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      1 /*	$NetBSD: pthread_queue.h,v 1.7 2022/04/19 20:32:17 rillig Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Nathan J. Williams.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _LIB_PTHREAD_QUEUE_H
     33 #define _LIB_PTHREAD_QUEUE_H
     34 
     35 /*
     36  * Definition of a queue interface for the pthread library.
     37  * Style modeled on the sys/queue.h macros; implementation taken from
     38  * the tail queue, with the added property of static initializability
     39  * (and a corresponding extra cost in the _INSERT_TAIL() function.
     40 */
     41 
     42 /*
     43  * Queue definitions.
     44  */
     45 
     46 #define PTQ_HEAD(name, type)						\
     47 struct name {								\
     48 	struct type *ptqh_first;/* first element */			\
     49 	struct type **ptqh_last;/* addr of last next element */		\
     50 }
     51 
     52 #define PTQ_HEAD_INITIALIZER { NULL, NULL }
     53 
     54 #define PTQ_ENTRY(type)							\
     55 struct {								\
     56 	struct type *ptqe_next;	/* next element */			\
     57 	struct type **ptqe_prev;/* address of previous next element */	\
     58 }
     59 
     60 /*
     61  * Queue functions.
     62  */
     63 
     64 #define	PTQ_INIT(head) do {						\
     65 	(head)->ptqh_first = NULL;					\
     66 	(head)->ptqh_last = &(head)->ptqh_first;			\
     67 } while (0)
     68 
     69 #define	PTQ_INSERT_HEAD(head, elm, field) do {				\
     70 	if (((elm)->field.ptqe_next = (head)->ptqh_first) != NULL)	\
     71 		(head)->ptqh_first->field.ptqe_prev =			\
     72 		    &(elm)->field.ptqe_next;				\
     73 	else								\
     74 		(head)->ptqh_last = &(elm)->field.ptqe_next;		\
     75 	(head)->ptqh_first = (elm);					\
     76 	(elm)->field.ptqe_prev = &(head)->ptqh_first;			\
     77 } while (0)
     78 
     79 #define	PTQ_INSERT_TAIL(head, elm, field) do {				\
     80 	(elm)->field.ptqe_next = NULL;					\
     81 	if ((head)->ptqh_last == NULL)					\
     82 		(head)->ptqh_last = &(head)->ptqh_first;		\
     83 	(elm)->field.ptqe_prev = (head)->ptqh_last;			\
     84 	*(head)->ptqh_last = (elm);					\
     85 	(head)->ptqh_last = &(elm)->field.ptqe_next;			\
     86 } while (0)
     87 
     88 #define	PTQ_INSERT_AFTER(head, listelm, elm, field) do {		\
     89 	if (((elm)->field.ptqe_next = (listelm)->field.ptqe_next) != NULL)\
     90 		(elm)->field.ptqe_next->field.ptqe_prev = 		\
     91 		    &(elm)->field.ptqe_next;				\
     92 	else								\
     93 		(head)->ptqh_last = &(elm)->field.ptqe_next;		\
     94 	(listelm)->field.ptqe_next = (elm);				\
     95 	(elm)->field.ptqe_prev = &(listelm)->field.ptqe_next;		\
     96 } while (0)
     97 
     98 #define	PTQ_INSERT_BEFORE(listelm, elm, field) do {			\
     99 	(elm)->field.ptqe_prev = (listelm)->field.ptqe_prev;		\
    100 	(elm)->field.ptqe_next = (listelm);				\
    101 	*(listelm)->field.ptqe_prev = (elm);				\
    102 	(listelm)->field.ptqe_prev = &(elm)->field.ptqe_next;		\
    103 } while (0)
    104 
    105 #define	PTQ_REMOVE(head, elm, field) do {				\
    106 	if (((elm)->field.ptqe_next) != NULL)				\
    107 		(elm)->field.ptqe_next->field.ptqe_prev = 		\
    108 		    (elm)->field.ptqe_prev;				\
    109 	else								\
    110 		(head)->ptqh_last = (elm)->field.ptqe_prev;		\
    111 	*(elm)->field.ptqe_prev = (elm)->field.ptqe_next;		\
    112 } while (0)
    113 
    114 /*
    115  * Queue access methods.
    116  */
    117 
    118 #define	PTQ_EMPTY(head)			((head)->ptqh_first == NULL)
    119 #define	PTQ_FIRST(head)			((head)->ptqh_first)
    120 #define	PTQ_NEXT(elm, field)		((elm)->field.ptqe_next)
    121 
    122 #define	PTQ_LAST(head, headname)					\
    123 	(*(((struct headname *)(void *)((head)->ptqh_last))->ptqh_last))
    124 #define	PTQ_PREV(elm, headname, field)					\
    125 	(*(((struct headname *)(void *)((elm)->field.ptqe_prev))->ptqh_last))
    126 
    127 #define	PTQ_FOREACH(var, head, field)					\
    128 	for ((var) = ((head)->ptqh_first);				\
    129 		(var);							\
    130 		(var) = ((var)->field.ptqe_next))
    131 
    132 #define	PTQ_FOREACH_REVERSE(var, head, headname, field)			\
    133 	for ((var) = (*(((struct headname *)(void *)((head)->ptqh_last))->ptqh_last));	\
    134 		(var);							\
    135 		(var) = (*(((struct headname *)(void *)((var)->field.ptqe_prev))->ptqh_last)))
    136 
    137 #endif /* _LIB_PTHREAD_QUEUE_H */
    138