Add channel selection

audio-worklet/src/jsMain/kotlin/nl/astraeus/vst/chip/ChipProcessor.kt

@@ -59,6 +59,7 @@ enum class Waveform {
 @ExperimentalJsExport
 @JsExport
 class VstChipProcessor : AudioWorkletProcessor() {
+  var midiChannel = 0
   val notes = Array(POLYPHONICS) {
     PlayingNote(
       0
@@ -78,41 +79,58 @@ class VstChipProcessor : AudioWorkletProcessor() {
   }
 
   private fun handleMessage(message: MessageEvent) {
-    //console.log("VstChipProcessor: Received message", message)
+    console.log("VstChipProcessor: Received message:", message.data)
 
     val data = message.data
 
-    when (data) {
-      "test_on" -> {
-        playMidi(Int32Array(arrayOf(0x90, 60, 64)))
-
-      }
-      "test_off" -> {
-        playMidi(Int32Array(arrayOf(0x90, 60, 0)))
-      }
-      is String -> {
-      }
-      is ArrayBuffer -> {
-      }
-      is Uint8Array -> {
-        val data32 = Int32Array(data.length)
-        for (i in 0 until data.length) {
-          data32[i] = (data[i].toInt() and 0xff)
+    try {
+      when (data) {
+        is String -> {
+          if (data.startsWith("set_channel")) {
+            val parts = data.split('\n')
+            if (parts.size == 2) {
+              midiChannel = parts[1].toInt()
+              println("Setting channel: $midiChannel")
+            }
+          }
         }
-        playMidi(data32)
+
+        is Uint8Array -> {
+          val data32 = Int32Array(data.length)
+          for (i in 0 until data.length) {
+            data32[i] = (data[i].toInt() and 0xff)
+          }
+          playMidi(data32)
+        }
+
+        is Int32Array -> {
+          playMidi(data)
+        }
+
+        else ->
+          console.error("Don't kow how to handle message", message)
       }
-      is Int32Array -> {
-        playMidi(data)
-      }
-      else ->
-        console.error("Don't kow how to handle message", message)
+    } catch(e: Exception) {
+      console.log(e.message, e)
     }
   }
 
   private fun playMidi(bytes: Int32Array) {
+    console.log("playMidi", bytes)
     if (bytes.length > 0) {
+      var cmdByte = bytes[0]
+      val channelCmd = ((cmdByte shr 4) and 0xf) in 0x8 .. 0xe
+      val channel = cmdByte and 0xf
+      println("Channel cmd: $channelCmd")
+      if (channelCmd && channel != midiChannel) {
+        console.log("Wrong channel", midiChannel, bytes)
+        return
+      }
+
+      cmdByte = cmdByte and 0xf0
+
       //console.log("Received", bytes)
-      when(bytes[0]) {
+      when(cmdByte) {
         0x90 -> {
           if (bytes.length == 3) {
             val note = bytes[1]