1 files changed, 176 insertions, 0 deletions
diff --git a/src/queue.c b/src/queue.c
new file mode 100644
index 0000000..8d48401
--- /dev/null
+++ b/src/queue.c
@@ -0,0 +1,176 @@
+#include <bh/internal/queue.h>
+#include <stdlib.h>
+#include <string.h>
+
+bh_queue_t *bh_queue_new(void)
+{
+    bh_queue_t *result;
+
+    result = malloc(sizeof(*result));
+    if (result)
+        bh_queue_init(result);
+
+    return result;
+}
+
+void bh_queue_free(bh_queue_t *queue)
+{
+    bh_queue_destroy(queue);
+    free(queue);
+}
+
+void bh_queue_init(bh_queue_t *queue)
+{
+    memset(queue, 0, sizeof(*queue));
+}
+
+void bh_queue_destroy(bh_queue_t *queue)
+{
+    if (queue->capacity)
+        free(queue->data);
+}
+
+void bh_queue_clear(bh_queue_t *queue)
+{
+    queue->head = 0;
+    queue->tail = 0;
+    queue->size = 0;
+}
+
+int bh_queue_reserve(bh_queue_t *queue,
+                     size_t size)
+{
+    bh_queue_t other;
+
+    /* New capacity should be great or equal to current size */
+    if (size < queue->size)
+        size = queue->size;
+
+    /* New capacity should not exceed maximum capacity */
+    if (size > ((size_t)-1) / sizeof(void *))
+        return -1;
+
+    /* Prevent same size memory reallocation */
+    if (size == queue->capacity)
+        return 0;
+
+    /* Prepare new empty queue */
+    bh_queue_init(&other);
+    if (size)
+    {
+        void *iter;
+
+        /* Allocate new capacity for the queue */
+        other.data = malloc(size * sizeof(void *));
+        other.capacity = size;
+        if (!other.data)
+            return -1;
+
+        /* Iterate over old queue and insert data into new queue */
+        iter = bh_queue_iter_next(queue, NULL);
+        while (iter)
+        {
+            bh_queue_insert(&other, bh_queue_iter_value(iter));
+            iter = bh_queue_iter_next(queue, iter);
+        }
+    }
+
+    /* If old queue had allocated data - free it */
+    if (queue->capacity)
+        free(queue->data);
+
+    /* Copy queue information */
+    *queue = other;
+    return 0;
+}
+
+int bh_queue_insert(bh_queue_t *queue,
+                    void *value)
+{
+    /* Check if queue can contain new element */
+    if (queue->size + 1 > queue->capacity)
+    {
+        size_t capacity;
+
+        /* Check potential size overflow and reserve capacity */
+        capacity = (queue->capacity) ? (queue->capacity * 2) : (16);
+        if (capacity < queue->capacity || bh_queue_reserve(queue, capacity))
+            return -1;
+    }
+
+    /* Increase queue size and advance tail index */
+    queue->data[queue->tail] = value;
+    queue->size++;
+    if (++queue->tail >= queue->capacity)
+        queue->tail = 0;
+
+    return 0;
+}
+
+void bh_queue_remove(bh_queue_t *queue)
+{
+    /* Do nothing if queue is empty */
+    if (!queue->size)
+        return;
+
+    /* Decrease queue size and advance head index */
+    queue->size--;
+    if (++queue->head >= queue->capacity)
+        queue->head = 0;
+}
+
+void *bh_queue_front(bh_queue_t *queue)
+{
+    /* Do nothing if queue is empty */
+    if (!queue->size)
+        return NULL;
+
+    /* Return front element */
+    return queue->data[queue->head];
+}
+
+int bh_queue_empty(bh_queue_t *queue)
+{
+    return !queue->size;
+}
+
+size_t bh_queue_size(bh_queue_t *queue)
+{
+    return queue->size;
+}
+
+size_t bh_queue_capacity(bh_queue_t *queue)
+{
+    return queue->capacity;
+}
+
+void *bh_queue_iter_next(bh_queue_t *queue,
+                         void *iter)
+{
+    void **element = (void **)iter;
+
+    /* Do nothing if queue is empty */
+    if (!queue->size)
+        return NULL;
+
+    /* Advance or set iterator */
+    if (element)
+    {
+        element++;
+        if (element == queue->data + queue->capacity)
+            element = queue->data;
+
+        /* Check if we reached the end */
+        if (element == queue->data + queue->tail)
+            return NULL;
+    }
+    else
+        element = queue->data + queue->head;
+
+    return element;
+}
+
+void *bh_queue_iter_value(void *iter)
+{
+    return *(void **)iter;
+}