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);
}
// Forward callback to user-provided function
private void MidiProc(IntPtr hMidiIn,
EMMMidiMessages wMsg,
IntPtr dwInstance,
IntPtr dwParam1,
IntPtr dwParam2)
{
if (wMsg == EMMMidiMessages.MIM_DATA)
{
if (MidiInputReceived != null)
{
// Make a midi event out of the incoming params
MidiEvent e = MidiInParser.ParseMimDataMessage((uint)dwParam1, (uint)dwParam2);
// Give it to the user
MidiInputReceived.Invoke(this, new WindowsMidiEventArgs(e, dwParam1, dwParam2));
}
}
else if (wMsg == EMMMidiMessages.MIMLONG_DATA)
{
// The first parameter is a pointer to a buffer descriptor
var header = dwParam1;
// Find this buffer in our buffer set
int index = (int)MidiBuffer.GetUserData(header);
if (index < 0 || index >= buffers.Length)
{
throw new InvalidOperationException("midiInputPort: MIMLONG_DATA buffer not found - index " + index);
}
var buffer = buffers[index];
if (buffer != null)
{
// Get data from buffer
var data = buffer.GetRecordedData();
if (data.Length == 0)
{
// This happens on Reset(), all the buffers are freed by windows and we get a MIMLONG_DATA for each of them.
// Free the buffer.
buffer.RemoveMidiInBuffer(handle);
buffer.Dispose();
buffers[index] = null;
}
else
{
// Give the buffer back to windows, we are done with it
buffer.AddMidiInBuffer(handle);
// If we have a callback, either generate a sysex or
// memorize the data if we don't have a full sysex
if (MidiInputReceived != null)
{
MidiSysexMessage sysex = null;
if (data[0] == (byte)EMidiCommand.SystemExclusive)
{
// This buffer contains the beginning of the sysex - check we don't have an ongoing sysex
if (this.partialSysex != null)
{
throw new InvalidOperationException("midiInputPort: Beginning of new sysex received while previous one still on-going");
}
if (data[data.Length - 1] == (byte)EMidiCommand.EndOfSystemExclusive)
{
// This buffer contains a full sysex
sysex = new MidiSysexMessage(data);
}
else
{
// This buffer contains the beginning of a sysex
this.partialSysex = data;
}
}
else
{
// This buffer is a continuation of a sysex. Verify we have an ongoing sysex
if (this.partialSysex == null)
{
throw new InvalidOperationException("midiInputPort: Continuation sysex without beginning");
}
// Concatenate the partial data and the new data
var dataSoFar = new byte[partialSysex.Length + data.Length];
partialSysex.CopyTo(dataSoFar, 0);
data.CopyTo(dataSoFar, dataSoFar.Length);
if (data[data.Length - 1] == (byte)EMidiCommand.EndOfSystemExclusive)
{
// This buffer concludes the sysex
sysex = new MidiSysexMessage(dataSoFar);
this.partialSysex = null;
}
else
{
// This buffer contains a partial sysex, add it to the partial sysex
this.partialSysex = dataSoFar;
}
}
// Create sysex event if we have a sysex
if (sysex != null)
{
// Make a midi event out of the sysex
var e = new MidiEvent(sysex, (uint)dwParam2);
// Give it to the user
MidiInputReceived.Invoke(this, new WindowsMidiEventArgs(e, dwParam1, dwParam2));
}
}
}
}
}
}
