public string Open()
{
// Open the port
var st = AlsaNativeMethods.Snd_rawmidi_open_input(
ref handle, IntPtr.Zero, Device, AlsaNativeMethods.EMode.SND_RAWMIDI_NONBLOCK);
return(AlsaUtils.StrError(st));
}
public string Start()
{
int st = (int)AlsaNativeMethods.Snd_rawmidi_read(handle, null, 0);
if (st == 0)
{
stop = false;
readThread = new Thread(ReadThreadStart);
readThread.Start();
}
return(AlsaUtils.StrError(st));
}
public string Close()
{
int st = 0;
if (handle != IntPtr.Zero)
{
st = AlsaNativeMethods.Snd_rawmidi_close(handle);
handle = IntPtr.Zero;
}
return(AlsaUtils.StrError(st));
}
// Send a message
public string Send(MidiMessage m)
{
byte[] data = m.GetAsByteArray();
// Meta messages are not sent over the wire
if (data == null)
{
return(null);
}
ulong size = (ulong)data.Length;
long st = AlsaNativeMethods.Snd_rawmidi_write(handle, data, size);
return(AlsaUtils.StrError((int)st));
}
private void ReadThreadStart()
{
byte[] buf = new byte[512];
byte[] overflowBuf = null;
// Compute number of pollfd structures required to poll
int numPollStructs = AlsaNativeMethods.Snd_rawmidi_poll_descriptors_count(handle);
// Allocate space for the poll structures
IntPtr pollAreaPtr = Marshal.AllocHGlobal(numPollStructs * AlsaNativeMethods.POLLFDSZ);
int st = AlsaNativeMethods.Snd_rawmidi_poll_descriptors(handle, pollAreaPtr, (uint)numPollStructs);
while (!stop)
{
st = AlsaNativeMethods.Poll(pollAreaPtr, numPollStructs, 200);
if (st < 0)
{
var errno = Marshal.GetLastWin32Error();
if (errno == 4 /* EINTR */)
{
continue;
}
Console.WriteLine("MidiIn: Cannot poll - errno = " + errno);
break;
}
if (st == 0)
{
continue;
}
// We got something - scan the poll struct
ushort revent = 0;
st = AlsaNativeMethods.Snd_rawmidi_poll_descriptors_revents(
handle, pollAreaPtr, (uint)numPollStructs, ref revent);
if (st < 0)
{
Console.WriteLine("MidiIn: Cannot parse poll - " + AlsaUtils.StrError(st));
break;
}
AlsaNativeMethods.EPoll evt = (AlsaNativeMethods.EPoll)revent;
if (evt.HasFlag(AlsaNativeMethods.EPoll.POLLERR) ||
evt.HasFlag(AlsaNativeMethods.EPoll.POLLHUP))
{
break;
}
if (evt.HasFlag(AlsaNativeMethods.EPoll.POLLIN))
{
// We have something to read - read it
int nRead = (int)AlsaNativeMethods.Snd_rawmidi_read(handle, buf, (uint)buf.Length);
if (nRead < 0)
{
int errno = Marshal.GetLastWin32Error();
if (errno == 4 /* EINTR */)
{
continue;
}
Console.WriteLine("MidiIn: Cannot parse poll - " + AlsaUtils.StrError(st));
break;
}
// Combine with overflow buffer if we had an overflow last time
if (overflowBuf != null)
{
var newBuf = new byte[buf.Length + overflowBuf.Length];
Array.Copy(overflowBuf, 0, newBuf, 0, overflowBuf.Length);
Array.Copy(buf, 0, newBuf, overflowBuf.Length, buf.Length);
buf = newBuf;
overflowBuf = null;
}
// Translate the input to midi message
int nParsed = 0;
while (true)
{
st = ParseBuffer(buf, nParsed, nRead, out MidiMessage midiMessage);
if (st < 0)
{
// buffer contains an incomplete message
overflowBuf = buf;
buf = new byte[overflowBuf.Length];
}
else if (st == 0)
{
// Message not supported - drop everything.
break;
}
else // st > 0
{
// Send message
var midiEvent = new MidiEvent(midiMessage, 0);
var midiEventArg = new WindowsMultiMedia.WindowsMidiEventArgs(midiEvent, IntPtr.Zero, IntPtr.Zero);
MidiInputReceived?.Invoke(this, midiEventArg);
// Update counters
nParsed += st;
nRead -= st;
if (nRead <= 0)
{
// Normal end
break;
}
}
}
}
}
Marshal.FreeHGlobal(pollAreaPtr);
}
public string Reset()
{
int st = AlsaNativeMethods.Snd_rawmidi_drop(handle);
return(AlsaUtils.StrError(st));
}