,                                     -- Chip Select
    DRAM_BA_0,                                     -- Bank Address 0
    DRAM_BA_1,                                     -- Bank Address 0
    DRAM_CLK,                                      -- Clock
    DRAM_CKE : out std_logic;                      -- Clock Enable

    -- FLASH

    FL_DQ : inout std_logic_vector(7 downto 0);      -- Data bus
    FL_ADDR : out std_logic_vector(21 downto 0);  -- Address bus
    FL_WE_N,                                         -- Write Enable
    FL_RST_N,                                        -- Reset
    FL_OE_N,                                         -- Output Enable
    FL_CE_N : out std_logic;                         -- Chip Enable

    -- SRAM

    SRAM_DQ : inout std_logic_vector(15 downto 0); -- Data bus 16 Bits
    SRAM_ADDR : out std_logic_vector(17 downto 0); -- Address bus 18 Bits
    SRAM_UB_N,                                     -- High-byte Data Mask
    SRAM_LB_N,                                     -- Low-byte Data Mask
    SRAM_WE_N,                                     -- Write Enable
    SRAM_CE_N,                                     -- Chip Enable
    SRAM_OE_N : out std_logic;                     -- Output Enable

    -- SD card interface

    SD_DAT,                     -- SD Card Data
    SD_DAT3,                    -- SD Card Data 3
    SD_CMD : inout std_logic;   -- SD Card Command Signal
    SD_CLK : out std_logic;     -- SD Card Clock

    -- USB JTAG link

    TDI,                        -- CPLD -> FPGA (data in)
    TCK,                        -- CPLD -> FPGA (clk)
    TCS : in std_logic;         -- CPLD -> FPGA (CS)
    TDO : out std_logic;        -- FPGA -> CPLD (data out)

    -- I2C bus

    I2C_SDAT : inout std_logic; -- I2C Data
    I2C_SCLK : out std_logic;   -- I2C Clock

    -- PS/2 port

    PS2_DAT,                    -- Data
    PS2_CLK : in std_logic;     -- Clock

    -- VGA output

    VGA_HS,                                             -- H_SYNC
    VGA_VS: out std_logic;                               -- V_SYNC
    VGA_R,                                              -- Red[3:0]
    VGA_G,                                              -- Green[3:0]
    VGA_B : out std_logic_vector(3 downto 0);           -- Blue[3:0]

    -- Audio CODEC

    AUD_ADCLRCK : inout std_logic;                      -- ADC LR Clock
    AUD_ADCDAT : in std_logic;                          -- ADC Data
    AUD_DACLRCK : inout std_logic;                      -- DAC LR Clock
    AUD_DACDAT : out std_logic;                         -- DAC Data
    AUD_BCLK : inout std_logic;                         -- Bit-Stream Clock
    AUD_XCK : out std_logic;                            -- Chip Clock

    -- General-purpose I/O

    GPIO_0,                                      -- GPIO Connection 0
    GPIO_1 : inout std_logic_vector(35 downto 0); -- GPIO Connection 1

    --teclado
    keyboard_clk, keyboard_data, clock_50MHz ,
    reset, read : IN STD_LOGIC;
    scan_code : OUT STD_LOGIC_VECTOR( 7 DOWNTO 0 );
    scan_ready : OUT STD_LOGIC


    );
END Calculadora;

ARCHITECTURE comportamental OF Calculadora IS
--talvez vire uma maquina de estados, usada quando se aperta o igual
TYPE operacao IS (ENTER, SOMA, SUBTRACAO, MULTIPLICACAO, DIVISAO);
SIGNAL OPERACAOKB: operacao := ENTER;

SIGNAL VALOR_ANTERIOR:INTEGER:=0;
SIGNAL VALOR_ATUAL:INTEGER:=0;
SIGNAL Resultado:INTEGER:=0;


--seria a TeclaDigitada do teclado
SIGNAL TeclaDigitada: STD_LOGIC_VECTOR (3 DOWNTO 0):=KEY;
--esse valor de saida sera convertido num process para os displays
SIGNAL saida: INTEGER:=0;

--nao vou acender led nenhum pra memoria
SIGNAL memoria:INTEGER:=0;
--quando o valor for muito alto, esse signal fica positivo, indicando um buffer overflow
SIGNAL erro: BIT:='0';

--signal section (teclado)
SIGNAL INCNT : STD_LOGIC_VECTOR( 3 DOWNTO 0 );
SIGNAL SHIFTIN : STD_LOGIC_VECTOR( 8 DOWNTO 0 );
SIGNAL CodigoTeclado : STD_LOGIC_VECTOR( 8 DOWNTO 0 );
SIGNAL READ_CHAR, clock_enable : STD_LOGIC;
SIGNAL INFLAG, ready_set : STD_LOGIC;
SIGNAL keyboard_clk_filtered : STD_LOGIC;
SIGNAL filter : STD_LOGIC_VECTOR( 7 DOWNTO 0 );


