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 MATTHIAS 24 * RINGWALD 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 */ 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 */ 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 */ 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 */ 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