Help to remove reinterpret_cast from c++ code

Hi, I have been reading a class that I found online that creates an
object to represent a joystick. Now i recall reading that any use of
'reinterpret cast' is dangerous as it is highly machine dependent. The
code I found unfortunately uses this and i was hoping to improve it,
before attempting to use the class in my program. Note, I have not
tested the class as yet - even on the assumption it works on my machine,
i need it to be as general as possible as my program will run on other
machines as well.

This is the offending member function definition:

//loop function attempts to read an event from the device, and, if an
//event is waiting to be processed,
//updates the state structure based on the event type.

void* cJoystick::loop(void *obj)
{
    while (reinterpret_cast<cJoystick *>(obj)->active)
reinterpret_cast<cJoystick *>(obj)->readEv();
}

- so how can this be re-written so there are no re-interpret casts?

This is the complete class & member function definitions -if you need to
test it.
----------------------- CODE--------------------------
#ifndef JOYSTICK_H
#define JOYSTICK_H

#include <unistd.h>

class cJoystick {
   public:
    cJoystick();
    ~cJoystick();

    static void* loop(void* obj);
    void readEv();
    joystick_position joystickPosition(int n);
    bool buttonPressed(int n);
 private:
    pthread_t thread;
    bool active;
    int joystick_fd;
    js_event *joystick_ev;
    joystick_state *joystick_st;
    __u32 version;
    __u8 axes;
    __u8 buttons;
    char name[256];
};

/*constructor -
When a joystick is connected to a USB port, udev, the device manager for
the Linux kernel, presents
device nodes at "/dev/input/js*". constructor attempts to
1. access a device node
2. query the device for the number of buttons and axes
3. reserve space in our state structure for the buttons and axes
4. finally, create a thread to populate the state structure. */

cJoystick::cJoystick() {
    active = false;
    joystick_fd = 0;
    joystick_ev = new js_event();
    joystick_st = new joystick_state();
    joystick_fd = open(JOYSTICK_DEV, O_RDONLY | O_NONBLOCK);
    if (joystick_fd > 0) {
        ioctl(joystick_fd, JSIOCGNAME(256), name);
        ioctl(joystick_fd, JSIOCGVERSION, &version);
        ioctl(joystick_fd, JSIOCGAXES, &axes);
        ioctl(joystick_fd, JSIOCGBUTTONS, &buttons);
        std::cout << " Name: " << name << std::endl;
        std::cout << "Version: " << version << std::endl;
        std::cout << " Axes: " << (int)axes << std::endl;
        std::cout << "Buttons: " << (int)buttons << std::endl;
        joystick_st->axis.reserve(axes);
        joystick_st->button.reserve(buttons);
        active = true;
        pthread_create(&thread, 0, &cJoystick::loop, this);
    }
}

void cJoystick::readEv() {
    int bytes = read(joystick_fd, joystick_ev, sizeof(*joystick_ev));
    if (bytes > 0) {
        joystick_ev->type &= ~JS_EVENT_INIT;
        if (joystick_ev->type & JS_EVENT_BUTTON) {
            joystick_st->button[joystick_ev->number] = joystick_ev->value;
        }
        if (joystick_ev->type & JS_EVENT_AXIS) {
            joystick_st->axis[joystick_ev->number] = joystick_ev->value;
        }
    }
}

// function to query the state of a button.
bool cJoystick::buttonPressed(int n) {
    return n > -1 && n < buttons ? joystick_st->button[n] : 0;
}

// function to to query the state of an analog stick
joystick_position cJoystick::joystickPosition(int n) {
    joystick_position pos;

    if (n > -1 && n < buttons) {
        int i0 = n*2, i1 = n*2+1;
        float x0 = joystick_st->axis[i0]/32767.0f, y0 =
-joystick_st->axis[i1]/32767.0f;
        float x = x0 * sqrt(1 - pow(y0, 2)/2.0f), y = y0 * sqrt(1 -
pow(x0, 2)/2.0f);

        pos.x = x0;
        pos.y = y0;

        pos.theta = atan2(y, x);
        pos.r = sqrt(pow(y, 2) + pow(x, 2));
    } else {
        pos.theta = pos.r = pos.x = pos.y = 0.0f;
    }
    return pos;
}

// destructor.
cJoystick::~cJoystick() {
    if (joystick_fd > 0) {
        active = false;
        pthread_join(thread, 0);
        close(joystick_fd);
    }
    delete joystick_st;
    delete joystick_ev;
    joystick_fd = 0;
}

#endif

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