feat(dsp): add core synthesizer oscillators, wavetable and voice engine

Source/NoiseOscillator.cpp

@@ -0,0 +1,36 @@
+#include "NoiseOscillator.h"
+
+namespace serum
+{
+
+void NoiseOscillator::reset()
+{
+    pinkB0 = pinkB1 = pinkB2 = 0.0f;
+}
+
+void NoiseOscillator::noteOn (juce::uint32 seed)
+{
+    rng.setSeed (seed);
+}
+
+void NoiseOscillator::processAdd (int type, float level, float& out) noexcept
+{
+    if (level <= 0.0f)
+        return;
+
+    const float white = rng.nextFloat() * 2.0f - 1.0f;
+
+    float s = white;
+    if (type == (int) NoiseType::Pink)
+    {
+        // Paul Kellet's economy pink-noise filter.
+        pinkB0 = 0.99765f * pinkB0 + white * 0.0990460f;
+        pinkB1 = 0.96300f * pinkB1 + white * 0.2965164f;
+        pinkB2 = 0.57000f * pinkB2 + white * 1.0526913f;
+        s = pinkB0 + pinkB1 + pinkB2 + white * 0.1848f;
+    }
+
+    out += s * level;
+}
+
+} // namespace serum