src/joystick/riscos/SDL_sysjoystick.c

   1 /*
   2     SDL - Simple DirectMedia Layer
   3     Copyright (C) 1997-2009 Sam Lantinga
   4
   5     This library is free software; you can redistribute it and/or
   6     modify it under the terms of the GNU Lesser General Public
   7     License as published by the Free Software Foundation; either
   8     version 2.1 of the License, or (at your option) any later version.
   9
  10     This library is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13     Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public
  16     License along with this library; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18
  19     Sam Lantinga
  20     slouken@libsdl.org
  21 */
  22 #include "SDL_config.h"
  23
  24 #ifdef SDL_JOYSTICK_RISCOS
  25
  26 /*
  27    RISC OS - Joystick support by Alan Buckley (alan_baa@hotmail.com) - 10 April 2003
  28
  29    Note: Currently assumes joystick is present if joystick module is loaded
  30    and that there is one joystick with four buttons.
  31 */
  32
  33 /* This is the system specific header for the SDL joystick API */
  34
  35 #include "SDL_events.h"
  36 #include "SDL_joystick.h"
  37 #include "../SDL_sysjoystick.h"
  38 #include "../SDL_joystick_c.h"
  39
  40 #include "kernel.h"
  41
  42 #define JOYSTICK_READ 0x43F40
  43
  44 struct joystick_hwdata
  45 {
  46         int joystate;
  47 };
  48
  49
  50 /* Function to scan the system for joysticks.
  51  * This function should set SDL_numjoysticks to the number of available
  52  * joysticks.  Joystick 0 should be the system default joystick.
  53  * It should return number of joysticks, or -1 on an unrecoverable fatal error.
  54  */
  55 int SDL_SYS_JoystickInit(void)
  56 {
  57         _kernel_swi_regs regs;
  58
  59          /* Try to read joystick 0 */
  60         regs.r[0] = 0;
  61         if (_kernel_swi(JOYSTICK_READ, &regs, &regs) == NULL)
  62         {
  63                 /* Switch works so assume we've got a joystick */
  64                 return 1;
  65         }
  66         /* Switch fails so it looks like there's no joystick here */
  67
  68         return(0);
  69 }
  70
  71 /* Function to get the device-dependent name of a joystick */
  72 const char *SDL_SYS_JoystickName(int index)
  73 {
  74         if (index == 0)
  75         {
  76                 return "RISC OS Joystick 0";
  77         }
  78
  79         SDL_SetError("No joystick available with that index");
  80         return(NULL);
  81 }
  82
  83 /* Function to open a joystick for use.
  84    The joystick to open is specified by the index field of the joystick.
  85    This should fill the nbuttons and naxes fields of the joystick structure.
  86    It returns 0, or -1 if there is an error.
  87  */
  88 int SDL_SYS_JoystickOpen(SDL_Joystick *joystick)
  89 {
  90         _kernel_swi_regs regs;
  91
  92         if(!(joystick->hwdata=SDL_malloc(sizeof(struct joystick_hwdata))))
  93                 return -1;
  94
  95         regs.r[0] = joystick->index;
  96
  97         /* Don't know how to get exact count of buttons so assume max of 4 for now */
  98         joystick->nbuttons=4;
  99
 100         joystick->nhats=0;
 101         joystick->nballs=0;
 102         joystick->naxes=2;
 103         joystick->hwdata->joystate=0;
 104
 105         return 0;
 106
 107 }
 108
 109 /* Function to update the state of a joystick - called as a device poll.
 110  * This function shouldn't update the joystick structure directly,
 111  * but instead should call SDL_PrivateJoystick*() to deliver events
 112  * and update joystick device state.
 113  */
 114 void SDL_SYS_JoystickUpdate(SDL_Joystick *joystick)
 115 {
 116         _kernel_swi_regs regs;
 117         regs.r[0] = joystick->index;
 118
 119         if (_kernel_swi(JOYSTICK_READ, &regs, &regs) == NULL)
 120         {
 121                 int newstate = regs.r[0];
 122                 int oldstate = joystick->hwdata->joystate;
 123                 if (newstate != oldstate)
 124                 {
 125                         if ((newstate & 0xFF) != (oldstate & 0xFF))
 126                         {
 127                                 int y = regs.r[0] & 0xFF;
 128                                 /* Convert to signed values */
 129                                 if (y >= 128) y -= 256;
 130                                 SDL_PrivateJoystickAxis(joystick,1,-y * 256); /* Up and down opposite to result in SDL */
 131                         }
 132                         if ((newstate & 0xFF00) != (oldstate & 0xFF00))
 133                         {
 134                                 int x = (regs.r[0] & 0xFF00) >> 8;
 135                                 if (x >= 128) x -= 256;
 136                                 SDL_PrivateJoystickAxis(joystick,0,x * 256);
 137                         }
 138
 139                         if ((newstate & 0xFF0000) != (oldstate & 0xFF0000))
 140                         {
 141                                 int buttons = (regs.r[0] & 0xFF0000) >> 16;
 142                                 int oldbuttons = (oldstate & 0xFF0000) >> 16;
 143                                 int i;
 144                                 for (i = 0; i < joystick->nbuttons; i++)
 145                                 {
 146                                         if ((buttons & (1<<i)) != (oldbuttons & (1<<i)))
 147                                         {
 148                                                 if (buttons & (1<<i)) SDL_PrivateJoystickButton(joystick,i,SDL_PRESSED);
 149                                                 else SDL_PrivateJoystickButton(joystick,i,SDL_RELEASED);
 150                                         }
 151                                 }
 152                         }
 153                         joystick->hwdata->joystate = newstate;
 154                 }
 155         }
 156
 157         return;
 158 }
 159
 160 /* Function to close a joystick after use */
 161 void SDL_SYS_JoystickClose(SDL_Joystick *joystick)
 162 {
 163         if(joystick->hwdata)
 164                 SDL_free(joystick->hwdata);
 165         return;
 166 }
 167
 168 /* Function to perform any system-specific joystick related cleanup */
 169 void SDL_SYS_JoystickQuit(void)
 170 {
 171         SDL_numjoysticks=0;
 172
 173         return;
 174 }
 175
 176 #endif /* SDL_JOYSTICK_RISCOS */