MidiTunnel.swift

import Foundation
import CoreMIDI

let source = Int(CommandLine.arguments[1])!
let dest = Int(CommandLine.arguments[2])!

var owner = "uk.me.rb.thru" as CFString?

// dispose of any existing connections with the same owner
var obj = Data()
var ref = Unmanaged<CFData>.passUnretained(obj as CFData)
print(MIDIThruConnectionFind(owner!, &ref))

var data = ref.takeUnretainedValue() as Data
var refs = data.withUnsafeBytes {
	Array(UnsafeBufferPointer<MIDIThruConnectionRef>(start: $0, count: data.count / MemoryLayout<MIDIThruConnectionRef>.stride))
}

refs.forEach {
	MIDIThruConnectionDispose($0)
}

// set up the new connection
var params = MIDIThruConnectionParams()
var connRef = MIDIThruConnectionRef()

MIDIThruConnectionParamsInitialize(&params)

params.numSources = 2
params.numDestinations = 2

params.sources.0.endpointRef = MIDIGetSource(source)
params.sources.1.endpointRef = MIDIGetSource(dest)
params.destinations.0.endpointRef = MIDIGetDestination(dest)
params.destinations.1.endpointRef = MIDIGetDestination(source)

var paramsRef = NSData(bytes: &params, length: MIDIThruConnectionParamsSize(&params))
MIDIThruConnectionCreate(owner, paramsRef, &connRef)