sysdeps/mach/i386/machine-lock.h

   1 /* Machine-specific definition for spin locks.  i386 version.
   2    Copyright (C) 1994-2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _MACHINE_LOCK_H
  20 #define _MACHINE_LOCK_H
  21
  22 /* The type of a spin lock variable.  */
  23
  24 typedef volatile int __spin_lock_t;
  25
  26 /* Value to initialize `__spin_lock_t' variables to.  */
  27
  28 #define __SPIN_LOCK_INITIALIZER 0
  29
  30
  31 #ifndef _EXTERN_INLINE
  32 #define _EXTERN_INLINE __extern_inline
  33 #endif
  34
  35 /* Unlock LOCK.  */
  36
  37 _EXTERN_INLINE void
  38 __spin_unlock (__spin_lock_t *__lock)
  39 {
  40    register int __unlocked;
  41    __asm__ __volatile ("xchgl %0, %1"
  42                        : "=&r" (__unlocked), "=m" (*__lock) : "0" (0)
  43                        : "memory");
  44 }
  45
  46 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  47
  48 _EXTERN_INLINE int
  49 __spin_try_lock (__spin_lock_t *__lock)
  50 {
  51   register int __locked;
  52   __asm__ __volatile ("xchgl %0, %1"
  53                       : "=&r" (__locked), "=m" (*__lock) : "0" (1)
  54                       : "memory");
  55   return !__locked;
  56 }
  57
  58 /* Return nonzero if LOCK is locked.  */
  59
  60 _EXTERN_INLINE int
  61 __spin_lock_locked (__spin_lock_t *__lock)
  62 {
  63   return *__lock != 0;
  64 }
  65
  66
  67 #endif /* machine-lock.h */