Bug fix for sysex messages longer than 64K in CoreMIDI API.

krysbia · Aug 23, 2021 · 6e4e763 · 6e4e763
1 parent 3fe256b
commit 6e4e763
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Showing 2 changed files with 51 additions and 47 deletions.
diff --git a/RtMidi.cpp b/RtMidi.cpp
@@ -1471,50 +1471,54 @@ void MidiOutCore :: sendMessage( const unsigned char *message, size_t size )
     return;
   }
 
-  MIDITimeStamp timeStamp = AudioGetCurrentHostTime();
-  CoreMidiData *data = static_cast<CoreMidiData *> (apiData_);
-  OSStatus result;
-
   if ( message[0] != 0xF0 && nBytes > 3 ) {
     errorString_ = "MidiOutCore::sendMessage: message format problem ... not sysex but > 3 bytes?";
     error( RtMidiError::WARNING, errorString_ );
     return;
   }
 
-  Byte buffer[nBytes+(sizeof( MIDIPacketList ))];
+  MIDITimeStamp timeStamp = AudioGetCurrentHostTime();
+  CoreMidiData *data = static_cast<CoreMidiData *> (apiData_);
+  OSStatus result;
+
+  ByteCount bufsize = nBytes > 65535 ? 65535 : nBytes;
+  Byte buffer[bufsize+16]; // pad for other struct members
   ByteCount listSize = sizeof( buffer );
   MIDIPacketList *packetList = (MIDIPacketList*)buffer;
-  MIDIPacket *packet = MIDIPacketListInit( packetList );
 
   ByteCount remainingBytes = nBytes;
-  while ( remainingBytes && packet ) {
-    ByteCount bytesForPacket = remainingBytes > 65535 ? 65535 : remainingBytes; // 65535 = maximum size of a MIDIPacket
+  while ( remainingBytes ) {
+    MIDIPacket *packet = MIDIPacketListInit( packetList );
+    // A MIDIPacketList can only contain a maximum of 64K of data, so if our message is longer,
+    // break it up into chunks of 64K or less and send out as a MIDIPacketList with only one
+    // MIDIPacket. Here, we reuse the memory allocated above on the stack for all.
+    ByteCount bytesForPacket = remainingBytes > 65535 ? 65535 : remainingBytes;
     const Byte* dataStartPtr = (const Byte *) &message[nBytes - remainingBytes];
     packet = MIDIPacketListAdd( packetList, listSize, packet, timeStamp, bytesForPacket, dataStartPtr );
     remainingBytes -= bytesForPacket;
-  }
 
-  if ( !packet ) {
-    errorString_ = "MidiOutCore::sendMessage: could not allocate packet list";
-    error( RtMidiError::DRIVER_ERROR, errorString_ );
-    return;
-  }
+    if ( !packet ) {
+      errorString_ = "MidiOutCore::sendMessage: could not allocate packet list";
+      error( RtMidiError::DRIVER_ERROR, errorString_ );
+      return;
+    }
 
-  // Send to any destinations that may have connected to us.
-  if ( data->endpoint ) {
-    result = MIDIReceived( data->endpoint, packetList );
-    if ( result != noErr ) {
-      errorString_ = "MidiOutCore::sendMessage: error sending MIDI to virtual destinations.";
-      error( RtMidiError::WARNING, errorString_ );
+    // Send to any destinations that may have connected to us.
+    if ( data->endpoint ) {
+      result = MIDIReceived( data->endpoint, packetList );
+      if ( result != noErr ) {
+        errorString_ = "MidiOutCore::sendMessage: error sending MIDI to virtual destinations.";
+        error( RtMidiError::WARNING, errorString_ );
+      }
     }
-  }
 
-  // And send to an explicit destination port if we're connected.
-  if ( connected_ ) {
-    result = MIDISend( data->port, data->destinationId, packetList );
-    if ( result != noErr ) {
-      errorString_ = "MidiOutCore::sendMessage: error sending MIDI message to port.";
-      error( RtMidiError::WARNING, errorString_ );
+    // And send to an explicit destination port if we're connected.
+    if ( connected_ ) {
+      result = MIDISend( data->port, data->destinationId, packetList );
+      if ( result != noErr ) {
+        errorString_ = "MidiOutCore::sendMessage: error sending MIDI message to port.";
+        error( RtMidiError::WARNING, errorString_ );
+      }
     }
   }
 }

diff --git a/tests/sysextest.cpp b/tests/sysextest.cpp
@@ -13,7 +13,7 @@
 
 void usage( void ) {
   std::cout << "\nuseage: sysextest N\n";
-  std::cout << "    where N = length of sysex message to send / receive.\n\n";
+  std::cout << "    where N = length of sysex data to send / receive.\n\n";
   exit( 0 );
 }
 
@@ -37,7 +37,7 @@ void mycallback( double deltatime, std::vector< unsigned char > *message, void *
   for ( unsigned int i=0; i<nBytes; i++ )
     std::cout << "Byte " << i << " = " << (int)message->at(i) << ", ";
   if ( nBytes > 0 )
-    std::cout << "stamp = " << deltatime << std::endl;
+    std::cout << "# of bytes = " << nBytes << ", stamp = " << deltatime << std::endl;
 }
 
 int main( int argc, char *argv[] )
@@ -67,28 +67,28 @@ int main( int argc, char *argv[] )
   try {
     if ( chooseMidiPort( midiin ) == false ) goto cleanup;
     if ( chooseMidiPort( midiout ) == false ) goto cleanup;
-  }
-  catch ( RtMidiError &error ) {
-    error.printMessage();
-    goto cleanup;
-  }
-
-  midiin->setCallback( &mycallback );
 
-  message.push_back( 0xF6 );
-  midiout->sendMessage( &message );
-  SLEEP( 500 ); // pause a little
+    midiin->setCallback( &mycallback );
 
-  // Create a long sysex message of numbered bytes and send it out ... twice.
-  for ( int n=0; n<2; n++ ) {
-    message.clear();
-    message.push_back( 240 );
-    for ( i=0; i<nBytes; i++ )
-      message.push_back( i % 128 );
-    message.push_back( 247 );
+    message.push_back( 0xF6 );
     midiout->sendMessage( &message );
-
     SLEEP( 500 ); // pause a little
+
+    // Create a long sysex message of numbered bytes and send it out ... twice.
+    for ( int n=0; n<2; n++ ) {
+      message.clear();
+      message.push_back( 240 );
+      for ( i=0; i<nBytes; i++ )
+        message.push_back( i % 128 );
+      message.push_back( 247 );
+      midiout->sendMessage( &message );
+
+      SLEEP( 500 ); // pause a little
+    }
+  }
+  catch ( RtMidiError &error ) {
+    error.printMessage();
+    goto cleanup;
   }
 
   // Clean up