/* $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */ /* * slirp version: Copy from QEMU, removed all but tail queues. */ /* * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * 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 QTAILQ_H #define QTAILQ_H /* * 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. */ 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. */ #define QTAILQ_HEAD(name, type) \ union name { \ struct type *tqh_first; /* first element */ \ QTailQLink tqh_circ; /* link for circular backwards list */ \ } #define QTAILQ_HEAD_INITIALIZER(head) \ { .tqh_circ = { NULL, &(head).tqh_circ } } #define QTAILQ_ENTRY(type) \ union { \ struct type *tqe_next; /* next element */ \ QTailQLink tqe_circ; /* link for circular backwards list */ \ } #define QTAILQ_INIT(head) do { \ (head)->tqh_first = NULL; \ (head)->tqh_circ.tql_prev = &(head)->tqh_circ; \ } while (/*CONSTCOND*/0) #define QTAILQ_INSERT_HEAD(head, elm, field) do { \ if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ (head)->tqh_first->field.tqe_circ.tql_prev = \ &(elm)->field.tqe_circ; \ else \ (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \ (head)->tqh_first = (elm); \ (elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ; \ } while (/*CONSTCOND*/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 (/*CONSTCOND*/0) #define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ (elm)->field.tqe_next->field.tqe_circ.tql_prev = \ &(elm)->field.tqe_circ; \ else \ (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \ (listelm)->field.tqe_next = (elm); \ (elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ; \ } while (/*CONSTCOND*/0) #define QTAILQ_INSERT_BEFORE(listelm, elm, field) do { \ (elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \ (elm)->field.tqe_next = (listelm); \ (listelm)->field.tqe_circ.tql_prev->tql_next = (elm); \ (listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ; \ } while (/*CONSTCOND*/0) #define QTAILQ_REMOVE(head, elm, field) do { \ if (((elm)->field.tqe_next) != NULL) \ (elm)->field.tqe_next->field.tqe_circ.tql_prev = \ (elm)->field.tqe_circ.tql_prev; \ else \ (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \ (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \ (elm)->field.tqe_circ.tql_prev = NULL; \ } while (/*CONSTCOND*/0) #define QTAILQ_FOREACH(var, head, field) \ for ((var) = ((head)->tqh_first); \ (var); \ (var) = ((var)->field.tqe_next)) #define QTAILQ_FOREACH_SAFE(var, head, field, next_var) \ for ((var) = ((head)->tqh_first); \ (var) && ((next_var) = ((var)->field.tqe_next), 1); \ (var) = (next_var)) #define QTAILQ_FOREACH_REVERSE(var, head, field) \ for ((var) = QTAILQ_LAST(head); \ (var); \ (var) = QTAILQ_PREV(var, field)) #define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var) \ for ((var) = QTAILQ_LAST(head); \ (var) && ((prev_var) = QTAILQ_PREV(var, field)); \ (var) = (prev_var)) /* * 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 QTAILQ_IN_USE(elm, field) ((elm)->field.tqe_circ.tql_prev != NULL) #define QTAILQ_LINK_PREV(link) \ ((link).tql_prev->tql_prev->tql_next) #define QTAILQ_LAST(head) \ ((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ)) #define QTAILQ_PREV(elm, field) \ ((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ)) #define field_at_offset(base, offset, type) \ ((type *) (((char *) (base)) + (offset))) /* * Raw access of elements of a tail queue head. Offsets are all zero * because it's a union. */ #define QTAILQ_RAW_FIRST(head) \ field_at_offset(head, 0, void *) #define QTAILQ_RAW_TQH_CIRC(head) \ field_at_offset(head, 0, QTailQLink) /* * Raw access of elements of a tail entry */ #define QTAILQ_RAW_NEXT(elm, entry) \ field_at_offset(elm, entry, void *) #define QTAILQ_RAW_TQE_CIRC(elm, entry) \ field_at_offset(elm, entry, QTailQLink) /* * Tail queue traversal using pointer arithmetic. */ #define QTAILQ_RAW_FOREACH(elm, head, entry) \ for ((elm) = *QTAILQ_RAW_FIRST(head); \ (elm); \ (elm) = *QTAILQ_RAW_NEXT(elm, entry)) /* * Tail queue insertion using pointer arithmetic. */ #define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do { \ *QTAILQ_RAW_NEXT(elm, entry) = NULL; \ QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \ QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm); \ QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry); \ } while (/*CONSTCOND*/0) #endif /* QTAILQ_H */