radare2/libr/util/queue.c
2018-09-13 10:17:26 +02:00

89 lines
1.4 KiB
C

/* radare - LGPL - Copyright 2007-2015 - ret2libc */
#include <r_util.h>
R_API RQueue *r_queue_new (int n) {
if (n <= 0) {
return NULL;
}
RQueue *q = R_NEW0 (RQueue);
if (!q) {
return NULL;
}
q->elems = R_NEWS0 (void *, n);
if (!q->elems){
free (q);
return NULL;
}
q->front = 0;
q->rear = -1;
q->size = 0;
q->capacity = n;
return q;
}
R_API void r_queue_free(RQueue *q) {
free (q->elems);
free (q);
}
static int is_full(RQueue *q) {
return q->size == q->capacity;
}
static int increase_capacity(RQueue *q) {
unsigned int new_capacity = q->capacity * 2;
void **newelems;
int i, tmp_front;
newelems = R_NEWS0(void *, new_capacity);
if (!newelems) {
return false;
}
i = -1;
tmp_front = q->front;
while (i + 1 < q->size) {
i++;
newelems[i] = q->elems[tmp_front];
tmp_front = (tmp_front + 1) % q->capacity;
}
free (q->elems);
q->elems = newelems;
q->front = 0;
q->rear = i;
q->capacity = new_capacity;
return true;
}
R_API int r_queue_enqueue(RQueue *q, void *el) {
if (is_full(q)) {
int res = increase_capacity (q);
if (!res) {
return false;
}
}
q->rear = (q->rear + 1) % q->capacity;
q->elems[q->rear] = el;
q->size++;
return true;
}
R_API void *r_queue_dequeue(RQueue *q) {
void *res;
if (r_queue_is_empty (q)) {
return NULL;
}
res = q->elems[q->front];
q->front = (q->front + 1) % q->capacity;
q->size--;
return res;
}
R_API int r_queue_is_empty(RQueue *q) {
return q->size == 0;
}