dsp/reverb/reverb.hpp

#ifndef REVERB_H
#define REVERB_H

#include <cstdlib>
#include <delay/buffer_multi.hpp>
#include <common/mix.hpp>

template<typename T, size_t numCh>
class Delay
{
	dsp::BufferMulti<T, numCh> m_buf;
	int m_delay_spec[numCh];

	public:
	Delay(uint maxDelaySize, int delayOffset=0)
	: m_buf(maxDelaySize)
	{
		float delayRagePerWindow = (float)(maxDelaySize-delayOffset)/(float)numCh;

		// Delay spec
		for (int i=0; i < numCh; i++)
		{
			float base_delay = i*delayRagePerWindow + delayOffset;
			float z = (float)rand()/(float)RAND_MAX;
			int delay = (int)(base_delay + z*delayRagePerWindow);

			m_delay_spec[i] = -delay;
		}
	}

	void process(T in, T out[numCh])
	{
		m_buf = in;
		m_buf.quer(out, m_delay_spec);
		++m_buf;
	}

	void process(T data[numCh])
	{
		m_buf = data;
		m_buf.quer(data, m_delay_spec);
		++m_buf;
	}

	void process(T in[numCh], T out[numCh])
	{
		m_buf = in;
		m_buf.quer(out, m_delay_spec);
		++m_buf;
	}
	
};

template<typename T, size_t numCh>
class Diffusor
{
	Delay<T, numCh> m_dly;
	int m_shuffle_spec[numCh];

	public:
	Diffusor(uint maxDelaySize)
	: m_dly(maxDelaySize)
	{
		// Shuffle spec
		for (int i=0; i < numCh; i++)
		{
			m_shuffle_spec[i] = i;
		}

		// Shuffle values
		for (int i=0; i < 2*numCh; i++)
		{
			int i1 = rand() & (numCh-1);
			int i2 = rand() & (numCh-1);
			int temp = m_shuffle_spec[i1];
			m_shuffle_spec[i1] = m_shuffle_spec[i2];
			m_shuffle_spec[i2] = temp;
		}

		// Shuffle signs
		float p = 0.3;
		for (int i=0; i < numCh; i++)
		{
			float z = (float)rand()/(float)RAND_MAX;
			if (z <= p)
			{
				m_shuffle_spec[i] *= (T)-1;
			}
		}
	}

	inline T process(T in)
	{
		T temp[numCh];
		m_dly.process(in, temp);

		Shuffle<T, numCh>::inPlace(temp, m_shuffle_spec);
		Hadamard<T, numCh>::inPlace(temp);
		Householder<T, numCh>::inPlace(temp);

		return temp[0];
	}

	inline void process_multi(T in_out[numCh])
	{
		m_dly.process(in_out);

		Shuffle<T, numCh>::inPlace(in_out, m_shuffle_spec);
		Hadamard<T, numCh>::inPlace(in_out);
	}
};

template<typename T, uint numCh>
class Reverb
{
	std::array<Diffusor<T, numCh>, 3> m_diffusors;
	Delay<T, numCh> m_feedbackDly;
	T fb_dly_out[numCh];

	public:
	Reverb(uint maxDelay)
	: m_diffusors({maxDelay, maxDelay, maxDelay})
	, m_feedbackDly(9600, 4800)
	{
		for (int c=0; c < numCh; c++)
		{
			fb_dly_out[c] = 0;
		}
	}

	void process_multi(float *in, float *out, unsigned numPoints)
	{
		for (int i=0; i < numPoints; i++)
		{
			T temp[numCh];
			Mix<T, numCh>::split(in[i], temp);
			for (auto diffusor: m_diffusors)
			{
				diffusor.process_multi(temp);
			}
			// Sum
			for (int c=0; c < numCh; c++)
			{
				temp[c] += fb_dly_out[c];
			}
			m_feedbackDly.process(temp, fb_dly_out);
			
			// Mix
			out[i] = fb_dly_out[0];

			T fb_gain = 0.85;
			for (int c=0; c < numCh; c++)
			{
				fb_dly_out[c] *= fb_gain;
			}
			Householder<T, numCh>::inPlace(fb_dly_out);
		}
	}

	void process(float *in, float *out, unsigned numPoints)
	{
		for (int i=0; i < numPoints; i++)
		{
			T temp = in[i];
			for (auto diffusor: m_diffusors)
			{
				temp = diffusor.process(temp);
			}
			out[i] = temp;
		}
	}

};

#endif