private unsafe int ProcessRead(SerialStreamIORequest r)
{
SerialStreamReadRequest readRequest = (SerialStreamReadRequest)r;
Span <byte> buff = readRequest.Buffer.Span;
fixed(byte *bufPtr = buff)
{
// assumes dequeue-ing happens on a single thread
int numBytes = Interop.Serial.Read(_handle, bufPtr, buff.Length);
if (numBytes < 0)
{
Interop.ErrorInfo lastError = Interop.Sys.GetLastErrorInfo();
// ignore EWOULDBLOCK since we handle timeout elsewhere
if (lastError.Error != Interop.Error.EWOULDBLOCK)
{
readRequest.Complete(Interop.GetIOException(lastError));
}
}
else if (numBytes > 0)
{
readRequest.Complete(numBytes);
return(numBytes);
}
else // numBytes == 0
{
RaiseDataReceivedEof();
}
}
return(0);
}
public override ValueTask <int> ReadAsync(Memory <byte> buffer, CancellationToken cancellationToken = default)
{
CheckHandle();
if (buffer.IsEmpty)
{
return(new ValueTask <int>(0));
}
SerialStreamReadRequest result = new SerialStreamReadRequest(cancellationToken, buffer);
_readQueue.Enqueue(result);
EnsureIOLoopRunning();
return(new ValueTask <int>(result.Task));
}
public override Task <int> ReadAsync(byte[] array, int offset, int count, CancellationToken cancellationToken)
{
CheckReadWriteArguments(array, offset, count);
if (count == 0)
{
return(Task <int> .FromResult(0)); // return immediately if no bytes requested; no need for overhead.
}
Memory <byte> buffer = new Memory <byte>(array, offset, count);
SerialStreamReadRequest result = new SerialStreamReadRequest(cancellationToken, buffer);
_readQueue.Enqueue(result);
EnsureIOLoopRunning();
return(result.Task);
}
