------- Comment #1 From Max Horn 2006-04-17 03:08 [reply] -------
authorSam Lantinga <slouken@libsdl.org>
Sat, 29 Apr 2006 20:22:31 +0000
changeset 17485e86e34453d4
parent 1747 e75d0cbcf3c8
child 1749 18e44c267283
------- Comment #1 From Max Horn 2006-04-17 03:08 [reply] -------

Created an attachment (id=106) [edit]
Patch for src/joystick/win32/SDL_mmjoystick.c

I am not even a Windows user, so take the following with a grain of salt:

SDL_mmjoystick.c has a function GetJoystickName which obtains the joystick
name by looking at the registry. The way it does that seems very fishy to me.
Namely, it uses the parameter "index" to construct a registry value name (BTW,
those variables used in the code are really badly named). The value of "index"
in turn equals the current value of "numdevs", as called from
SDL_SYS_JoystickInit.

I read through the MSDN docs at
<http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dnarinput/html/msdn_extdirect.asp>,
and I believe the simple fix is to replace line 183 of said file
SYS_JoystickName[numdevs] = GetJoystickName(numdevs, joycaps.szRegKey);
by the following:
SYS_JoystickName[numdevs] = GetJoystickName(SYS_JoystickID[i],
joycaps.szRegKey);

However, that is only *hiding* the real issue. Problem is, the list of
joysticks as returned by windows may contains "gaps", and the code deals
incorrectly with that. Namely those gaps occur if joysticks are
removed/(re)added, as the reporter observed.

The attached patch fixes this and another (off-by-one) issue in the code. But
since I have no Windows machine, I can't even test-compile it, so use with
caution.
src/joystick/win32/SDL_mmjoystick.c
     1.1 --- a/src/joystick/win32/SDL_mmjoystick.c	Sat Apr 29 17:56:06 2006 +0000
     1.2 +++ b/src/joystick/win32/SDL_mmjoystick.c	Sat Apr 29 20:22:31 2006 +0000
     1.3 @@ -154,34 +154,26 @@
     1.4  	JOYCAPS	joycaps;
     1.5  	MMRESULT result;
     1.6  
     1.7 -	numdevs = 0;
     1.8 -	maxdevs = joyGetNumDevs();
     1.9 -
    1.10 -	if ( maxdevs > MAX_JOYSTICKS ) {
    1.11 -		maxdevs = MAX_JOYSTICKS;
    1.12 -	}
    1.13 -
    1.14 -
    1.15 -	for ( i = 0; i < MAX_JOYSTICKS; i++ ) {
    1.16 -		SYS_JoystickID[i] = JOYSTICKID1 + i;
    1.17 +	/* Reset the joystick ID & name mapping tables */
    1.18 +	for ( i = 0; i < MAX_JOYSTICKS; ++i ) {
    1.19 +		SYS_JoystickID[i] = 0;
    1.20  		SYS_JoystickName[i] = NULL;
    1.21  	}
    1.22  
    1.23 -
    1.24 -	for ( i = 0; (i < maxdevs); ++i ) {
    1.25 +	/* Loop over all potential joystick devices */
    1.26 +	numdevs = 0;
    1.27 +	maxdevs = joyGetNumDevs();
    1.28 +	for ( i = JOYSTICKID1; i < maxdevs && numdevs < MAX_JOYSTICKS; ++i ) {
    1.29  		
    1.30 -		/* added 8/31/2001 By Vitaliy Mikitchenko */
    1.31  		joyinfo.dwSize = sizeof(joyinfo);
    1.32  		joyinfo.dwFlags = JOY_RETURNALL;
    1.33 -		/* end addition */
    1.34 -
    1.35  		result = joyGetPosEx(SYS_JoystickID[i], &joyinfo);
    1.36  		if ( result == JOYERR_NOERROR ) {
    1.37 -			result = joyGetDevCaps(SYS_JoystickID[i], &joycaps, sizeof(joycaps));
    1.38 +			result = joyGetDevCaps(i, &joycaps, sizeof(joycaps));
    1.39  			if ( result == JOYERR_NOERROR ) {
    1.40 -				SYS_JoystickID[numdevs] = SYS_JoystickID[i];
    1.41 +				SYS_JoystickID[numdevs] = i;
    1.42  				SYS_Joystick[numdevs] = joycaps;
    1.43 -				SYS_JoystickName[numdevs] = GetJoystickName(numdevs, joycaps.szRegKey);
    1.44 +				SYS_JoystickName[numdevs] = GetJoystickName(i, joycaps.szRegKey);
    1.45  				numdevs++;
    1.46  			}
    1.47  		}