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

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

src/machine/usb/adc/doc.go

@@ -0,0 +1,2 @@
+// package adc is for USB Audio Device Class devices.
+package adc

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

@@ -0,0 +1,52 @@
+package midi
+
+import (
+	"runtime/volatile"
+)
+
+const bufferSize = 128
+
+// RingBuffer is ring buffer implementation inspired by post at
+// https://www.embeddedrelated.com/showthread/comp.arch.embedded/77084-1.php
+type RingBuffer struct {
+	rxbuffer [bufferSize][4]byte
+	head     volatile.Register8
+	tail     volatile.Register8
+}
+
+// NewRingBuffer returns a new ring buffer.
+func NewRingBuffer() *RingBuffer {
+	return &RingBuffer{}
+}
+
+// Used returns how many bytes in buffer have been used.
+func (rb *RingBuffer) Used() uint8 {
+	return uint8(rb.head.Get() - rb.tail.Get())
+}
+
+// Put stores a byte in the buffer. If the buffer is already
+// full, the method will return false.
+func (rb *RingBuffer) Put(val []byte) bool {
+	if rb.Used() != bufferSize {
+		rb.head.Set(rb.head.Get() + 1)
+		copy(rb.rxbuffer[rb.head.Get()%bufferSize][:], val)
+		return true
+	}
+	return false
+}
+
+// Get returns a byte from the buffer. If the buffer is empty,
+// the method will return a false as the second value.
+func (rb *RingBuffer) Get() ([]byte, bool) {
+	if rb.Used() != 0 {
+		rb.tail.Set(rb.tail.Get() + 1)
+		return rb.rxbuffer[rb.tail.Get()%bufferSize][:], true
+	}
+	return nil, false
+}
+
+// Clear resets the head and tail pointer to zero.
+func (rb *RingBuffer) Clear() {
+	rb.head.Set(0)
+	rb.tail.Set(0)
+}

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

@@ -0,0 +1,19 @@
+package midi
+
+// NoteOn sends a note on message.
+func (m *midi) NoteOn(cable, channel uint8, note Note, velocity uint8) {
+	m.msg[0], m.msg[1], m.msg[2], m.msg[3] = (cable&0xf<<4)|0x9, 0x90|(channel&0xf), byte(note)&0x7f, velocity&0x7f
+	m.Write(m.msg[:])
+}
+
+// NoteOff sends a note off message.
+func (m *midi) NoteOff(cable, channel uint8, note Note, velocity uint8) {
+	m.msg[0], m.msg[1], m.msg[2], m.msg[3] = (cable&0xf<<4)|0x8, 0x80|(channel&0xf), byte(note)&0x7f, velocity&0x7f
+	m.Write(m.msg[:])
+}
+
+// SendCC sends a continuous controller message.
+func (m *midi) SendCC(cable, channel, control, value uint8) {
+	m.msg[0], m.msg[1], m.msg[2], m.msg[3] = (cable&0xf<<4)|0xB, 0xB0|(channel&0xf), control&0x7f, value&0x7f
+	m.Write(m.msg[:])
+}

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)
+	}
+}

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

@@ -0,0 +1,108 @@
+package midi
+
+// Note represents a MIDI note number. For example, Note(69) is A4 or 440Hz.
+type Note uint8
+
+// Define all the notes in a format similar to the Tone library in the Arduino
+// IDE.
+const (
+	A0 Note = iota + 21 // 27.5Hz
+	AS0
+	B0
+	C1
+	CS1
+	D1
+	DS1
+	E1
+	F1
+	FS1
+	G1
+	GS1
+	A1 // 55Hz
+	AS1
+	B1
+	C2
+	CS2
+	D2
+	DS2
+	E2
+	F2
+	FS2
+	G2
+	GS2
+	A2 // 110Hz
+	AS2
+	B2
+	C3
+	CS3
+	D3
+	DS3
+	E3
+	F3
+	FS3
+	G3
+	GS3
+	A3 // 220Hz
+	AS3
+	B3
+	C4
+	CS4
+	D4
+	DS4
+	E4
+	F4
+	FS4
+	G4
+	GS4
+	A4 // 440Hz
+	AS4
+	B4
+	C5
+	CS5
+	D5
+	DS5
+	E5
+	F5
+	FS5
+	G5
+	GS5
+	A5 // 880Hz
+	AS5
+	B5
+	C6
+	CS6
+	D6
+	DS6
+	E6
+	F6
+	FS6
+	G6
+	GS6
+	A6 // 1760Hz
+	AS6
+	B6
+	C7
+	CS7
+	D7
+	DS7
+	E7
+	F7
+	FS7
+	G7
+	GS7
+	A7 // 3520Hz
+	AS7
+	B7
+	C8
+	CS8
+	D8
+	DS8
+	E8
+	F8
+	FS8
+	G8
+	GS8
+	A8 // 7040Hz
+	AS8
+	B8
+)