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/*
Copyright (c) 2010 Frank Lahm <franklahm@gmail.com>
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.
*/
/*!
* @file
* Netatalk utility functions: queue
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#include <stdlib.h>
#include <atalk/queue.h>
static qnode_t *alloc_init_node(void *data)
{
qnode_t *node;
if ((node = malloc(sizeof(qnode_t))) == NULL)
return NULL;
node->data = data;
return node;
}
/********************************************************************************
* Interface
*******************************************************************************/
q_t *queue_init(void)
{
q_t *queue;
if ((queue = alloc_init_node(NULL)) == NULL)
return NULL;
queue->prev = queue->next = queue;
return queue;
}
/* Insert at tail */
qnode_t *enqueue(q_t *q, void *data)
{
qnode_t *node;
if ((node = alloc_init_node(data)) == NULL)
return NULL;
/* insert at tail */
node->next = q;
node->prev = q->prev;
q->prev->next = node;
q->prev = node;
return node;
}
/* Insert at head */
qnode_t *prequeue(q_t *q, void *data)
{
qnode_t *node;
if ((node = alloc_init_node(data)) == NULL)
return NULL;
/* insert at head */
q->next->prev = node;
node->next = q->next;
node->prev = q;
q->next = node;
return node;
}
/* Take from head */
void *dequeue(q_t *q)
{
qnode_t *node;
void *data;
if (q == NULL || q->next == q)
return NULL;
/* take first node from head */
node = q->next;
data = node->data;
q->next = node->next;
node->next->prev = node->prev;
free(node);
return data;
}
void queue_destroy(q_t *q, void (*callback)(void *))
{
void *p;
while ((p = dequeue(q)) != NULL)
callback(p);
free(q);
q = NULL;
}
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