annotate examples/10-Instruments/oscillator_bank/render.cpp @ 464:8fcfbfb32aa0 prerelease

Examples reorder with subdirectories. Added header to each project. Moved Doxygen to bottom of render.cpp.

/*
 ____  _____ _        _    
| __ )| ____| |      / \   
|  _ \|  _| | |     / _ \  
| |_) | |___| |___ / ___ \ 
|____/|_____|_____/_/   \_\.io

 */

/*
 * render.cpp
 *
 *  Created on: Oct 24, 2014
 *      Author: parallels
 */

/**
\example 4_oscillator_bank

Oscillator Bank
----------------------

These files demonstrate an oscillator bank implemented in assembly code 
that is used as part of the d-box project.
*/

#include <Bela.h>
#include <rtdk.h>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <time.h>

const float kMinimumFrequency = 20.0f;
const float kMaximumFrequency = 8000.0f;

float *gWavetable;		// Buffer holding the precalculated sine lookup table
float *gPhases;			// Buffer holding the phase of each oscillator
float *gFrequencies;	// Buffer holding the frequencies of each oscillator
float *gAmplitudes;		// Buffer holding the amplitudes of each oscillator
float *gDFrequencies;	// Buffer holding the derivatives of frequency
float *gDAmplitudes;	// Buffer holding the derivatives of amplitude

float gAudioSampleRate;
int gSampleCount;		// Sample counter for indicating when to update frequencies
float gNewMinFrequency;
float gNewMaxFrequency;

// Task for handling the update of the frequencies using the matrix
AuxiliaryTask gFrequencyUpdateTask;

// These settings are carried over from main.cpp
// Setting global variables is an alternative approach
// to passing a structure to userData in setup()

extern int gNumOscillators;
extern int gWavetableLength;

void recalculate_frequencies();

extern "C" {
	// Function prototype for ARM assembly implementation of oscillator bank
	void oscillator_bank_neon(int numAudioFrames, float *audioOut,
							  int activePartialNum, int lookupTableSize,
							  float *phases, float *frequencies, float *amplitudes,
							  float *freqDerivatives, float *ampDerivatives,
							  float *lookupTable);
}

// setup() is called once before the audio rendering starts.
// Use it to perform any initialisation and allocation which is dependent
// on the period size or sample rate.
//
// userData holds an opaque pointer to a data structure that was passed
// in from the call to initAudio().
//
// Return true on success; returning false halts the program.
bool setup(BelaContext *context, void *userData)
{
	srandom(time(NULL));

	if(context->audioChannels != 2) {
		rt_printf("Error: this example needs stereo audio enabled\n");
		return false;
	}

	// Initialise the sine wavetable
	if(posix_memalign((void **)&gWavetable, 8, (gWavetableLength + 1) * sizeof(float))) {
		rt_printf("Error allocating wavetable\n");
		return false;
	}
	for(int n = 0; n < gWavetableLength + 1; n++)
		gWavetable[n] = sinf(2.0 * M_PI * (float)n / (float)gWavetableLength);

	// Allocate the other buffers
	if(posix_memalign((void **)&gPhases, 16, gNumOscillators * sizeof(float))) {
		rt_printf("Error allocating phase buffer\n");
		return false;
	}
	if(posix_memalign((void **)&gFrequencies, 16, gNumOscillators * sizeof(float))) {
		rt_printf("Error allocating frequency buffer\n");
		return false;
	}
	if(posix_memalign((void **)&gAmplitudes, 16, gNumOscillators * sizeof(float))) {
		rt_printf("Error allocating amplitude buffer\n");
		return false;
	}
	if(posix_memalign((void **)&gDFrequencies, 16, gNumOscillators * sizeof(float))) {
		rt_printf("Error allocating frequency derivative buffer\n");
		return false;
	}
	if(posix_memalign((void **)&gDAmplitudes, 16, gNumOscillators * sizeof(float))) {
		rt_printf("Error allocating amplitude derivative buffer\n");
		return false;
	}

