// SPDX-License-Identifier: BSD-3-Clause

/*      $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.
 */

/*
 * 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 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.
 */

//#include "qemu/atomic.h" /* for smp_wmb() */

/*
 * List definitions.
 */
#define QLIST_HEAD(name, type)                     \
	struct name                                    \
	{                                              \
		struct type* lh_first; /* first element */ \
	}

#define QLIST_HEAD_INITIALIZER(head) \
	{                                \
		NULL                         \
	}

#define QLIST_ENTRY(type)                                             \
	struct                                                            \
	{                                                                 \
		struct type* le_next;  /* next element */                     \
		struct type** le_prev; /* address of previous next element */ \
	}

/*
 * List functions.
 */
#define QLIST_INIT(head)         \
	do                           \
	{                            \
		(head)->lh_first = NULL; \
	} while (/*CONSTCOND*/ 0)

#define QLIST_SWAP(dstlist, srclist, field)                            \
	do                                                                 \
	{                                                                  \
		void* tmplist;                                                 \
		tmplist = (srclist)->lh_first;                                 \
		(srclist)->lh_first = (dstlist)->lh_first;                     \
		if ((srclist)->lh_first != NULL)                               \
		{                                                              \
			(srclist)->lh_first->field.le_prev = &(srclist)->lh_first; \
		}                                                              \
		(dstlist)->lh_first = tmplist;                                 \
		if ((dstlist)->lh_first != NULL)                               \
		{                                                              \
			(dstlist)->lh_first->field.le_prev = &(dstlist)->lh_first; \
		}                                                              \
	} while (/*CONSTCOND*/ 0)

#define QLIST_INSERT_AFTER(listelm, elm, field)                        \
	do                                                                 \
	{                                                                  \
		if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
			(listelm)->field.le_next->field.le_prev =                  \
				&(elm)->field.le_next;                                 \
		(listelm)->field.le_next = (elm);                              \
		(elm)->field.le_prev = &(listelm)->field.le_next;              \
	} while (/*CONSTCOND*/ 0)

#define QLIST_INSERT_BEFORE(listelm, elm, field)          \
	do                                                    \
	{                                                     \
		(elm)->field.le_prev = (listelm)->field.le_prev;  \
		(elm)->field.le_next = (listelm);                 \
		*(listelm)->field.le_prev = (elm);                \
		(listelm)->field.le_prev = &(elm)->field.le_next; \
	} while (/*CONSTCOND*/ 0)

#define QLIST_INSERT_HEAD(head, elm, field)                          \
	do                                                               \
	{                                                                \
		if (((elm)->field.le_next = (head)->lh_first) != NULL)       \
			(head)->lh_first->field.le_prev = &(elm)->field.le_next; \
		(head)->lh_first = (elm);                                    \
		(elm)->field.le_prev = &(head)->lh_first;                    \
	} while (/*CONSTCOND*/ 0)

#define QLIST_REMOVE(elm, field)                      \
	do                                                \
	{                                                 \
		if ((elm)->field.le_next != NULL)             \
			(elm)->field.le_next->field.le_prev =     \
				(elm)->field.le_prev;                 \
		*(elm)->field.le_prev = (elm)->field.le_next; \
	} while (/*CONSTCOND*/ 0)

#define QLIST_FOREACH(var, head, field) \
	for ((var) = ((head)->lh_first);    \
		 (var);                         \
		 (var) = ((var)->field.le_next))

#define QLIST_FOREACH_SAFE(var, head, field, next_var)      \
	for ((var) = ((head)->lh_first);                        \
		 (var) && ((next_var) = ((var)->field.le_next), 1); \
		 (var) = (next_var))

/*
 * List access methods.
 */
#define QLIST_EMPTY(head) ((head)->lh_first == NULL)
#define QLIST_FIRST(head) ((head)->lh_first)
#define QLIST_NEXT(elm, field) ((elm)->field.le_next)


/*
 * Singly-linked List definitions.
 */
#define QSLIST_HEAD(name, type)                     \
	struct name                                     \
	{                                               \
		struct type* slh_first; /* first element */ \
	}

