MonoStep: monophonic 2-oscillator step-sequencer synth

Source/dsp/WaveTables.h

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <cmath>
+#include <algorithm>
+
+namespace monostep
+{
+
+enum class Waveform : int
+{
+    sine = 0,
+    triangle = 1,
+    saw = 2,
+    square = 3
+};
+
+inline float frac (float x)
+{
+    return x - std::floor (x);
+}
+
+inline float polyBlep (float t, float dt)
+{
+    if (t < dt)
+    {
+        t /= dt;
+        return t + t - t * t - 1.0f;
+    }
+
+    if (t > 1.0f - dt)
+    {
+        t = (t - 1.0f) / dt;
+        return t * t + t + t + 1.0f;
+    }
+
+    return 0.0f;
+}
+
+inline float renderWave (Waveform w, float phase, float inc)
+{
+    switch (w)
+    {
+        case Waveform::sine:
+            return std::sin (phase * 6.283185307179586f);
+
+        case Waveform::triangle:
+        {
+            const float f = frac (phase);
+            return 4.0f * std::min (f, 1.0f - f) - 1.0f;
+        }
+
+        case Waveform::saw:
+        {
+            const float f = frac (phase);
+            return (2.0f * f - 1.0f) - polyBlep (f, inc);
+        }
+
+        case Waveform::square:
+        {
+            const float f = frac (phase);
+            float v = (f < 0.5f) ? 1.0f : -1.0f;
+            v += polyBlep (f, inc);
+            v -= polyBlep (frac (f + 0.5f), inc);
+            return v;
+        }
+    }
+
+    return 0.0f;
+}
+
+} // namespace monostep