MIDI CC 11 (Expression) (#830)

* Simple implementation of MIDI CC 11 (Expression) as a live, MIDI only, multiplier for channel volume.

* Add config option for global MIDI CC Expression channel

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;

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;

src/mididevice.cpp

@@ -37,14 +37,15 @@ LOGMODULE ("mididevice");
 #define MIDI_CHANNEL_AFTERTOUCH 0b1101   // right now Synth_Dexed just manage Channel Aftertouch not Polyphonic AT -> 0b1010
 #define MIDI_CONTROL_CHANGE	0b1011
 	#define MIDI_CC_BANK_SELECT_MSB		0
-	#define MIDI_CC_MODULATION			1
+	#define MIDI_CC_MODULATION		1
 	#define MIDI_CC_BREATH_CONTROLLER	2 
 	#define MIDI_CC_FOOT_PEDAL 		4
-	#define MIDI_CC_VOLUME				7
+	#define MIDI_CC_VOLUME			7
 	#define MIDI_CC_PAN_POSITION		10
+	#define MIDI_CC_EXPRESSION		11
 	#define MIDI_CC_BANK_SELECT_LSB		32
 	#define MIDI_CC_BANK_SUSTAIN		64
-	#define MIDI_CC_RESONANCE			71
+	#define MIDI_CC_RESONANCE		71
 	#define MIDI_CC_FREQUENCY_CUTOFF	74
 	#define MIDI_CC_REVERB_LEVEL		91
 	#define MIDI_CC_DETUNE_LEVEL		94
@@ -94,6 +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) {
@@ -279,6 +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]);
@@ -398,6 +419,13 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 							m_pSynthesizer->SetPan (pMessage[2], nTG);
 							break;
 		
+						case MIDI_CC_EXPRESSION:
+							if (m_nMIDIGlobalExpression == Disabled) {
+								// Expression is per channel only
+								m_pSynthesizer->SetExpression (pMessage[2], nTG);
+							}
+							break;
+		
 						case MIDI_CC_BANK_SELECT_MSB:
 							m_pSynthesizer->BankSelectMSB (pMessage[2], nTG);
 							break;

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;
 

src/minidexed.cpp

@@ -72,6 +72,7 @@ CMiniDexed::CMiniDexed (CConfig *pConfig, CInterruptSystem *pInterrupt,
 		m_nVoiceBankIDMSB[i] = 0;
 		m_nProgram[i] = 0;
 		m_nVolume[i] = 100;
+		m_nExpression[i] = 127;
 		m_nPan[i] = 64;
 		m_nMasterTune[i] = 0;
 		m_nCutoff[i] = 99;
@@ -280,6 +281,7 @@ bool CMiniDexed::Initialize (void)
 		assert (m_pTG[i]);
 
 		SetVolume (100, i);
+		SetExpression (127, i);
 		ProgramChange (0, i);
 
 		m_pTG[i]->setTranspose (24);
@@ -648,11 +650,28 @@ void CMiniDexed::SetVolume (unsigned nVolume, unsigned nTG)
 	m_nVolume[nTG] = nVolume;
 
 	assert (m_pTG[nTG]);
-	m_pTG[nTG]->setGain (nVolume / 127.0f);
+	m_pTG[nTG]->setGain ((m_nVolume[nTG] * m_nExpression[nTG]) / (127.0f * 127.0f));
 
 	m_UI.ParameterChanged ();
 }
 
+void CMiniDexed::SetExpression (unsigned nExpression, unsigned nTG)
+{
+	nExpression=constrain((int)nExpression,0,127);
+
+	assert (nTG < CConfig::AllToneGenerators);
+	if (nTG >= m_nToneGenerators) return;  // Not an active TG
+
+	m_nExpression[nTG] = nExpression;
+
+	assert (m_pTG[nTG]);
+	m_pTG[nTG]->setGain ((m_nVolume[nTG] * m_nExpression[nTG]) / (127.0f * 127.0f));
+
+	// Expression is a "live performance" parameter only set
+	// via MIDI and not via the UI.
+	//m_UI.ParameterChanged ();
+}
+
 void CMiniDexed::SetPan (unsigned nPan, unsigned nTG)
 {
 	nPan=constrain((int)nPan,0,127);

src/minidexed.h

@@ -74,6 +74,7 @@ public:
 	void ProgramChange (unsigned nProgram, unsigned nTG);
 	void ProgramChangePerformance (unsigned nProgram);
 	void SetVolume (unsigned nVolume, unsigned nTG);
+	void SetExpression (unsigned nExpression, unsigned nTG);
 	void SetPan (unsigned nPan, unsigned nTG);			// 0 .. 127
 	void SetMasterTune (int nMasterTune, unsigned nTG);		// -99 .. 99
 	void SetCutoff (int nCutoff, unsigned nTG);			// 0 .. 99
@@ -261,6 +262,7 @@ private:
 	unsigned m_nVoiceBankIDMSBPerformance;
 	unsigned m_nProgram[CConfig::AllToneGenerators];
 	unsigned m_nVolume[CConfig::AllToneGenerators];
+	unsigned m_nExpression[CConfig::AllToneGenerators];
 	unsigned m_nPan[CConfig::AllToneGenerators];
 	int m_nMasterTune[CConfig::AllToneGenerators];
 	int m_nCutoff[CConfig::AllToneGenerators];