view src/thread/linux/clone.S @ 892:dc29e5907694

Date: Sun, 18 Apr 2004 16:09:53 -0400 (EDT) From: David MacCormack Subject: [SDL] Linux joystick patch I recently got myself a PS2 -> USB converter (a super joybox 5). It accepts 4 PSX/PS2 controllers. It's implemented as a HID, which is nice because it doesn't require its own driver, but the problem is that it's implemented as a *single* HID -- that is, it shows up as a single joystick with 19 axes, 4 hats, and 48 buttons. This poses a problem for a number of apps which use SDL (stella, fce ultra, zsnes, to name a few) and see only a single (physical) joystick even though there are really 4 (logical) joysticks. There are a number of these types of devices on the market, and I've seen others post messages (in the zsnes forum, for example) with the same problem, so I came up with what I think is a pretty generic solution. I patched src/joystick/linux/SDL_sysjoystic.c to include support for logical joysticks; basically, it's a static array and supporting functions that map a single physical joystick to multiple logical joysticks. The attached patch has the new code. It's wrapped inside #ifndef statements so that you can get the old behavior if you want.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 16 May 2004 18:46:24 +0000 (2004-05-16)
parents 74212992fb08
children 974ba6ae0fa3
line wrap: on
line source

/* Taken with thanks from LinuxThreads 0.6 */

/* This is no longer necessary with glibc-2.1, which has it's own clone() */
#ifdef linux
/* Look to see if glibc is available, and if so, what version */
#include <features.h>

#if (__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 1))
#define HAVE_CLONE
#endif /* glibc 2.1 or newer */
#endif /* linux */

#if defined(linux) && !defined(SDL_USE_PTHREADS) && !defined(HAVE_CLONE)

#if defined(__i386__)
/************************************************************************/
/* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   Contributed by Richard Henderson (rth@tamu.edu)

The GNU C 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.

The GNU C 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 the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif
Cambridge, MA 02139, USA.  */

/* clone() is even more special than fork() as it mucks with stacks
   and invokes a function in the right context after its all over.  */

#include <asm/errno.h>
#include <asm/unistd.h>

/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg); */

        .text
	.align	4
	.globl	__clone
        .type   __clone,@function
	.weak	clone
	clone   = __clone
__clone:
	/* Sanity check arguments.  */
	movl	$-EINVAL,%eax
	movl	4(%esp),%ecx		/* no NULL function pointers */
	testl	%ecx,%ecx
	jz	syscall_error
	movl	8(%esp),%ecx		/* no NULL stack pointers */
	testl	%ecx,%ecx
	jz	syscall_error

	/* Insert the argument onto the new stack.  */
	subl	$8,%ecx
	movl	16(%esp),%eax
	movl	%eax,4(%ecx)

	/* Save the function pointer as the zeroth argument. */
	/* It will be popped off in the child in the ebx frobbing below.  */
	movl	4(%esp),%eax
	movl	%eax,0(%ecx)

	/* Do the system call */
	pushl	%ebx
	movl	16(%esp),%ebx
	movl	$__NR_clone,%eax
	int	$0x80
	popl	%ebx

	test	%eax,%eax
	jl	syscall_error
	jz	thread_start

	ret

syscall_error:
	negl    %eax
        pushl   %eax
#ifdef __PIC__
        call    __errno_location@PLT
#else
        call    __errno_location
#endif
        popl    0(%eax)
	movl	$-1, %eax
	ret

thread_start:
	subl	%ebp,%ebp	/* terminate the stack frame */
	call	*%ebx
        pushl   %eax
#ifdef __PIC__
	call	_exit@PLT
#else
	call	_exit
#endif
/************************************************************************/
#elif defined(sparc)
/************************************************************************/
/* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   Contributed by Miguel de Icaza (miguel@nuclecu.unam.mx)
   Based on code written for the Intel by Richard 
   Henderson (rth@tamu.edu)
	
The GNU C 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.

The GNU C 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 the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

/* clone() is even more special than fork() as it mucks with stacks
   and invokes a function in the right context after its all over.  */
	
#include <asm/errno.h>
#include <asm/unistd.h>

/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg); */

	.text
	.align	4
	.globl	__clone
	.type	__clone,@function
	.weak	clone
	clone   = __clone
__clone:	
	save	%sp,-96,%sp
	/* sanity check arguments */
	tst	%i0
	be	__clone_syscall_error
	tst	%i1
	be	__clone_syscall_error
        nop

	/* Do the system call */
	mov	%i1,%o1
	mov	%i2,%o0
	set	__NR_clone,%g1
	ta	0x10
	bcs	__clone_syscall_error
	tst	%o1
	bne	__thread_start
	nop
	mov	%o0,%i0
	ret
	restore
	
__clone_syscall_error:
	call	__errno_location
	set	EINVAL,%i0
	st	%i0,[%o0]
	mov	-1,%i0
	ret
	restore

__thread_start:
	call	%i0
	mov	%i3,%o0
	call	_exit,0
	nop
/************************************************************************/
#else 
#error "Unknown Linux architecture"
#endif

#endif /* Linux && ! SDL_USE_PTHREADS */