1/*
2    SDL - Simple DirectMedia Layer
3    Copyright (C) 1997-2012 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
44struct 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 */
55int 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 */
72const 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 */
88int 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 */
114void 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 */
161void 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 */
169void SDL_SYS_JoystickQuit(void)
170{
171	SDL_numjoysticks=0;
172
173	return;
174}
175
176#endif /* SDL_JOYSTICK_RISCOS */
177