machine/usb: move MIDI under usb/adc (Audio Device Class) package

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/machine/usb/adc/midi/midi.go

@@ -0,0 +1,89 @@
+package midi
+
+import (
+	"machine"
+	"machine/usb"
+)
+
+const (
+	midiEndpointOut = usb.MIDI_ENDPOINT_OUT // from PC
+	midiEndpointIn  = usb.MIDI_ENDPOINT_IN  // to PC
+)
+
+var Midi *midi
+
+type midi struct {
+	msg       [4]byte
+	buf       *RingBuffer
+	rxHandler func([]byte)
+	waitTxc   bool
+}
+
+func init() {
+	if Midi == nil {
+		Midi = newMidi()
+	}
+}
+
+// New returns the USB MIDI port.
+// Deprecated, better to just use Port()
+func New() *midi {
+	return Port()
+}
+
+// Port returns the USB midi port.
+func Port() *midi {
+	return Midi
+}
+
+func newMidi() *midi {
+	m := &midi{
+		buf: NewRingBuffer(),
+	}
+	machine.EnableMIDI(m.Handler, m.RxHandler, nil)
+	return m
+}
+
+func (m *midi) SetHandler(rxHandler func([]byte)) {
+	m.rxHandler = rxHandler
+}
+
+func (m *midi) Write(b []byte) (n int, err error) {
+	i := 0
+	for i = 0; i < len(b); i += 4 {
+		m.tx(b[i : i+4])
+	}
+	return i, nil
+}
+
+// sendUSBPacket sends a MIDIPacket.
+func (m *midi) sendUSBPacket(b []byte) {
+	machine.SendUSBInPacket(midiEndpointIn, b)
+}
+
+// from BulkIn
+func (m *midi) Handler() {
+	m.waitTxc = false
+	if b, ok := m.buf.Get(); ok {
+		m.waitTxc = true
+		m.sendUSBPacket(b)
+	}
+}
+
+func (m *midi) tx(b []byte) {
+	if machine.USBDev.InitEndpointComplete {
+		if m.waitTxc {
+			m.buf.Put(b)
+		} else {
+			m.waitTxc = true
+			m.sendUSBPacket(b)
+		}
+	}
+}
+
+// from BulkOut
+func (m *midi) RxHandler(b []byte) {
+	if m.rxHandler != nil {
+		m.rxHandler(b)
+	}
+}