func (s *SystemPort) Open() error {
if s.isOpen && s.stream == nil {
return errors.New("Underlying portmidi port is already opened, " +
"but stream is not connected to this SystemPort.")
}
if s.id == -1 || s.isOpen { // Fake port or opened already, ignore.
return nil
}
var errNum C.PmError
if s.IsInputPort {
// The input / output naming LOOKS backwards, but we're opening a
// portmidi "output stream" for input Ports and vice versa.
errNum = C.Pm_OpenOutput(&(s.stream), C.PmDeviceID(s.id),
nil, C.int32_t(512), nil, nil, 0)
} else {
errNum = C.Pm_OpenInput(&(s.stream), C.PmDeviceID(s.id),
nil, C.int32_t(512), nil, nil)
}
if errNum == 0 {
s.isOpen = true
s.stop = make(chan bool, 1)
s.noteOns = make(chan Note, BufferSize)
s.noteOffs = make(chan Note, BufferSize)
s.controlChanges = make(chan ControlChange, BufferSize)
}
return makePortMidiError(errNum)
}
func getSystemDevices() (inputs, outputs []SystemDevice) {
numDevices := int(C.Pm_CountDevices())
for i := 0; i < numDevices; i++ {
info := C.Pm_GetDeviceInfo(C.PmDeviceID(i))
name := C.GoString(info.name)
var isInputPort, isOutputPort, isOpen bool
if info.output > 0 { // "output" means "output stream" in portmidi-speak.
isInputPort = true // An OUTPUT stream is for an INPUT port.
}
if info.input > 0 { // "input" means "input stream" in portmidi-speak.
isOutputPort = true // An INPUT stream is for an OUTPUT port.
}
if info.opened > 0 {
isOpen = true
}
port := &SystemPort{isOpen: isOpen, id: i, IsInputPort: isInputPort}
device := SystemDevice{Name: name}
if isInputPort {
device.inPort = port
device.outPort = &SystemPort{isOpen: false, id: -1}
inputs = append(inputs, device)
} else if isOutputPort {
device.outPort = port
device.inPort = &SystemPort{isOpen: false, id: -1}
outputs = append(outputs, device)
}
}
return inputs, outputs
}
// Returns the device info for the device indentified with deviceId.
func GetDeviceInfo(deviceId DeviceID) *DeviceInfo {
info := C.Pm_GetDeviceInfo(C.PmDeviceID(deviceId))
return &DeviceInfo{
Interface: C.GoString(info.interf),
Name: C.GoString(info.name),
IsInputAvailable: info.input > 0,
IsOutputAvailable: info.output > 0,
IsOpened: info.opened > 0,
}
}
// Initializes a new output stream.
func NewOutputStream(deviceId DeviceId, bufferSize int64, latency int64) (stream *Stream, err error) {
var str *C.PmStream
errCode := C.Pm_OpenOutput(
(*unsafe.Pointer)(unsafe.Pointer(&str)),
C.PmDeviceID(deviceId), nil, C.int32_t(bufferSize), nil, nil, C.int32_t(latency))
if errCode != 0 {
return nil, convertToError(errCode)
}
return &Stream{deviceId: deviceId, pmStream: str}, nil
}
// NewOutputStream initializes a new output stream.
func NewOutputStream(id DeviceID, bufferSize int64, latency int64) (stream *Stream, err error) {
var str *C.PmStream
errCode := C.Pm_OpenOutput(
(*unsafe.Pointer)(unsafe.Pointer(&str)),
C.PmDeviceID(id), nil, C.int32_t(bufferSize), nil, nil, C.int32_t(latency))
if errCode != 0 {
return nil, convertToError(errCode)
}
if info := Info(id); !info.IsOutputAvailable {
return nil, ErrOutputUnavailable
}
return &Stream{deviceID: id, pmStream: str}, nil
}
// Initializes a new input stream.
func NewInputStream(deviceId DeviceID, bufferSize int64) (stream *Stream, err error) {
var str *C.PmStream
errCode := C.Pm_OpenInput(
(*unsafe.Pointer)(unsafe.Pointer(&str)),
C.PmDeviceID(deviceId), nil, C.int32_t(bufferSize), nil, nil)
if errCode != 0 {
return nil, convertToError(errCode)
}
if info := GetDeviceInfo(deviceId); !info.IsInputAvailable {
return nil, ErrInputUnavailable
}
return &Stream{deviceId: deviceId, pmStream: str}, nil
}