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glibc  2.9
machine-lock.h
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00001 /* Machine-specific definition for spin locks.  i386 version.
00002    Copyright (C) 1994,1997,2007,2008 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
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 #ifndef _MACHINE_LOCK_H
00021 #define       _MACHINE_LOCK_H
00022 
00023 /* The type of a spin lock variable.  */
00024 
00025 typedef __volatile int __spin_lock_t;
00026 
00027 /* Value to initialize `__spin_lock_t' variables to.  */
00028 
00029 #define       __SPIN_LOCK_INITIALIZER     0
00030 
00031 
00032 #ifndef _EXTERN_INLINE
00033 #define _EXTERN_INLINE __extern_inline
00034 #endif
00035 
00036 /* Unlock LOCK.  */
00037 
00038 _EXTERN_INLINE void
00039 __spin_unlock (__spin_lock_t *__lock)
00040 {
00041    register int __unlocked;
00042    __asm__ __volatile ("xchgl %0, %1"
00043                      : "=&r" (__unlocked), "=m" (*__lock) : "0" (0)
00044                      : "memory");
00045 }
00046 
00047 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
00048 
00049 _EXTERN_INLINE int
00050 __spin_try_lock (__spin_lock_t *__lock)
00051 {
00052   register int __locked;
00053   __asm__ __volatile ("xchgl %0, %1"
00054                     : "=&r" (__locked), "=m" (*__lock) : "0" (1)
00055                     : "memory");
00056   return !__locked;
00057 }
00058 
00059 /* Return nonzero if LOCK is locked.  */
00060 
00061 _EXTERN_INLINE int
00062 __spin_lock_locked (__spin_lock_t *__lock)
00063 {
00064   return *__lock != 0;
00065 }
00066 
00067 
00068 #endif /* machine-lock.h */