	// Initialise buffer contents

	float freq = kMinimumFrequency;
	float increment = (kMaximumFrequency - kMinimumFrequency) / (float)gNumOscillators;

	for(int n = 0; n < gNumOscillators; n++) {
		gPhases[n] = 0.0;

		if(context->analogFrames == 0) {
			// Random frequencies when used without matrix
			gFrequencies[n] = kMinimumFrequency + (kMaximumFrequency - kMinimumFrequency) * ((float)random() / (float)RAND_MAX);
		}
		else {
			// Constant spread of frequencies when used with matrix
			gFrequencies[n] = freq;
			freq += increment;
		}

		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
		gFrequencies[n] *= (float)gWavetableLength / context->audioSampleRate;
		gAmplitudes[n] = ((float)random() / (float)RAND_MAX) / (float)gNumOscillators;
		gDFrequencies[n] = gDAmplitudes[n] = 0.0;
	}

	increment = 0;
	freq = 440.0;

	for(int n = 0; n < gNumOscillators; n++) {
		// Update the frequencies to a regular spread, plus a small amount of randomness
		// to avoid weird phase effects
		float randScale = 0.99 + .02 * (float)random() / (float)RAND_MAX;
		float newFreq = freq * randScale;

		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
		gFrequencies[n] = newFreq * (float)gWavetableLength / context->audioSampleRate;

		freq += increment;
	}

	// Initialise auxiliary tasks
	if((gFrequencyUpdateTask = Bela_createAuxiliaryTask(&recalculate_frequencies, 85, "bela-update-frequencies")) == 0)
		return false;

	//for(int n = 0; n < gNumOscillators; n++)
	//	rt_printf("%f\n", gFrequencies[n]);

	gAudioSampleRate = context->audioSampleRate;
	gSampleCount = 0;

	return true;
}

// render() is called regularly at the highest priority by the audio engine.
// Input and output are given from the audio hardware and the other
// ADCs and DACs (if available). If only audio is available, numMatrixFrames
// will be 0.

void render(BelaContext *context, void *userData)
{
	// Initialise buffer to 0
	memset(context->audioOut, 0, 2 * context->audioFrames * sizeof(float));

	// Render audio frames
	oscillator_bank_neon(context->audioFrames, context->audioOut,
			gNumOscillators, gWavetableLength,
			gPhases, gFrequencies, gAmplitudes,
			gDFrequencies, gDAmplitudes,
			gWavetable);

	if(context->analogFrames != 0 && (gSampleCount += context->audioFrames) >= 128) {
		gSampleCount = 0;
		gNewMinFrequency = map(context->analogIn[0], 0, 1.0, 1000.0f, 8000.0f);
		gNewMaxFrequency = map(context->analogIn[1], 0, 1.0, 1000.0f, 8000.0f);

		// Make sure max >= min
		if(gNewMaxFrequency < gNewMinFrequency) {
			float temp = gNewMaxFrequency;
			gNewMaxFrequency = gNewMinFrequency;
			gNewMinFrequency = temp;
		}

		// Request that the lower-priority task run at next opportunity
		//Bela_scheduleAuxiliaryTask(gFrequencyUpdateTask);
	}
}

// This is a lower-priority call to update the frequencies which will happen
// periodically when the matrix is enabled. By placing it at a lower priority,
// it has minimal effect on the audio performance but it will take longer to
// complete if the system is under heavy audio load.

void recalculate_frequencies()
{
	float freq = gNewMinFrequency;
	float increment = (gNewMaxFrequency - gNewMinFrequency) / (float)gNumOscillators;

	for(int n = 0; n < gNumOscillators; n++) {
		// Update the frequencies to a regular spread, plus a small amount of randomness
		// to avoid weird phase effects
		float randScale = 0.99 + .02 * (float)random() / (float)RAND_MAX;
		float newFreq = freq * randScale;

		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
		gFrequencies[n] = newFreq * (float)gWavetableLength / gAudioSampleRate;

		freq += increment;
	}
}


// cleanup() is called once at the end, after the audio has stopped.
// Release any resources that were allocated in setup().

void cleanup(BelaContext *context, void *userData)
{
	free(gWavetable);
	free(gPhases);
	free(gFrequencies);
	free(gAmplitudes);
	free(gDFrequencies);
	free(gDAmplitudes);
}