src/joystick/SDL_joystick.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2011 Sam Lantinga <slouken@libsdl.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 "SDL_config.h"

/* This is the joystick API for Simple DirectMedia Layer */

#include "SDL_events.h"
#include "SDL_sysjoystick.h"
#include "SDL_joystick_c.h"
#if !SDL_EVENTS_DISABLED
#include "../events/SDL_events_c.h"
#endif

Uint8 SDL_numjoysticks = 0;
SDL_Joystick **SDL_joysticks = NULL;

int
SDL_JoystickInit(void)
{
    int arraylen;
    int status;

    SDL_numjoysticks = 0;
    status = SDL_SYS_JoystickInit();
    if (status >= 0) {
        arraylen = (status + 1) * sizeof(*SDL_joysticks);
        SDL_joysticks = (SDL_Joystick **) SDL_malloc(arraylen);
        if (SDL_joysticks == NULL) {
            SDL_numjoysticks = 0;
        } else {
            SDL_memset(SDL_joysticks, 0, arraylen);
            SDL_numjoysticks = status;
        }
        status = 0;
    }
    return (status);
}

/*
 * Count the number of joysticks attached to the system
 */
int
SDL_NumJoysticks(void)
{
    return SDL_numjoysticks;
}

/*
 * Get the implementation dependent name of a joystick
 */
const char *
SDL_JoystickName(int device_index)
{
    if ((device_index < 0) || (device_index >= SDL_numjoysticks)) {
        SDL_SetError("There are %d joysticks available", SDL_numjoysticks);
        return (NULL);
    }
    return (SDL_SYS_JoystickName(device_index));
}

/*
 * Open a joystick for use - the index passed as an argument refers to
 * the N'th joystick on the system.  This index is the value which will
 * identify this joystick in future joystick events.
 *
 * This function returns a joystick identifier, or NULL if an error occurred.
 */
SDL_Joystick *
SDL_JoystickOpen(int device_index)
{
    int i;
    SDL_Joystick *joystick;

    if ((device_index < 0) || (device_index >= SDL_numjoysticks)) {
        SDL_SetError("There are %d joysticks available", SDL_numjoysticks);
        return (NULL);
    }

    /* If the joystick is already open, return it */
    for (i = 0; SDL_joysticks[i]; ++i) {
        if (device_index == SDL_joysticks[i]->index) {
            joystick = SDL_joysticks[i];
            ++joystick->ref_count;
            return (joystick);
        }
    }

    /* Create and initialize the joystick */
    joystick = (SDL_Joystick *) SDL_malloc((sizeof *joystick));
    if (joystick == NULL) {
        SDL_OutOfMemory();
        return NULL;
    }

    SDL_memset(joystick, 0, (sizeof *joystick));
    joystick->index = device_index;
    if (SDL_SYS_JoystickOpen(joystick) < 0) {
        SDL_free(joystick);
        return NULL;
    }
    if (joystick->naxes > 0) {
        joystick->axes = (Sint16 *) SDL_malloc
            (joystick->naxes * sizeof(Sint16));
    }
    if (joystick->nhats > 0) {
        joystick->hats = (Uint8 *) SDL_malloc
            (joystick->nhats * sizeof(Uint8));
    }
    if (joystick->nballs > 0) {
        joystick->balls = (struct balldelta *) SDL_malloc
            (joystick->nballs * sizeof(*joystick->balls));
    }
    if (joystick->nbuttons > 0) {
        joystick->buttons = (Uint8 *) SDL_malloc
            (joystick->nbuttons * sizeof(Uint8));
    }
    if (((joystick->naxes > 0) && !joystick->axes)
        || ((joystick->nhats > 0) && !joystick->hats)
        || ((joystick->nballs > 0) && !joystick->balls)
        || ((joystick->nbuttons > 0) && !joystick->buttons)) {
        SDL_OutOfMemory();
        SDL_JoystickClose(joystick);
        return NULL;
    }
    if (joystick->axes) {
        SDL_memset(joystick->axes, 0, joystick->naxes * sizeof(Sint16));
    }
    if (joystick->hats) {
        SDL_memset(joystick->hats, 0, joystick->nhats * sizeof(Uint8));
    }
    if (joystick->balls) {
        SDL_memset(joystick->balls, 0,
            joystick->nballs * sizeof(*joystick->balls));
    }
    if (joystick->buttons) {
        SDL_memset(joystick->buttons, 0, joystick->nbuttons * sizeof(Uint8));
    }

    /* Add joystick to list */
    ++joystick->ref_count;
    for (i = 0; SDL_joysticks[i]; ++i)
        /* Skip to next joystick */ ;
    SDL_joysticks[i] = joystick;

    return (joystick);
}

/*
 * Returns 1 if the joystick has been opened, or 0 if it has not.
 */
int
SDL_JoystickOpened(int device_index)
{
    int i, opened;

    opened = 0;
    for (i = 0; SDL_joysticks[i]; ++i) {
        if (SDL_joysticks[i]->index == (Uint8) device_index) {
            opened = 1;
            break;
        }
    }
    return (opened);
}


