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