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glibc  2.9
pthread_spin_lock.c
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00001 /* Copyright (C) 2002,2003,2004 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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 "pthreadP.h"
00021 
00022 #ifndef LOCK_PREFIX
00023 # ifdef UP
00024 #  define LOCK_PREFIX       /* nothing */
00025 # else
00026 #  define LOCK_PREFIX       "lock;"
00027 # endif
00028 #endif
00029 
00030 
00031 int
00032 pthread_spin_lock (lock)
00033      pthread_spinlock_t *lock;
00034 {
00035   asm ("\n"
00036        "1:\t" LOCK_PREFIX "decl %0\n\t"
00037        "jne 2f\n\t"
00038        ".subsection 1\n\t"
00039        ".align 16\n"
00040        "2:\trep; nop\n\t"
00041        "cmpl $0, %0\n\t"
00042        "jg 1b\n\t"
00043        "jmp 2b\n\t"
00044        ".previous"
00045        : "=m" (*lock)
00046        : "m" (*lock));
00047 
00048   return 0;
00049 }