/*
 *  Copyright (C) James R. Leu 2000
 *  jleu@mindspring.com
 *
 *  This software is covered under the LGPL, for more
 *  info check out http://www.gnu.org/copyleft/lgpl.html
 */

#ifndef _LDP_LIST_H_
#define _LDP_LIST_H_

#define LDP_LIST_ROOT(name,type)	\
struct name {				\
  struct type *llh_first;		\
  struct type *llh_last;		\
}

#define LDP_LIST_ELEM(type)		\
struct {				\
  struct type *lle_next;		\
  struct type *lle_prev;		\
}

#define LDP_LIST_REMOVE(head, elm, field) {				\
  if((elm)->field.lle_next == (void *)(head))				\
    (head)->llh_last = (elm)->field.lle_prev;				\
  else									\
    (elm)->field.lle_next->field.lle_prev = (elm)->field.lle_prev;	\
  if((elm)->field.lle_prev == (void *)(head))				\
    (head)->llh_first = (elm)->field.lle_next;				\
  else									\
    (elm)->field.lle_prev->field.lle_next = (elm)->field.lle_next;	\
}

#define LDP_LIST_INSERT_BEFORE(head,listelm,elm,field) {	\
  (elm)->field.lle_next = (listelm);				\
  (elm)->field.lle_prev = (listelm)->field.lle_prev;		\
  if((listelm)->field.lle_prev == (void *)(head))		\
    (head)->llh_first = (elm);					\
  else								\
    (listelm)->field.lle_prev->field.lle_next = (elm);		\
  (listelm)->field.lle_prev = (elm);				\
}

#define LDP_LIST_INIT(head,type) {		\
  (head)->llh_first = (struct type *)(head);	\
  (head)->llh_last = (struct type *)(head);	\
}

#define LDP_LIST_ADD_HEAD(head, elm, field, type) {	\
  (elm)->field.lle_next = (head)->llh_first;		\
  (elm)->field.lle_prev = (struct type *)(head);	\
  if ((head)->llh_last == (struct type *)(head))	\
    (head)->llh_last = (elm);				\
  else							\
    (head)->llh_first->field.lle_prev = (elm);		\
  (head)->llh_first = (elm);				\
}

#define LDP_LIST_ADD_TAIL(head, elm, field, type) {	\
  (elm)->field.lle_next = (struct type *)(head);	\
  (elm)->field.lle_prev = (head)->llh_last;		\
  if ((head)->llh_first == (struct type *)(head))	\
    (head)->llh_first = (elm);				\
  else							\
    (head)->llh_last->field.lle_next = (elm);		\
  (head)->llh_last = (elm);				\
}

#define LDP_LIST_REMOVE_TAIL(root,elem,field) {	\
  (elem) = (root)->llh_last;			\
  if((elem) && (elem) != (void*)(root)) {	\
    LDP_LIST_REMOVE(root,elem,field);		\
  } else {					\
    (elem) = NULL;				\
  }						\
}

#define LDP_LIST_REMOVE_HEAD(root,elem,field) {	\
  (elem) = (root)->llh_first;			\
  if((elem) && (elem) != (void*)(root)) {	\
    LDP_LIST_REMOVE(root,elem,field);		\
  } else {					\
    (elem) = NULL;				\
  }						\
}

#define LDP_LIST_ELEM_INIT(elem,field) {	\
  (elem)->field.lle_next = NULL;		\
  (elem)->field.lle_prev = NULL;		\
}

#define LDP_LIST_HEAD(root)		(((root)->llh_first == (void*)(root))?(NULL):((root)->llh_first))
#define LDP_LIST_NEXT(root,elem,field)	((((elem)->field.lle_next) == (void*)(root))?(NULL):((elem)->field.lle_next))
#define LDP_LIST_PREV(root,elem,field)	((((elem)->field.lle_prev) == (void*)(root))?(NULL):((elem)->field.lle_prev))
#define LDP_LIST_TAIL(root)		(((root)->llh_last == (void*)(root))?(NULL):((root)->llh_last))

#endif