/*
 * Checks to make sure the joystick is valid.
 */
int
SDL_PrivateJoystickValid(SDL_Joystick ** joystick)
{
    int valid;

    if (*joystick == NULL) {
        SDL_SetError("Joystick hasn't been opened yet");
        valid = 0;
    } else {
        valid = 1;
    }
    return valid;
}

/*
 * Get the device index of an opened joystick.
 */
int
SDL_JoystickIndex(SDL_Joystick * joystick)
{
    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }
    return (joystick->index);
}

/*
 * Get the number of multi-dimensional axis controls on a joystick
 */
int
SDL_JoystickNumAxes(SDL_Joystick * joystick)
{
    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }
    return (joystick->naxes);
}

/*
 * Get the number of hats on a joystick
 */
int
SDL_JoystickNumHats(SDL_Joystick * joystick)
{
    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }
    return (joystick->nhats);
}

/*
 * Get the number of trackballs on a joystick
 */
int
SDL_JoystickNumBalls(SDL_Joystick * joystick)
{
    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }
    return (joystick->nballs);
}

/*
 * Get the number of buttons on a joystick
 */
int
SDL_JoystickNumButtons(SDL_Joystick * joystick)
{
    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }
    return (joystick->nbuttons);
}

/*
 * Get the current state of an axis control on a joystick
 */
Sint16
SDL_JoystickGetAxis(SDL_Joystick * joystick, int axis)
{
    Sint16 state;

    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (0);
    }
    if (axis < joystick->naxes) {
        state = joystick->axes[axis];
    } else {
        SDL_SetError("Joystick only has %d axes", joystick->naxes);
        state = 0;
    }
    return (state);
}

/*
 * Get the current state of a hat on a joystick
 */
Uint8
SDL_JoystickGetHat(SDL_Joystick * joystick, int hat)
{
    Uint8 state;

    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (0);
    }
    if (hat < joystick->nhats) {
        state = joystick->hats[hat];
    } else {
        SDL_SetError("Joystick only has %d hats", joystick->nhats);
        state = 0;
    }
    return (state);
}

/*
 * Get the ball axis change since the last poll
 */
int
SDL_JoystickGetBall(SDL_Joystick * joystick, int ball, int *dx, int *dy)
{
    int retval;

    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (-1);
    }

    retval = 0;
    if (ball < joystick->nballs) {
        if (dx) {
            *dx = joystick->balls[ball].dx;
        }
        if (dy) {
            *dy = joystick->balls[ball].dy;
        }
        joystick->balls[ball].dx = 0;
        joystick->balls[ball].dy = 0;
    } else {
        SDL_SetError("Joystick only has %d balls", joystick->nballs);
        retval = -1;
    }
    return (retval);
}

/*
 * Get the current state of a button on a joystick
 */
Uint8
SDL_JoystickGetButton(SDL_Joystick * joystick, int button)
{
    Uint8 state;

    if (!SDL_PrivateJoystickValid(&joystick)) {
        return (0);
    }
    if (button < joystick->nbuttons) {
        state = joystick->buttons[button];
    } else {
        SDL_SetError("Joystick only has %d buttons", joystick->nbuttons);
        state = 0;
    }
    return (state);
}

/*
 * Close a joystick previously opened with SDL_JoystickOpen()
 */
void
SDL_JoystickClose(SDL_Joystick * joystick)
{
    int i;

    if (!SDL_PrivateJoystickValid(&joystick)) {
        return;
    }

    /* First decrement ref count */
    if (--joystick->ref_count > 0) {
        return;
    }

    SDL_SYS_JoystickClose(joystick);

    /* Remove joystick from list */
    for (i = 0; SDL_joysticks[i]; ++i) {
        if (joystick == SDL_joysticks[i]) {
            SDL_memmove(&SDL_joysticks[i], &SDL_joysticks[i + 1],
                        (SDL_numjoysticks - i) * sizeof(joystick));
            break;
        }
    }

    /* Free the data associated with this joystick */
    if (joystick->axes) {
        SDL_free(joystick->axes);
    }
    if (joystick->hats) {
        SDL_free(joystick->hats);
    }
    if (joystick->balls) {
        SDL_free(joystick->balls);
    }
    if (joystick->buttons) {
        SDL_free(joystick->buttons);
    }
    SDL_free(joystick);
}

void
SDL_JoystickQuit(void)
{
    const int numsticks = SDL_numjoysticks;
    int i;

    /* Stop the event polling */
    SDL_numjoysticks = 0;

    SDL_assert( (SDL_joysticks == NULL) == (numsticks == 0) );

    for (i = 0; i < numsticks; i++) {
        SDL_Joystick *stick = SDL_joysticks[i];
        if (stick && (stick->ref_count >= 1)) {
            stick->ref_count = 1;
            SDL_JoystickClose(stick);
        }
    }

    /* Quit the joystick setup */
    SDL_SYS_JoystickQuit();
    if (SDL_joysticks) {
        SDL_free(SDL_joysticks);
        SDL_joysticks = NULL;
    }
}


