diff examples/10-Instruments/oscillator-bank/render.cpp @ 493:a23d74e2f6cb prerelease

Minor changes to doxygen

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/10-Instruments/oscillator-bank/render.cpp	Tue Jun 21 18:50:03 2016 +0100
@@ -0,0 +1,247 @@
+/*
+ ____  _____ _        _    
+| __ )| ____| |      / \   
+|  _ \|  _| | |     / _ \  
+| |_) | |___| |___ / ___ \ 
+|____/|_____|_____/_/   \_\
+
+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 <rtdk.h>
+#include <cstdlib>
+#include <cmath>
+#include <cstring>
+#include <time.h>
+
+const float kMinimumFrequency = 20.0f;
+const float kMaximumFrequency = 8000.0f;
+
+float *gWavetable;		// Buffer holding the precalculated sine lookup table
+float *gPhases;			// Buffer holding the phase of each oscillator
+float *gFrequencies;	// Buffer holding the frequencies of each oscillator
+float *gAmplitudes;		// Buffer holding the amplitudes of each oscillator
+float *gDFrequencies;	// Buffer holding the derivatives of frequency
+float *gDAmplitudes;	// Buffer holding the derivatives of amplitude
+
+float gAudioSampleRate;
+int gSampleCount;		// Sample counter for indicating when to update frequencies
+float gNewMinFrequency;
+float gNewMaxFrequency;
+
+// Task for handling the update of the frequencies using the matrix
+AuxiliaryTask gFrequencyUpdateTask;
+
+// These settings are carried over from main.cpp
+// Setting global variables is an alternative approach
+// to passing a structure to userData in setup()
+
+extern int gNumOscillators;
+extern int gWavetableLength;
+
+void recalculate_frequencies();
+
+extern "C" {
+	// Function prototype for ARM assembly implementation of oscillator bank
+	void oscillator_bank_neon(int numAudioFrames, float *audioOut,
+							  int activePartialNum, int lookupTableSize,
+							  float *phases, float *frequencies, float *amplitudes,
+							  float *freqDerivatives, float *ampDerivatives,
+							  float *lookupTable);
+}
+
+// setup() 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 setup(BelaContext *context, void *userData)
+{
+	srandom(time(NULL));
+
+	if(context->audioChannels != 2) {
+		rt_printf("Error: this example needs stereo audio enabled\n");
+		return false;
+	}
+
+	// Initialise the sine wavetable
+	if(posix_memalign((void **)&gWavetable, 8, (gWavetableLength + 1) * sizeof(float))) {
+		rt_printf("Error allocating wavetable\n");
+		return false;
+	}
+	for(int n = 0; n < gWavetableLength + 1; n++)
+		gWavetable[n] = sinf(2.0 * M_PI * (float)n / (float)gWavetableLength);
+
+	// Allocate the other buffers
+	if(posix_memalign((void **)&gPhases, 16, gNumOscillators * sizeof(float))) {
+		rt_printf("Error allocating phase buffer\n");
+		return false;
+	}
+	if(posix_memalign((void **)&gFrequencies, 16, gNumOscillators * sizeof(float))) {
+		rt_printf("Error allocating frequency buffer\n");
+		return false;
+	}
+	if(posix_memalign((void **)&gAmplitudes, 16, gNumOscillators * sizeof(float))) {
+		rt_printf("Error allocating amplitude buffer\n");
+		return false;
+	}
+	if(posix_memalign((void **)&gDFrequencies, 16, gNumOscillators * sizeof(float))) {
+		rt_printf("Error allocating frequency derivative buffer\n");
+		return false;
+	}
+	if(posix_memalign((void **)&gDAmplitudes, 16, gNumOscillators * sizeof(float))) {
+		rt_printf("Error allocating amplitude derivative buffer\n");
+		return false;
+	}
+
+	// Initialise buffer contents
+
+	float freq = kMinimumFrequency;
+	float increment = (kMaximumFrequency - kMinimumFrequency) / (float)gNumOscillators;
+
+	for(int n = 0; n < gNumOscillators; n++) {
+		gPhases[n] = 0.0;
+
+		if(context->analogFrames == 0) {
+			// Random frequencies when used without matrix