BEGIN
    PROCESS(CLOCK_50, TeclaDigitada, CodigoTeclado) BEGIN
    --uma variavel auxiliar para fazer as contas
    --a saida recebe ela



        IF CLOCK_50'EVENT AND CLOCK_50='1' THEN
        --detectar tecla digitada (numero, numero da tecla, scan_code)
-- 0  -  99   -  70
-- 1  -  93   -  69
-- 2  -  98   -  72
-- 3  -  103  -  7A
-- 4  -  76   -  E0 70
-- 5  -  97   -  73
-- 6  -  102  -  74
-- 7  -  91   -  6C
-- 8  -  96   -  75
-- 9  -  101  -  7D
-- +  -  106  -  79
-- -  -  105  -  7B
-- *  -  100  -  7C
-- /  -  95   -  E0 4A
-- E  -  108  -  5A

        -- Processa tecla digitada
        CASE TeclaDigitada IS
            WHEN "0000" => VALOR_ATUAL <= VALOR_ATUAL*10;
            WHEN "0001" => VALOR_ATUAL <= VALOR_ATUAL*10 + 1;
            WHEN "0010" => VALOR_ATUAL <= VALOR_ATUAL*10 + 2;
            WHEN "0011" => VALOR_ATUAL <= VALOR_ATUAL*10 + 3;
            WHEN "0100" => VALOR_ATUAL <= VALOR_ATUAL*10 + 4;
            WHEN "0101" => VALOR_ATUAL <= VALOR_ATUAL*10 + 5;
            WHEN "0110" => VALOR_ATUAL <= VALOR_ATUAL*10 + 6;
            WHEN "0111" => VALOR_ATUAL <= VALOR_ATUAL*10 + 7;
            WHEN "1000" => VALOR_ATUAL <= VALOR_ATUAL*10 + 8;
            WHEN "1001" => VALOR_ATUAL <= VALOR_ATUAL*10 + 9;

            WHEN "1010"  => OPERACAOKB<=SOMA;
                            VALOR_ANTERIOR<=VALOR_ATUAL;
                            VALOR_ATUAL<=0;
            WHEN "1011"  => OPERACAOKB<=SUBTRACAO;
                            VALOR_ANTERIOR<=VALOR_ATUAL;
                            VALOR_ATUAL<=0;
            WHEN "1100"  => OPERACAOKB<=MULTIPLICACAO;
                            VALOR_ANTERIOR<=VALOR_ATUAL;
                            VALOR_ATUAL<=0;
            WHEN "1101"  => OPERACAOKB<=DIVISAO;
                            VALOR_ANTERIOR<=VALOR_ATUAL;
                            VALOR_ATUAL<=0;
            WHEN "1111"  => -- Tecla =, faz operações
                CASE OPERACAOKB IS
                WHEN SOMA =>
                    RESULTADO <= VALOR_ATUAL+VALOR_ANTERIOR;
                    VALOR_ATUAL <= 0;
                    VALOR_ANTERIOR <= 0;
                WHEN SUBTRACAO =>
                    RESULTADO <= VALOR_ATUAL - VALOR_ANTERIOR;
                    VALOR_ATUAL <= 0;
                    VALOR_ANTERIOR <= 0;
                WHEN MULTIPLICACAO =>
                    RESULTADO <= VALOR_ATUAL * VALOR_ANTERIOR;
                    VALOR_ATUAL <= 0;
                    VALOR_ANTERIOR <= 0;
                WHEN DIVISAO =>
                    RESULTADO <= VALOR_ATUAL / VALOR_ANTERIOR;
                    VALOR_ATUAL <= 0;
                    VALOR_ANTERIOR <= 0;
                WHEN OTHERS => RESULTADO <= RESULTADO;
                END CASE;
            WHEN OTHERS => VALOR_ATUAL <= VALOR_ATUAL;
        END CASE;

            IF RESULTADO<=9999 THEN
                saida<=RESULTADO;
            ELSE
                saida<=0;
            END IF;
        END IF;
    END PROCESS;


PROCESS (saida)
    VARIABLE valor:INTEGER;
    VARIABLE um: INTEGER;
    VARIABLE c: INTEGER;
    VARIABLE d: INTEGER;
    VARIABLE u: INTEGER;
BEGIN
    --separa o numero em casas decimais
    valor := saida;
    um:= valor / 1000;

    valor := valor - um*1000;
    c := valor / 100;

    valor := valor - c*100;
    d := valor /10;

