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@56: #include <BeagleRT.h>
andrewm@0: #include <cmath>
giuliomoro@180: #include <Utilities.h>
andrewm@0: 
andrewm@56: float gFrequency = 440.0;
andrewm@0: float gPhase;
andrewm@0: float gInverseSampleRate;
andrewm@0: 
andrewm@56: // setup() 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@56: bool setup(BeagleRTContext *context, void *userData)
andrewm@0: {
andrewm@0: 	// Retrieve a parameter passed in from the initAudio() call
andrewm@56: 	if(userData != 0)
andrewm@56: 		gFrequency = *(float *)userData;
andrewm@0: 
andrewm@45: 	gInverseSampleRate = 1.0 / context->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@45: void render(BeagleRTContext *context, void *userData)
andrewm@0: {
andrewm@45: 	for(unsigned int n = 0; n < context->audioFrames; n++) {
andrewm@0: 		float out = 0.8f * sinf(gPhase);
andrewm@0: 		gPhase += 2.0 * M_PI * gFrequency * gInverseSampleRate;
andrewm@0: 		if(gPhase > 2.0 * M_PI)
andrewm@0: 			gPhase -= 2.0 * M_PI;
andrewm@0: 
giuliomoro@180: 		for(unsigned int channel = 0; channel < context->audioChannels; channel++) {
giuliomoro@180: 			// Two equivalent ways to write this code
giuliomoro@180: 
giuliomoro@180: 			// The long way, using the buffers directly:
giuliomoro@180: 			// context->audioOut[n * context->audioChannels + channel] = out;
giuliomoro@180: 
giuliomoro@180: 			// Or using the macros:
giuliomoro@180: 			audioWriteFrame(context, n, channel, out);
giuliomoro@180: 		}
andrewm@0: 	}
andrewm@0: }
andrewm@0: 
andrewm@56: // cleanup() is called once at the end, after the audio has stopped.
andrewm@56: // Release any resources that were allocated in setup().
andrewm@0: 
andrewm@56: void cleanup(BeagleRTContext *context, void *userData)
andrewm@0: {
andrewm@0: 
andrewm@0: }