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Diffstat (limited to 'queue.h')
| -rw-r--r-- | queue.h | 142 |
1 files changed, 142 insertions, 0 deletions
@@ -0,0 +1,142 @@ +/* $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */ + +/* + * QEMU version: Copy from netbsd, removed debug code, removed some of + * the implementations. Left in singly-linked lists, lists, simple + * queues, and tail queues. + */ + +/* + * Based on queue.h of QEMU project + * + * Copyright (c) 1991, 1993 + * The Regents of the University of California. All rights reserved. + * + * Copyright (c) 2022 Virtual Open Systems SAS. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)queue.h 8.5 (Berkeley) 8/20/94 + */ + +#ifndef QEMU_SYS_QUEUE_H +#define QEMU_SYS_QUEUE_H + +/* + * This file defines four types of data structures: singly-linked lists, + * lists, simple queues, and tail queues. + * + * A singly-linked list is headed by a single forward pointer. The + * elements are singly linked for minimum space and pointer manipulation + * overhead at the expense of O(n) removal for arbitrary elements. New + * elements can be added to the list after an existing element or at the + * head of the list. Elements being removed from the head of the list + * should use the explicit macro for this purpose for optimum + * efficiency. A singly-linked list may only be traversed in the forward + * direction. Singly-linked lists are ideal for applications with large + * datasets and few or no removals or for implementing a LIFO queue. + * + * A list is headed by a single forward pointer (or an array of forward + * pointers for a hash table header). The elements are doubly linked + * so that an arbitrary element can be removed without a need to + * traverse the list. New elements can be added to the list before + * or after an existing element or at the head of the list. A list + * may only be traversed in the forward direction. + * + * A simple queue is headed by a pair of pointers, one the head of the + * list and the other to the tail of the list. The elements are singly + * linked to save space, so elements can only be removed from the + * head of the list. New elements can be added to the list after + * an existing element, at the head of the list, or at the end of the + * list. A simple queue may only be traversed in the forward direction. + * + * A tail queue is headed by a pair of pointers, one to the head of the + * list and the other to the tail of the list. The elements are doubly + * linked so that an arbitrary element can be removed without a need to + * traverse the list. New elements can be added to the list before or + * after an existing element, at the head of the list, or at the end of + * the list. A tail queue may be traversed in either direction. + * + * For details on the use of these macros, see the queue(3) manual page. + */ + + +typedef struct QTailQLink { + void *tql_next; + struct QTailQLink *tql_prev; +} QTailQLink; + +/* + * Tail queue definitions. The union acts as a poor man template, as if + * it were QTailQLink<type>. + */ +#define QTAILQ_HEAD(name, type) \ +union name { \ + struct type *tqh_first; \ + QTailQLink tqh_circ; \ +} + +#define QTAILQ_HEAD_INITIALIZER(head) \ + { .tqh_circ = { NULL, &(head).tqh_circ } } + +#define QTAILQ_ENTRY(type) \ +union { \ + struct type *tqe_next; \ + QTailQLink tqe_circ; \ +} + +/* + * Tail queue functions. + */ +#define QTAILQ_INIT(head) do { \ + (head)->tqh_first = NULL; \ + (head)->tqh_circ.tql_prev = &(head)->tqh_circ; \ +} while (0) + +#define QTAILQ_INSERT_TAIL(head, elm, field) do { \ + (elm)->field.tqe_next = NULL; \ + (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev; \ + (head)->tqh_circ.tql_prev->tql_next = (elm); \ + (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \ +} while (0) + + +#define QTAILQ_FOREACH(var, head, field) \ + for ((var) = ((head)->tqh_first); \ + (var); \ + (var) = ((var)->field.tqe_next)) + +/* + * Tail queue access methods. + */ +#define QTAILQ_EMPTY(head) ((head)->tqh_first == NULL) +#define QTAILQ_FIRST(head) ((head)->tqh_first) +#define QTAILQ_NEXT(elm, field) ((elm)->field.tqe_next) + +#define field_at_offset(base, offset, type) \ + ((type *) (((char *) (base)) + (offset))) + + +#endif /* QEMU_SYS_QUEUE_H */ |