#define QSLIST_HEAD_INITIALIZER(head) \
	{                                 \
		NULL                          \
	}

#define QSLIST_ENTRY(type)                        \
	struct                                        \
	{                                             \
		struct type* sle_next; /* next element */ \
	}

/*
 * Singly-linked List functions.
 */
#define QSLIST_INIT(head)         \
	do                            \
	{                             \
		(head)->slh_first = NULL; \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_INSERT_AFTER(slistelm, elm, field)           \
	do                                                      \
	{                                                       \
		(elm)->field.sle_next = (slistelm)->field.sle_next; \
		(slistelm)->field.sle_next = (elm);                 \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_INSERT_HEAD(head, elm, field)       \
	do                                             \
	{                                              \
		(elm)->field.sle_next = (head)->slh_first; \
		(head)->slh_first = (elm);                 \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field)                          \
	do                                                                       \
	{                                                                        \
		typeof(elm) save_sle_next;                                           \
		do                                                                   \
		{                                                                    \
			save_sle_next = (elm)->field.sle_next = (head)->slh_first;       \
		} while (atomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) != \
				 save_sle_next);                                             \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_MOVE_ATOMIC(dest, src)                             \
	do                                                            \
	{                                                             \
		(dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL); \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_REMOVE_HEAD(head, field)                        \
	do                                                         \
	{                                                          \
		(head)->slh_first = (head)->slh_first->field.sle_next; \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_REMOVE_AFTER(slistelm, field)                    \
	do                                                          \
	{                                                           \
		(slistelm)->field.sle_next =                            \
			QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field); \
	} while (/*CONSTCOND*/ 0)

#define QSLIST_FOREACH(var, head, field) \
	for ((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)

#define QSLIST_FOREACH_SAFE(var, head, field, tvar)        \
	for ((var) = QSLIST_FIRST((head));                     \
		 (var) && ((tvar) = QSLIST_NEXT((var), field), 1); \
		 (var) = (tvar))

/*
 * Singly-linked List access methods.
 */
#define QSLIST_EMPTY(head) ((head)->slh_first == NULL)
#define QSLIST_FIRST(head) ((head)->slh_first)
#define QSLIST_NEXT(elm, field) ((elm)->field.sle_next)


/*
 * Simple queue definitions.
 */
#define QSIMPLEQ_HEAD(name, type)                               \
	struct name                                                 \
	{                                                           \
		struct type* sqh_first; /* first element */             \
		struct type** sqh_last; /* addr of last next element */ \
	}

#define QSIMPLEQ_HEAD_INITIALIZER(head) \
	{                                   \
		NULL, &(head).sqh_first         \
	}

#define QSIMPLEQ_ENTRY(type)                      \
	struct                                        \
	{                                             \
		struct type* sqe_next; /* next element */ \
	}

/*
 * Simple queue functions.
 */
#define QSIMPLEQ_INIT(head)                    \
	do                                         \
	{                                          \
		(head)->sqh_first = NULL;              \
		(head)->sqh_last = &(head)->sqh_first; \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_INSERT_HEAD(head, elm, field)                   \
	do                                                           \
	{                                                            \
		if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
			(head)->sqh_last = &(elm)->field.sqe_next;           \
		(head)->sqh_first = (elm);                               \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_INSERT_TAIL(head, elm, field)     \
	do                                             \
	{                                              \
		(elm)->field.sqe_next = NULL;              \
		*(head)->sqh_last = (elm);                 \
		(head)->sqh_last = &(elm)->field.sqe_next; \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field)                 \
	do                                                                   \
	{                                                                    \
		if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
			(head)->sqh_last = &(elm)->field.sqe_next;                   \
		(listelm)->field.sqe_next = (elm);                               \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_REMOVE_HEAD(head, field)                                    \
	do                                                                       \
	{                                                                        \
		if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
			(head)->sqh_last = &(head)->sqh_first;                           \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed)              \
	do                                                               \
	{                                                                \
		QSIMPLEQ_INIT(removed);                                      \
		if (((removed)->sqh_first = (head)->sqh_first) != NULL)      \
		{                                                            \
			if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) \
			{                                                        \
				(head)->sqh_last = &(head)->sqh_first;               \
			}                                                        \
			(removed)->sqh_last = &(elm)->field.sqe_next;            \
			(elm)->field.sqe_next = NULL;                            \
		}                                                            \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_REMOVE(head, elm, type, field)                       \
	do                                                                \
	{                                                                 \
		if ((head)->sqh_first == (elm))                               \
		{                                                             \
			QSIMPLEQ_REMOVE_HEAD((head), field);                      \
		}                                                             \
		else                                                          \
		{                                                             \
			struct type* curelm = (head)->sqh_first;                  \
			while (curelm->field.sqe_next != (elm))                   \
				curelm = curelm->field.sqe_next;                      \
			if ((curelm->field.sqe_next =                             \
					 curelm->field.sqe_next->field.sqe_next) == NULL) \
				(head)->sqh_last = &(curelm)->field.sqe_next;         \
		}                                                             \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_FOREACH(var, head, field) \
	for ((var) = ((head)->sqh_first);      \
		 (var);                            \
		 (var) = ((var)->field.sqe_next))

