added simple keyboard control

src/NoteQueue.cpp

@@ -0,0 +1,23 @@
+
+#include "NoteQueue.h"
+
+bool NoteQueue::push(const NoteEvent& event) {
+    size_t head = head_.load(std::memory_order_relaxed);
+    size_t next = (head + 1) % SIZE;
+
+    if(next == tail_.load(std::memory_order_relaxed)) return false; // full
+
+    buffer_[head] = event;
+    head_.store(next, std::memory_order_relaxed);
+    return true;
+}
+
+bool NoteQueue::pop(NoteEvent& event) {
+    size_t tail = tail_.load(std::memory_order_relaxed);
+
+    if(tail == head_.load(std::memory_order_acquire)) return false; // empty
+
+    event = buffer_[tail];
+    tail_.store((tail + 1) % SIZE, std::memory_order_release);
+    return true;
+}