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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [config/] [vxlib.c] - Rev 433
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/* Copyright (C) 2002, 2003, 2004, 2005, 2009 Free Software Foundation, Inc. Contributed by Zack Weinberg <zack@codesourcery.com> This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC 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 General Public License for more details. Under Section 7 of GPL version 3, you are granted additional permissions described in the GCC Runtime Library Exception, version 3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License and a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ /* Threads compatibility routines for libgcc2 for VxWorks. These are out-of-line routines called from gthr-vxworks.h. */ #include "tconfig.h" #include "tsystem.h" #include "gthr.h" #if defined(__GTHREADS) #include <vxWorks.h> #ifndef __RTP__ #include <vxLib.h> #endif #include <taskLib.h> #ifndef __RTP__ #include <taskHookLib.h> #else # include <errno.h> #endif /* Init-once operation. This would be a clone of the implementation from gthr-solaris.h, except that we have a bootstrap problem - the whole point of this exercise is to prevent double initialization, but if two threads are racing with each other, once->mutex is liable to be initialized by both. Then each thread will lock its own mutex, and proceed to call the initialization routine. So instead we use a bare atomic primitive (vxTas()) to handle mutual exclusion. Threads losing the race then busy-wait, calling taskDelay() to yield the processor, until the initialization is completed. Inefficient, but reliable. */ int __gthread_once (__gthread_once_t *guard, void (*func)(void)) { if (guard->done) return 0; #ifdef __RTP__ __gthread_lock_library (); #else while (!vxTas ((void *)&guard->busy)) { #ifdef __PPC__ /* This can happen on powerpc, which is using all 32 bits of the gthread_once_t structure. */ if (guard->done) return; #endif taskDelay (1); } #endif /* Only one thread at a time gets here. Check ->done again, then go ahead and call func() if no one has done it yet. */ if (!guard->done) { func (); guard->done = 1; } #ifdef __RTP__ __gthread_unlock_library (); #else guard->busy = 0; #endif return 0; } #endif /* __GTHREADS */
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