sysdeps/stub/machine-lock.h

   1 /* Machine-specific definition for spin locks.  Stub version.
   2 Copyright (C) 1994 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, 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   *__lock = 0;
  42 }
  43
  44 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  45
  46 _EXTERN_INLINE int
  47 __spin_try_lock (__spin_lock_t *__lock)
  48 {
  49   if (*__lock)
  50     return 0;
  51   *__lock = 1;
  52   return 1;
  53 }
  54
  55 /* Return nonzero if LOCK is locked.  */
  56
  57 _EXTERN_INLINE int
  58 __spin_lock_locked (__spin_lock_t *__lock)
  59 {
  60   return *__lock != 0;
  61 }
  62
  63
  64 #endif /* machine-lock.h */