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)						\
47struct 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)							\
55struct {								\
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