Mercurial > sdl-ios-xcode
view src/thread/linux/clone.S @ 968:4675910b0b7b
Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST)
From: Hannu Savolainen
Subject: Re: SDL uses obsolete OSS features
I did some work on getting OSS to work better with SDL. There have been
some problems with select which should be fixed now.
I'm having some problems in understanding what is the purpose of the
DSP_WaitAudio() routine. I added a return to the very beginning of this
routine and commendted out the define for USE_BLOCKING_WRITES. At least
lbreakout2 seems to work as well as earlier. The latencies are the same.
An ordinary blocking write does exactly the same thing than DSP_WaitAudio
does. So I would recommend using the USE_BLOCKING_WRITES approach and
removing everything from the DSP_WaitAudio routine. Also enabling
USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because
you don't need to handle the partial writes (the do-while loop).
Attached is a patch against SDL-1.2.7. After these changes SDL will use
OSS as it's designed to be used (make it as simple as possible). This code
should work with all OSS implementations because it uses only the very
fundamental features that have been there since the jurassic times.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Fri, 12 Nov 2004 21:39:04 +0000 |
parents | 74212992fb08 |
children | 974ba6ae0fa3 |
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/* 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 */