138 lines
4.5 KiB
C++
138 lines
4.5 KiB
C++
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#include "Synth.h"
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#include <iostream>
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#include <cmath>
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#ifndef M_PI // I hate my stupid chungus life
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#define M_PI 3.14159265358979323846
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#endif
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// TODO: you get it, also in a yml config
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#define SYNTH_PITCH_STANDARD 432.0f // frequency of home pitch
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#define SYNTH_MIDI_HOME 69 // midi note index of home pitch
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#define SYNTH_NOTES_PER_OCTAVE 12
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Synth::Synth(const ParameterStore& params) : paramStore_(params) {
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}
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void Synth::updateParams() {
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for(size_t i = 0; i < PARAM_COUNT; i++) {
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params_[i].target = paramStore_.get(static_cast<ParamId>(i));
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}
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}
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inline float Synth::getParam(ParamId id) {
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return params_[static_cast<size_t>(id)].current;
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}
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inline float Synth::noteToFrequency(uint8_t note) {
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return SYNTH_PITCH_STANDARD * pow(2.0f, static_cast<float>(note - SYNTH_MIDI_HOME) / static_cast<float>(SYNTH_NOTES_PER_OCTAVE));
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}
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void Synth::handleNoteEvent(const NoteEvent& event) {
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if(event.type == NoteEventType::NoteOn) {
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// add note to activeNotes list
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if (std::find(heldNotes_.begin(), heldNotes_.end(), event.note) == heldNotes_.end()) {
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heldNotes_.push_back(event.note);
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gainEnvelope_.noteOn();
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}
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} else {
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// remove note from activeNotes list
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auto it = std::find(heldNotes_.begin(), heldNotes_.end(), event.note);
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if (it != heldNotes_.end()) {
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heldNotes_.erase(it);
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}
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}
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updateCurrentNote();
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}
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void Synth::updateCurrentNote() {
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if(heldNotes_.empty()) {
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gainEnvelope_.noteOff(); // TODO: move somewhere else when polyphony
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return;
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}
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uint8_t note = heldNotes_.back();
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frequency_ = noteToFrequency(note);
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}
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void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
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// yeah really only need to update this once per buffer if its ~6ms latency
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updateParams();
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float sampleOut = 0.0f;
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bool triggered = false;
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for (uint32_t i = 0; i < nFrames; i++) {
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// updates internal buffered parameters for smoothing
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for(auto& p : params_) p.update(); // TODO: profile this
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// process all envelopes
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// should be easy enough if all the envelopes are in an array to loop over them
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gainEnvelope_.set(getParam(ParamId::Osc1VolumeEnvA), getParam(ParamId::Osc1VolumeEnvD), getParam(ParamId::Osc1VolumeEnvS), getParam(ParamId::Osc1VolumeEnvR));
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float gain = gainEnvelope_.process();
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// TODO: envelope is shared between all notes so this sequence involves a note change but only one envelope attack:
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// NOTE_A_ON > NOTE_B_ON > NOTE_A_OFF and note B starts playing part-way through note A's envelope
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// skip if no active notes
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if(!gainEnvelope_.isActive()) {
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out[2*i] = 0.0f;
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out[2*i+1] = 0.0f;
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scope_->push(0.0f);
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continue;
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}
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float phaseInc = 2.0f * M_PI * frequency_ / static_cast<float>(sampleRate);
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// sample generation
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// TODO: wavetables
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// TODO: wavetables should be scaled by their RMS for equal loudness (prelim standard = 0.707)
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float sineSample = std::sin(phase_);
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float squareSample = (phase_ >= M_PI) ? 0.707f : -0.707f;
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float sawSample = ((phase_ / M_PI) - 1.0f) / 0.577f * 0.707f;
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// switch statement will be replaced with an array index for our array of wavetables
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switch (static_cast<int32_t>(std::round(getParam(ParamId::Osc1WaveSelector1)))) {
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case 0:
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sampleOut = sineSample * gain;
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break;
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case 1:
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sampleOut = squareSample * gain;
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break;
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case 2:
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sampleOut = sawSample * gain;
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break;
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case 3:
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// TODO: no triable wave yet :(
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sampleOut = sineSample * gain;
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break;
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default: // unreachable
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break;
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}
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// write to buffer
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out[2*i] = sampleOut; // left
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out[2*i+1] = sampleOut; // right
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// write to scope buffer
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if (scope_) {
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scope_->push(sampleOut); // visualization tap
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}
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// sampling business
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phase_ += phaseInc;
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if (phase_ > 2.0f * M_PI) {
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phase_ -= 2.0f * M_PI;
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if(!triggered) {
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scope_->setTrigger(i); // this is where we consider the start of a waveform
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triggered = true;
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// TODO: investigate triggering accross buffers when a single wave period transcends a single audio buffer
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}
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}
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}
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} |