+			gFrequencies[n] = kMinimumFrequency + (kMaximumFrequency - kMinimumFrequency) * ((float)random() / (float)RAND_MAX);
+		}
+		else {
+			// Constant spread of frequencies when used with matrix
+			gFrequencies[n] = freq;
+			freq += increment;
+		}
+
+		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
+		gFrequencies[n] *= (float)gWavetableLength / context->audioSampleRate;
+		gAmplitudes[n] = ((float)random() / (float)RAND_MAX) / (float)gNumOscillators;
+		gDFrequencies[n] = gDAmplitudes[n] = 0.0;
+	}
+
+	increment = 0;
+	freq = 440.0;
+
+	for(int n = 0; n < gNumOscillators; n++) {
+		// Update the frequencies to a regular spread, plus a small amount of randomness
+		// to avoid weird phase effects
+		float randScale = 0.99 + .02 * (float)random() / (float)RAND_MAX;
+		float newFreq = freq * randScale;
+
+		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
+		gFrequencies[n] = newFreq * (float)gWavetableLength / context->audioSampleRate;
+
+		freq += increment;
+	}
+
+	// Initialise auxiliary tasks
+	if((gFrequencyUpdateTask = Bela_createAuxiliaryTask(&recalculate_frequencies, 85, "bela-update-frequencies")) == 0)
+		return false;
+
+	//for(int n = 0; n < gNumOscillators; n++)
+	//	rt_printf("%f\n", gFrequencies[n]);
+
+	gAudioSampleRate = context->audioSampleRate;
+	gSampleCount = 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)
+{
+	// Initialise buffer to 0
+	memset(context->audioOut, 0, 2 * context->audioFrames * sizeof(float));
+
+	// Render audio frames
+	oscillator_bank_neon(context->audioFrames, context->audioOut,
+			gNumOscillators, gWavetableLength,
+			gPhases, gFrequencies, gAmplitudes,
+			gDFrequencies, gDAmplitudes,
+			gWavetable);
+
+	if(context->analogFrames != 0 && (gSampleCount += context->audioFrames) >= 128) {
+		gSampleCount = 0;
+		gNewMinFrequency = map(context->analogIn[0], 0, 1.0, 1000.0f, 8000.0f);
+		gNewMaxFrequency = map(context->analogIn[1], 0, 1.0, 1000.0f, 8000.0f);
+
+		// Make sure max >= min
+		if(gNewMaxFrequency < gNewMinFrequency) {
+			float temp = gNewMaxFrequency;
+			gNewMaxFrequency = gNewMinFrequency;
+			gNewMinFrequency = temp;
+		}
+
+		// Request that the lower-priority task run at next opportunity
+		//Bela_scheduleAuxiliaryTask(gFrequencyUpdateTask);
+	}
+}
+
+// This is a lower-priority call to update the frequencies which will happen
+// periodically when the matrix is enabled. By placing it at a lower priority,
+// it has minimal effect on the audio performance but it will take longer to
+// complete if the system is under heavy audio load.
+
+void recalculate_frequencies()
+{
+	float freq = gNewMinFrequency;
+	float increment = (gNewMaxFrequency - gNewMinFrequency) / (float)gNumOscillators;
+
+	for(int n = 0; n < gNumOscillators; n++) {
+		// Update the frequencies to a regular spread, plus a small amount of randomness
+		// to avoid weird phase effects
+		float randScale = 0.99 + .02 * (float)random() / (float)RAND_MAX;
+		float newFreq = freq * randScale;
+
+		// For efficiency, frequency is expressed in change in wavetable position per sample, not Hz or radians
+		gFrequencies[n] = newFreq * (float)gWavetableLength / gAudioSampleRate;
+
+		freq += increment;
+	}
+}
+
+
+// cleanup() is called once at the end, after the audio has stopped.
+// Release any resources that were allocated in setup().
+
+void cleanup(BelaContext *context, void *userData)
+{
+	free(gWavetable);
+	free(gPhases);
+	free(gFrequencies);
+	free(gAmplitudes);
+	free(gDFrequencies);
+	free(gDAmplitudes);
+}
+
+/**
+\example 10-oscillator-bank
+
+Oscillator Bank
+----------------------
+
+These files demonstrate an oscillator bank implemented in assembly code 
+that is used as part of the d-box project.
+*/
+