src/joystick/SDL_joystick.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2010 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#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;
static SDL_Joystick *default_joystick = 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;
    }
    default_joystick = NULL;
    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) {
        *joystick = default_joystick;
    }
    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;
    }

    if (joystick == default_joystick) {
        default_joystick = NULL;
    }
    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)
{
    /* Stop the event polling */
    SDL_numjoysticks = 0;

    /* 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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