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mini_SDL_joystick.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id: SDL_joystick.c,v 1.4 2002/03/06 11:23:02 slouken Exp $";
#endif

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

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

#include "SDL_sysjoystick.h"

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 **)malloc(arraylen);
            if ( SDL_joysticks == NULL ) {
                  SDL_numjoysticks = 0;
            } else {
                  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 *)malloc((sizeof *joystick));
      if ( joystick != NULL ) {
            memset(joystick, 0, (sizeof *joystick));
            joystick->index = device_index;
            if ( SDL_SYS_JoystickOpen(joystick) < 0 ) {
                  free(joystick);
                  joystick = NULL;
            } else {
                  if ( joystick->naxes > 0 ) {
                        joystick->axes = (Sint16 *)malloc
                              (joystick->naxes*sizeof(Sint16));
                  }
                  if ( joystick->nhats > 0 ) {
                        joystick->hats = (Uint8 *)malloc
                              (joystick->nhats*sizeof(Uint8));
                  }
                  if ( joystick->nballs > 0 ) {
                        joystick->balls = (struct balldelta *)malloc
                          (joystick->nballs*sizeof(*joystick->balls));
                  }
                  if ( joystick->nbuttons > 0 ) {
                        joystick->buttons = (Uint8 *)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);
                        joystick = NULL;
                  }
                  if ( joystick->axes ) {
                        memset(joystick->axes, 0,
                              joystick->naxes*sizeof(Sint16));
                  }
                  if ( joystick->hats ) {
                        memset(joystick->hats, 0,
                              joystick->nhats*sizeof(Uint8));
                  }
                  if ( joystick->balls ) {
                        memset(joystick->balls, 0,
                          joystick->nballs*sizeof(*joystick->balls));
                  }
                  if ( joystick->buttons ) {
                        memset(joystick->buttons, 0,
                              joystick->nbuttons*sizeof(Uint8));
                  }
            }
      }
      if ( joystick ) {
            /* 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);
}

static int ValidJoystick(SDL_Joystick **joystick)
{
      int valid;

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

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

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

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

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

/*
 * Get the number of buttons on a joystick
 */
int SDL_JoystickNumButtons(SDL_Joystick *joystick)
{
      if ( ! ValidJoystick(&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 ( ! ValidJoystick(&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 ( ! ValidJoystick(&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 ( ! ValidJoystick(&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 ( ! ValidJoystick(&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 ( ! ValidJoystick(&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] ) {
                  memcpy(&SDL_joysticks[i], &SDL_joysticks[i+1],
                         (SDL_numjoysticks-i)*sizeof(joystick));
                  break;
            }
      }

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

void SDL_JoystickQuit(void)
{
      SDL_numjoysticks = 0;

      /* Quit the joystick setup */
      SDL_SYS_JoystickQuit();
      if ( SDL_joysticks ) {
            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;
      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;
      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;
      return(posted);
}

int SDL_PrivateJoystickButton(SDL_Joystick *joystick, Uint8 button, Uint8 state)
{
      int posted;

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

      /* Post the event, if desired */
      posted = 0;
      return(posted);
}

void SDL_JoystickUpdate(void)
{
      int i;

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



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