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glibc  2.9
machine-lock.h
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00001 /* Machine-specific definition for spin locks.  PowerPC version.
00002    Copyright (C) 1994,97,2002,2007 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 long int __spin_lock_t;
00026 
00027 /* Value to initialize `__spin_lock_t' variables to.  */
00028 
00029 #define       __SPIN_LOCK_INITIALIZER     0L
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   long int __locked;
00042   __asm__ __volatile__ ("\
00043 0:     lwarx  %0,0,%1\n\
00044        stwcx. %2,0,%1\n\
00045        bne-   0b\n\
00046 " : "=&r" (__locked) : "r" (__lock), "r" (0) : "cr0");
00047 }
00048 
00049 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
00050 
00051 _EXTERN_INLINE int
00052 __spin_try_lock (register __spin_lock_t *__lock)
00053 {
00054   long int __rtn;
00055   __asm__ __volatile__ ("\
00056 0:     lwarx  %0,0,%1\n\
00057        stwcx. %2,0,%1\n\
00058        bne-   0b\n\
00059 " : "=&r" (__rtn) : "r" (__lock), "r" (1) : "cr0");
00060   return !__rtn;
00061 }
00062 
00063 /* Return nonzero if LOCK is locked.  */
00064 
00065 _EXTERN_INLINE int
00066 __spin_lock_locked (__spin_lock_t *__lock)
00067 {
00068   long int __rtn;
00069   __asm__ __volatile__ ("\
00070 0:     lwarx  %0,0,%1\n\
00071        stwcx. %0,0,%1\n\
00072        bne-   0b\n\
00073 " : "=&r" (__rtn) : "r" (__lock) : "cr0");
00074   return __rtn;
00075 }
00076 
00077 
00078 #endif /* machine-lock.h */