machine-lock.h

来自「一个C源代码分析器」· C头文件 代码 · 共 67 行

/* Machine-specific definition for spin locks.  i386 version.
Copyright (C) 1994 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#ifndef _MACHINE_LOCK_H
#define	_MACHINE_LOCK_H

/* The type of a spin lock variable.  */

typedef __volatile int __spin_lock_t;

/* Value to initialize `__spin_lock_t' variables to.  */

#define	__SPIN_LOCK_INITIALIZER	0


#ifndef _EXTERN_INLINE
#define _EXTERN_INLINE extern __inline
#endif

/* Unlock LOCK.  */

_EXTERN_INLINE void
__spin_unlock (__spin_lock_t *__lock)
{
   register int __unlocked;
   __asm__ __volatile ("xchgl %0, %1"
		       : "=&r" (__unlocked), "=m" (*__lock) : "0" (0));
}

/* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */

_EXTERN_INLINE int
__spin_try_lock (__spin_lock_t *__lock)
{
  register int __locked;
  __asm__ __volatile ("xchgl %0, %1"
		      : "=&r" (__locked), "=m" (*__lock) : "0" (1));
  return !__locked;
}

/* Return nonzero if LOCK is locked.  */

_EXTERN_INLINE int
__spin_lock_locked (__spin_lock_t *__lock)
{
  return *__lock != 0;
}


#endif /* machine-lock.h */