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/*
* Copyright (c) 1995-1993 The University of Utah and
* the Computer Systems Laboratory at the University of Utah (CSL).
* All rights reserved.
*
* Permission to use, copy, modify and distribute this software is hereby
* granted provided that (1) source code retains these copyright, permission,
* and disclaimer notices, and (2) redistributions including binaries
* reproduce the notices in supporting documentation, and (3) all advertising
* materials mentioning features or use of this software display the following
* acknowledgement: ``This product includes software developed by the
* Computer Systems Laboratory at the University of Utah.''
*
* 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 atomic reference count data type.
* (This file will often be overridden
* by better machine-dependent implementations.)
*
*/
#ifndef _KERN_REF_COUNT_H_
#define _KERN_REF_COUNT_H_
#include <mach/macro_help.h>
#include "simple_lock.h"
struct ref_count {
decl_simple_lock_data(,lock) /* lock for reference count */
int count; /* number of references */
};
#define ref_count_init(refcount, refs) \
MACRO_BEGIN \
simple_lock_init(&(refcount)->lock); \
((refcount)->count = (refs)); \
MACRO_END
#define ref_count_take(refcount) \
MACRO_BEGIN \
simple_lock(&(refcount)->lock); \
(refcount)->count++; \
simple_unlock(&(refcount)->lock); \
MACRO_END
#define ref_count_drop(refcount, func) \
MACRO_BEGIN \
int new_value; \
simple_lock(&(refcount)->lock); \
new_value = --(refcount)->count; \
simple_unlock(&(refcount)->lock); \
if (new_value == 0) { func; } \
MACRO_END
#endif _KERN_REF_COUNT_H_
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