sysdeps/mach/i386/machine-lock.h

   1 /* Machine-specific definition for spin locks.  i386 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    register int __unlocked;
  44    __asm__ __volatile ("xchgl %0, %1"
  45                        : "=&r" (__unlocked), "=m" (*__lock) : "0" (0)
  46                        : "memory");
  47 }
  48 #endif
  49
  50 /* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
  51
  52 extern int __spin_try_lock (__spin_lock_t *__lock);
  53
  54 #if defined __USE_EXTERN_INLINES && defined _LIBC
  55 _EXTERN_INLINE int
  56 __spin_try_lock (__spin_lock_t *__lock)
  57 {
  58   register int __locked;
  59   __asm__ __volatile ("xchgl %0, %1"
  60                       : "=&r" (__locked), "=m" (*__lock) : "0" (1)
  61                       : "memory");
  62   return !__locked;
  63 }
  64 #endif
  65
  66 /* Return nonzero if LOCK is locked.  */
  67
  68 extern int __spin_lock_locked (__spin_lock_t *__lock);
  69
  70 #if defined __USE_EXTERN_INLINES && defined _LIBC
  71 _EXTERN_INLINE int
  72 __spin_lock_locked (__spin_lock_t *__lock)
  73 {
  74   return *__lock != 0;
  75 }
  76 #endif
  77
  78
  79 #endif /* machine-lock.h */