Handle CC 124, 125, 126, 127 (Omni Mode Off, Omni Mode On, Mono Mode On, Poly Mode On) (#837)

1. Omni Mode On/Off via MIDI CC: MIDI CC **124** and **125** are now handled to switch Omni Mode Off and On, respectively.
2. Mono Mode On, Poly Mode On via MIDI CC: MIDI CC **126** and **127** are now handled to switch Mono Mode On, Poly Mode On, respectively.
3. If `MIDIDumpEnabled=1` and syslog is configured, then MIDI messages are now also sent to syslog over the network. This helps to see what is going on without the need for a HDMI screen.

src/midi.h

@@ -45,6 +45,10 @@
 #define MIDI_CC_DETUNE_LEVEL		94
 #define MIDI_CC_ALL_SOUND_OFF		120
 #define MIDI_CC_ALL_NOTES_OFF		123
+#define MIDI_CC_OMNI_MODE_OFF		124
+#define MIDI_CC_OMNI_MODE_ON		125
+#define MIDI_CC_MONO_MODE_ON		126
+#define MIDI_CC_POLY_MODE_ON		127
 
 #define MIDI_PROGRAM_CHANGE	0b1100
 #define MIDI_PITCH_BEND		0b1110

src/mididevice.cpp

@@ -32,7 +32,6 @@
 
 LOGMODULE ("mididevice");
 
-
 // MIDI "System" level (i.e. all TG) custom CC maps
 // Note: Even if number of TGs is not 8, there are only 8
 //       available to be used in the mappings here.
@@ -63,6 +62,7 @@ CMIDIDevice::CMIDIDevice (CMiniDexed *pSynthesizer, CConfig *pConfig, CUserInter
 	for (unsigned nTG = 0; nTG < CConfig::AllToneGenerators; nTG++)
 	{
 		m_ChannelMap[nTG] = Disabled;
+		m_PreviousChannelMap[nTG] = Disabled; // Initialize previous channel map
 	}
 
 	m_nMIDISystemCCVol = m_pConfig->GetMIDISystemCCVol();
@@ -111,6 +111,12 @@ CMIDIDevice::~CMIDIDevice (void)
 void CMIDIDevice::SetChannel (u8 ucChannel, unsigned nTG)
 {
 	assert (nTG < CConfig::AllToneGenerators);
+	
+	// When changing to OMNI mode, store the previous channel
+	if (ucChannel == OmniMode && m_ChannelMap[nTG] != OmniMode) {
+		m_PreviousChannelMap[nTG] = m_ChannelMap[nTG];
+	}
+	
 	m_ChannelMap[nTG] = ucChannel;
 }
 
@@ -133,17 +139,17 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 			if (   pMessage[0] != MIDI_TIMING_CLOCK
 			    && pMessage[0] != MIDI_ACTIVE_SENSING)
 			{
-				fprintf (stderr, "MIDI%u: %02X\n", nCable, (unsigned) pMessage[0]);
+				LOGNOTE("MIDI%u: %02X", nCable, (unsigned) pMessage[0]);
 			}
 			break;
 
 		case 2:
-			fprintf (stderr, "MIDI%u: %02X %02X\n", nCable,
+			LOGNOTE("MIDI%u: %02X %02X", nCable,
 				(unsigned) pMessage[0], (unsigned) pMessage[1]);
 			break;
 
 		case 3:
-			fprintf (stderr, "MIDI%u: %02X %02X %02X\n", nCable,
+			LOGNOTE("MIDI%u: %02X %02X %02X", nCable,
 				(unsigned) pMessage[0], (unsigned) pMessage[1],
 				(unsigned) pMessage[2]);
 			break;
@@ -152,17 +158,17 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 			switch(pMessage[0])
 			{
 				case MIDI_SYSTEM_EXCLUSIVE_BEGIN:
-					fprintf(stderr, "MIDI%u: SysEx data length: [%d]:",nCable, uint16_t(nLength));
+					LOGNOTE("MIDI%u: SysEx data length: [%d]:",nCable, uint16_t(nLength));
 					for (uint16_t i = 0; i < nLength; i++)
 					{
 						if((i % 16) == 0)
-							fprintf(stderr, "\n%04d:",i);
+							LOGNOTE("%04d:",i);
-						fprintf(stderr, " 0x%02x",pMessage[i]);
+						LOGNOTE(" 0x%02x",pMessage[i]);
 					}
-					fprintf(stderr, "\n");
+					LOGNOTE("");
 					break;
 				default:
-					fprintf(stderr, "MIDI%u: Unhandled MIDI event type %0x02x\n",nCable,pMessage[0]);
+					LOGNOTE("MIDI%u: Unhandled MIDI event type %0x02x",nCable,pMessage[0]);
 			}
 			break;
 		}
@@ -472,6 +478,35 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 							}
 							break;
 
+						case MIDI_CC_OMNI_MODE_OFF:
+							// Sets to "Omni Off" mode
+							if (m_ChannelMap[nTG] == OmniMode) {
+								// Restore the previous channel if available, otherwise use current channel
+								u8 channelToRestore = (m_PreviousChannelMap[nTG] != Disabled) ? 
+									m_PreviousChannelMap[nTG] : ucChannel;
+								m_pSynthesizer->SetMIDIChannel(channelToRestore, nTG);
+								LOGDBG("Omni Mode Off: TG %d restored to MIDI channel %d", nTG, channelToRestore+1);
+							}
+							break;
+						
+						case MIDI_CC_OMNI_MODE_ON:
+							// Sets to "Omni On" mode
+							m_pSynthesizer->SetMIDIChannel(OmniMode, nTG);
+							LOGDBG("Omni Mode On: TG %d set to OMNI", nTG);
+							break;
+
+						case MIDI_CC_MONO_MODE_ON:
+							// Sets monophonic mode
+							m_pSynthesizer->setMonoMode(1, nTG);
+							LOGDBG("Mono Mode On: TG %d set to MONO", nTG);
+							break;
+
+						case MIDI_CC_POLY_MODE_ON:
+							// Sets polyphonic mode
+							m_pSynthesizer->setMonoMode(0, nTG);
+							LOGDBG("Poly Mode On: TG %d set to POLY", nTG);
+							break;
+
 						default:
 							// Check for system-level, cross-TG MIDI Controls, but only do it once.
 							// Also, if successfully handled, then no need to process other TGs,

src/mididevice.h

@@ -70,6 +70,7 @@ private:
 	CUserInterface *m_pUI;
 
 	u8 m_ChannelMap[CConfig::AllToneGenerators];
+	u8 m_PreviousChannelMap[CConfig::AllToneGenerators]; // Store previous channels for OMNI OFF restore
 	
 	unsigned m_nMIDISystemCCVol;
 	unsigned m_nMIDISystemCCPan;