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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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