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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/config/vxlib.c | |
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Diffstat (limited to 'gcc/config/vxlib.c')
-rw-r--r-- | gcc/config/vxlib.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/gcc/config/vxlib.c b/gcc/config/vxlib.c new file mode 100644 index 000000000..0ff996cfc --- /dev/null +++ b/gcc/config/vxlib.c @@ -0,0 +1,95 @@ +/* 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 */ |