From f43935b5c873676a632b23cbfcef45a4431b233d Mon Sep 17 00:00:00 2001
From: Bent Bisballe Nyeng <deva@aasimon.org>
Date: Sun, 8 Aug 2021 10:34:54 +0200
Subject: Add support for a single midi note that plays multiple instruments.

---
 src/audioinputenginemidi.cc | 51 ++++++++++++++++++++++++---------------------
 src/midimapparser.cc        |  3 ++-
 src/midimapper.cc           | 24 +++++++++++----------
 src/midimapper.h            | 16 +++++++++-----
 4 files changed, 53 insertions(+), 41 deletions(-)

(limited to 'src')

diff --git a/src/audioinputenginemidi.cc b/src/audioinputenginemidi.cc
index 8732d8d..69aeeb6 100644
--- a/src/audioinputenginemidi.cc
+++ b/src/audioinputenginemidi.cc
@@ -117,32 +117,35 @@ void AudioInputEngineMidi::processNote(const std::uint8_t* midi_buffer,
 	auto key = midi_buffer[1];
 	auto velocity = midi_buffer[2];
 	auto instrument_idx = mmap.lookup(key);
-
-	switch(midi_buffer[0] & NoteMask)
+	auto instruments = mmap.lookup(key);
+	for(const auto& instrument_idx : instruments)
 	{
-	case NoteOff:
-		// Ignore for now
-		break;
-
-	case NoteOn:
-		if(velocity != 0 && instrument_idx != -1)
-		{
-			// maps velocities to [.5/127, 126.5/127]
-			auto centered_velocity = (velocity-.5f)/127.0f;
-			events.push_back({EventType::OnSet, (std::size_t)instrument_idx,
-			                  offset, centered_velocity});
-		}
-		break;
-
-	case NoteAftertouch:
-		if(velocity > 0 && instrument_idx != -1)
+		switch(midi_buffer[0] & NoteMask)
 		{
-			events.push_back({EventType::Choke, (std::size_t)instrument_idx,
-			                  offset, .0f});
+		case NoteOff:
+			// Ignore for now
+			break;
+
+		case NoteOn:
+			if(velocity != 0)
+			{
+				// maps velocities to [.5/127, 126.5/127]
+				auto centered_velocity = (velocity-.5f)/127.0f;
+				events.push_back({EventType::OnSet, (std::size_t)instrument_idx,
+				                  offset, centered_velocity});
+			}
+			break;
+
+		case NoteAftertouch:
+			if(velocity > 0)
+			{
+				events.push_back({EventType::Choke, (std::size_t)instrument_idx,
+				                  offset, .0f});
+			}
+			break;
+
+		default:
+			break;
 		}
-		break;
-
-	default:
-		break;
 	}
 }
diff --git a/src/midimapparser.cc b/src/midimapparser.cc
index 059dfec..363e1d5 100644
--- a/src/midimapparser.cc
+++ b/src/midimapparser.cc
@@ -50,7 +50,8 @@ bool MidiMapParser::parseFile(const std::string& filename)
 			continue;
 		}
 
-		midimap[note] = instr;
+		MidimapEntry entry{note, instr};
+		midimap.push_back(entry);
 	}
 
 	return true;
diff --git a/src/midimapper.cc b/src/midimapper.cc
index 9593aae..b9316c5 100644
--- a/src/midimapper.cc
+++ b/src/midimapper.cc
@@ -26,23 +26,25 @@
  */
 #include "midimapper.h"
 
-int MidiMapper::lookup(int note)
+std::vector<int> MidiMapper::lookup(int note_id)
 {
-	std::lock_guard<std::mutex> guard(mutex);
+	std::vector<int> instruments;
 
-	auto midimap_it = midimap.find(note);
-	if(midimap_it == midimap.end())
-	{
-		return -1;
-	}
+	std::lock_guard<std::mutex> guard(mutex);
 
-	auto instrmap_it = instrmap.find(midimap_it->second);
-	if(instrmap_it == instrmap.end())
+	for(const auto& map_entry : midimap)
 	{
-		return -1;
+		if(map_entry.note_id == note_id)
+		{
+			auto instrmap_it = instrmap.find(map_entry.instrument_name);
+			if(instrmap_it != instrmap.end())
+			{
+				instruments.push_back(instrmap_it->second);
+			}
+		}
 	}
 
-	return instrmap_it->second;
+	return instruments;
 }
 
 void MidiMapper::swap(instrmap_t& instrmap, midimap_t& midimap)
diff --git a/src/midimapper.h b/src/midimapper.h
index 4673e33..94781d4 100644
--- a/src/midimapper.h
+++ b/src/midimapper.h
@@ -29,16 +29,22 @@
 #include <map>
 #include <string>
 #include <mutex>
+#include <vector>
 
-typedef std::map<int, std::string> midimap_t;
-typedef std::map<std::string, int> instrmap_t;
+struct MidimapEntry
+{
+	int note_id;
+	std::string instrument_name;
+};
+
+using midimap_t = std::vector<MidimapEntry>;
+using instrmap_t = std::map<std::string, int>;
 
 class MidiMapper
 {
 public:
-	//! Lookup note in map and return its index.
-	//! \returns -1 if not found or the note index.
-	int lookup(int note);
+	//! Lookup note in map and returns the corresponding instrument index list.
+	std::vector<int> lookup(int note_id);
 
 	//! Set new map sets.
 	void swap(instrmap_t& instrmap, midimap_t& midimap);
-- 
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