annotate projects/basic_sensor/render.cpp @ 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.

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


#include "../../include/render.h"
#include "../../include/Utilities.h"
#include <rtdk.h>
#include <cmath>

float gPhase;
float gInverseSampleRate;
int gMatrixFramesPerAudioFrame;

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

extern int gSensorInputFrequency;
extern int gSensorInputAmplitude;

// 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.

bool initialise_render(int numMatrixChannels, int numAudioChannels,
					   int numMatrixFramesPerPeriod,
					   int numAudioFramesPerPeriod,
					   float matrixSampleRate, float audioSampleRate,
					   void *userData)
{
	if(numMatrixFramesPerPeriod == 0 || numMatrixFramesPerPeriod > numAudioFramesPerPeriod) {
		rt_printf("Error: this example needs the matrix enabled, with 4 or 8 channels\n");
		return false;
	}

	gMatrixFramesPerAudioFrame = numAudioFramesPerPeriod / numMatrixFramesPerPeriod;
	gInverseSampleRate = 1.0 / audioSampleRate;
	gPhase = 0.0;

	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(int numMatrixFrames, int numAudioFrames, float *audioIn, float *audioOut,
			uint16_t *matrixIn, uint16_t *matrixOut)
{
	float frequency = 0;
	float amplitude = 0;

	// There are twice as many audio frames as matrix frames since audio sample rate
	// is twice as high

	for(int n = 0; n < numAudioFrames; n++) {
		if(!(n % gMatrixFramesPerAudioFrame)) {
			// Even audio samples: update frequency and amplitude from the matrix
			frequency = map(analogRead(gSensorInputFrequency, n/gMatrixFramesPerAudioFrame), 0, MATRIX_MAX, 100, 1000);
			amplitude = (float)analogRead(gSensorInputAmplitude, n/gMatrixFramesPerAudioFrame) / MATRIX_MAX;
		}

		float out = amplitude * sinf(gPhase);

		for(int channel = 0; channel < gNumAudioChannels; channel++)
			audioOut[n * gNumAudioChannels + channel] = out;

		gPhase += 2.0 * M_PI * frequency * gInverseSampleRate;
		if(gPhase > 2.0 * M_PI)
			gPhase -= 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_render()
{

}