add scope widget

src/synth/ScopeBuffer.cpp

@@ -0,0 +1,19 @@
+
+#include "ScopeBuffer.h"
+
+ScopeBuffer::ScopeBuffer(size_t size) : buffer_(size) {
+
+}
+
+void ScopeBuffer::push(float sample) {
+    size_t w = writeIndex_.fetch_add(1, std::memory_order_relaxed);
+    buffer_[w % buffer_.size()] = sample;
+}
+
+void ScopeBuffer::read(std::vector<float>& out) const {
+    size_t w = writeIndex_.load(std::memory_order_relaxed);
+    for (size_t i = 0; i < out.size(); i++) {
+        size_t idx = (w + trigger_ + i * wavelength_ / out.size()) % buffer_.size();
+        out[i] = buffer_[idx];
+    }
+}