machine/usb/adc/midi: improve code readability and error handling tha…

…nks to helpful feedback from community Signed-off-by: deadprogram <[email protected]>
tinygo-org · Sep 5, 2023 · e138256 · e138256
1 parent 7973f06
commit e138256
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Showing 2 changed files with 51 additions and 83 deletions.
diff --git a/src/machine/usb/adc/midi/messages.go b/src/machine/usb/adc/midi/messages.go
@@ -88,15 +88,12 @@ var (
 // The cable parameter is the cable number 0-15.
 // The channel parameter is the MIDI channel number 1-16.
 func (m *midi) NoteOn(cable, channel uint8, note Note, velocity uint8) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if channel == 0 || channel > 16 {
+	case channel == 0 || channel > 16:
 		return errInvalidMIDIChannel
-	}
-
-	if velocity > 127 {
+	case velocity > 127:
 		return errInvalidMIDIVelocity
 	}
 
@@ -109,15 +106,12 @@ func (m *midi) NoteOn(cable, channel uint8, note Note, velocity uint8) error {
 // The cable parameter is the cable number 0-15.
 // The channel parameter is the MIDI channel number 1-16.
 func (m *midi) NoteOff(cable, channel uint8, note Note, velocity uint8) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if channel == 0 || channel > 16 {
+	case channel == 0 || channel > 16:
 		return errInvalidMIDIChannel
-	}
-
-	if velocity > 127 {
+	case velocity > 127:
 		return errInvalidMIDIVelocity
 	}
 
@@ -132,19 +126,14 @@ func (m *midi) NoteOff(cable, channel uint8, note Note, velocity uint8) error {
 // The control parameter is the controller number 0-127.
 // The value parameter is the controller value 0-127.
 func (m *midi) ControlChange(cable, channel, control, value uint8) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if channel == 0 || channel > 16 {
+	case channel == 0 || channel > 16:
 		return errInvalidMIDIChannel
-	}
-
-	if control > 127 {
+	case control > 127:
 		return errInvalidMIDIControl
-	}
-
-	if value > 127 {
+	case value > 127:
 		return errInvalidMIDIControlValue
 	}
 
@@ -158,15 +147,12 @@ func (m *midi) ControlChange(cable, channel, control, value uint8) error {
 // The channel parameter is the MIDI channel number 1-16.
 // The patch parameter is the program number 0-127.
 func (m *midi) ProgramChange(cable, channel uint8, patch uint8) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if channel == 0 || channel > 16 {
+	case channel == 0 || channel > 16:
 		return errInvalidMIDIChannel
-	}
-
-	if patch > 127 {
+	case patch > 127:
 		return errInvalidMIDIPatch
 	}
 
@@ -182,15 +168,12 @@ func (m *midi) ProgramChange(cable, channel uint8, patch uint8) error {
 // Setting bend above 0x2000 (up to 0x3FFF) will increase the pitch.
 // Setting bend below 0x2000 (down to 0x0000) will decrease the pitch.
 func (m *midi) PitchBend(cable, channel uint8, bend uint16) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if channel == 0 || channel > 16 {
+	case channel == 0 || channel > 16:
 		return errInvalidMIDIChannel
-	}
-
-	if bend > 0x3FFF {
+	case bend > 0x3FFF:
 		return errInvalidMIDIPitchBend
 	}
 
@@ -207,59 +190,44 @@ func (m *midi) PitchBend(cable, channel uint8, bend uint16) error {
 // The data slice should not include the SysEx start (0xF0) or
 // end (0xF7) bytes, only the data in between.
 func (m *midi) SysEx(cable uint8, data []byte) error {
-	if cable > 15 {
+	switch {
+	case cable > 15:
 		return errInvalidMIDICable
-	}
-
-	if len(data) < 3 {
+	case len(data) < 3:
 		return errInvalidMIDISysExData
 	}
 
+	// write start
 	m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExStart, MsgSysExStart
 	m.msg[2], m.msg[3] = data[0], data[1]
-
 	if _, err := m.Write(m.msg[:]); err != nil {
 		return err
 	}
 
-	for i := 2; i <= len(data); i += 3 {
-		switch len(data) - i {
-		case 2:
-			m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd3, data[i]
-			m.msg[2], m.msg[3] = data[i+1], MsgSysExEnd
-
-			if _, err := m.Write(m.msg[:]); err != nil {
-				return err
-			}
-
-			break
-		case 1:
-			m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd2, data[i]
-			m.msg[2], m.msg[3] = MsgSysExEnd, 0
-
-			if _, err := m.Write(m.msg[:]); err != nil {
-				return err
-			}
-
-			break
-		case 0:
-			m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd1, MsgSysExEnd
-			m.msg[2], m.msg[3] = 0, 0
-
-			if _, err := m.Write(m.msg[:]); err != nil {
-				return err
-			}
-
-			break
-		default:
-			m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExStart, data[i]
-			m.msg[2], m.msg[3] = data[i+1], data[i+2]
-
-			if _, err := m.Write(m.msg[:]); err != nil {
-				return err
-			}
+	// write middle
+	i := 2
+	for ; i < len(data)-2; i += 3 {
+		m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExStart, data[i]
+		m.msg[2], m.msg[3] = data[i+1], data[i+2]
+		if _, err := m.Write(m.msg[:]); err != nil {
+			return err
 		}
 	}
+	// write end
+	switch len(data) - i {
+	case 2:
+		m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd3, data[i]
+		m.msg[2], m.msg[3] = data[i+1], MsgSysExEnd
+	case 1:
+		m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd2, data[i]
+		m.msg[2], m.msg[3] = MsgSysExEnd, 0
+	case 0:
+		m.msg[0], m.msg[1] = (cable&0xf<<4)|CINSysExEnd1, MsgSysExEnd
+		m.msg[2], m.msg[3] = 0, 0
+	}
+	if _, err := m.Write(m.msg[:]); err != nil {
+		return err
+	}
 
 	return nil
 }
diff --git a/src/machine/usb/adc/midi/midi.go b/src/machine/usb/adc/midi/midi.go
@@ -97,15 +97,15 @@ func (m *midi) sendUSBPacket(b []byte) {
 
 // from BulkIn
 func (m *midi) TxHandler() {
-	if m.txHandler != nil {
-		m.txHandler()
-	}
-
 	m.waitTxc = false
 	if b, ok := m.buf.Get(); ok {
 		m.waitTxc = true
 		m.sendUSBPacket(b)
 	}
+
+	if m.txHandler != nil {
+		m.txHandler()
+	}
 }
 
 func (m *midi) tx(b []byte) {