/* These are global for SDL_sysjoystick.c and SDL_events.c */

int
SDL_PrivateJoystickAxis(SDL_Joystick * joystick, Uint8 axis, Sint16 value)
{
    int posted;

    /* Update internal joystick state */
    joystick->axes[axis] = value;

    /* Post the event, if desired */
    posted = 0;
#if !SDL_EVENTS_DISABLED
    if (SDL_GetEventState(SDL_JOYAXISMOTION) == SDL_ENABLE) {
        SDL_Event event;
        event.type = SDL_JOYAXISMOTION;
        event.jaxis.which = joystick->index;
        event.jaxis.axis = axis;
        event.jaxis.value = value;
        if ((SDL_EventOK == NULL)
            || (*SDL_EventOK) (SDL_EventOKParam, &event)) {
            posted = 1;
            SDL_PushEvent(&event);
        }
    }
#endif /* !SDL_EVENTS_DISABLED */
    return (posted);
}

int
SDL_PrivateJoystickHat(SDL_Joystick * joystick, Uint8 hat, Uint8 value)
{
    int posted;

    /* Update internal joystick state */
    joystick->hats[hat] = value;

    /* Post the event, if desired */
    posted = 0;
#if !SDL_EVENTS_DISABLED
    if (SDL_GetEventState(SDL_JOYHATMOTION) == SDL_ENABLE) {
        SDL_Event event;
        event.jhat.type = SDL_JOYHATMOTION;
        event.jhat.which = joystick->index;
        event.jhat.hat = hat;
        event.jhat.value = value;
        if ((SDL_EventOK == NULL)
            || (*SDL_EventOK) (SDL_EventOKParam, &event)) {
            posted = 1;
            SDL_PushEvent(&event);
        }
    }
#endif /* !SDL_EVENTS_DISABLED */
    return (posted);
}

int
SDL_PrivateJoystickBall(SDL_Joystick * joystick, Uint8 ball,
                        Sint16 xrel, Sint16 yrel)
{
    int posted;

    /* Update internal mouse state */
    joystick->balls[ball].dx += xrel;
    joystick->balls[ball].dy += yrel;

    /* Post the event, if desired */
    posted = 0;
#if !SDL_EVENTS_DISABLED
    if (SDL_GetEventState(SDL_JOYBALLMOTION) == SDL_ENABLE) {
        SDL_Event event;
        event.jball.type = SDL_JOYBALLMOTION;
        event.jball.which = joystick->index;
        event.jball.ball = ball;
        event.jball.xrel = xrel;
        event.jball.yrel = yrel;
        if ((SDL_EventOK == NULL)
            || (*SDL_EventOK) (SDL_EventOKParam, &event)) {
            posted = 1;
            SDL_PushEvent(&event);
        }
    }
#endif /* !SDL_EVENTS_DISABLED */
    return (posted);
}

int
SDL_PrivateJoystickButton(SDL_Joystick * joystick, Uint8 button, Uint8 state)
{
    int posted;
#if !SDL_EVENTS_DISABLED
    SDL_Event event;

    switch (state) {
    case SDL_PRESSED:
        event.type = SDL_JOYBUTTONDOWN;
        break;
    case SDL_RELEASED:
        event.type = SDL_JOYBUTTONUP;
        break;
    default:
        /* Invalid state -- bail */
        return (0);
    }
#endif /* !SDL_EVENTS_DISABLED */

    /* Update internal joystick state */
    joystick->buttons[button] = state;

    /* Post the event, if desired */
    posted = 0;
#if !SDL_EVENTS_DISABLED
    if (SDL_GetEventState(event.type) == SDL_ENABLE) {
        event.jbutton.which = joystick->index;
        event.jbutton.button = button;
        event.jbutton.state = state;
        if ((SDL_EventOK == NULL)
            || (*SDL_EventOK) (SDL_EventOKParam, &event)) {
            posted = 1;
            SDL_PushEvent(&event);
        }
    }
#endif /* !SDL_EVENTS_DISABLED */
    return (posted);
}

void
SDL_JoystickUpdate(void)
{
    int i;

    for (i = 0; SDL_joysticks[i]; ++i) {
        SDL_SYS_JoystickUpdate(SDL_joysticks[i]);
    }
}

int
SDL_JoystickEventState(int state)
{
#if SDL_EVENTS_DISABLED
    return SDL_IGNORE;
#else
    const Uint32 event_list[] = {
        SDL_JOYAXISMOTION, SDL_JOYBALLMOTION, SDL_JOYHATMOTION,
        SDL_JOYBUTTONDOWN, SDL_JOYBUTTONUP,
    };
    unsigned int i;

    switch (state) {
    case SDL_QUERY:
        state = SDL_IGNORE;
        for (i = 0; i < SDL_arraysize(event_list); ++i) {
            state = SDL_EventState(event_list[i], SDL_QUERY);
            if (state == SDL_ENABLE) {
                break;
            }
        }
        break;
    default:
        for (i = 0; i < SDL_arraysize(event_list); ++i) {
            SDL_EventState(event_list[i], state);
        }
        break;
    }
    return (state);
#endif /* SDL_EVENTS_DISABLED */
}

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