Add a noise generator (Lua DSP)

3 files changed, 121 insertions, 0 deletions

diff --git a/libs/ardour/ardour/dsp_filter.h b/libs/ardour/ardour/dsp_filter.h
index f54eeac302..f3100efac5 100644
--- a/libs/ardour/ardour/dsp_filter.h
+++ b/libs/ardour/ardour/dsp_filter.h
@@ -310,5 +310,33 @@ namespace ARDOUR { namespace DSP {
 			fftwf_plan _fftplan;
 	};
 
+	class LIBARDOUR_API Generator {
+		public:
+			Generator ();
+
+			enum Type {
+				UniformWhiteNoise,
+				GaussianWhiteNoise,
+				PinkNoise,
+			};
+
+			void run (float *data, const uint32_t n_samples);
+			void set_type (Type t);
+
+		private:
+			uint32_t randi ();
+			float    randf () { return (randi () / 1073741824.f) - 1.f; }
+			float    grandf ();
+
+			Type     _type;
+			uint32_t _rseed;
+			/* pink-noise */
+			float _b0, _b1, _b2, _b3, _b4, _b5, _b6;
+			/* gaussian white */
+			bool _pass;
+			float _rn;
+
+	};
+
 } } /* namespace */
 #endif
diff --git a/libs/ardour/dsp_filter.cc b/libs/ardour/dsp_filter.cc
index cff1128aa1..5e2cff6799 100644
--- a/libs/ardour/dsp_filter.cc
+++ b/libs/ardour/dsp_filter.cc
@@ -425,3 +425,85 @@ FFTSpectrum::power_at_bin (const uint32_t b, const float norm) const {
 	const float a = _fft_power[b] * norm;
 	return a > 1e-12 ? 10.0 * fast_log10 (a) : -INFINITY;
 }
+
+Generator::Generator ()
+	: _type (UniformWhiteNoise)
+	, _rseed (1)
+{
+	set_type (UniformWhiteNoise);
+}
+
+void
+Generator::set_type (Generator::Type t) {
+	_type = t;
+	_b0 = _b1 = _b2 = _b3 = _b4 = _b5 = _b6 = 0;
+	_pass = false;
+	_rn = 0;
+}
+
+void
+Generator::run (float *data, const uint32_t n_samples)
+{
+	switch (_type) {
+		default:
+		case UniformWhiteNoise:
+			for (uint32_t i = 0; i < n_samples; ++i) {
+				data[i] = randf();
+			}
+			break;
+		case GaussianWhiteNoise:
+			for (uint32_t i = 0 ; i < n_samples; ++i) {
+				data[i] = 0.7079f * grandf();
+			}
+			break;
+		case PinkNoise:
+			for (uint32_t i = 0 ; i < n_samples; ++i) {
+				const float white = .39572f * randf ();
+				_b0 = .99886f * _b0 + white * .0555179f;
+				_b1 = .99332f * _b1 + white * .0750759f;
+				_b2 = .96900f * _b2 + white * .1538520f;
+				_b3 = .86650f * _b3 + white * .3104856f;
+				_b4 = .55000f * _b4 + white * .5329522f;
+				_b5 = -.7616f * _b5 - white * .0168980f;
+				data[i] = _b0 + _b1 + _b2 + _b3 + _b4 + _b5 + _b6 + white * 0.5362f;
+				_b6 = white * 0.115926f;
+			}
+			break;
+	}
+}
+
+inline uint32_t
+Generator::randi ()
+{
+	// 31bit Park-Miller-Carta Pseudo-Random Number Generator
+	uint32_t hi, lo;
+	lo = 16807 * (_rseed & 0xffff);
+	hi = 16807 * (_rseed >> 16);
+	lo += (hi & 0x7fff) << 16;
+	lo += hi >> 15;
+	lo = (lo & 0x7fffffff) + (lo >> 31);
+	return (_rseed = lo);
+}
+
+inline float
+Generator::grandf ()
+{
+	float x1, x2, r;
+
+	if (_pass) {
+		_pass = false;
+		return _rn;
+	}
+
+	do {
+		x1 = randf ();
+		x2 = randf ();
+		r = x1 * x1 + x2 * x2;
+	} while ((r >= 1.0f) || (r < 1e-22f));
+
+	r = sqrtf (-2.f * logf (r) / r);
+
+	_pass = true;
+	_rn = r * x2;
+	return r * x1;
+}
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 80101cd571..00e5b98884 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -2353,6 +2353,11 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("power_at_bin", &DSP::FFTSpectrum::power_at_bin)
 		.addFunction ("freq_at_bin", &DSP::FFTSpectrum::freq_at_bin)
 		.endClass ()
+		.beginClass <DSP::Generator> ("Generator")
+		.addVoidConstructor ()
+		.addFunction ("run", &DSP::Generator::run)
+		.addFunction ("set_type", &DSP::Generator::set_type)
+		.endClass ()
 
 		/* DSP enums */
 		.beginNamespace ("BiquadType")
@@ -2367,6 +2372,12 @@ LuaBindings::common (lua_State* L)
 		.addConst ("HighShelf", ARDOUR::DSP::Biquad::HighShelf)
 		.endNamespace ()
 
+		.beginNamespace ("NoiseType")
+		.addConst ("UniformWhiteNoise", ARDOUR::DSP::Generator::UniformWhiteNoise)
+		.addConst ("GaussianWhiteNoise", ARDOUR::DSP::Generator::GaussianWhiteNoise)
+		.addConst ("PinkNoise", ARDOUR::DSP::Generator::PinkNoise)
+		.endNamespace ()
+
 		.beginClass <DSP::DspShm> ("DspShm")
 		.addConstructor<void (*) (size_t)> ()
 		.addFunction ("allocate", &DSP::DspShm::allocate)