annotate examples/04-Audio/bucket-brigade-chorus/render.cpp @ 534:e2364e1711c2 prerelease

Updated doxygen for the tremolo audio example.

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

The platform for ultra-low latency audio and sensor processing

http://bela.io

A project of the Augmented Instruments Laboratory within the
Centre for Digital Music at Queen Mary University of London.
http://www.eecs.qmul.ac.uk/~andrewm

(c) 2016 Augmented Instruments Laboratory: Andrew McPherson,
	Astrid Bin, Liam Donovan, Christian Heinrichs, Robert Jack,
	Giulio Moro, Laurel Pardue, Victor Zappi. All rights reserved.

The Bela software is distributed under the GNU Lesser General Public License
(LGPL 3.0), available here: https://www.gnu.org/licenses/lgpl-3.0.txt
*/


#include <Bela.h> 
#include <Scope.h>
#include <cmath>

float gPhase1, gPhase2;
float gFrequency1, gFrequency2;
float gInverseSampleRate;

// initialise_render() 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.
#include <I2c_Codec.h>
#include <PRU.h>
extern I2c_Codec *gAudioCodec;
extern PRU *gPRU;
float D=5264;
#define delayLength 256
float delay[delayLength];
int writePointer=0;
int readPointer=writePointer+1;
AuxiliaryTask updatePll;

void updatePllFunction(){
//	gPRU->setGPIOTestPin();
	static int count = 0;
	while(!gShouldStop){
		gAudioCodec->setPllD(D);
		count++;
		if((count&4095)==0)
			printf("sampling rate: %f\n",gAudioCodec->getAudioSamplingRate());
		usleep(100);
	}
//	gPRU->clearGPIOTestPin();
}

bool setup(BelaContext *context, void *userData)
{
	gInverseSampleRate = 1.0/context->audioSampleRate;
	
	gPhase1 = 0.0;
	gPhase2 = 0.0;
	
	gFrequency1 = 200.0;
	gFrequency2 = 201.0;
	updatePll=Bela_createAuxiliaryTask(&updatePllFunction, 91, "update PLL");
	for(int n=0; n<delayLength; n++){
		delay[n]=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)
{
//	printf("here\n");
	static bool init = false;
	if(init == false){
		Bela_scheduleAuxiliaryTask(updatePll);
//		gAudioCodec->setPllP(2);
//		gAudioCodec->setPllR();
//		gAudioCodec->setAudioSamplingRate(43600);
//		printf("samplingRate: %f, k: %f\n", gAudioCodec->getAudioSamplingRate(), gAudioCodec->getPllK());
		init = true;
	}
	static int count=0;
	static float lfoPhase=0;
	static float feedback=0;
	int updateRate=1;
	if((count&(updateRate-1))==0){
		float amplitude = 8000;
		float rate = 2;
		lfoPhase+=rate*2*M_PI*updateRate*context->analogFrames/context->audioSampleRate;
		D=amplitude+amplitude*sinf(lfoPhase);
		if((count&255)==0){
//			rt_printf("frequency: %f\n", gAudioCodec->getAudioSamplingRate());
//			rt_printf("D: %.0f\n", D);
//			rt_printf("rate: %f\n", rate);
//			rt_printf("amplitude: %.3f\n", amplitude);
//			rt_printf("feedback: %.3f\n\n", feedback);
		}
	}
	count++;

	for(unsigned int n = 0; n < context->audioFrames; n++) {
		feedback = 0.4;
		float input = audioRead(context, n, 0) + audioRead(context, n, 1);
	    delay[writePointer++] = input + delay[readPointer]*feedback;
	    float output = (input + 0.9*delay[readPointer++] ) * 0.5;
		audioWrite(context, n, 0, output);
		audioWrite(context, n, 1, output);
		if(writePointer>=delayLength)
			writePointer-=delayLength;
		if(readPointer>=delayLength)
			readPointer-=delayLength;

		gPhase1 += 2.0 * M_PI * gFrequency1 * gInverseSampleRate;
	    gPhase2 += 2.0 * M_PI * gFrequency2 * gInverseSampleRate;
		if(gPhase1 > 2.0 * M_PI)
			gPhase1 -= 2.0 * M_PI;
		if(gPhase2 > 2.0 * M_PI)
			gPhase2 -= 2.0 * M_PI;
	}
}

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

void cleanup(BelaContext *context, void *userData)
{
    
}