MonoStep: monophonic 2-oscillator step-sequencer synth

Source/dsp/StepSequencer.h

@@ -0,0 +1,56 @@
+#pragma once
+
+#include <array>
+#include <cmath>
+
+namespace monostep
+{
+
+static constexpr int numSteps   = 16;
+static constexpr int minSemitone = -12;
+static constexpr int maxSemitone = 12;
+static constexpr int numRows    = maxSemitone - minSemitone + 1;
+
+struct Step
+{
+    bool gate    = false;
+    int  semitone = 0;    // -12 .. +12
+    float cents  = 0.0f;  // -50 .. +50
+    bool slide   = false;
+};
+
+class StepSequencer
+{
+public:
+    Step& step (int i) { return steps[i]; }
+    const Step& step (int i) const { return steps[i]; }
+
+    void clear()
+    {
+        for (auto& s : steps)
+            s = Step{};
+    }
+
+    int stepsPerBeatFromRate (int rateIndex) const
+    {
+        // 0: 1/4, 1: 1/8, 2: 1/8T, 3: 1/16, 4: 1/32
+        switch (rateIndex)
+        {
+            case 0: return 1;
+            case 1: return 2;
+            case 2: return 3;
+            case 4: return 8;
+            default: return 4;
+        }
+    }
+
+    float stepLenPpq (int rateIndex) const
+    {
+        return 1.0f / (float) stepsPerBeatFromRate (rateIndex);
+    }
+
+private:
+    std::array<Step, numSteps> steps;
+};
+
+} // namespace monostep