sysdeps/generic/machine-lock.h

   1 /* Machine-specific definition for spin locks.  Stub version.
   2    Copyright (C) 1994-2019 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    <https://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 void __spin_unlock (__spin_lock_t *__lock);
  38
  39 #if defined __USE_EXTERN_INLINES && defined _LIBC
  40 _EXTERN_INLINE void
  41 __spin_unlock (__spin_lock_t *__lock)
  42 {
  43   *__lock = 0;
  44 }
  45 #endif
  46
  47 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  48
  49 extern int __spin_try_lock (__spin_lock_t *__lock);
  50
  51 #if defined __USE_EXTERN_INLINES && defined _LIBC
  52 _EXTERN_INLINE int
  53 __spin_try_lock (__spin_lock_t *__lock)
  54 {
  55   if (*__lock)
  56     return 0;
  57   *__lock = 1;
  58   return 1;
  59 }
  60 #endif
  61
  62 /* Return nonzero if LOCK is locked.  */
  63
  64 extern int __spin_lock_locked (__spin_lock_t *__lock);
  65
  66 #if defined __USE_EXTERN_INLINES && defined _LIBC
  67 _EXTERN_INLINE int
  68 __spin_lock_locked (__spin_lock_t *__lock)
  69 {
  70   return *__lock != 0;
  71 }
  72 #endif
  73
  74
  75 #endif /* machine-lock.h */