annotate projects/d-box/FeedbackOscillator.h @ 45:579c86316008 newapi

Major API overhaul. Moved to a single data structure for handling render functions. Functionally, generally similar except for scheduling within PRU loop function, which now uses interrupts from the PRU rather than polling. This requires an updated kernel.

/*
 * FeedbackOscillator.h
 *
 *  Created on: June 8, 2014
 *      Author: Andrew McPherson
 */

#ifndef FEEDBACKOSCILLATOR_H
#define FEEDBACKOSCILLATOR_H

#include <stdint.h>

class FeedbackOscillator
{
public:
	FeedbackOscillator();
	~FeedbackOscillator();

	// Initialise the settings for the feedback oscillator
	void initialise(int maxTableSize, float hpfCutoffFrequency, float matrixSampleRate);

	// Process one sample and store the output value
	// Returns the length of table to interpolate; or 0 if nothing to process further
	int process(uint16_t input, uint16_t *output);

	float *wavetable() { return wavetableRead; }

private:
	float coeffs[3];			// Coefficients of first-order high-pass filter
	float lastInput;			// last input sample for HPF
	float lastOutput;			// last output sample of HPF
	bool triggered;				// whether we are currently saving samples
	bool canTrigger;			// whether we are able to begin saving samples
	int wavetableMaxLength;		// how long the stored wavetable can be
	int sampleCount;			// how many samples have elapsed
	int lastTriggerCount;		// sample count when we last triggered

	float *wavetable1, *wavetable2;			// Two wavetables where we record samples
	float *wavetableRead, *wavetableWrite;	// Pointers to the above wavetables
	int wavetableWritePointer;				// Where we are currently writing
};

#endif