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lft_queue.h

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. 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
 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.4 2001/03/31 03:33:39 hsu Exp $
 */

#ifndef _LFT_QUEUE_H_
#define     _LFT_QUEUE_H_

#define __offsetof(type, field) ((size_t)(&((type *)0)->field))

/*
 * This file defines five types of data structures: singly-linked lists,
 * singly-linked tail queues, lists, tail queues, and circular 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 singly-linked 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
 * 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, at the head of the list, or at the
 * end of the list. Elements being removed from the head of the tail queue
 * should use the explicit macro for this purpose for optimum efficiency.
 * A singly-linked tail queue may only be traversed in the forward direction.
 * Singly-linked tail queues are ideal for applications with large datasets
 * and few or no removals or for implementing a FIFO 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 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.
 *
 * A circle 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 circle queue may be traversed in either direction, but has a more
 * complex end of list detection.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 *
 *
 *                SLIST LIST  STAILQ      TAILQ CIRCLEQ
 * _HEAD          +     +     +     +     +
 * _ENTRY         +     +     +     +     +
 * _INIT          +     +     +     +     +
 * _EMPTY         +     +     +     +     +
 * _FIRST         +     +     +     +     +
 * _NEXT          +     +     +     +     +
 * _PREV          -     -     -     +     +
 * _LAST          -     -     +     +     +
 * _FOREACH       +     +     +     +     +
 * _FOREACH_REVERSE     -     -     -     +     +
 * _INSERT_HEAD         +     +     +     +     +
 * _INSERT_BEFORE -     +     -     +     +
 * _INSERT_AFTER  +     +     +     +     +
 * _INSERT_TAIL         -     -     +     +     +
 * _REMOVE_HEAD         +     -     +     -     -
 * _REMOVE        +     +     +     +     +
 *
 */

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

#define SLIST_HEAD_INITIALIZER(head)                              \
      { NULL }
 
#define SLIST_ENTRY(type)                                   \
struct {                                              \
      struct type *sle_next;  /* next element */                  \
}
 
/*
 * Singly-linked List functions.
 */
#define     SLIST_EMPTY(head) ((head)->slh_first == NULL)

#define     SLIST_FIRST(head) ((head)->slh_first)

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

#define SLIST_INIT(head) {                                  \
      (head)->slh_first = NULL;                             \
}

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

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

#define SLIST_NEXT(elm, field)      ((elm)->field.sle_next)

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

#define SLIST_REMOVE(head, elm, type, field) do {                 \
      if ((head)->slh_first == (elm)) {                     \
            SLIST_REMOVE_HEAD((head), field);               \
      }                                               \
      else {                                                \
            struct type *curelm = (head)->slh_first;        \
            while( curelm->field.sle_next != (elm) )        \
                  curelm = curelm->field.sle_next;          \
            curelm->field.sle_next =                        \
                curelm->field.sle_next->field.sle_next;           \
      }                                               \
} while (0)

/*
 * Singly-linked Tail queue definitions.
 */
#define STAILQ_HEAD(name, type)                                   \
struct name {                                               \
      struct type *stqh_first;/* first element */                 \
      struct type **stqh_last;/* addr of last next element */           \
}

#define STAILQ_HEAD_INITIALIZER(head)                             \
      { NULL, &(head).stqh_first }

#define STAILQ_ENTRY(type)                                  \
struct {                                              \
      struct type *stqe_next; /* next element */                  \
}

/*
 * Singly-linked Tail queue functions.
 */
#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)

#define     STAILQ_INIT(head) do {                                \
      (head)->stqh_first = NULL;                            \
      (head)->stqh_last = &(head)->stqh_first;              \
} while (0)

#define STAILQ_FIRST(head)    ((head)->stqh_first)

#define     STAILQ_LAST(head, type, field)                              \
      (STAILQ_EMPTY(head) ?                                 \
            NULL :                                          \
              ((struct type *)                              \
            ((char *)((head)->stqh_last) - __offsetof(struct type, field))))

#define STAILQ_FOREACH(var, head, field)                    \
      for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)

#define STAILQ_INSERT_HEAD(head, elm, field) do {                 \
      if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)  \
            (head)->stqh_last = &(elm)->field.stqe_next;          \
      (head)->stqh_first = (elm);                           \
} while (0)

#define STAILQ_INSERT_TAIL(head, elm, field) do {                 \
      (elm)->field.stqe_next = NULL;                              \
      *(head)->stqh_last = (elm);                           \
      (head)->stqh_last = &(elm)->field.stqe_next;                \
} while (0)

#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {         \
      if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
            (head)->stqh_last = &(elm)->field.stqe_next;          \
      (tqelm)->field.stqe_next = (elm);                     \
} while (0)

#define STAILQ_NEXT(elm, field)     ((elm)->field.stqe_next)

#define STAILQ_REMOVE_HEAD(head, field) do {                      \
      if (((head)->stqh_first =                             \
           (head)->stqh_first->field.stqe_next) == NULL)          \
            (head)->stqh_last = &(head)->stqh_first;        \
} while (0)

#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
      if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)  \
            (head)->stqh_last = &(head)->stqh_first;        \
} while (0)

#define STAILQ_REMOVE(head, elm, type, field) do {                \
      if ((head)->stqh_first == (elm)) {                    \
            STAILQ_REMOVE_HEAD(head, field);                \
      }                                               \
      else {                                                \
            struct type *curelm = (head)->stqh_first;       \
            while( curelm->field.stqe_next != (elm) )       \
                  curelm = curelm->field.stqe_next;         \
            if((curelm->field.stqe_next =                   \
                curelm->field.stqe_next->field.stqe_next) == NULL)      \
                  (head)->stqh_last = &(curelm)->field.stqe_next; \
      }                                               \
} while (0)

