From 9095a6952ade035fae79375bb4db9d16a225c0ac Mon Sep 17 00:00:00 2001
From: Chris <chris@ternar.tech>
Date: Sun, 3 Aug 2025 00:35:55 +0200
Subject: [PATCH] refined voice allocation procedure

---
 synth/synth.h | 100 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 62 insertions(+), 38 deletions(-)

diff --git a/synth/synth.h b/synth/synth.h
index 195b760..e9871dc 100644
--- a/synth/synth.h
+++ b/synth/synth.h
@@ -1,7 +1,7 @@
 #pragma once
 
+#include <array>
 #include <cstddef>
-#include <memory>
 #include <vector>
 
 using namespace std;
@@ -23,67 +23,91 @@ struct m_event {
 	double data;
 };
 
+constexpr size_t MAX_VOICES = 8;
+constexpr size_t MAX_EVENTS_PER_VOICE = 32;
+
+template <typename voice, typename sample>
+void voice_process_block(voice& v, sample** audio, int num_frames, const array<m_event, MAX_EVENTS_PER_VOICE>& events,
+						 size_t num_events);
+
 template <typename voice>
 struct synth {
-	vector<shared_ptr<voice>> voice_ptrs;
-	int active_voice_count;
+	array<voice, MAX_VOICES> voices;
+	array<array<m_event, MAX_EVENTS_PER_VOICE>, MAX_VOICES> voice_events;
+	array<size_t, MAX_VOICES> counts;
+	int active_voice_count = 1;
+	size_t index_to_steal = 0;
 };
 
 template <typename voice>
-void synth_init(const synth<voice>& s, size_t num_voices, double samplerate)
+void synth_init(synth<voice>& s, double samplerate)
 {
-	s.active_voice_count = 0;
-	s.voice_ptrs.reserve(num_voices);
-	for (size_t i = 0; i < num_voices; ++i) { s.voice_ptrs.emplace_back(make_shared<voice>()); }
+	for (size_t i = 0; i < MAX_VOICES; ++i) {
+		s.voices[i] = voice();
+		s.voices[i].voice_init(samplerate);
+		s.counts[i] = 0;
+	}
 }
 
 template <typename voice, typename sample>
-void synth_process_block(const synth<voice>& s, sample** audio, const vector<m_event>& midi_events, int frames)
+void synth_process_block(synth<voice>& s, sample** audio, const vector<m_event>& midi_events, int num_frames)
 {
-	int current_frame = 0;
-	int event_index = 0;
+	// reset voice events and counts
+	for (int i = 0; i < MAX_VOICES; i++) {
+		s.voice_events[i].fill(m_event {});
+		s.counts[i] = 0;
+	}
 
 	for (const auto& ev : midi_events) {
-
-		int event_frame = ev.offset;
-		int voice_index = -1;
-
 		switch (ev.type) {
-		case note_on:
+		case note_on: {
+			bool found = false;
+			// attempt to find a free voice
 			for (size_t i = 0; i < s.active_voice_count; ++i) {
-				// attempt to find a free voice
-				if (!s.voice_ptrs[i]->is_busy) { voice_index = i; }
-			}
-			// if no free voice is found, steal one
-			if (voice_index < 0) {
-				// Try to find a voice that is not gated (not playing a note)
-				for (size_t i = 0; i < s.active_voice_count; ++i) {
-					if (!s.voice_ptrs[i]->gate) { voice_index = i; }
+				if (!s.voices[i].is_busy) {
+					s.voice_events[i][s.counts[i]++] = ev;
+					found = true;
+					break;
 				}
-				// If all voices are gated, steal one round-robin
-				voice_index = s.index_to_steal;
-				s.index_to_steal = (s.index_to_steal + 1) % s.active_voice_count;
 			}
 
-			// If a voice is found, remember index
-			// if (voice_index >= 0) { v->note_on(ev.midi_note, ev.velocity); }
+			if (found) break;
+
+			// try to find a voice that is not gated
+			for (size_t i = 0; i < s.active_voice_count; ++i) {
+				if (!s.voices[i].gate) {
+					s.voice_events[i][s.counts[i]++] = ev;
+					found = true;
+					break;
+				}
+			}
+
+			if (found) break;
+
+			// if all voices are gated, steal one round-robin
+			s.voice_events[s.index_to_steal][s.counts[s.index_to_steal]++] = ev;
+			s.index_to_steal++;
+			if (s.index_to_steal >= s.active_voice_count) s.index_to_steal = 0;
 			break;
-		case note_off:
+		}
+		case note_off: {
+			for (size_t i = 0; i < s.active_voice_count; ++i) {
+				if (s.voices[i].midi_note == ev.midi_note) s.voice_events[i][s.counts[i]++] = ev;
+			}
 			break;
+		}
 		case pitch_wheel:
-			break;
-		case mod_wheel:
+		case mod_wheel: {
+			for (size_t i = 0; i < s.active_voice_count; ++i) { s.voice_events[i][s.counts[i]++] = ev; }
 			break;
 		}
-
-		// process all voices from current frame to event frame
-		for (int i = 0; i < s.active_voice_count; i++) {
-			auto& v = s.voice_ptrs[i];
-			if (i == voice_index) { v.midi_event = ev; }
-			if (current_frame < event_frame) { v->process_block(audio, current_frame, event_frame); }
 		}
+	}
 
-		current_frame = event_frame;
+	for (size_t i = 0; i < s.active_voice_count; ++i) {
+		auto& v = s.voices[i];
+		auto& events = s.voice_events[i];
+		voice_process_block(v, audio, num_frames, events, s.counts[i]);
 	}
 }
 } // namespace trnr