sysdeps/generic/machine-lock.h

   1 /* Machine-specific definition for spin locks.  Stub version.
   2    Copyright (C) 1994, 1997, 2007 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   *__lock = 0;
  41 }
  42
  43 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  44
  45 _EXTERN_INLINE int
  46 __spin_try_lock (__spin_lock_t *__lock)
  47 {
  48   if (*__lock)
  49     return 0;
  50   *__lock = 1;
  51   return 1;
  52 }
  53
  54 /* Return nonzero if LOCK is locked.  */
  55
  56 _EXTERN_INLINE int
  57 __spin_lock_locked (__spin_lock_t *__lock)
  58 {
  59   return *__lock != 0;
  60 }
  61
  62
  63 #endif /* machine-lock.h */