#define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)    \
	for ((var) = ((head)->sqh_first);                    \
		 (var) && ((next = ((var)->field.sqe_next)), 1); \
		 (var) = (next))

#define QSIMPLEQ_CONCAT(head1, head2)                \
	do                                               \
	{                                                \
		if (!QSIMPLEQ_EMPTY((head2)))                \
		{                                            \
			*(head1)->sqh_last = (head2)->sqh_first; \
			(head1)->sqh_last = (head2)->sqh_last;   \
			QSIMPLEQ_INIT((head2));                  \
		}                                            \
	} while (/*CONSTCOND*/ 0)

#define QSIMPLEQ_LAST(head, type, field) \
	(QSIMPLEQ_EMPTY((head)) ?            \
		 NULL :                          \
		 ((struct type*)(void*)((char*)((head)->sqh_last) - offsetof(struct type, field))))

/*
 * Simple queue access methods.
 */
#define QSIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL)
#define QSIMPLEQ_FIRST(head) ((head)->sqh_first)
#define QSIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)


/*
 * Tail queue definitions.
 */
#define Q_TAILQ_HEAD(name, type, qual)                             \
	struct name                                                    \
	{                                                              \
		qual type* tqh_first;      /* first element */             \
		qual type* qual* tqh_last; /* addr of last next element */ \
	}
#define QTAILQ_HEAD(name, type) Q_TAILQ_HEAD(name, struct type, )

#define QTAILQ_HEAD_INITIALIZER(head) \
	{                                 \
		NULL, &(head).tqh_first       \
	}

#define Q_TAILQ_ENTRY(type, qual)                                         \
	struct                                                                \
	{                                                                     \
		qual type* tqe_next;       /* next element */                     \
		qual type* qual* tqe_prev; /* address of previous next element */ \
	}
#define QTAILQ_ENTRY(type) Q_TAILQ_ENTRY(struct type, )

/*
 * Tail queue functions.
 */
#define QTAILQ_INIT(head)                      \
	do                                         \
	{                                          \
		(head)->tqh_first = NULL;              \
		(head)->tqh_last = &(head)->tqh_first; \
	} 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_prev =                  \
				&(elm)->field.tqe_next;                          \
		else                                                     \
			(head)->tqh_last = &(elm)->field.tqe_next;           \
		(head)->tqh_first = (elm);                               \
		(elm)->field.tqe_prev = &(head)->tqh_first;              \
	} while (/*CONSTCOND*/ 0)

#define QTAILQ_INSERT_TAIL(head, elm, field)       \
	do                                             \
	{                                              \
		(elm)->field.tqe_next = NULL;              \
		(elm)->field.tqe_prev = (head)->tqh_last;  \
		*(head)->tqh_last = (elm);                 \
		(head)->tqh_last = &(elm)->field.tqe_next; \
	} 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_prev =                      \
				&(elm)->field.tqe_next;                                  \
		else                                                             \
			(head)->tqh_last = &(elm)->field.tqe_next;                   \
		(listelm)->field.tqe_next = (elm);                               \
		(elm)->field.tqe_prev = &(listelm)->field.tqe_next;              \
	} while (/*CONSTCOND*/ 0)

