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/*
* Copyright (c) 1993,1994 The University of Utah and
* the Computer Systems Laboratory (CSL). All rights reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
* IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
* ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* CSL requests users of this software to return to csl-dist@cs.utah.edu any
* improvements that they make and grant CSL redistribution rights.
*
* Author: Bryan Ford, University of Utah CSL
*/
/*
* File: refcount.h
*
* This defines the system-independent part of the atomic reference count data type.
*
*/
#ifndef _KERN_REFCOUNT_H_
#define _KERN_REFCOUNT_H_
#include <kern/macros.h>
/* Unless the above include file specified otherwise,
use the system-independent (unoptimized) atomic reference counter. */
#ifndef MACHINE_REFCOUNT
#include <kern/lock.h>
struct RefCount {
decl_simple_lock_data(,lock) /* lock for reference count */
int ref_count; /* number of references */
};
typedef struct RefCount RefCount;
#define refcount_init(refcount, refs) \
MACRO_BEGIN \
simple_lock_init(&(refcount)->lock); \
((refcount)->ref_count = (refs)); \
MACRO_END
#define refcount_take(refcount) \
MACRO_BEGIN \
simple_lock(&(refcount)->lock); \
(refcount)->ref_count++; \
simple_unlock(&(refcount)->lock); \
MACRO_END
#define refcount_drop(refcount, func) \
MACRO_BEGIN \
int new_value; \
simple_lock(&(refcount)->lock); \
new_value = --(refcount)->ref_count; \
simple_unlock(&(refcount)->lock); \
if (new_value == 0) { func; } \
MACRO_END
#endif /* MACHINE_REFCOUNT */
#endif /* _KERN_REFCOUNT_H_ */
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