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145 lines
4.1 KiB
145 lines
4.1 KiB
/*
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* LowFrequencyOscillator.cpp
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*
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* Created on: October 12, 2018
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* Author: Steve Lascos
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.*
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <assert.h>
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#include "Audio.h"
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#include "LibBasicFunctions.h"
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namespace BALibrary {
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template <class T>
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void LowFrequencyOscillatorVector<T>::m_initPhase(T radiansPerSample)
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{
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// Initialize the phase vector starting at 0 radians, and incrementing
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// by radiansPerSample for each element in the vector.
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T initialPhase[AUDIO_BLOCK_SAMPLES];
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for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
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initialPhase[i] = (T)i * radiansPerSample;
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}
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m_radiansPerBlock = radiansPerSample * (T)AUDIO_BLOCK_SAMPLES;
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// there could be different threads controlling the LFO rate and consuming
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// the LFO output, so we need to protected the m_phaseVec for thread-safety.
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while (m_phaseLock.test_and_set()) {}
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memcpy(m_phaseVec, initialPhase, sizeof(T)*AUDIO_BLOCK_SAMPLES);
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m_phaseLock.clear();
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}
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// This function takes in the frequency of the LFO in hertz and uses knowledge
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// about the the audio sample rate to calcuate the correct radians per sample.
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template <class T>
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void LowFrequencyOscillatorVector<T>::setRateAudio(float frequencyHz)
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{
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T radiansPerSample;
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if (frequencyHz == 0) {
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radiansPerSample = 0;
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} else {
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T periodSamples = AUDIO_SAMPLE_RATE_EXACT / frequencyHz;
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radiansPerSample = (T)TWO_PI_F / periodSamples;
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}
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m_initPhase(radiansPerSample);
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}
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// This function is used when the LFO is being called at some rate other than
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// the audio rate. Here you can manually set the radians per sample as a fraction
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// of 2*PI
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template <class T>
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void LowFrequencyOscillatorVector<T>::setRateRatio(float ratio)
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{
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T radiansPerSample;
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if (ratio == 0) {
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radiansPerSample = 0;
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} else {
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radiansPerSample = (T)TWO_PI_F * ratio;
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}
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m_initPhase(radiansPerSample);
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}
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// When this function is called, it will update the phase vector by incrementing by
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// radians per block which is radians per sample * block size.
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template <class T>
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inline void LowFrequencyOscillatorVector<T>::m_updatePhase()
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{
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if (m_phaseLock.test_and_set()) { return; }
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if (m_phaseVec[0] > TWO_PI_F) {
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arm_offset_f32(m_phaseVec, -TWO_PI_F + m_radiansPerBlock, m_phaseVec, AUDIO_BLOCK_SAMPLES);
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} else {
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arm_offset_f32(m_phaseVec, m_radiansPerBlock, m_phaseVec, AUDIO_BLOCK_SAMPLES);
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}
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m_phaseLock.clear();
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}
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// This function will compute the vector of samples for the output waveform using
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// the current phase vector.
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template <class T>
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T *LowFrequencyOscillatorVector<T>::getNextVector()
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{
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switch(m_waveform) {
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case Waveform::SINE :
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for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
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m_outputVec[i] = arm_sin_f32(m_phaseVec[i]);
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}
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break;
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case Waveform::SQUARE :
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for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
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if (m_phaseVec[i] > 3*PI_F) {
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m_outputVec[i] = 0.0f;
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}
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else if (m_phaseVec[i] > 2*PI_F) {
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m_outputVec[i] = 1.0f;
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}
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else if (m_phaseVec[i] > PI_F) {
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m_outputVec[i] = 0.0f;
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} else {
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m_outputVec[i] = 1.0f;
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}
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}
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break;
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case Waveform::TRIANGLE :
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// for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
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// if (m_phaseVec[i] > 3*PI_F) {
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// m_outputVec[i] = ;
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// }
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// else if (m_phaseVec[i] > 2*PI_F) {
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// m_outputVec[i] = 1.0f;
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// }
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// else if (m_phaseVec[i] > PI_F) {
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// m_outputVec[i] = 0.0f;
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// } else {
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// m_outputVec[i] = 1.0f;
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// }
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// }
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break;
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case Waveform::RANDOM :
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break;
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default :
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assert(0); // This occurs if a Waveform type is missing from the switch statement
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}
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m_updatePhase();
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return m_outputVec;
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}
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template class LowFrequencyOscillatorVector<float>;
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} // namespace BALibrary
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