Add support for MIDI via raw UDP socket

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Support for network MIDI via raw UDP socket (new configuration file option). This is compatible with [MiSTer MidiLink](https://github.com/bbond007/MiSTer_MidiLink).
+
 ## Changed
 
 - Update to circle-stdlib v15.12/Circle Step 44.4.1.

Kernel.mk

@@ -24,6 +24,7 @@ OBJS		:=	src/config.o \
 				src/net/applemidi.o \
 				src/net/ftpdaemon.o \
 				src/net/ftpworker.o \
+				src/net/udpmidi.o \
 				src/pisound.o \
 				src/power.o \
 				src/rommanager.o \

include/config.def

@@ -108,6 +108,7 @@ CFG(default_gateway,		CIPAddress,			NetworkDefaultGateway,			0xc0a80101					)
 CFG(dns_server,			CIPAddress,			NetworkDNSServer,			0xc0a80101					)
 CFG(hostname,			CString,			NetworkHostname,			"mt32-pi"					)
 CFG(rtp_midi,			bool,				NetworkRTPMIDI,				true						)
+CFG(udp_midi,			bool,				NetworkUDPMIDI,				true						)
 CFG(ftp,			bool,				NetworkFTPServer,			true						)
 CFG(ftp_username,		CString,			NetworkFTPUsername,			"mt32-pi"					)
 CFG(ftp_password,		CString,			NetworkFTPPassword,			"mt32-pi"					)

include/mt32pi.h

@@ -55,6 +55,7 @@
 #include "midiparser.h"
 #include "net/applemidi.h"
 #include "net/ftpdaemon.h"
+#include "net/udpmidi.h"
 #include "pisound.h"
 #include "power.h"
 #include "ringbuffer.h"
@@ -65,7 +66,7 @@
 
 //#define MONITOR_TEMPERATURE
 
-class CMT32Pi : CMultiCoreSupport, CPower, CMIDIParser, CAppleMIDIHandler
+class CMT32Pi : CMultiCoreSupport, CPower, CMIDIParser, CAppleMIDIHandler, CUDPMIDIHandler
 {
 public:
 	CMT32Pi(CI2CMaster* pI2CMaster, CSPIMaster* pSPIMaster, CInterruptSystem* pInterrupt, CGPIOManager* pGPIOManager, CSerialDevice* pSerialDevice, CUSBHCIDevice* pUSBHCI);
@@ -104,6 +105,9 @@ private:
 	virtual void OnAppleMIDIConnect(const CIPAddress* pIPAddress, const char* pName) override;
 	virtual void OnAppleMIDIDisconnect(const CIPAddress* pIPAddress, const char* pName) override;
 
+	// CUDPMIDIHandler
+	virtual void OnUDPMIDIDataReceived(const u8* pData, size_t nSize) override { ParseMIDIBytes(pData, nSize); };
+
 	// Initialization
 	bool InitNetwork();
 	bool InitMT32Synth();
@@ -159,6 +163,7 @@ private:
 	CWPASupplicant m_WPASupplicant;
 	bool m_bNetworkReady;
 	CAppleMIDIParticipant* m_pAppleMIDIParticipant;
+	CUDPMIDIReceiver* m_pUDPMIDIReceiver;
 	CFTPDaemon* m_pFTPDaemon;
 
 	CBcmRandomNumberGenerator m_Random;

include/net/udpmidi.h

@@ -0,0 +1,57 @@
+//
+// udpmidi.h
+//
+// mt32-pi - A baremetal MIDI synthesizer for Raspberry Pi
+// Copyright (C) 2020-2022 Dale Whinham <daleyo@gmail.com>
+//
+// This file is part of mt32-pi.
+//
+// mt32-pi is free software: you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// mt32-pi is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+// details.
+//
+// You should have received a copy of the GNU General Public License along with
+// mt32-pi. If not, see <http://www.gnu.org/licenses/>.
+//
+
+#ifndef _udpmidi_h
+#define _udpmidi_h
+
+#include <circle/net/ipaddress.h>
+#include <circle/net/socket.h>
+#include <circle/sched/task.h>
+
+class CUDPMIDIHandler
+{
+public:
+	virtual void OnUDPMIDIDataReceived(const u8* pData, size_t nSize) = 0;
+};
+
+class CUDPMIDIReceiver : protected CTask
+{
+public:
+	CUDPMIDIReceiver(CUDPMIDIHandler* pHandler);
+	virtual ~CUDPMIDIReceiver() override;
+
+	bool Initialize();
+
+	virtual void Run() override;
+
+private:
+	// UDP sockets
+	CSocket* m_pMIDISocket;
+
+	// Socket receive buffer
+	u8 m_MIDIBuffer[FRAME_BUFFER_SIZE];
+
+	// Callback handler
+	CUDPMIDIHandler* m_pHandler;
+};
+
+#endif

sdcard/mt32-pi.cfg

@@ -480,6 +480,14 @@ hostname = mt32-pi
 # Values: on*, off
 rtp_midi = on
 
+# Enable or disable the UDP MIDI server.
+#
+# This allows you to send MIDI data to mt32-pi via raw UDP socket on port 1999.
+# Compatible with MiSTer MidiLink.
+#
+# Values: on*, off
+udp_midi = on
+
 # Enable or disable the embedded FTP server.
 #
 # This FTP server is a very basic implementation which DOES NOT feature any kind

