SC: sclang, C++: where does the magic happens?

flower · April 20, 2024, 9:10am

When diving a bit in the code, I’m able to find where the code is for a particular subject, like MIDIClient init (ALSA).

Sclang is ‘calling’ the c++ code? How does this work in general terms?

A contributor needs to change the c++ and the sc code, or is there more to it?

github.com

supercollider/supercollider/blob/28a0b12216fb97e4487373b2cf00a5ec28850f1f/SCClassLibrary/Common/Control/MIDIOut.sc#L12


      
          	var <>device, <>name, <>uid;
          	*new{ arg device, name, uid;
          		^super.newCopyArgs(device, name, uid)
          	}
          	printOn { arg stream;
          		stream << this.class.name << "(" <<<*
          			[device, name]  <<")"
          	}
          }
          
          MIDIClient {
          	classvar <myinports, <myoutports; // for linux it is useful to keep track of how many we open ourselves
          	classvar <sources, <destinations;
          	classvar <initialized=false;
          	*init { arg inports, outports, verbose=true; // by default initialize all available ports
          								// you still must connect to them using MIDIIn.connect
          
          		this.prInitClient;
          		this.list;
          		if(inports.isNil,{inports = sources.size});
          		if(outports.isNil,{outports = destinations.size});

github.com

supercollider/supercollider/blob/28a0b12216fb97e4487373b2cf00a5ec28850f1f/lang/LangPrimSource/SC_AlsaMIDI.cpp#L527


      
              snd_seq_ev_schedule_real(evt, mQueue, 1, &time);
              snd_seq_event_output_direct(mHandle, evt);
              //  	snd_seq_event_output(mHandle, evt);
          
              // 	snd_seq_continue_queue(mHandle, mQueue, 0);
              // 	snd_seq_drain_output(mHandle);
          
              return errNone;
          }
          
          int initMIDI(int numIn, int numOut) {
              SC_AlsaMidiClient* client = &gMIDIClient;
              int i;
          
              if (client->mHandle)
                  cleanUpMIDI();
          
              if (numIn > kMaxMidiPorts) {
                  printf("MIDI: note that maximum midi in ports is limited to %d.\n", kMaxMidiPorts);
              }
              if (numOut > kMaxMidiPorts) {

jamshark70 · April 20, 2024, 9:31am

Primitives – for example:

	*prInitClient {
		_InitMIDIClient
		^this.primitiveFailed
	}

AlsaMIDI.cpp, near the end:

    definePrimitive(base, index++, "_InitMIDIClient", prInitMIDIClient, 1, 0);

Then find prInitMIDIClient() (in the same file, generally).

hjh