andrewm@0: /*
andrewm@0:  * render.cpp
andrewm@0:  *
andrewm@0:  *  Created on: Oct 24, 2014
andrewm@0:  *      Author: parallels
andrewm@0:  */
andrewm@0: 
andrewm@0: 
andrewm@0: #include "../../include/render.h"
andrewm@0: #include "../../include/Utilities.h"
andrewm@0: #include <rtdk.h>
andrewm@0: #include <cmath>
andrewm@0: 
andrewm@0: float gPhase;
andrewm@0: float gInverseSampleRate;
andrewm@0: int gNumChannels;
andrewm@0: 
andrewm@0: // These settings are carried over from main.cpp
andrewm@0: // Setting global variables is an alternative approach
andrewm@0: // to passing a structure to userData in initialise_render()
andrewm@0: 
andrewm@0: extern int gSensorInputFrequency;
andrewm@0: extern int gSensorInputAmplitude;
andrewm@0: 
andrewm@0: // initialise_render() is called once before the audio rendering starts.
andrewm@0: // Use it to perform any initialisation and allocation which is dependent
andrewm@0: // on the period size or sample rate.
andrewm@0: //
andrewm@0: // userData holds an opaque pointer to a data structure that was passed
andrewm@0: // in from the call to initAudio().
andrewm@0: //
andrewm@0: // Return true on success; returning false halts the program.
andrewm@0: 
andrewm@0: bool initialise_render(int numChannels, int numMatrixFramesPerPeriod,
andrewm@0: 					   int numAudioFramesPerPeriod, float matrixSampleRate,
andrewm@0: 					   float audioSampleRate, void *userData)
andrewm@0: {
andrewm@0: 	if(numMatrixFramesPerPeriod*2 != numAudioFramesPerPeriod) {
andrewm@0: 		rt_printf("Error: this example needs the matrix enabled, running at half audio rate\n");
andrewm@0: 		return false;
andrewm@0: 	}
andrewm@0: 
andrewm@0: 	gNumChannels = numChannels;
andrewm@0: 	gInverseSampleRate = 1.0 / audioSampleRate;
andrewm@0: 	gPhase = 0.0;
andrewm@0: 
andrewm@0: 	return true;
andrewm@0: }
andrewm@0: 
andrewm@0: // render() is called regularly at the highest priority by the audio engine.
andrewm@0: // Input and output are given from the audio hardware and the other
andrewm@0: // ADCs and DACs (if available). If only audio is available, numMatrixFrames
andrewm@0: // will be 0.
andrewm@0: 
andrewm@0: void render(int numMatrixFrames, int numAudioFrames, float *audioIn, float *audioOut,
andrewm@0: 			uint16_t *matrixIn, uint16_t *matrixOut)
andrewm@0: {
andrewm@0: 	float frequency = 0;
andrewm@0: 	float amplitude = 0;
andrewm@0: 
andrewm@0: 	// There are twice as many audio frames as matrix frames since audio sample rate
andrewm@0: 	// is twice as high
andrewm@0: 
andrewm@0: 	for(int n = 0; n < numAudioFrames; n++) {
andrewm@0: 		if(!(n % 2)) {
andrewm@0: 			// Even audio samples: update frequency and amplitude from the matrix
andrewm@5: 			frequency = map((float)analogRead(gSensorInputFrequency, n/2), 0, MATRIX_MAX, 100, 1000);
andrewm@5: 			amplitude = (float)analogRead(gSensorInputAmplitude, n/2) / MATRIX_MAX;
andrewm@0: 		}
andrewm@0: 
andrewm@0: 		float out = amplitude * sinf(gPhase);
andrewm@0: 
andrewm@0: 		for(int channel = 0; channel < gNumChannels; channel++)
andrewm@0: 			audioOut[n * gNumChannels + channel] = out;
andrewm@0: 
andrewm@0: 		gPhase += 2.0 * M_PI * frequency * gInverseSampleRate;
andrewm@0: 		if(gPhase > 2.0 * M_PI)
andrewm@0: 			gPhase -= 2.0 * M_PI;
andrewm@0: 	}
andrewm@0: }
andrewm@0: 
andrewm@0: // cleanup_render() is called once at the end, after the audio has stopped.
andrewm@0: // Release any resources that were allocated in initialise_render().
andrewm@0: 
andrewm@0: void cleanup_render()
andrewm@0: {
andrewm@0: 
andrewm@0: }