sysdeps/mach/i386/machine-lock.h

   1 /* Machine-specific definition for spin locks.  i386 version.
   2    Copyright (C) 1994,1997,2007,2008 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #ifndef _MACHINE_LOCK_H
  21 #define _MACHINE_LOCK_H
  22
  23 /* The type of a spin lock variable.  */
  24
  25 typedef __volatile int __spin_lock_t;
  26
  27 /* Value to initialize `__spin_lock_t' variables to.  */
  28
  29 #define __SPIN_LOCK_INITIALIZER 0
  30
  31
  32 #ifndef _EXTERN_INLINE
  33 #define _EXTERN_INLINE __extern_inline
  34 #endif
  35
  36 /* Unlock LOCK.  */
  37
  38 _EXTERN_INLINE void
  39 __spin_unlock (__spin_lock_t *__lock)
  40 {
  41    register int __unlocked;
  42    __asm__ __volatile ("xchgl %0, %1"
  43                        : "=&r" (__unlocked), "=m" (*__lock) : "0" (0)
  44                        : "memory");
  45 }
  46
  47 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  48
  49 _EXTERN_INLINE int
  50 __spin_try_lock (__spin_lock_t *__lock)
  51 {
  52   register int __locked;
  53   __asm__ __volatile ("xchgl %0, %1"
  54                       : "=&r" (__locked), "=m" (*__lock) : "0" (1)
  55                       : "memory");
  56   return !__locked;
  57 }
  58
  59 /* Return nonzero if LOCK is locked.  */
  60
  61 _EXTERN_INLINE int
  62 __spin_lock_locked (__spin_lock_t *__lock)
  63 {
  64   return *__lock != 0;
  65 }
  66
  67
  68 #endif /* machine-lock.h */