code.delx.au - pulseaudio/blob - src/queue.c

   1 #include <assert.h>
   2 #include <stdlib.h>
   3
   4 #include "queue.h"
   5
   6 struct queue_entry {
   7     struct queue_entry *next;
   8     void *data;
   9 };
  10
  11 struct queue {
  12     struct queue_entry *front, *back;
  13     unsigned length;
  14 };
  15
  16 struct queue* queue_new(void) {
  17     struct queue *q = malloc(sizeof(struct queue));
  18     assert(q);
  19     q->front = q->back = NULL;
  20     q->length = 0;
  21     return q;
  22 }
  23
  24 void queue_free(struct queue* q, void (*destroy)(void *p, void *userdata), void *userdata) {
  25     struct queue_entry *e;
  26     assert(q);
  27
  28     e = q->front;
  29     while (e) {
  30         struct queue_entry *n = e->next;
  31
  32         if (destroy)
  33             destroy(e->data, userdata);
  34
  35         free(e);
  36         e = n;
  37     }
  38
  39     free(q);
  40 }
  41
  42 void queue_push(struct queue *q, void *p) {
  43     struct queue_entry *e;
  44
  45     e = malloc(sizeof(struct queue_entry));
  46
  47     e->data = p;
  48     e->next = NULL;
  49
  50     if (q->back)
  51         q->back->next = e;
  52     else {
  53         assert(!q->front);
  54         q->front = e;
  55     }
  56
  57     q->back = e;
  58     q->length++;
  59 }
  60
  61 void* queue_pop(struct queue *q) {
  62     void *p;
  63     struct queue_entry *e;
  64     assert(q);
  65
  66     if (!(e = q->front))
  67         return NULL;
  68
  69     q->front = e->next;
  70     if (q->back == e)
  71         q->back = NULL;
  72
  73     p = e->data;
  74     free(e);
  75
  76     q->length--;
  77
  78     return p;
  79 }
  80
  81 int queue_is_empty(struct queue *q) {
  82     assert(q);
  83     return q->length == 0;
  84 }