#define QTAILQ_INSERT_BEFORE(listelm, elm, field)           \
	do                                                      \
	{                                                       \
		(elm)->field.tqe_prev = (listelm)->field.tqe_prev;  \
		(elm)->field.tqe_next = (listelm);                  \
		*(listelm)->field.tqe_prev = (elm);                 \
		(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
	} while (/*CONSTCOND*/ 0)

#define QTAILQ_REMOVE(head, elm, field)                 \
	do                                                  \
	{                                                   \
		if (((elm)->field.tqe_next) != NULL)            \
			(elm)->field.tqe_next->field.tqe_prev =     \
				(elm)->field.tqe_prev;                  \
		else                                            \
			(head)->tqh_last = (elm)->field.tqe_prev;   \
		*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
		(elm)->field.tqe_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, headname, field)              \
	for ((var) = (*(((struct headname*)((head)->tqh_last))->tqh_last)); \
		 (var);                                                         \
		 (var) = (*(((struct headname*)((var)->field.tqe_prev))->tqh_last)))

/*
 * 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_prev != NULL)

#define QTAILQ_LAST(head, headname) \
	(*(((struct headname*)((head)->tqh_last))->tqh_last))
#define QTAILQ_PREV(elm, headname, field) \
	(*(((struct headname*)((elm)->field.tqe_prev))->tqh_last))

#define field_at_offset(base, offset, type) \
	((type)(((char*)(base)) + (offset)))

typedef struct DUMMY_Q_ENTRY DUMMY_Q_ENTRY;
typedef struct DUMMY_Q DUMMY_Q;

struct DUMMY_Q_ENTRY
{
	QTAILQ_ENTRY(DUMMY_Q_ENTRY)
	next;
};

struct DUMMY_Q
{
	QTAILQ_HEAD(DUMMY_Q_HEAD, DUMMY_Q_ENTRY)
	head;
};

#define dummy_q ((DUMMY_Q*)0)
#define dummy_qe ((DUMMY_Q_ENTRY*)0)

/*
 * Offsets of layout of a tail queue head.
 */
#define QTAILQ_FIRST_OFFSET (offsetof(typeof(dummy_q->head), tqh_first))
#define QTAILQ_LAST_OFFSET (offsetof(typeof(dummy_q->head), tqh_last))
/*
 * Raw access of elements of a tail queue
 */
#define QTAILQ_RAW_FIRST(head) \
	(*field_at_offset(head, QTAILQ_FIRST_OFFSET, void**))
#define QTAILQ_RAW_TQH_LAST(head) \
	(*field_at_offset(head, QTAILQ_LAST_OFFSET, void***))

/*
 * Offsets of layout of a tail queue element.
 */
#define QTAILQ_NEXT_OFFSET (offsetof(typeof(dummy_qe->next), tqe_next))
#define QTAILQ_PREV_OFFSET (offsetof(typeof(dummy_qe->next), tqe_prev))

/*
 * Raw access of elements of a tail entry
 */
#define QTAILQ_RAW_NEXT(elm, entry) \
	(*field_at_offset(elm, entry + QTAILQ_NEXT_OFFSET, void**))
#define QTAILQ_RAW_TQE_PREV(elm, entry) \
	(*field_at_offset(elm, entry + QTAILQ_PREV_OFFSET, void***))
/*
 * Tail queue tranversal 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_PREV(elm, entry) = QTAILQ_RAW_TQH_LAST(head); \
		*QTAILQ_RAW_TQH_LAST(head) = (elm);                          \
		QTAILQ_RAW_TQH_LAST(head) = &QTAILQ_RAW_NEXT(elm, entry);    \
	} while (/*CONSTCOND*/ 0)

#endif /* QEMU_SYS_QUEUE_H */
