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      1 /*--------------------------------------------------------------------------
      2 Copyright (c) 2010-2011, 2013, The Linux Foundation. All rights reserved.
      3 
      4 Redistribution and use in source and binary forms, with or without
      5 modification, are permitted provided that the following conditions are met:
      6     * Redistributions of source code must retain the above copyright
      7       notice, this list of conditions and the following disclaimer.
      8     * Redistributions in binary form must reproduce the above copyright
      9       notice, this list of conditions and the following disclaimer in the
     10       documentation and/or other materials provided with the distribution.
     11     * Neither the name of The Linux Foundation nor
     12       the names of its contributors may be used to endorse or promote
     13       products derived from this software without specific prior written
     14       permission.
     15 
     16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
     17 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18 IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     19 NON-INFRINGEMENT ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
     20 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     21 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     22 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     23 OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     24 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     25 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     26 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 --------------------------------------------------------------------------*/
     28 /*
     29    Queue with Linked list
     30  */
     31 
     32 #include "queue.h"
     33 #include <stdio.h>
     34 #include <stdlib.h>
     35 
     36 
     37 typedef struct Node {
     38     void *element;
     39     struct Node *next;
     40 } Node;
     41 
     42 struct Queue {
     43     Node *head;
     44     Node *tail;
     45     int  current_size;
     46 };
     47 
     48 Queue *alloc_queue()
     49 {
     50     Queue *q = (Queue *) malloc(sizeof(Queue));
     51 
     52     if (q) {
     53         q->head = q->tail = NULL;
     54         q->current_size = 0;
     55     }
     56 
     57     return q;
     58 }
     59 
     60 void free_queue(Queue *q)
     61 {
     62     while (q->current_size) {
     63         pop(q);
     64     }
     65 }
     66 
     67 void free_queue_and_qelement(Queue *q)
     68 {
     69     while (q->current_size) {
     70         void *element = pop(q);
     71 
     72         if (element)
     73             free(element);
     74     }
     75 }
     76 
     77 int push(Queue *q, void * element)
     78 {
     79     Node *new_node = (Node *) malloc(sizeof(Node));
     80 
     81     if (new_node == NULL)
     82         return -1;
     83 
     84     new_node->element = element;
     85     new_node->next = NULL;
     86 
     87     if (q->current_size == 0) {
     88         q->head = new_node;
     89     } else {
     90         q->tail->next = new_node;
     91     }
     92 
     93     q->tail = new_node;
     94     q->current_size++;
     95 
     96     return 0;
     97 }
     98 
     99 void *pop(Queue *q)
    100 {
    101     Node *temp;
    102     void *element;
    103 
    104     if (q->current_size == 0)
    105         return NULL;
    106 
    107     temp = q->head;
    108     element = temp->element;
    109 
    110     if (q->current_size == 1) {
    111         q->head = q->tail = NULL;
    112     } else {
    113         q->head = q->head->next;
    114     }
    115 
    116     free(temp);
    117     q->current_size--;
    118     return element;
    119 }
    120 
    121