/*
 * spacenavi.c - a proof-of-concept hack to access the
 * 3dconnexion space navigator
 *
 * compile with  gcc -Wall -o spacenavi spacenavi.c
 *
 * run with ./spacenavi [/path/to/eventdevice]
 *
 * Written by Simon Budig, placed in the public domain.
 * it helps to read http://www.frogmouth.net/hid-doco/linux-hid.html .
 *
 * For the LED to work a patch to the linux kernel is needed:
 *   http://www.home.unix-ag.org/simon/files/spacenavigator-hid.patch
 *
 */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

#include <linux/types.h>
#include <linux/input.h>

#define test_bit(bit, array)  (array [bit / 8] & (1 << (bit % 8)))

int
snavi_set_led (int snavi_dev, int led_state)
{
  /* this does not seem to work with 2.6.19, it apparently
   * has worked with 2.6.8. Needs further investigation  */
  struct input_event event;
  int ret;

  event.type  = EV_LED;
  event.code  = LED_MISC;
  event.value = led_state;

  ret = write (snavi_dev, &event, sizeof (struct input_event));

  if (ret < 0)
    perror ("setting led state failed");

  return ret < sizeof (struct input_event);
}


int
main (int argc, char *argv[])
{
  int snavi, i;
  char name[256]= "Unknown";
  u_int8_t evtype_bitmask[(EV_MAX + 7) / 8];
  u_int8_t rel_bitmask[(REL_MAX + 7) / 8];
  u_int8_t led_bitmask[(LED_MAX + 7) / 8];
  struct input_event event;
  int axes[6];
  int buttons[2];
  int led_state = 0;

  snavi = open (argc > 1 ? argv[1] : "/dev/input/3d-nav", O_RDWR);

  if (snavi < 0)
    {
      perror ("opening the device failed");
      exit (1);
    }

  if (ioctl (snavi, EVIOCGNAME (sizeof (name)), name) < 0)
    {
      perror ("EVIOCGNAME ioctl failed");
      exit (1);
    }

  printf ("found \"%s\" on %s\n", name, argv[1]);

  if (ioctl (snavi, EVIOCGBIT (0, sizeof (evtype_bitmask)), evtype_bitmask) < 0)
    {
      perror ("EVIOCGBIT ioctl failed");
      exit (1);
    }

  printf ("Supported event types:\n");
  for (i = 0; i < EV_MAX; i++)
    {
      if (test_bit (i, evtype_bitmask))
        {
          /* this means that the bit is set in the event types list */
          printf("  Event type 0x%02x ", i);
          switch (i)
              {
              case EV_SYN :
                  printf(" (Sync?)\n");
                  break;
              case EV_KEY :
                  printf(" (Keys or Buttons)\n");
                  break;
              case EV_REL :
                  printf(" (Relative Axes)\n");
                  break;
              case EV_ABS :
                  printf(" (Absolute Axes)\n");
                  break;
              case EV_LED :
                  printf(" (LEDs)\n");
                  break;
              case EV_REP :
                  printf(" (Repeat)\n");
                  break;
              default:
                  printf(" (Unknown event type)\n");
              }
        }
    }

  memset (rel_bitmask, 0, sizeof (rel_bitmask));

  memset (led_bitmask, 0, sizeof (led_bitmask));
  if (ioctl (snavi, EVIOCGBIT (EV_LED, sizeof (led_bitmask)), led_bitmask) < 0)
    {
      perror ("EVIOCGBIT ioctl failed");
      exit (1);
    }

  printf ("detected leds:\n  ");
  for (i = 0; i < LED_MAX; i++)
    {
      if (test_bit (i, led_bitmask))
        printf ("%d, ", i);
    }
  printf ("\n");


  axes[0] = axes[1] = axes[2] = axes[3] = axes[4] = axes[5] = 0;
  buttons[0] = buttons[1] = 0;

  while (1)
    {
      if (read (snavi, &event, sizeof (struct input_event)) < 0)
        {
          perror ("read error");
          break;
        }

      switch (event.type)
        {
          case EV_REL:
            if (event.code <= REL_RZ)
              axes[event.code - REL_X] = event.value;
            break;

          case EV_KEY:
            if (event.code >= BTN_0 && event.code <= BTN_1)
              buttons[event.code - BTN_0] = event.value;

            if (event.code - BTN_0 == 1)
              {
                led_state = 1 - led_state;
                snavi_set_led (snavi, led_state);
              }
            break;

          case EV_SYN:
            /* if multiple axes change simultaneously the linux
             * input system sends multiple EV_REL events. EV_SYN
             * then indicates that all changes have been reported.
             */
            fprintf (stderr,
                     "\rState: %4d %4d %4d %4d %4d %4d - %3s %3s",
                     axes[0], axes[1], axes[2], axes[3], axes[4], axes[5],
                     buttons[0] ? "on" : "off",
                     buttons[1] ? "on" : "off");
            axes[0] = axes[1] = axes[2] = axes[3] = axes[4] = axes[5] = 0;
            break;

          case EV_LED:
            break;

          default:
            fprintf (stderr, "\nunknown event type %d\n", event.code);
        }
     }

  close (snavi);

  exit (0);
}