main: move more tiny objects out of main.cpp

src/inputs/BPM.h

@@ -0,0 +1,52 @@
+#pragma once
+#include <Figments.h>
+
+class BPM : public InputSource {
+public:
+  BPM() : InputSource("BPM") {}
+  void handleEvent(const InputEvent& evt) override {
+      if (evt.intent == InputEvent::BeatDetect) {
+        m_nextBpm = millis();
+        m_timings.insert(millis());
+        Log.notice("%d timings", m_timings.size());
+        if (m_timings.size() >= 5) {
+          updateBPM();
+        }
+      }
+  }
+
+  InputEvent read() override {
+    if (m_bpm > 0) {
+      uint16_t now = millis();
+      if (now >= m_nextBpm) {
+        m_nextBpm += m_bpm;
+        return InputEvent{InputEvent::Beat, m_bpm};
+      }
+      if (now >= m_nextLearn && m_nextLearn != 0) {
+        m_timings.clear();
+        m_nextLearn = 0;
+      }
+    }
+    return InputEvent{};
+  }
+
+private:
+  uint16_t m_bpm = 0;
+  uint16_t m_nextBpm = 0;
+  uint16_t m_nextLearn = 0;
+  Ringbuf<uint16_t, 7> m_timings;
+
+  void updateBPM() {
+    uint16_t avgDelta = 0;
+    for(uint8_t i = 0; i < m_timings.size() - 1; i++) {
+      uint16_t delta = m_timings.peek(i+1) - m_timings.peek(i);
+      Log.notice("Timing %d Delta %d", m_timings.peek(i), delta);
+      avgDelta += delta;
+    }
+    m_bpm = avgDelta / 4;
+    m_nextLearn = m_bpm * 5 + millis();
+    Log.notice("BPM is now %d", m_bpm);
+    uint16_t trash;
+    m_timings.take(trash);
+  }
+};