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diff --git a/sysdeps/mach/i386/machine-lock.h b/sysdeps/mach/i386/machine-lock.h
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+/* 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 */