#include <parapin.h>
#include <stdlib.h>         /* atoi() */
#include <unistd.h>         /* usleep() */

#define LED_A LP_PIN02
#define LED_B LP_PIN03
#define LED_C LP_PIN04
#define LED_D LP_PIN05
#define LED_E LP_PIN06
#define LED_F LP_PIN07
#define LED_G LP_PIN08
#define LED_DP LP_PIN09

#define LED_1 LP_PIN17
#define LED_2 LP_PIN16
#define LED_3 LP_PIN14

#define LED_POSITION_MASK (LED_1 | LED_2 | LED_3)

#define LED_ALL (LED_A | LED_B | LED_C | LED_D | LED_E | LED_F | LED_G | LED_DP | LED_1 | LED_2 | LED_3)

#define DELAY 250 /* microsecond delay between displaying digits */

int digit2pins[] = {
    LED_A | LED_B | LED_C | LED_D | LED_E | LED_F,
    LED_B | LED_C,
    LED_A | LED_B | LED_G | LED_E | LED_D,
    LED_A | LED_B | LED_G | LED_C | LED_D,
    LED_F | LED_G | LED_B | LED_C,
    LED_A | LED_F | LED_G | LED_C | LED_D,
    LED_A | LED_F | LED_G | LED_E | LED_C | LED_D,
    LED_A | LED_B | LED_C,
    LED_A | LED_B | LED_C | LED_D | LED_E | LED_F | LED_G,
    LED_A | LED_B | LED_C | LED_D | LED_F | LED_G
};

int position2pins[] = {
    LED_1,
    LED_2,
    LED_3
};

void turnOnDigit(int digitPosition, int value);
void shutDown(int p);

int main(int argc, char * argv[])
{
    /* initialize the parapin user-land library */
    pin_init_user(LPT1);

    /* set up pins as output pins */
    pin_output_mode(LED_ALL);

    if (argc == 2)
    {
        /* get the value to display from the command-line */
        int value = atoi(argv[1]);

        /* register an interrupt signal handler to clear the pins */
        signal(SIGINT, shutDown);

        int digits[3];
        register int i;
        for (i = 0; i < 3; i++)
        {
            digits[2-i] = value % 10;
            value /= 10;
        }

        /* loop displaying digits */
        i = 0;
        for (;;)
        {
            turnOnDigit(i, digits[i]);
            usleep(DELAY);
            i++;
            if (i == 3)
                i = 0;
        }
    }
    else
    {
        clear_pin(LED_ALL);
    }
}

void turnOnDigit(int digitPosition, int value)
{
    /* turn all pins off */
    clear_pin(LED_ALL);

    /* enable the positional pin */
    register int pinSet = LED_POSITION_MASK & ~position2pins[digitPosition];
    pinSet |= digit2pins[value];
    set_pin(pinSet);
}

void shutDown(int p)
{
    clear_pin(LED_ALL);
}