1 files changed, 176 insertions, 0 deletions
diff --git a/libavfilter/dnn/queue.c b/libavfilter/dnn/queue.c
new file mode 100644
index 0000000000..0a07c5473d
--- /dev/null
+++ b/libavfilter/dnn/queue.c
@@ -0,0 +1,176 @@
+/*
+ * 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"
+#include "libavutil/avassert.h"
+
+typedef struct _queue_entry queue_entry;
+
+typedef struct _queue {
+    queue_entry *head;
+    queue_entry *tail;
+    size_t length;
+}queue;
+
+typedef struct _queue_entry {
+    void *value;
+    queue_entry *prev;
+    queue_entry *next;
+} queue_entry;
+
+static inline queue_entry *create_entry(void *val)
+{
+    queue_entry *entry = av_malloc(sizeof(*entry));
+    av_assert0(entry != NULL);
+    entry->value = val;
+    return entry;
+}
+
+queue* queue_create(void)
+{
+    queue *q = av_malloc(sizeof(*q));
+    if (!q)
+        return NULL;
+
+    q->head = create_entry(q);
+    q->tail = create_entry(q);
+    q->head->next = q->tail;
+    q->tail->prev = q->head;
+    q->head->prev = NULL;
+    q->tail->next = NULL;
+    q->length = 0;
+
+    return q;
+}
+
+void queue_destroy(queue *q)
+{
+    queue_entry *entry;
+    if (!q)
+        return;
+
+    entry = q->head;
+    while (entry != NULL) {
+        queue_entry *temp = entry;
+        entry = entry->next;
+        av_freep(&temp);
+    }
+
+    av_freep(&q);
+}
+
+size_t queue_size(queue *q)
+{
+     return q ? q->length : 0;
+}
+
+void *queue_peek_front(queue *q)
+{
+    if (!q || q->length == 0)
+        return NULL;
+
+    return q->head->next->value;
+}
+
+void *queue_peek_back(queue *q)
+{
+    if (!q || q->length == 0)
+        return NULL;
+
+    return q->tail->prev->value;
+}
+
+void queue_push_front(queue *q, void *v)
+{
+    queue_entry *new_entry;
+    queue_entry *original_next;
+    if (!q)
+        return;
+
+    new_entry = create_entry(v);
+    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++;
+}
+
+void queue_push_back(queue *q, void *v)
+{
+    queue_entry *new_entry;
+    queue_entry *original_prev;
+    if (!q)
+        return;
+
+    new_entry = create_entry(v);
+    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++;
+}
+
+void *queue_pop_front(queue *q)
+{
+    queue_entry *front;
+    queue_entry *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 *queue_pop_back(queue *q)
+{
+    queue_entry *back;
+    queue_entry *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;
+}