glfw/lib/x11/x11_joystick.c

//========================================================================
// GLFW - An OpenGL framework
// Platform:    X11/GLX
// API version: 3.0
// WWW:         http://www.glfw.org/
//------------------------------------------------------------------------
// Copyright (c) 2002-2006 Marcus Geelnard
// Copyright (c) 2006-2010 Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================

#include "internal.h"


//========================================================================
// Note: Only Linux joystick input is supported at the moment. Other
// systems will behave as if there are no joysticks connected.
//========================================================================


//************************************************************************
//****                  GLFW internal functions                       ****
//************************************************************************

#ifdef _GLFW_USE_LINUX_JOYSTICKS

//------------------------------------------------------------------------
// Here are the Linux joystick driver v1.x interface definitions that we
// use (we do not want to rely on <linux/joystick.h>):
//------------------------------------------------------------------------

#include <sys/ioctl.h>
#include <fcntl.h>
#include <errno.h>

// Joystick event types
#define JS_EVENT_BUTTON     0x01    /* button pressed/released */
#define JS_EVENT_AXIS       0x02    /* joystick moved */
#define JS_EVENT_INIT       0x80    /* initial state of device */

// Joystick event structure
struct js_event {
    unsigned int  time;    /* (u32) event timestamp in milliseconds */
    signed short  value;   /* (s16) value */
    unsigned char type;    /* (u8)  event type */
    unsigned char number;  /* (u8)  axis/button number */
};

// Joystick IOCTL commands
#define JSIOCGVERSION  _IOR('j', 0x01, int)   /* get driver version (u32) */
#define JSIOCGAXES     _IOR('j', 0x11, char)  /* get number of axes (u8) */
#define JSIOCGBUTTONS  _IOR('j', 0x12, char)  /* get number of buttons (u8) */

#endif // _GLFW_USE_LINUX_JOYSTICKS


//========================================================================
// Initialize joystick interface
//========================================================================

void _glfwInitJoysticks( void )
{
#ifdef _GLFW_USE_LINUX_JOYSTICKS
    int  k, n, fd, joy_count;
    char *joy_base_name, joy_dev_name[ 20 ];
    int  driver_version = 0x000800;
    char ret_data;
#endif // _GLFW_USE_LINUX_JOYSTICKS
    int  i;

    // Start by saying that there are no sticks
    for( i = 0; i <= GLFW_JOYSTICK_LAST; ++ i )
        _glfwJoy[ i ].Present = GL_FALSE;

#ifdef _GLFW_USE_LINUX_JOYSTICKS

    // Try to open joysticks (nonblocking)
    joy_count = 0;
    for( k = 0; k <= 1 && joy_count <= GLFW_JOYSTICK_LAST; ++ k )
    {
        // Pick joystick base name
        switch( k )
        {
        case 0:
            joy_base_name = "/dev/input/js";  // USB sticks
            break;
        case 1:
            joy_base_name = "/dev/js";        // "Legacy" sticks
            break;
        default:
            continue;                         // (should never happen)
        }

        // Try to open a few of these sticks
        for( i = 0; i <= 50 && joy_count <= GLFW_JOYSTICK_LAST; ++ i )
        {
            sprintf( joy_dev_name, "%s%d", joy_base_name, i );
            fd = open( joy_dev_name, O_NONBLOCK );
            if( fd != -1 )
            {
                // Remember fd
                _glfwJoy[ joy_count ].fd = fd;

                // Check that the joystick driver version is 1.0+
                ioctl( fd, JSIOCGVERSION, &driver_version );
                if( driver_version < 0x010000 )
                {
                    // It's an old 0.x interface (we don't support it)
                    close( fd );
                    continue;
                }

                // Get number of joystick axes
                ioctl( fd, JSIOCGAXES, &ret_data );
                _glfwJoy[ joy_count ].NumAxes = (int) ret_data;

                // Get number of joystick buttons
                ioctl( fd, JSIOCGBUTTONS, &ret_data );
                _glfwJoy[ joy_count ].NumButtons = (int) ret_data;

                // Allocate memory for joystick state
                _glfwJoy[ joy_count ].Axis =
                    (float *) malloc( sizeof(float) *
                                      _glfwJoy[ joy_count ].NumAxes );
                if( _glfwJoy[ joy_count ].Axis == NULL )
                {
                    close( fd );
                    continue;
                }
                _glfwJoy[ joy_count ].Button =
                    (unsigned char *) malloc( sizeof(char) *
                                     _glfwJoy[ joy_count ].NumButtons );
                if( _glfwJoy[ joy_count ].Button == NULL )
                {
                    free( _glfwJoy[ joy_count ].Axis );
                    close( fd );
                    continue;
                }

