src/x11_joystick.c

//========================================================================
// GLFW - An OpenGL library
// 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.
//========================================================================


#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>
#include <stdio.h>
#include <stdlib.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


//////////////////////////////////////////////////////////////////////////
//////                       GLFW internal API                      //////
//////////////////////////////////////////////////////////////////////////

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

void _glfwInitJoysticks(void)
{
#ifdef _GLFW_USE_LINUX_JOYSTICKS
    int  k, n, fd, joy_count;
    const char* joy_base_name;
    char 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:
                // USB joysticks
                joy_base_name = "/dev/input/js";
                break;
            case 1:
                // "Legacy" joysticks
                joy_base_name = "/dev/js";
                break;
            default:
                // This should never happen
                continue;
        }

        // 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
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW platform API                      //////
//////////////////////////////////////////////////////////////////////////

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

int _glfwPlatformGetJoystickParam(int joy, int param)
{
    if (!_glfwJoy[joy].Present)
    {
        // TODO: Figure out if this is an error
        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)
    {
        // TODO: Figure out if this is an error
        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)
    {
        // TODO: Figure out if this is an error
        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;
}