Feat: lab 3 w/o adv 2

kernel/include/ringbuffer.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <stddef.h>
+
+typedef struct {
+  size_t size;
+  size_t cap;
+  uint8_t *data;
+  uint8_t *read, *write;
+} ringbuffer_t;
+
+ringbuffer_t *make_ringbuffer(size_t size);
+int ringbuffer_push(ringbuffer_t *buf, uint8_t val);
+uint8_t ringbuffer_bump(ringbuffer_t *buf);