linux joystick

Sunday, 20 March 2011 13:13

/* this is the linux 2.2.x way of handling joysticks. It allows an arbitrary
* number of axis and buttons. It's event driven, and has full signed int
* ranges of the axis (-32768 to 32767). It also lets you pull the joysticks
* name. The only place this works of that I know of is in the linux 1.x
* joystick driver, which is included in the linux 2.2.x kernels
*/

#include
#include
#include
#include
#include

#define JOY_DEV "/dev/js0"

int main()
{
int joy_fd, *axis=NULL, num_of_axis=0, num_of_buttons=0, x;
char *button=NULL, name_of_joystick[80];
struct js_event js;

if( ( joy_fd = open( JOY_DEV , O_RDONLY)) == -1 )
{
printf( "Couldn't open joystick\n" );
return -1;
}

ioctl( joy_fd, JSIOCGAXES, &num_of_axis );
ioctl( joy_fd, JSIOCGBUTTONS, &num_of_buttons );
ioctl( joy_fd, JSIOCGNAME(80), &name_of_joystick );

axis = (int *) calloc( num_of_axis, sizeof( int ) );
button = (char *) calloc( num_of_buttons, sizeof( char ) );

printf("Joystick detected: %s\n\t%d axis\n\t%d buttons\n\n"
, name_of_joystick
, num_of_axis
, num_of_buttons );

fcntl( joy_fd, F_SETFL, O_NONBLOCK ); /* use non-blocking mode */

while( 1 ) /* infinite loop */
{

/* read the joystick state */
read(joy_fd, &js, sizeof(struct js_event));

/* see what to do with the event */
switch (js.type & ~JS_EVENT_INIT)
{
case JS_EVENT_AXIS:
axis [ js.number ] = js.value;
break;
case JS_EVENT_BUTTON:
button [ js.number ] = js.value;
break;
}

/* print the results */
printf( "X: %6d Y: %6d ", axis[0], axis[1] );

if( num_of_axis > 2 )
printf("Z: %6d ", axis[2] );

if( num_of_axis > 3 )
printf("R: %6d ", axis[3] );

for( x=0 ; x printf("B%d: %d ", x, button[x] );

printf(" \r");
fflush(stdout);
}

close( joy_fd ); /* too bad we never get here */
return 0;
}