nes-proj/os/lib/dbl-list.c

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2017-12-10 20:41:09 +00:00
/*
* Copyright (c) 2017, George Oikonomou - http://www.spd.gr
* Copyright (c) 2017, James Pope
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
/*---------------------------------------------------------------------------*/
/**
* \addtogroup doubly-linked-list
* @{
*
* \file
* Implementation of doubly-linked lists
*/
/*---------------------------------------------------------------------------*/
#include "contiki.h"
#include "lib/dbl-list.h"
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
/*---------------------------------------------------------------------------*/
struct dll {
struct dll *next;
struct dll *previous;
};
/*---------------------------------------------------------------------------*/
void
dbl_list_init(dbl_list_t dll)
{
*dll = NULL;
}
/*---------------------------------------------------------------------------*/
void *
dbl_list_head(dbl_list_t dll)
{
return *dll;
}
/*---------------------------------------------------------------------------*/
void *
dbl_list_tail(dbl_list_t dll)
{
struct dll *this;
if(*dll == NULL) {
return NULL;
}
for(this = *dll; this->next != NULL; this = this->next);
return this;
}
/*---------------------------------------------------------------------------*/
void
dbl_list_remove(dbl_list_t dll, void *element)
{
struct dll *this, *previous, *next;
if(*dll == NULL || element == NULL) {
return;
}
for(this = *dll; this != NULL; this = this->next) {
if(this == element) {
previous = this->previous;
next = this->next;
if(previous) {
previous->next = this->next;
}
if(next) {
next->previous = this->previous;
}
if(*dll == this) {
*dll = next;
}
return;
}
}
}
/*---------------------------------------------------------------------------*/
void
dbl_list_add_head(dbl_list_t dll, void *element)
{
struct dll *head;
if(element == NULL) {
return;
}
/* Don't add twice */
dbl_list_remove(dll, element);
head = dbl_list_head(dll);
((struct dll *)element)->previous = NULL;
((struct dll *)element)->next = head;
if(head) {
/* If the list was not empty, update ->previous on the old head */
head->previous = element;
}
*dll = element;
}
/*---------------------------------------------------------------------------*/
void
dbl_list_add_tail(dbl_list_t dll, void *element)
{
struct dll *tail;
if(element == NULL) {
return;
}
/* Don't add twice */
dbl_list_remove(dll, element);
tail = dbl_list_tail(dll);
if(tail == NULL) {
/* The list was empty */
*dll = element;
} else {
tail->next = element;
}
((struct dll *)element)->previous = tail;
((struct dll *)element)->next = NULL;
}
/*---------------------------------------------------------------------------*/
void
dbl_list_add_after(dbl_list_t dll, void *existing, void *element)
{
if(element == NULL || existing == NULL) {
return;
}
/* Don't add twice */
dbl_list_remove(dll, element);
((struct dll *)element)->next = ((struct dll *)existing)->next;
((struct dll *)element)->previous = existing;
if(((struct dll *)existing)->next) {
((struct dll *)existing)->next->previous = element;
}
((struct dll *)existing)->next = element;
}
/*---------------------------------------------------------------------------*/
void
dbl_list_add_before(dbl_list_t dll, void *existing, void *element)
{
if(element == NULL || existing == NULL) {
return;
}
/* Don't add twice */
dbl_list_remove(dll, element);
((struct dll *)element)->next = existing;
((struct dll *)element)->previous = ((struct dll *)existing)->previous;
if(((struct dll *)existing)->previous) {
((struct dll *)existing)->previous->next = element;
}
((struct dll *)existing)->previous = element;
/* If we added before the list's head, we must update the head */
if(*dll == existing) {
*dll = element;
}
}
/*---------------------------------------------------------------------------*/
unsigned long
dbl_list_length(dbl_list_t dll)
{
unsigned long len = 0;
struct dll *this;
if(*dll == NULL) {
return 0;
}
for(this = *dll; this != NULL; this = this->next) {
len++;
}
return len;
}
/*---------------------------------------------------------------------------*/
bool
dbl_list_is_empty(dbl_list_t dll)
{
return *dll == NULL ? true : false;
}
/*---------------------------------------------------------------------------*/
/** @} */