From 3d79d24effb5a53517bd998ac4a7efbf191084e7 Mon Sep 17 00:00:00 2001
From: Chris <chris@ternar.tech>
Date: Sun, 3 Aug 2025 11:18:23 +0200
Subject: [PATCH] procedural audio buffer, add mods to synth

---
 synth/synth.h       | 37 +++++++++--------
 util/audio_buffer.h | 97 +++++++++++----------------------------------
 2 files changed, 44 insertions(+), 90 deletions(-)

diff --git a/synth/synth.h b/synth/synth.h
index e9871dc..9aff873 100644
--- a/synth/synth.h
+++ b/synth/synth.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "audio_buffer.h"
 #include <array>
 #include <cstddef>
 #include <vector>
@@ -8,15 +9,15 @@ using namespace std;
 
 namespace trnr {
 
-enum m_event_type {
+enum midi_event_type {
 	note_on = 0,
 	note_off,
 	pitch_wheel,
 	mod_wheel
 };
 
-struct m_event {
-	m_event_type type;
+struct midi_event {
+	midi_event_type type;
 	int offset;
 	int midi_note;
 	float velocity;
@@ -26,35 +27,36 @@ struct m_event {
 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 t_voice, typename t_sample>
+void voice_process_block(t_voice& v, t_sample** frames, size_t num_frames, midi_event* events, size_t num_events,
+						 const vector<audio_buffer<t_sample>>& mods = {});
 
-template <typename voice>
+template <typename t_voice>
 struct synth {
-	array<voice, MAX_VOICES> voices;
-	array<array<m_event, MAX_EVENTS_PER_VOICE>, MAX_VOICES> voice_events;
+	array<t_voice, MAX_VOICES> voices;
+	array<array<midi_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(synth<voice>& s, double samplerate)
+template <typename t_voice>
+void synth_init(synth<t_voice>& s, double samplerate)
 {
 	for (size_t i = 0; i < MAX_VOICES; ++i) {
-		s.voices[i] = voice();
+		s.voices[i] = t_voice();
 		s.voices[i].voice_init(samplerate);
 		s.counts[i] = 0;
 	}
 }
 
-template <typename voice, typename sample>
-void synth_process_block(synth<voice>& s, sample** audio, const vector<m_event>& midi_events, int num_frames)
+template <typename t_voice, typename t_sample>
+void synth_process_block(synth<t_voice>& s, t_sample** frames, int num_frames, const vector<midi_event>& midi_events,
+						 const vector<audio_buffer<t_sample>>& mods = {})
 {
 	// reset voice events and counts
 	for (int i = 0; i < MAX_VOICES; i++) {
-		s.voice_events[i].fill(m_event {});
+		s.voice_events[i].fill(midi_event {});
 		s.counts[i] = 0;
 	}
 
@@ -106,8 +108,9 @@ void synth_process_block(synth<voice>& s, sample** audio, const vector<m_event>&
 
 	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]);
+		auto& events = s.voice_events[i].data();
+		size_t num_events = s.counts[i];
+		voice_process_block(v, frames, num_frames, events, num_events, mods);
 	}
 }
 } // namespace trnr
diff --git a/util/audio_buffer.h b/util/audio_buffer.h
index bbbdf1f..568ee8c 100644
--- a/util/audio_buffer.h
+++ b/util/audio_buffer.h
@@ -1,81 +1,32 @@
 #pragma once
 
-#include <algorithm>
-#include <cassert>
 #include <vector>
 
+using namespace std;
+
 namespace trnr {
 template <typename t_sample>
-class audio_buffer {
-public:
-	audio_buffer(const t_sample** input, int channels, int frames)
-		: m_data(channels * frames)
-		, m_channels(channels)
-		, m_frames(frames)
-		, m_channel_ptrs(channels)
-	{
-		for (int ch = 0; ch < channels; ++ch) {
-			std::copy(input[ch], input[ch] + frames, m_data.begin() + ch * frames);
-		}
-		update_channel_ptrs();
-	}
+struct audio_buffer {
+	size_t channels;
+	size_t frames;
 
-	audio_buffer(int channels = 1, int frames = 1024)
-		: m_channels(channels)
-		, m_frames(frames)
-		, m_data(channels * frames)
-		, m_channel_ptrs(channels)
-	{
-		update_channel_ptrs();
-	}
-
-	void set_size(int channels, int frames)
-	{
-		m_channels = channels;
-		m_frames = frames;
-		m_data.resize(channels * frames);
-		m_channel_ptrs.resize(channels);
-		update_channel_ptrs();
-	}
-
-	void set_data(const t_sample** input, int channels, int frames)
-	{
-		set_size(channels, frames);
-		for (int ch = 0; ch < channels; ++ch) {
-			std::copy(input[ch], input[ch] + frames, m_data.begin() + ch * frames);
-		}
-		update_channel_ptrs();
-	}
-
-	int num_samples() const { return m_frames; }
-
-	int num_channels() const { return m_channels; }
-
-	t_sample* data() { return m_data.data(); }
-
-	const t_sample* data() const { return m_data.data(); }
-
-	// t_sample** access, always up-to-date after construction/resize
-	t_sample** write_ptrs() { return m_channel_ptrs.data(); }
-
-	t_sample* write_ptr(int channel)
-	{
-		assert(channel >= 0 && channel < m_channels);
-		return m_channel_ptrs[channel];
-	}
-
-	const t_sample* const* channel_ptrs() const { return m_channel_ptrs.data(); }
-
-private:
-	void update_channel_ptrs()
-	{
-		for (int ch = 0; ch < m_channels; ++ch) { m_channel_ptrs[ch] = m_data.data() + ch * m_frames; }
-	}
-
-	std::vector<t_sample> m_data;
-	std::vector<t_sample*> m_channel_ptrs;
-
-	int m_channels;
-	int m_frames; // samples per channel
+	vector<t_sample> flat_data;
+	vector<t_sample*> channel_ptrs;
 };
-} // namespace trnr
\ No newline at end of file
+
+template <typename t_sample>
+void audio_buffer_init(audio_buffer<t_sample>& a, size_t channels, size_t frames)
+{
+	a.channels = channels;
+	a.frames = frames;
+	a.flat_data.resize(channels * frames);
+	a.channel_ptrs.resize(channels);
+	audio_buffer_update_ptrs(a);
+}
+
+template <typename t_sample>
+void audio_buffer_update_ptrs(audio_buffer<t_sample>& a)
+{
+	for (int ch = 0; ch < a.channels; ++ch) { a.channel_ptrs[ch] = a.flat_data.data() + ch * a.frames; }
+}
+} // namespace trnr