From d42b1a868a80dd0bd470030325b925a8237129a2 Mon Sep 17 00:00:00 2001
From: Kevin <68612569+diyelectromusic@users.noreply.github.com>
Date: Fri, 28 Mar 2025 21:37:11 +0000
Subject: [PATCH] Add config option for global MIDI CC Expression channel

---
 src/config.cpp     |  6 ++++++
 src/config.h       |  2 ++
 src/mididevice.cpp | 25 ++++++++++++++++++++++++-
 src/mididevice.h   |  1 +
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/config.cpp b/src/config.cpp
index 482b2b2..5a6fc88 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -112,6 +112,7 @@ void CConfig::Load (void)
 	m_nMIDISystemCCVol = m_Properties.GetNumber ("MIDISystemCCVol", 0);
 	m_nMIDISystemCCPan = m_Properties.GetNumber ("MIDISystemCCPan", 0);
 	m_nMIDISystemCCDetune = m_Properties.GetNumber ("MIDISystemCCDetune", 0);
+	m_nMIDIGlobalExpression = m_Properties.GetNumber ("MIDIGlobalExpression", 0);
 
 	m_bLCDEnabled = m_Properties.GetNumber ("LCDEnabled", 0) != 0;
 	m_nLCDPinEnable = m_Properties.GetNumber ("LCDPinEnable", 4);
@@ -353,6 +354,11 @@ unsigned CConfig::GetMIDISystemCCDetune (void) const
 	return m_nMIDISystemCCDetune;
 }
 
+unsigned CConfig::GetMIDIGlobalExpression (void) const
+{
+	return m_nMIDIGlobalExpression;
+}
+
 bool CConfig::GetLCDEnabled (void) const
 {
 	return m_bLCDEnabled;
diff --git a/src/config.h b/src/config.h
index 5d0cbc1..166a14e 100644
--- a/src/config.h
+++ b/src/config.h
@@ -131,6 +131,7 @@ public:
 	unsigned GetMIDISystemCCVol (void) const;
 	unsigned GetMIDISystemCCPan (void) const;
 	unsigned GetMIDISystemCCDetune (void) const;
+	unsigned GetMIDIGlobalExpression (void) const;
 
 	// HD44780 LCD
 	// GPIO pin numbers are chip numbers, not header positions
@@ -267,6 +268,7 @@ private:
 	unsigned m_nMIDISystemCCVol;
 	unsigned m_nMIDISystemCCPan;
 	unsigned m_nMIDISystemCCDetune;
+	unsigned m_nMIDIGlobalExpression;
 
 	bool m_bLCDEnabled;
 	unsigned m_nLCDPinEnable;
diff --git a/src/mididevice.cpp b/src/mididevice.cpp
index 40a3a75..fefe9fc 100644
--- a/src/mididevice.cpp
+++ b/src/mididevice.cpp
@@ -95,6 +95,15 @@ CMIDIDevice::CMIDIDevice (CMiniDexed *pSynthesizer, CConfig *pConfig, CUserInter
 	m_MIDISystemCCBitmap[2] = 0;
 	m_MIDISystemCCBitmap[3] = 0;
 
+	m_nMIDIGlobalExpression = m_pConfig->GetMIDIGlobalExpression();
+	// convert from config channels 1..16 to internal channels
+	if ((m_nMIDIGlobalExpression >= 1) && (m_nMIDIGlobalExpression <= 16)) {
+		m_nMIDIGlobalExpression = m_nMIDIGlobalExpression - 1;
+	} else {
+		// Either disabled or OMNI means disabled
+		m_nMIDIGlobalExpression = Disabled;
+	}
+
 	for (int tg=0; tg<8; tg++)
 	{
 		if (m_nMIDISystemCCVol != 0) {
@@ -280,6 +289,17 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 					}
 				}
 			}
+			if (m_nMIDIGlobalExpression != Disabled)
+			{
+				// Expression is global so check for expression MIDI channel
+				// NB: OMNI not supported
+				if (ucChannel == m_nMIDIGlobalExpression) {
+					// Send to all TGs regardless of their own channel
+					for (unsigned nTG = 0; nTG < m_pConfig->GetToneGenerators(); nTG++) {
+						m_pSynthesizer->SetExpression (pMessage[2], nTG);
+					}
+				}
+			}
 			if (nLength == 3)
 			{
 				m_pUI->UIMIDICmdHandler (ucChannel, ucStatus & 0xF0, pMessage[1], pMessage[2]);
@@ -400,7 +420,10 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 							break;
 		
 						case MIDI_CC_EXPRESSION:
-							m_pSynthesizer->SetExpression (pMessage[2], nTG);
+							if (m_nMIDIGlobalExpression == Disabled) {
+								// Expression is per channel only
+								m_pSynthesizer->SetExpression (pMessage[2], nTG);
+							}
 							break;
 		
 						case MIDI_CC_BANK_SELECT_MSB:
diff --git a/src/mididevice.h b/src/mididevice.h
index 44f1691..a8eae40 100644
--- a/src/mididevice.h
+++ b/src/mididevice.h
@@ -75,6 +75,7 @@ private:
 	unsigned m_nMIDISystemCCPan;
 	unsigned m_nMIDISystemCCDetune;
 	u32	 m_MIDISystemCCBitmap[4]; // to allow for 128 bit entries
+	unsigned m_nMIDIGlobalExpression;
 
 	std::string m_DeviceName;