350 lines
8.9 KiB
C
350 lines
8.9 KiB
C
/*
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* Copyright (c) 2004, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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/**
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* \file
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* Linked list library implementation.
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*
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* \author Adam Dunkels <adam@sics.se>
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*
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*/
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/**
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* \addtogroup list
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* @{
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*/
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#include "contiki.h"
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#include "lib/list.h"
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#include <string.h>
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/*---------------------------------------------------------------------------*/
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struct list {
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struct list *next;
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};
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/*---------------------------------------------------------------------------*/
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/**
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* Initialize a list.
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*
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* This function initalizes a list. The list will be empty after this
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* function has been called.
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*
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* \param list The list to be initialized.
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*/
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void
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list_init(list_t list)
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{
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*list = NULL;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Get a pointer to the first element of a list.
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*
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* This function returns a pointer to the first element of the
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* list. The element will \b not be removed from the list.
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*
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* \param list The list.
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* \return A pointer to the first element on the list.
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*
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* \sa list_tail()
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*/
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void *
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list_head(list_t list)
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{
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return *list;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Duplicate a list.
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*
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* This function duplicates a list by copying the list reference, but
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* not the elements.
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*
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* \note This function does \b not copy the elements of the list, but
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* merely duplicates the pointer to the first element of the list.
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*
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* \param dest The destination list.
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* \param src The source list.
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*/
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void
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list_copy(list_t dest, list_t src)
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{
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*dest = *src;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Get the tail of a list.
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*
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* This function returns a pointer to the elements following the first
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* element of a list. No elements are removed by this function.
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*
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* \param list The list
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* \return A pointer to the element after the first element on the list.
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*
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* \sa list_head()
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*/
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void *
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list_tail(list_t list)
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{
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struct list *l;
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if(*list == NULL) {
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return NULL;
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}
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for(l = *list; l->next != NULL; l = l->next);
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return l;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Add an item at the end of a list.
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*
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* This function adds an item to the end of the list.
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*
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* \param list The list.
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* \param item A pointer to the item to be added.
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*
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* \sa list_push()
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*
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*/
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void
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list_add(list_t list, void *item)
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{
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struct list *l;
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/* Make sure not to add the same element twice */
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list_remove(list, item);
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((struct list *)item)->next = NULL;
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l = list_tail(list);
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if(l == NULL) {
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*list = item;
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} else {
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l->next = item;
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}
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Add an item to the start of the list.
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*/
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void
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list_push(list_t list, void *item)
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{
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/* Make sure not to add the same element twice */
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list_remove(list, item);
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((struct list *)item)->next = *list;
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*list = item;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Remove the last object on the list.
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*
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* This function removes the last object on the list and returns it.
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*
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* \param list The list
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* \return The removed object
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*
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*/
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void *
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list_chop(list_t list)
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{
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struct list *l, *r;
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if(*list == NULL) {
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return NULL;
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}
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if(((struct list *)*list)->next == NULL) {
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l = *list;
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*list = NULL;
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return l;
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}
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for(l = *list; l->next->next != NULL; l = l->next);
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r = l->next;
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l->next = NULL;
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return r;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Remove the first object on a list.
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*
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* This function removes the first object on the list and returns a
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* pointer to it.
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*
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* \param list The list.
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* \return Pointer to the removed element of list.
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*/
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/*---------------------------------------------------------------------------*/
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void *
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list_pop(list_t list)
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{
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struct list *l;
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l = *list;
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if(*list != NULL) {
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*list = ((struct list *)*list)->next;
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}
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return l;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Remove a specific element from a list.
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*
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* This function removes a specified element from the list.
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*
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* \param list The list.
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* \param item The item that is to be removed from the list.
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*
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*/
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/*---------------------------------------------------------------------------*/
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void
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list_remove(list_t list, void *item)
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{
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struct list *l, *r;
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if(*list == NULL) {
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return;
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}
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r = NULL;
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for(l = *list; l != NULL; l = l->next) {
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if(l == item) {
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if(r == NULL) {
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/* First on list */
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*list = l->next;
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} else {
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/* Not first on list */
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r->next = l->next;
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}
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l->next = NULL;
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return;
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}
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r = l;
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}
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Get the length of a list.
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*
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* This function counts the number of elements on a specified list.
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*
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* \param list The list.
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* \return The length of the list.
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*/
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/*---------------------------------------------------------------------------*/
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int
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list_length(list_t list)
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{
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struct list *l;
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int n = 0;
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for(l = *list; l != NULL; l = l->next) {
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++n;
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}
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return n;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Insert an item after a specified item on the list
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* \param list The list
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* \param previtem The item after which the new item should be inserted
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* \param newitem The new item that is to be inserted
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* \author Adam Dunkels
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*
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* This function inserts an item right after a specified
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* item on the list. This function is useful when using
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* the list module to ordered lists.
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*
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* If previtem is NULL, the new item is placed at the
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* start of the list.
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*
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*/
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void
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list_insert(list_t list, void *previtem, void *newitem)
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{
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if(previtem == NULL) {
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list_push(list, newitem);
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} else {
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list_remove(list, newitem);
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((struct list *)newitem)->next = ((struct list *)previtem)->next;
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((struct list *)previtem)->next = newitem;
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}
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Get the next item following this item
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* \param item A list item
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* \returns A next item on the list
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*
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* This function takes a list item and returns the next
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* item on the list, or NULL if there are no more items on
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* the list. This function is used when iterating through
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* lists.
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*/
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void *
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list_item_next(void *item)
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{
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return item == NULL ? NULL : ((struct list *)item)->next;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Check if the list contains an item
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* \param list The list that is checked
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* \param item An item to look for in the list
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* \returns 0 if the list does not contains the item, and 1 otherwise
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*
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* This function searches for an item in the list and returns
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* 0 if the list does not contain the item, and 1 if the item
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* is present in the list.
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*/
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bool
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list_contains(list_t list, void *item)
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{
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struct list *l;
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for(l = *list; l != NULL; l = l->next) {
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if(item == l) {
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return true;
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}
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}
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return false;
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}
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/*---------------------------------------------------------------------------*/
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/** @} */
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