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FFmpeg/libavfilter/dnn/queue.c

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/*
* Copyright (c) 2020
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include "queue.h"
#include "libavutil/mem.h"
typedef struct QueueEntry QueueEntry;
struct QueueEntry {
void *value;
QueueEntry *prev;
QueueEntry *next;
};
struct Queue {
QueueEntry *head;
QueueEntry *tail;
size_t length;
};
static inline QueueEntry *create_entry(void *val)
{
QueueEntry *entry = av_malloc(sizeof(*entry));
if (entry)
entry->value = val;
return entry;
}
Queue* ff_queue_create(void)
{
Queue *q = av_malloc(sizeof(*q));
if (!q)
return NULL;
q->head = create_entry(q);
q->tail = create_entry(q);
if (!q->head || !q->tail) {
av_freep(&q->head);
av_freep(&q->tail);
av_freep(&q);
return NULL;
}
q->head->next = q->tail;
q->tail->prev = q->head;
q->head->prev = NULL;
q->tail->next = NULL;
q->length = 0;
return q;
}
void ff_queue_destroy(Queue *q)
{
QueueEntry *entry;
if (!q)
return;
entry = q->head;
while (entry != NULL) {
QueueEntry *temp = entry;
entry = entry->next;
av_freep(&temp);
}
av_freep(&q);
}
size_t ff_queue_size(Queue *q)
{
return q ? q->length : 0;
}
void *ff_queue_peek_front(Queue *q)
{
if (!q || q->length == 0)
return NULL;
return q->head->next->value;
}
void *ff_queue_peek_back(Queue *q)
{
if (!q || q->length == 0)
return NULL;
return q->tail->prev->value;
}
int ff_queue_push_front(Queue *q, void *v)
{
QueueEntry *new_entry;
QueueEntry *original_next;
if (!q)
return 0;
new_entry = create_entry(v);
if (!new_entry)
return -1;
original_next = q->head->next;
q->head->next = new_entry;
original_next->prev = new_entry;
new_entry->prev = q->head;
new_entry->next = original_next;
q->length++;
return q->length;
}
int ff_queue_push_back(Queue *q, void *v)
{
QueueEntry *new_entry;
QueueEntry *original_prev;
if (!q)
return 0;
new_entry = create_entry(v);
if (!new_entry)
return -1;
original_prev = q->tail->prev;
q->tail->prev = new_entry;
original_prev->next = new_entry;
new_entry->next = q->tail;
new_entry->prev = original_prev;
q->length++;
return q->length;
}
void *ff_queue_pop_front(Queue *q)
{
QueueEntry *front;
QueueEntry *new_head_next;
void *ret;
if (!q || q->length == 0)
return NULL;
front = q->head->next;
new_head_next = front->next;
ret = front->value;
q->head->next = new_head_next;
new_head_next->prev = q->head;
av_freep(&front);
q->length--;
return ret;
}
void *ff_queue_pop_back(Queue *q)
{
QueueEntry *back;
QueueEntry *new_tail_prev;
void *ret;
if (!q || q->length == 0)
return NULL;
back = q->tail->prev;
new_tail_prev = back->prev;
ret = back->value;
q->tail->prev = new_tail_prev;
new_tail_prev->next = q->tail;
av_freep(&back);
q->length--;
return ret;
}