1 /*
2 * Copyright (C) 2019 BlueKitchen GmbH
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the copyright holders nor the names of
14 * contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * 4. Any redistribution, use, or modification is done solely for
17 * personal benefit and not for any commercial purpose or for
18 * monetary gain.
19 *
20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
24 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * Please inquire about commercial licensing options at
34 * [email protected]
35 *
36 */
37
38 #define BTSTACK_FILE__ "btstack_linked_queue.c"
39
40 #include "btstack_linked_queue.h"
41 #include "btstack_debug.h"
42 #include <stdlib.h>
43
44 /**
45 * @brief Tests if queue is empty
46 * @return true if emtpy
47 */
btstack_linked_queue_empty(btstack_linked_queue_t * queue)48 bool btstack_linked_queue_empty(btstack_linked_queue_t * queue){
49 return queue->head == NULL;
50 }
51
52 /**
53 * @brief Append item to queue
54 * @param queue
55 * @param item
56 */
btstack_linked_queue_enqueue(btstack_linked_queue_t * queue,btstack_linked_item_t * item)57 void btstack_linked_queue_enqueue(btstack_linked_queue_t * queue, btstack_linked_item_t * item){
58 if (queue->head == NULL){
59 // empty queue
60 item->next = NULL;
61 queue->head = item;
62 queue->tail = item;
63 } else {
64 // non-empty
65 item->next = NULL;
66 queue->tail->next = item;
67 queue->tail = item;
68 }
69 }
70
71 /**
72 * @brief Get first item from queue
73 * @param queue
74 * @return item or NULL if queue empty
75 */
btstack_linked_queue_first(btstack_linked_queue_t * queue)76 btstack_linked_item_t * btstack_linked_queue_first(btstack_linked_queue_t * queue){
77 return queue->head;
78 }
79
80 /**
81 * @brief Pop next item from queue
82 * @param queue
83 * @return item or NULL if queue empty
84 */
btstack_linked_queue_dequeue(btstack_linked_queue_t * queue)85 btstack_linked_item_t * btstack_linked_queue_dequeue(btstack_linked_queue_t * queue){
86 if (queue->head == NULL){
87 return NULL;
88 }
89 btstack_linked_item_t * item = queue->head;
90 queue->head = item->next;
91 // reset tail if head becomes NULL
92 if (queue->head == NULL){
93 queue->tail = NULL;
94 }
95 return item;
96 }
97