                // Clear joystick state
                for( n = 0; n < _glfwJoy[ joy_count ].NumAxes; ++ n )
                    _glfwJoy[ joy_count ].Axis[ n ] = 0.0f;

                for( n = 0; n < _glfwJoy[ joy_count ].NumButtons; ++ n )
                    _glfwJoy[ joy_count ].Button[ n ] = GLFW_RELEASE;

                // The joystick is supported and connected
                _glfwJoy[ joy_count ].Present = GL_TRUE;
                joy_count ++;
            }
        }
    }

#endif // _GLFW_USE_LINUX_JOYSTICKS

}


//========================================================================
// Close all opened joystick handles
//========================================================================

void _glfwTerminateJoysticks( void )
{

#ifdef _GLFW_USE_LINUX_JOYSTICKS

    int i;

    // Close any opened joysticks
    for( i = 0; i <= GLFW_JOYSTICK_LAST; ++ i )
    {
        if( _glfwJoy[ i ].Present )
        {
            close( _glfwJoy[ i ].fd );
            free( _glfwJoy[ i ].Axis );
            free( _glfwJoy[ i ].Button );
            _glfwJoy[ i ].Present = GL_FALSE;
        }
    }

#endif // _GLFW_USE_LINUX_JOYSTICKS

}


//========================================================================
// Empty joystick event queue
//========================================================================

static void pollJoystickEvents( void )
{

#ifdef _GLFW_USE_LINUX_JOYSTICKS

    struct js_event e;
    int i;

    // Get joystick events for all GLFW joysticks
    for( i = 0; i <= GLFW_JOYSTICK_LAST; ++ i )
    {
        // Is the stick present?
        if( _glfwJoy[ i ].Present )
        {
            // Read all queued events (non-blocking)
            while( read(_glfwJoy[i].fd, &e, sizeof(struct js_event)) > 0 )
            {
                // We don't care if it's an init event or not
                e.type &= ~JS_EVENT_INIT;

                // Check event type
                switch( e.type )
                {
                case JS_EVENT_AXIS:
                    _glfwJoy[ i ].Axis[ e.number ] = (float) e.value /
                                                             32767.0f;
                    // We need to change the sign for the Y axes, so that
                    // positive = up/forward, according to the GLFW spec.
                    if( e.number & 1 )
                    {
                        _glfwJoy[ i ].Axis[ e.number ] =
                            -_glfwJoy[ i ].Axis[ e.number ];
                    }
                    break;

                case JS_EVENT_BUTTON:
                    _glfwJoy[ i ].Button[ e.number ] =
                        e.value ? GLFW_PRESS : GLFW_RELEASE;
                    break;

                default:
                    break;
                }
            }
        }
    }

#endif // _GLFW_USE_LINUX_JOYSTICKS

}


//************************************************************************
//****               Platform implementation functions                ****
//************************************************************************

//========================================================================
// Determine joystick capabilities
//========================================================================

int _glfwPlatformGetJoystickParam( int joy, int param )
{
    if( !_glfwJoy[ joy ].Present )
        return 0;

    switch( param )
    {
    case GLFW_PRESENT:
        return GL_TRUE;

    case GLFW_AXES:
        return _glfwJoy[ joy ].NumAxes;

    case GLFW_BUTTONS:
        return _glfwJoy[ joy ].NumButtons;

    default:
        break;
    }

    return 0;
}


//========================================================================
// Get joystick axis positions
//========================================================================

int _glfwPlatformGetJoystickPos( int joy, float *pos, int numaxes )
{
    int i;

    if( !_glfwJoy[ joy ].Present )
        return 0;

    // Update joystick state
    pollJoystickEvents();

    // Does the joystick support less axes than requested?
    if( _glfwJoy[ joy ].NumAxes < numaxes )
        numaxes = _glfwJoy[ joy ].NumAxes;

    // Copy axis positions from internal state
    for( i = 0; i < numaxes; ++ i )
        pos[ i ] = _glfwJoy[ joy ].Axis[ i ];

    return numaxes;
}


//========================================================================
// Get joystick button states
//========================================================================

int _glfwPlatformGetJoystickButtons( int joy, unsigned char *buttons,
                                     int numbuttons )
{
    int i;

    if( !_glfwJoy[ joy ].Present )
        return 0;

    // Update joystick state
    pollJoystickEvents();

    // Does the joystick support less buttons than requested?
    if( _glfwJoy[ joy ].NumButtons < numbuttons )
        numbuttons = _glfwJoy[ joy ].NumButtons;

    // Copy button states from internal state
    for( i = 0; i < numbuttons; ++ i )
        buttons[ i ] = _glfwJoy[ joy ].Button[ i ];

    return numbuttons;
}