Listing 7. Determining Features with EVIOCGBIT
if ((fd = open(argv[1], O_RDONLY)) < 0) {
perror("evdev open");
exit(1);
}
memset(evtype_b, 0, sizeof(evtype_b));
if (ioctl(fd, EVIOCGBIT(0, EV_MAX), evtype_b) < 0) {
perror("evdev ioctl");
}
printf("Supported event types:\n");
for (yalv = 0; yalv < EV_MAX; yalv++) {
if (test_bit(yalv, evtype_b)) {
/* the bit is set in the event types list */
printf(" Event type 0x%02x ", yalv);
switch ( yalv)
{
case EV_SYN :
printf(" (Synch Events)\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_MSC :
printf(" (Miscellaneous)\n");
break;
case EV_LED :
printf(" (LEDs)\n");
break;
case EV_SND :
printf(" (Sounds)\n");
break;
case EV_REP :
printf(" (Repeat)\n");
break;
case EV_FF :
case EV_FF_STATUS:
printf(" (Force Feedback)\n");
break;
case EV_PWR:
printf(" (Power Management)\n");
break;
default:
printf(" (Unknown: 0x%04hx)\n",
yalv);
}
}
}
close(fd);
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