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

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/*
* 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-circular-list
* @{
*
* \file
* Implementation of circular, doubly-linked lists
*/
/*---------------------------------------------------------------------------*/
#include "contiki.h"
#include "lib/dbl-circ-list.h"
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
/*---------------------------------------------------------------------------*/
struct dblcl {
struct dblcl *next;
struct dblcl *previous;
};
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_init(dbl_circ_list_t dblcl)
{
*dblcl = NULL;
}
/*---------------------------------------------------------------------------*/
void *
dbl_circ_list_head(dbl_circ_list_t dblcl)
{
return *dblcl;
}
/*---------------------------------------------------------------------------*/
void *
dbl_circ_list_tail(dbl_circ_list_t dblcl)
{
struct dblcl *this;
if(*dblcl == NULL) {
return NULL;
}
for(this = *dblcl; this->next != *dblcl; this = this->next);
return this;
}
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_remove(dbl_circ_list_t dblcl, void *element)
{
struct dblcl *this;
if(*dblcl == NULL || element == NULL) {
return;
}
this = *dblcl;
do {
if(this == element) {
this->previous->next = this->next;
this->next->previous = this->previous;
/* We need to update the head of the list if we removed the head */
if(*dblcl == element) {
*dblcl = this->next == this ? NULL : this->next;
}
this->next = NULL;
this->previous = NULL;
return;
}
this = this->next;
} while(this != *dblcl);
}
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_add_head(dbl_circ_list_t dblcl, void *element)
{
struct dblcl *head;
if(element == NULL) {
return;
}
/* Don't add twice */
dbl_circ_list_remove(dblcl, element);
head = dbl_circ_list_head(dblcl);
if(head == NULL) {
/* If the list was empty */
((struct dblcl *)element)->next = element;
((struct dblcl *)element)->previous = element;
} else {
/* If the list was not empty */
((struct dblcl *)element)->next = head;
((struct dblcl *)element)->previous = head->previous;
head->previous->next = element;
head->previous = element;
}
*dblcl = element;
}
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_add_tail(dbl_circ_list_t dblcl, void *element)
{
struct dblcl *tail;
if(element == NULL) {
return;
}
/* Don't add twice */
dbl_circ_list_remove(dblcl, element);
tail = dbl_circ_list_tail(dblcl);
if(tail == NULL) {
/* If the list was empty */
((struct dblcl *)element)->next = element;
((struct dblcl *)element)->previous = element;
*dblcl = element;
} else {
/* If the list was not empty */
((struct dblcl *)element)->next = *dblcl;
((struct dblcl *)element)->previous = tail;
tail->next->previous = element;
tail->next = element;
}
}
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_add_after(dbl_circ_list_t dblcl, void *existing, void *element)
{
if(element == NULL || existing == NULL) {
return;
}
/* Don't add twice */
dbl_circ_list_remove(dblcl, element);
((struct dblcl *)element)->next = ((struct dblcl *)existing)->next;
((struct dblcl *)element)->previous = existing;
((struct dblcl *)existing)->next->previous = element;
((struct dblcl *)existing)->next = element;
}
/*---------------------------------------------------------------------------*/
void
dbl_circ_list_add_before(dbl_circ_list_t dblcl, void *existing, void *element)
{
if(element == NULL || existing == NULL) {
return;
}
/* Don't add twice */
dbl_circ_list_remove(dblcl, element);
((struct dblcl *)element)->next = existing;
((struct dblcl *)element)->previous = ((struct dblcl *)existing)->previous;
((struct dblcl *)existing)->previous->next = element;
((struct dblcl *)existing)->previous = element;
/* If we added before the list's head, we must update the head */
if(*dblcl == existing) {
*dblcl = element;
}
}
/*---------------------------------------------------------------------------*/
unsigned long
dbl_circ_list_length(dbl_circ_list_t dblcl)
{
unsigned long len = 1;
struct dblcl *this;
if(*dblcl == NULL) {
return 0;
}
for(this = *dblcl; this->next != *dblcl; this = this->next) {
len++;
}
return len;
}
/*---------------------------------------------------------------------------*/
bool
dbl_circ_list_is_empty(dbl_circ_list_t dblcl)
{
return *dblcl == NULL ? true : false;
}
/*---------------------------------------------------------------------------*/
/** @} */