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glibc  2.9
pthread_spin_trylock.c
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00001 /* Copyright (C) 2003 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include "pthreadP.h"
00022 
00023 int
00024 pthread_spin_trylock (lock)
00025      pthread_spinlock_t *lock;
00026 {
00027   unsigned int old;
00028   int err = EBUSY;
00029 
00030   asm ("1:    lwarx  %0,0,%2\n"
00031        "      cmpwi  0,%0,0\n"
00032        "      bne    2f\n"
00033        "      stwcx. %3,0,%2\n"
00034        "      bne-   1b\n"
00035        "      li     %1,0\n"
00036        "      isync\n"
00037        "2:    "
00038        : "=&r" (old), "=&r" (err)
00039        : "r" (lock), "r" (1), "1" (err)
00040        : "cr0", "memory");
00041 
00042   return err;
00043 }