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//
// Copyright 2016 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#include <stdlib.h>
#include <string.h>
#include "core/nng_impl.h"
// Linked list implementation. We implement a doubly linked list.
// Using pointer arithmetic, we can operate as a list of "anything".
#define NODE(list, item) \
(nni_list_node *) (void *) (((char *) item) + list->ll_offset)
#define ITEM(list, node) \
(void *) (((char *) node) - list->ll_offset)
void
nni_list_init_offset(nni_list *list, size_t offset)
{
list->ll_offset = offset;
list->ll_head.ln_next = &list->ll_head;
list->ll_head.ln_prev = &list->ll_head;
}
void *
nni_list_first(nni_list *list)
{
nni_list_node *node = list->ll_head.ln_next;
if (node == &list->ll_head) {
return (NULL);
}
return (ITEM(list, node));
}
void *
nni_list_last(nni_list *list)
{
nni_list_node *node = list->ll_head.ln_prev;
if (node == &list->ll_head) {
return (NULL);
}
return (ITEM(list, node));
}
void
nni_list_append(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
node->ln_prev = list->ll_head.ln_prev;
node->ln_next = &list->ll_head;
node->ln_next->ln_prev = node;
node->ln_prev->ln_next = node;
}
void
nni_list_prepend(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
node->ln_next = list->ll_head.ln_next;
node->ln_prev = &list->ll_head;
node->ln_next->ln_prev = node;
node->ln_prev->ln_next = node;
}
void *
nni_list_next(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
if ((node = node->ln_next) == &list->ll_head) {
return (NULL);
}
return (ITEM(list, node));
}
void *
nni_list_prev(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
if ((node = node->ln_prev) == &list->ll_head) {
return (NULL);
}
return (ITEM(list, node));
}
void
nni_list_remove(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
node->ln_prev->ln_next = node->ln_next;
node->ln_next->ln_prev = node->ln_prev;
}
void
nni_list_node_init(nni_list *list, void *item)
{
nni_list_node *node = NODE(list, item);
node->ln_prev = node->ln_next = NULL;
}
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