1 files changed, 80 insertions, 0 deletions
diff --git a/src/queue.c b/src/queue.c
new file mode 100644
index 0000000..012e986
--- /dev/null
+++ b/src/queue.c
@@ -0,0 +1,80 @@
+#include "queue.h"
+#include <stdlib.h>
+
+static int _queue_resize(queue* q, int new_cap)
+{
+    int* new_queue;
+    int i;
+
+    if (new_cap <= q->cap) {
+        return 0;
+    }
+    if ((new_queue = (int*)malloc(new_cap * sizeof(int))) == NULL) {
+        return 0;
+    }
+    if (q->front <= q->back) {
+        q->front = q->front + q->cap;
+    }
+    for (i = q->back; i < q->front; ++i) {
+        new_queue[i - q->back] = q->queue[i % q->cap];
+    }
+    free(q->queue);
+    q->queue = new_queue;
+    q->cap = new_cap;
+    q->front = q->size;
+    q->back = 0;
+
+    return 1;
+}
+
+int queue_init(queue* q, int cap)
+{
+    if (cap < 1) {
+        return 0;
+    }
+    if ((q->queue = (int*)malloc(cap * sizeof(int))) == NULL) {
+        return 0;
+    }
+    q->size = 0;
+    q->cap = cap;
+    q->front = 0;
+    q->back = 0;
+
+    return 1;
+}
+
+int enqueue(queue* q, int item)
+{
+    if (q->size == q->cap) {
+        if (!_queue_resize(q, 2 * q->cap)) {
+            return 0;
+        }
+    }
+    q->queue[q->front++] = item;
+    q->front %= q->cap;
+    ++q->size;
+
+    return 1;
+}
+
+int dequeue(queue* q)
+{
+    int ret;
+
+    if (q->size == 0) {
+        return -1;
+    }
+    ret = q->queue[q->back++];
+    q->back %= q->cap;
+    --q->size;
+
+    return ret;
+}
+
+void queue_delete(queue* q)
+{
+    free(q->queue);
+    q->queue = NULL;
+    q->size = 0;
+    q->cap = 0;
+}