andrewm@57: /*
andrewm@57:  * render.cpp
andrewm@57:  *
andrewm@57:  *  Created on: Oct 24, 2014
andrewm@57:  *      Author: parallels
andrewm@57:  */
andrewm@57: 
andrewm@57: 
andrewm@57: #include <BeagleRT.h>
andrewm@57: #include <Utilities.h>
andrewm@57: #include <rtdk.h>
andrewm@57: #include <cmath>
andrewm@57: 
andrewm@57: float gPhase;
andrewm@57: float gInverseSampleRate;
andrewm@57: int gAudioFramesPerAnalogFrame;
andrewm@57: 
andrewm@57: // These settings are carried over from main.cpp
andrewm@57: // Setting global variables is an alternative approach
andrewm@57: // to passing a structure to userData in setup()
andrewm@57: 
andrewm@57: extern int gSensorInputFrequency;
andrewm@57: extern int gSensorInputAmplitude;
andrewm@57: 
andrewm@57: // setup() is called once before the audio rendering starts.
andrewm@57: // Use it to perform any initialisation and allocation which is dependent
andrewm@57: // on the period size or sample rate.
andrewm@57: //
andrewm@57: // userData holds an opaque pointer to a data structure that was passed
andrewm@57: // in from the call to initAudio().
andrewm@57: //
andrewm@57: // Return true on success; returning false halts the program.
andrewm@57: 
andrewm@57: bool setup(BeagleRTContext *context, void *userData)
andrewm@57: {
andrewm@57: 	if(context->analogFrames == 0 || context->analogFrames > context->audioFrames) {
andrewm@57: 		rt_printf("Error: this example needs analog enabled, with 4 or 8 channels\n");
andrewm@57: 		return false;
andrewm@57: 	}
andrewm@57: 
andrewm@57: 	gAudioFramesPerAnalogFrame = context->audioFrames / context->analogFrames;
andrewm@57: 	gInverseSampleRate = 1.0 / context->audioSampleRate;
andrewm@57: 	gPhase = 0.0;
andrewm@57: 
andrewm@57: 	return true;
andrewm@57: }
andrewm@57: 
andrewm@57: // render() is called regularly at the highest priority by the audio engine.
andrewm@57: // Input and output are given from the audio hardware and the other
andrewm@57: // ADCs and DACs (if available). If only audio is available, numMatrixFrames
andrewm@57: // will be 0.
andrewm@57: 
andrewm@57: void render(BeagleRTContext *context, void *userData)
andrewm@57: {
andrewm@57: 	float frequency = 440.0;
andrewm@57: 	float amplitude = 0.8;
andrewm@57: 
andrewm@57: 	// There are twice as many audio frames as matrix frames since audio sample rate
andrewm@57: 	// is twice as high
andrewm@57: 
andrewm@57: 	for(unsigned int n = 0; n < context->audioFrames; n++) {
andrewm@57: 		if(!(n % gAudioFramesPerAnalogFrame)) {
andrewm@57: 			// Even audio samples: update frequency and amplitude from the matrix
andrewm@57: 			frequency = map(analogReadFrame(context, n/gAudioFramesPerAnalogFrame, gSensorInputFrequency), 0, 1, 100, 1000);
andrewm@57: 			amplitude = analogReadFrame(context, n/gAudioFramesPerAnalogFrame, gSensorInputAmplitude);
andrewm@57: 		}
andrewm@57: 
andrewm@57: 		float out = amplitude * sinf(gPhase);
andrewm@57: 
andrewm@57: 		for(unsigned int channel = 0; channel < context->audioChannels; channel++)
andrewm@57: 			context->audioOut[n * context->audioChannels + channel] = out;
andrewm@57: 
andrewm@57: 		gPhase += 2.0 * M_PI * frequency * gInverseSampleRate;
andrewm@57: 		if(gPhase > 2.0 * M_PI)
andrewm@57: 			gPhase -= 2.0 * M_PI;
andrewm@57: 	}
andrewm@57: }
andrewm@57: 
andrewm@57: // cleanup() is called once at the end, after the audio has stopped.
andrewm@57: // Release any resources that were allocated in setup().
andrewm@57: 
andrewm@57: void cleanup(BeagleRTContext *context, void *userData)
andrewm@57: {
andrewm@57: 
andrewm@57: }