started palindromatic task of bi0sCTF 23

bi0sctf23/pwn/palindromatic/src/palindromatic_util.c

@@ -0,0 +1,68 @@
+#include "palindromatic.h"
+
+static void pm_queue_init(queue_t *queue)
+{
+    queue->front = queue->rear = -1; 
+    for(int i = 0; i<QUEUE_SZ; i++) queue->reqs[i] = NULL;
+}
+
+
+static long pm_queue_enqueue(queue_t *queue, request_t *req)
+{
+    if((queue->front == 0 && queue->rear == QUEUE_SZ-1) || (queue->rear+1)%QUEUE_SZ == queue->front) return -1;
+
+    else if(queue->front == -1)
+    {
+        queue->front = queue->rear = 0;
+        queue->reqs[queue->rear] = req;
+    }
+
+    else if(queue->rear == QUEUE_SZ-1 && queue->front != 0)
+    {
+        queue->rear = 0;
+        queue->reqs[queue->rear] = req;
+    }
+
+    else 
+    {
+        queue->rear++;
+        queue->reqs[queue->rear] = req;
+    }
+
+    return queue->rear;
+}
+
+
+static request_t *pm_queue_dequeue(queue_t *queue)
+{
+    if(queue->front == -1) return NULL;
+
+    request_t *req = queue->reqs[queue->front];
+    queue->reqs[queue->front] = NULL;
+
+    if(queue->front == queue->rear) queue->front = queue->rear = -1;
+    else if(queue->front == QUEUE_SZ-1) queue->front = 0;
+    else queue->front++;
+
+    return req;
+}
+
+
+static request_t *pm_queue_peek(queue_t *queue)
+{
+    if(queue->front == -1) return NULL;
+    else return queue->reqs[queue->front];
+}
+
+
+static int pm_queue_count(queue_t *queue)
+{
+    if(queue->front == -1) 
+        return 0;
+
+    else if(queue->rear >= queue->front)
+        return queue->rear-queue->front+1;
+
+    else
+        return QUEUE_SZ - queue->front + queue->rear + 1;
+}