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

#define LIST_HEAD_INITIALIZER(head)                         \
      { NULL }

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

/*
 * List functions.
 */

#define     LIST_EMPTY(head) ((head)->lh_first == NULL)

#define LIST_FIRST(head)      ((head)->lh_first)

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

#define     LIST_INIT(head) do {                                  \
      (head)->lh_first = NULL;                              \
} while (0)

#define LIST_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 (0)

#define LIST_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 (0)

#define LIST_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 (0)

#define LIST_NEXT(elm, field) ((elm)->field.le_next)

#define LIST_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 (0)

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

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

#define TAILQ_ENTRY(type)                                   \
struct {                                              \
      struct type *tqe_next;  /* next element */                  \
      struct type **tqe_prev; /* address of previous next element */    \
}

/*
 * Tail queue functions.
 */
#define     TAILQ_EMPTY(head) ((head)->tqh_first == NULL)

#define TAILQ_FOREACH(var, head, field)                           \
      for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))

#define TAILQ_FOREACH_REVERSE(var, head, headname, field)         \
      for ((var) = TAILQ_LAST((head), headname);                  \
           (var);                                     \
           (var) = TAILQ_PREV((var), headname, field))

#define     TAILQ_FIRST(head) ((head)->tqh_first)

#define     TAILQ_LAST(head, headname) \
      (*(((struct headname *)((head)->tqh_last))->tqh_last))

#define     TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)

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

#define     TAILQ_INIT(head) do {                                 \
      (head)->tqh_first = NULL;                             \
      (head)->tqh_last = &(head)->tqh_first;                      \
} while (0)

#define TAILQ_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 (0)

#define TAILQ_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 (0)

#define TAILQ_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 (0)

#define TAILQ_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 (0)

#define TAILQ_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;             \
} while (0)

/*
 * Circular queue definitions.
 */
#define CIRCLEQ_HEAD(name, type)                            \
struct name {                                               \
      struct type *cqh_first;       /* first element */           \
      struct type *cqh_last;        /* last element */            \
}

#define CIRCLEQ_ENTRY(type)                                 \
struct {                                              \
      struct type *cqe_next;        /* next element */            \
      struct type *cqe_prev;        /* previous element */        \
}

/*
 * Circular queue functions.
 */
#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))

#define CIRCLEQ_FIRST(head) ((head)->cqh_first)

#define CIRCLEQ_FOREACH(var, head, field)                   \
      for((var) = (head)->cqh_first;                              \
          (var) != (void *)(head);                          \
          (var) = (var)->field.cqe_next)

#define CIRCLEQ_FOREACH_REVERSE(var, head, field)                 \
      for((var) = (head)->cqh_last;                         \
          (var) != (void *)(head);                          \
          (var) = (var)->field.cqe_prev)

#define     CIRCLEQ_INIT(head) do {                               \
      (head)->cqh_first = (void *)(head);                   \
      (head)->cqh_last = (void *)(head);                    \
} while (0)

#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
      (elm)->field.cqe_next = (listelm)->field.cqe_next;          \
      (elm)->field.cqe_prev = (listelm);                    \
      if ((listelm)->field.cqe_next == (void *)(head))            \
            (head)->cqh_last = (elm);                       \
      else                                            \
            (listelm)->field.cqe_next->field.cqe_prev = (elm);    \
      (listelm)->field.cqe_next = (elm);                    \
} while (0)

#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
      (elm)->field.cqe_next = (listelm);                    \
      (elm)->field.cqe_prev = (listelm)->field.cqe_prev;          \
      if ((listelm)->field.cqe_prev == (void *)(head))            \
            (head)->cqh_first = (elm);                      \
      else                                            \
            (listelm)->field.cqe_prev->field.cqe_next = (elm);    \
      (listelm)->field.cqe_prev = (elm);                    \
} while (0)

#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                \
      (elm)->field.cqe_next = (head)->cqh_first;                  \
      (elm)->field.cqe_prev = (void *)(head);                     \
      if ((head)->cqh_last == (void *)(head))                     \
            (head)->cqh_last = (elm);                       \
      else                                            \
            (head)->cqh_first->field.cqe_prev = (elm);            \
      (head)->cqh_first = (elm);                            \
} while (0)

#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                \
      (elm)->field.cqe_next = (void *)(head);                     \
      (elm)->field.cqe_prev = (head)->cqh_last;             \
      if ((head)->cqh_first == (void *)(head))              \
            (head)->cqh_first = (elm);                      \
      else                                            \
            (head)->cqh_last->field.cqe_next = (elm);       \
      (head)->cqh_last = (elm);                             \
} while (0)

#define CIRCLEQ_LAST(head) ((head)->cqh_last)

#define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)

#define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)

#define     CIRCLEQ_REMOVE(head, elm, field) do {                       \
      if ((elm)->field.cqe_next == (void *)(head))                \
            (head)->cqh_last = (elm)->field.cqe_prev;       \
      else                                            \
            (elm)->field.cqe_next->field.cqe_prev =               \
                (elm)->field.cqe_prev;                      \
      if ((elm)->field.cqe_prev == (void *)(head))                \
            (head)->cqh_first = (elm)->field.cqe_next;            \
      else                                            \
            (elm)->field.cqe_prev->field.cqe_next =               \
                (elm)->field.cqe_next;                      \
} while (0)

#endif /* !_LFT_QUEUE_H_ */

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