feat: add zoom2transport example

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

examples/zoom2transport.nim

@@ -0,0 +1,211 @@
+##
+## Control JACK transport with foot switch connected to Zoom R8 audio interface
+##
+## Requires: https://github.com/SpotlightKid/jacket
+
+import std/[cmdline, logging, os, re, strformat]
+import threading/channels
+import signal
+import jacket
+
+
+const MidiNoteOn: byte = 0x90
+const McpRewind: byte = 91
+const McpForward: byte = 92
+const McpStop: byte = 93
+const McpPlay: byte = 94
+const McpPunchInOut: byte = 95
+
+type
+  ConnectionInfo = tuple[name: string, pattern: string]
+
+  App = object
+    client: ClientP
+    logger: ConsoleLogger
+    midiIn: PortP
+
+var
+  jclient: ClientP
+  event: MidiEvent
+  midiPort: PortP
+  status: cint
+  srcPortPtn: string
+  portChan: Chan[ConnectionInfo]
+  portConnecter: Thread[App]
+  exitSignalled: bool = false
+
+var log = newConsoleLogger(when defined(release): lvlInfo else: lvlDebug)
+
+
+proc cleanup() =
+  debug "Cleaning up..."
+  if jclient != nil:
+    discard jclient.deactivate()
+
+    if portConnecter.running:
+        debug "Stopping port connecter thread..."
+        discard portChan.trySend((name: "", pattern: ""))
+
+    portConnecter.joinThread()
+
+    discard jclient.clientClose()
+    jclient = nil
+
+proc errorCb(msg: cstring) {.cdecl.} =
+  # Suppress verbose JACK error messages when server is not available by
+  # default. Pass ``lvlAll`` when creating the logger to enable them.
+  debug "JACK error: " & $msg
+
+proc signalCb(sig: cint) {.noconv.} =
+  debug "Received signal: " & $sig
+  exitSignalled = true
+
+proc shutdownCb(arg: pointer = nil) {.cdecl.} =
+  warn "JACK server has shut down."
+  exitSignalled = true
+
+proc isStatus(event: MidiEvent, status: byte): bool =
+  return (event.buffer[0] and 0xF0) == status
+
+proc processCb*(nFrames: NFrames, arg: pointer): cint {.cdecl.} =
+  let app = cast[ptr App](arg)
+  let inbuf = portGetBuffer(app.midiIn, nFrames)
+  let count = midiGetEventCount(inbuf)
+
+  for i in 0..<count:
+    if midiEventGet(event.addr, inbuf, i.uint32) == 0:
+      if isStatus(event, MidiNoteOn):
+        var pos: Position
+        let transportState = transportQuery(jclient, pos.addr)
+
+        case event.buffer[1].byte
+        of McpRewind:
+          app.logger.log(lvlDebug, "Setting transport position to frame = 0")
+          discard transportLocate(app.client, 0)
+        of McpForward:
+          let new_pos = pos.frame + pos.frame_rate
+          app.logger.log(lvlDebug, "Setting transport position to frame = " & $new_pos)
+          discard transportLocate(app.client, new_pos)
+        of McpStop:
+          if (transportState == TransportRolling or
+              transportState == TransportStarting or
+              transportState == TransportNetStarting):
+            app.logger.log(lvlDebug, "STOPPING JACK transport")
+            transportStop(app.client)
+        of McpPlay:
+          if transportState == TransportStopped:
+            app.logger.log(lvlDebug, "STARTING JACK transport")
+            transportStart(app.client)
+        of McpPunchInOut:
+          if transportState == TransportStopped:
+            app.logger.log(lvlDebug, "STARTING JACK transport")
+            transportStart(app.client)
+          else:
+            app.logger.log(lvlDebug, "STOPPING JACK transport")
+            transportStop(app.client)
+        else:
+          discard
+
+proc findPort(client: ClientP, pattern: string): string =
+  let ports = getPorts(client, pattern, JACK_DEFAULT_MIDI_TYPE, PortIsOutput)
+
+  if not ports.isNil():
+    result = $ports[0]
+    free(ports)
+
+proc portRegisterCb(port: PortId; flag: cint; arg: pointer) {.cdecl.} =
+  if flag == 0:
+    return
+
+  let portP = jclient.portById(port)
+
+  if not portP.isNil():
+    let info: ConnectionInfo = (name: $portName(portP), pattern: srcPortPtn)
+
+    if not portChan.trySend(info):
+      writeLine stderr, "Port connecter channel overflow!"
+
+proc portConnecterProc(app: App) {.thread.} =
+    var info: ConnectionInfo
+    addHandler(app.logger)
+    setLogFilter(when defined(release): lvlInfo else: lvlDebug)
+
+    while true:
+      portChan.recv(info)
+
+      if info.name == "":
+        break
+
+      debug &"New port: {info.name}"
+
+      if contains(info.name, re(info.pattern)):
+        if portConnectedTo(midiPort, info.name.cstring) != 1:
+          if app.client.connect(info.name.cstring, portName(app.midiIn)) != 1:
+            debug &"Connected input to port {info.name}"
+          else:
+            warn &"Failed to connect to port {info.name}"
+
+proc main() =
+  addHandler(log)
+
+  # Create JACK client
+  setErrorFunction(errorCb)
+  jclient = clientOpen("zoom2transport", NoStartServer or UseExactName, status.addr)
+  debug "JACK server status: " & $status
+
+  if jclient == nil:
+    error getJackStatusErrorString(status)
+    quit QuitFailure
+
+  # Set up signal handlers to clean up on exit
+  when defined(windows):
+    setSignalProc(signalCb, SIGABRT, SIGINT, SIGTERM)
+  else:
+    setSignalProc(signalCb, SIGABRT, SIGHUP, SIGINT, SIGQUIT, SIGTERM)
+
+  # Create output port
+  midiPort = jclient.portRegister("midi_in", JACK_DEFAULT_MIDI_TYPE, PortIsInput, 0)
+  var app = App(client: jclient, logger: log, midiIn: midiPort)
+
+  portChan = newChan[ConnectionInfo]()
+  createThread(portConnecter, portConnecterProc, app)
+
+  # Register JACK callbacks
+  if jclient.setProcessCallback(processCb, app.addr) != 0:
+    error "Could not set JACK process callback function."
+    cleanup()
+    quit QuitFailure
+
+  jclient.onShutdown(shutdownCb)
+
+  if paramCount() > 0:
+    srcPortPtn = paramStr(1)
+
+    if jclient.setPortRegistrationCallback(portRegisterCb) != 0:
+      error "Error: could not set JACK port registration callback."
+      cleanup()
+      quit QuitFailure
+  else:
+    srcPortPtn = ""
+
+  # Activate JACK client ...
+  if jclient.activate() == 0:
+    # try to connect input to port given via port pattern on command line
+    if srcPortPtn != "":
+      let srcPortName = findPort(jclient, srcPortPtn)
+
+      if srcPortName != "" and portConnectedTo(midiPort, srcPortName.cstring) != 1:
+        if jclient.connect(srcPortName.cstring, portName(midiPort)) != 1:
+          debug &"Connected input to port {srcPortName}"
+        else:
+          warn &"Failed to connect to port {srcPortName}"
+
+    # ... and keep running until a signal is received
+    while not exitSignalled:
+      sleep(100)
+
+  cleanup()
+
+
+when isMainModule:
+    main()