    valor := valor - d*10;
    u := valor;
    --acende os displays de acordo com os numeros
    -- unidades de milhar - display 0
    IF (um=1) THEN
        HEX0<="1001111";
    ELSIF (um=2) THEN
        HEX0<="0010010";
    ELSIF (um=3) THEN
        HEX0<="0000110";
    ELSIF (um=4) THEN
        HEX0<="1001100";
    ELSIF (um=5) THEN
        HEX0<="0100100";
    ELSIF (um=6) THEN
        HEX0<="0100000";
    ELSIF (um=7) THEN
        HEX0<="0001111";
    ELSIF (um=8) THEN
        HEX0<="0000000";
    ELSIF (um=9) THEN
        HEX0<="0000100";
    ELSIF (um=0) THEN
        HEX0<="0000001";
    END IF;
    --centenas - display 1
    IF (c=1) THEN
        HEX1<="1001111";
    ELSIF (c=2) THEN
        HEX1<="0010010";
    ELSIF (c=3) THEN
        HEX1<="0000110";
    ELSIF (c=4) THEN
        HEX1<="1001100";
    ELSIF (c=5) THEN
        HEX1<="0100100";
    ELSIF (c=6) THEN
        HEX1<="0100000";
    ELSIF (c=7) THEN
        HEX1<="0001111";
    ELSIF (c=8) THEN
        HEX1<="0000000";
    ELSIF (c=9) THEN
        HEX1<="0000100";
    ELSIF (c=0) THEN
        HEX1<="0000001";
    END IF;
    --dezena - display 2
    IF (d=1) THEN
        HEX2<="1001111";
    ELSIF (d=2) THEN
        HEX2<="0010010";
    ELSIF (d=3) THEN
        HEX2<="0000110";
    ELSIF (d=4) THEN
        HEX2<="1001100";
    ELSIF (d=5) THEN
        HEX2<="0100100";
    ELSIF (d=6) THEN
        HEX2<="0100000";
    ELSIF (d=7) THEN
        HEX2<="0001111";
    ELSIF (d=8) THEN
        HEX2<="0000000";
    ELSIF (d=9) THEN
        HEX2<="0000100";
    ELSIF (d=0) THEN
        HEX2<="0000001";
    END IF;
    --unidade - display 3
    IF (u=1) THEN
        HEX3<="1001111";
    ELSIF (u=2) THEN
        HEX3<="0010010";
    ELSIF (u=3) THEN
        HEX3<="0000110";
    ELSIF (u=4) THEN
        HEX3<="1001100";
    ELSIF (u=5) THEN
        HEX3<="0100100";
    ELSIF (u=6) THEN
        HEX3<="0100000";
    ELSIF (u=7) THEN
        HEX3<="0001111";
    ELSIF (u=8) THEN
        HEX3<="0000000";
    ELSIF (u=9) THEN
        HEX3<="0000100";
    ELSIF (u=0) THEN
        HEX3<="0000001";
    END IF;
END PROCESS;


PROCESS ( read, ready_set )
    BEGIN
    IF read = '1' THEN
        scan_ready <= '0';
    ELSIF ready_set'EVENT AND ready_set = '1' THEN
        scan_ready <= '1';
    END IF;
    END PROCESS;

    --This process filters the raw clock signal coming from the
    -- keyboard using a shift register and two AND gates
    Clock_filter:
    PROCESS
    BEGIN
    WAIT UNTIL clock_50MHz'EVENT AND clock_50MHz = '1';
        clock_enable <= NOT clock_enable;
    IF clock_enable = '1' THEN
        filter ( 6 DOWNTO 0 ) <= filter( 7 DOWNTO 1 ) ;
        filter( 7 ) <= keyboard_clk;
        IF filter = "11111111" THEN
            keyboard_clk_filtered <= '1';
        ELSIF filter = "00000000" THEN
            keyboard_clk_filtered <= '0';
        END IF;
    END IF;
    END PROCESS Clock_filter;

    --This process reads in serial scan code data coming from the keyboard
    PROCESS
    BEGIN
    WAIT UNTIL (KEYBOARD_CLK_filtered'EVENT AND KEYBOARD_CLK_filtered = '1');
        IF RESET = '0' THEN
            INCNT <= "0000";
            READ_CHAR <= '0';
        ELSE
            IF KEYBOARD_DATA = '0' AND READ_CHAR = '0' THEN
                READ_CHAR <= '1';
                ready_set <= '0';
            ELSE
    -- Shift in next 8 data bits to assemble a scan code
                IF READ_CHAR = '1' THEN
                    IF INCNT < "1001" THEN
                        INCNT <= INCNT + 1;
                        SHIFTIN( 7 DOWNTO 0 ) <= SHIFTIN( 8 DOWNTO 1 );
                        SHIFTIN( 8 ) <= KEYBOARD_DATA;
                        ready_set <= '0';
    -- End of scan code character, so set flags and exit loop
                    ELSE
                        scan_code <= SHIFTIN( 7 DOWNTO 0 );
                        CodigoTeclado <= SHIFTIN;
                        READ_CHAR <='0';
                        ready_set <= '1';
                        INCNT <= "0000";
                    END IF;
                END IF;
            END IF;
        END IF;
    END PROCESS;


END comportamental;