aedrix-kernel/kernel/list.c

/*
    Copyright (C) 2012, Aaron Lindsay <aaron@aclindsay.com>

    This file is part of Aedrix.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <list.h>

void init_list(struct dlist_node *n) {
	n->prev = n;
	n->next = n;
}

int list_empty(struct dlist_node *n) {
	return n->next == n;
}

void insert_after(struct dlist_node *n, struct dlist_node *to_add) {
	to_add->next = n->next;
	to_add->next->prev = to_add;
	n->next = to_add;
	to_add->prev = n;
}

void insert_before(struct dlist_node *n, struct dlist_node *to_add) {
	to_add->prev = n->prev;
	to_add->prev->next = to_add;
	n->prev = to_add;
	to_add->next = n;
}

void remove(struct dlist_node *to_remove) {
	if (!list_empty(to_remove)) {
		to_remove->next->prev = to_remove->prev;
		to_remove->prev->next = to_remove->next;
		init_list(to_remove);
	}
}

/*
 * Remove a series of nodes from a list. Note that this assumes the list is not
 * empty, and that 'from' comes before 'to' in the list. 'from' and 'to' will
 * both be removed from the list, along with any nodes which come after 'from'
 * but before 'to'.
 */
void remove_splice(struct dlist_node *from, struct dlist_node *to) {
	to->next->prev = from->prev;
	from->prev->next = to->next;

	//make the removed splice become its own wrap-around list, for easy access to the last member when re-splicing
	to->next = from;
	from->prev = to;
}

/*
 * Add a splice of nodes to a list (most likely a series previously removed via
 * remove_splice()).
 */
void insert_splice_before(struct dlist_node *n, struct dlist_node *first, struct dlist_node *last) {
	first->prev = n->prev;
	first->prev->next = first;
	n->prev = last;
	last->next = n;
}