161 lines
3.6 KiB
C++
161 lines
3.6 KiB
C++
#pragma once
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#include <array>
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#include <cstddef>
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#include <vector>
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using namespace std;
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namespace trnr {
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enum midi_event_type {
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NOTE_ON = 0,
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NOTE_OFF,
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PITCH_WHEEL,
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MOD_WHEEL
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};
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struct midi_event {
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midi_event_type type;
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int offset;
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int midi_note;
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float velocity;
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double data;
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};
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inline void make_note_on(midi_event& ev, int _midi_note, float _velocity, int _offset = 0)
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{
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ev.type = midi_event_type::NOTE_ON;
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ev.midi_note = _midi_note;
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ev.velocity = _velocity;
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ev.offset = _offset;
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}
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inline void make_note_off(midi_event& ev, int _midi_note, float _velocity, int _offset = 0)
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{
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ev.type = midi_event_type::NOTE_OFF;
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ev.midi_note = _midi_note;
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ev.velocity = _velocity;
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ev.offset = _offset;
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}
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inline void make_pitch_wheel(midi_event& ev, double _pitch, int _offset = 0)
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{
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ev.type = midi_event_type::PITCH_WHEEL;
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ev.data = _pitch;
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}
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inline void make_mod_wheel(midi_event& ev, double _mod, int _offset = 0)
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{
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ev.type = midi_event_type::PITCH_WHEEL;
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ev.data = _mod;
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}
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#ifndef MAX_VOICES
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#define MAX_VOICES 16
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#endif
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#ifndef MAX_EVENTS_PER_VOICE
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#define MAX_EVENTS_PER_VOICE 32
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#endif
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struct voice_state {
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int midi_note;
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bool is_busy = false;
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bool gate = false;
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bool trigger = false;
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float velocity = 0.0f;
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array<midi_event, MAX_EVENTS_PER_VOICE> events;
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size_t event_count = 0;
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};
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struct voice_allocator {
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array<voice_state, MAX_VOICES> voices;
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int active_voice_count = 1;
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size_t index_to_steal = 0;
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};
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inline void voice_allocator_init(voice_allocator& va)
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{
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for (size_t i = 0; i < MAX_VOICES; ++i) { va.voices[i].event_count = 0; }
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}
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inline void voice_allocator_process_block(voice_allocator& va, const vector<midi_event>& midi_events)
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{
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// reset voice events and counts
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for (int i = 0; i < MAX_VOICES; i++) {
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for (int j = 0; j < MAX_EVENTS_PER_VOICE; j++) { va.voices[i].events[j] = midi_event {}; }
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va.voices[i].event_count = 0;
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}
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for (const auto& ev : midi_events) {
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switch (ev.type) {
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case NOTE_ON: {
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bool found = false;
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// attempt to find a free voice
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for (size_t i = 0; i < va.active_voice_count; ++i) {
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if (!va.voices[i].is_busy) {
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voice_state& found_voice = va.voices[i];
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found_voice.is_busy = true;
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found_voice.events[va.voices[i].event_count++] = ev;
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found = true;
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break;
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}
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}
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if (found) break;
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// if all voices are busy, steal one round-robin
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voice_state& found_voice = va.voices[va.index_to_steal];
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found_voice.is_busy = true;
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found_voice.events[va.voices[va.index_to_steal].event_count++] = ev;
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va.index_to_steal++;
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if (va.index_to_steal >= va.active_voice_count) va.index_to_steal = 0;
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break;
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}
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case NOTE_OFF: {
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for (size_t i = 0; i < va.active_voice_count; ++i) {
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if (va.voices[i].midi_note == ev.midi_note) va.voices[i].events[va.voices[i].event_count++] = ev;
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}
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break;
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}
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case PITCH_WHEEL:
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case MOD_WHEEL: {
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for (size_t i = 0; i < va.active_voice_count; ++i) { va.voices[i].events[va.voices[i].event_count++] = ev; }
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break;
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}
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}
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}
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}
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inline void voice_process_event_for_frame(voice_state& v, size_t frame)
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{
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const midi_event* best_event = nullptr;
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for (int i = 0; i < v.event_count; i++) {
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const midi_event& ev = v.events[i];
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if (ev.offset == frame) {
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best_event = &ev;
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if (ev.type == NOTE_ON) break;
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}
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}
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if (best_event) switch (best_event->type) {
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case NOTE_ON:
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v.midi_note = best_event->midi_note;
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v.velocity = best_event->velocity;
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v.is_busy = true;
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v.gate = true;
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v.trigger = true;
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break;
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case NOTE_OFF:
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v.gate = false;
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break;
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// TODO: handle pitch wheel and mod wheel events
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case PITCH_WHEEL:
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case MOD_WHEEL:
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break;
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}
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}
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} // namespace trnr
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