00b67f09dd
Also known as ISC bind. This import adds utilities such as host(1), dig(1), and nslookup(1), as well as many other tools and libraries. Change-Id: I035ca46e64f1965d57019e773f4ff0ef035e4aa3
236 lines
6.2 KiB
C
236 lines
6.2 KiB
C
/* $NetBSD: refcount.h,v 1.6 2014/12/10 04:38:00 christos Exp $ */
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/*
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* Copyright (C) 2004-2007, 2009 Internet Systems Consortium, Inc. ("ISC")
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* Copyright (C) 2001, 2003 Internet Software Consortium.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* Id: refcount.h,v 1.17 2009/09/29 23:48:04 tbox Exp */
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#ifndef ISC_REFCOUNT_H
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#define ISC_REFCOUNT_H 1
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#include <isc/atomic.h>
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#include <isc/lang.h>
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#include <isc/mutex.h>
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#include <isc/platform.h>
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#include <isc/types.h>
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#include <isc/util.h>
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/*! \file isc/refcount.h
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* \brief Implements a locked reference counter.
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*
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* These functions may actually be
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* implemented using macros, and implementations of these macros are below.
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* The isc_refcount_t type should not be accessed directly, as its contents
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* depend on the implementation.
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*/
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ISC_LANG_BEGINDECLS
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/*
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* Function prototypes
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*/
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/*
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* isc_result_t
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* isc_refcount_init(isc_refcount_t *ref, unsigned int n);
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*
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* Initialize the reference counter. There will be 'n' initial references.
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*
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* Requires:
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* ref != NULL
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*/
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/*
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* void
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* isc_refcount_destroy(isc_refcount_t *ref);
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*
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* Destroys a reference counter.
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*
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* Requires:
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* ref != NULL
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* The number of references is 0.
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*/
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/*
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* void
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* isc_refcount_increment(isc_refcount_t *ref, unsigned int *targetp);
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* isc_refcount_increment0(isc_refcount_t *ref, unsigned int *targetp);
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*
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* Increments the reference count, returning the new value in targetp if it's
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* not NULL. The reference counter typically begins with the initial counter
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* of 1, and will be destroyed once the counter reaches 0. Thus,
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* isc_refcount_increment() additionally requires the previous counter be
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* larger than 0 so that an error which violates the usage can be easily
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* caught. isc_refcount_increment0() does not have this restriction.
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*
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* Requires:
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* ref != NULL.
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*/
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/*
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* void
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* isc_refcount_decrement(isc_refcount_t *ref, unsigned int *targetp);
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*
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* Decrements the reference count, returning the new value in targetp if it's
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* not NULL.
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*
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* Requires:
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* ref != NULL.
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*/
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/*
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* Sample implementations
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*/
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#ifdef ISC_PLATFORM_USETHREADS
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#ifdef ISC_PLATFORM_HAVEXADD
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#define ISC_REFCOUNT_HAVEATOMIC 1
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typedef struct isc_refcount {
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isc_int32_t refs;
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} isc_refcount_t;
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#define isc_refcount_destroy(rp) REQUIRE((rp)->refs == 0)
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#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
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#define isc_refcount_increment0(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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isc_int32_t prev; \
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prev = isc_atomic_xadd(&(rp)->refs, 1); \
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if (_tmp != NULL) \
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*_tmp = prev + 1; \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_increment(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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isc_int32_t prev; \
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prev = isc_atomic_xadd(&(rp)->refs, 1); \
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REQUIRE(prev > 0); \
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if (_tmp != NULL) \
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*_tmp = prev + 1; \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_decrement(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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isc_int32_t prev; \
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prev = isc_atomic_xadd(&(rp)->refs, -1); \
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REQUIRE(prev > 0); \
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if (_tmp != NULL) \
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*_tmp = prev - 1; \
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} while (/*CONSTCOND*/0)
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#else /* ISC_PLATFORM_HAVEXADD */
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typedef struct isc_refcount {
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int refs;
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isc_mutex_t lock;
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} isc_refcount_t;
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/*% Destroys a reference counter. */
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#define isc_refcount_destroy(rp) \
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do { \
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REQUIRE((rp)->refs == 0); \
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DESTROYLOCK(&(rp)->lock); \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
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/*% Increments the reference count, returning the new value in targetp if it's not NULL. */
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#define isc_refcount_increment0(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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LOCK(&(rp)->lock); \
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++((rp)->refs); \
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if (_tmp != NULL) \
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*_tmp = ((rp)->refs); \
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UNLOCK(&(rp)->lock); \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_increment(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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LOCK(&(rp)->lock); \
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REQUIRE((rp)->refs > 0); \
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++((rp)->refs); \
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if (_tmp != NULL) \
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*_tmp = ((rp)->refs); \
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UNLOCK(&(rp)->lock); \
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} while (/*CONSTCOND*/0)
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/*% Decrements the reference count, returning the new value in targetp if it's not NULL. */
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#define isc_refcount_decrement(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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LOCK(&(rp)->lock); \
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REQUIRE((rp)->refs > 0); \
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--((rp)->refs); \
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if (_tmp != NULL) \
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*_tmp = ((rp)->refs); \
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UNLOCK(&(rp)->lock); \
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} while (/*CONSTCOND*/0)
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#endif /* ISC_PLATFORM_HAVEXADD */
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#else /* ISC_PLATFORM_USETHREADS */
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typedef struct isc_refcount {
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int refs;
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} isc_refcount_t;
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#define isc_refcount_destroy(rp) REQUIRE((rp)->refs == 0)
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#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
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#define isc_refcount_increment0(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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int _n = ++(rp)->refs; \
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if (_tmp != NULL) \
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*_tmp = _n; \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_increment(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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int _n; \
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REQUIRE((rp)->refs > 0); \
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_n = ++(rp)->refs; \
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if (_tmp != NULL) \
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*_tmp = _n; \
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} while (/*CONSTCOND*/0)
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#define isc_refcount_decrement(rp, tp) \
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do { \
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unsigned int *_tmp = (unsigned int *)(tp); \
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int _n; \
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REQUIRE((rp)->refs > 0); \
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_n = --(rp)->refs; \
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if (_tmp != NULL) \
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*_tmp = _n; \
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} while (/*CONSTCOND*/0)
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#endif /* ISC_PLATFORM_USETHREADS */
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isc_result_t
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isc_refcount_init(isc_refcount_t *ref, unsigned int n);
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ISC_LANG_ENDDECLS
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#endif /* ISC_REFCOUNT_H */
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