src/mt32pi.cpp

@@ -82,6 +82,7 @@ CMT32Pi::CMT32Pi(CI2CMaster* pI2CMaster, CSPIMaster* pSPIMaster, CInterruptSyste
 	  m_WPASupplicant(WLANConfigFile),
 	  m_bNetworkReady(false),
 	  m_pAppleMIDIParticipant(nullptr),
+	  m_pUDPMIDIReceiver(nullptr),
 	  m_pFTPDaemon(nullptr),
 
 	  m_pLCD(nullptr),
@@ -852,6 +853,19 @@ void CMT32Pi::UpdateNetwork()
 				m_pLogger->Write(MT32PiName, LogNotice, "AppleMIDI receiver initialized");
 		}
 
+		if (m_pConfig->NetworkUDPMIDI)
+		{
+			m_pUDPMIDIReceiver = new CUDPMIDIReceiver(this);
+			if (!m_pUDPMIDIReceiver->Initialize())
+			{
+				m_pLogger->Write(MT32PiName, LogError, "Failed to init UDP MIDI receiver");
+				delete m_pUDPMIDIReceiver;
+				m_pUDPMIDIReceiver = nullptr;
+			}
+			else
+				m_pLogger->Write(MT32PiName, LogNotice, "UDP MIDI receiver initialized");
+		}
+
 		if (m_pConfig->NetworkFTPServer)
 		{
 			m_pFTPDaemon = new CFTPDaemon(m_pConfig->NetworkFTPUsername, m_pConfig->NetworkFTPPassword);
@@ -873,6 +887,8 @@ void CMT32Pi::UpdateNetwork()
 
 		delete m_pAppleMIDIParticipant;
 		m_pAppleMIDIParticipant = nullptr;
+		delete m_pUDPMIDIReceiver;
+		m_pUDPMIDIReceiver = nullptr;
 		delete m_pFTPDaemon;
 		m_pFTPDaemon = nullptr;
 	}

src/net/udpmidi.cpp

@@ -0,0 +1,91 @@
+//
+// udpmidi.cpp
+//
+// mt32-pi - A baremetal MIDI synthesizer for Raspberry Pi
+// Copyright (C) 2020-2022 Dale Whinham <daleyo@gmail.com>
+//
+// This file is part of mt32-pi.
+//
+// mt32-pi is free software: you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// mt32-pi is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+// details.
+//
+// You should have received a copy of the GNU General Public License along with
+// mt32-pi. If not, see <http://www.gnu.org/licenses/>.
+//
+
+#include <circle/logger.h>
+#include <circle/net/in.h>
+#include <circle/net/netsubsystem.h>
+#include <circle/sched/scheduler.h>
+
+#include "net/udpmidi.h"
+
+constexpr u16 MIDIPort = 1999;
+
+const char UDPMIDIName[] = "udpmidi";
+
+CUDPMIDIReceiver::CUDPMIDIReceiver(CUDPMIDIHandler* pHandler)
+	: CTask(TASK_STACK_SIZE, true),
+	  m_pMIDISocket(nullptr),
+	  m_MIDIBuffer{0},
+	  m_pHandler(pHandler)
+{
+}
+
+CUDPMIDIReceiver::~CUDPMIDIReceiver()
+{
+	if (m_pMIDISocket)
+		delete m_pMIDISocket;
+}
+
+bool CUDPMIDIReceiver::Initialize()
+{
+	assert(m_pMIDISocket == nullptr);
+
+	CLogger* const pLogger    = CLogger::Get();
+	CNetSubSystem* const pNet = CNetSubSystem::Get();
+
+	if ((m_pMIDISocket = new CSocket(pNet, IPPROTO_UDP)) == nullptr)
+		return false;
+
+	if (m_pMIDISocket->Bind(MIDIPort) != 0)
+	{
+		pLogger->Write(UDPMIDIName, LogError, "Couldn't bind to port %d", MIDIPort);
+		return false;
+	}
+
+	// We started as a suspended task; run now that initialization is successful
+	Start();
+
+	return true;
+}
+
+void CUDPMIDIReceiver::Run()
+{
+	assert(m_pHandler != nullptr);
+	assert(m_pMIDISocket != nullptr);
+
+	CLogger* const pLogger       = CLogger::Get();
+	CScheduler* const pScheduler = CScheduler::Get();
+
+	while (true)
+	{
+		// Blocking call
+		const int nMIDIResult = m_pMIDISocket->Receive(m_MIDIBuffer, sizeof(m_MIDIBuffer), 0);
+
+		if (nMIDIResult < 0)
+			pLogger->Write(UDPMIDIName, LogError, "MIDI socket receive error: %d", nMIDIResult);
+		else if (nMIDIResult > 0)
+			m_pHandler->OnUDPMIDIDataReceived(m_MIDIBuffer, nMIDIResult);
+
+		// Allow other tasks to run
+		pScheduler->Yield();
+	}
+}