private Task <ViscaPacket> SendAsync(CancellationToken cancellationToken, params byte[] packet)
{
var effectiveToken = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, new CancellationTokenSource(CommandTimeout).Token).Token;
var request = ViscaPacket.FromBytes(packet, 0, packet.Length);
return(client.SendAsync(request, effectiveToken));
}
internal async Task <ViscaPacket> ReadAsync(Stream stream, CancellationToken cancellationToken)
{
while (true)
{
if (FindEnd() is int count)
{
return(Consume(count));
}
if (size == buffer.Length)
{
// TODO: Should our buffer be smaller?
throw new ViscaProtocolException($"Read {size} bytes without a reaching the end of a VISCA packet");
}
using (var registration = cancellationToken.Register(() => stream.Close()))
{
int bytesRead = await stream.ReadAsync(buffer, size, buffer.Length - size).ConfigureAwait(false);
if (bytesRead == 0)
{
throw new ViscaProtocolException("Reached end of VISCA stream");
}
size += bytesRead;
}
}
int?FindEnd()
{
for (int i = 0; i < size; i++)
{
if (buffer[i] == 0xff)
{
// Include the trailing byte
return(i + 1);
}
}
return(null);
}
ViscaPacket Consume(int count)
{
// Exclude the trailing byte from the packet
var packet = ViscaPacket.FromBytes(buffer, 0, count - 1);
size -= count;
// Shift the content of the array if we need to.
// (Alternatively, we could construct the packet from middle of the byte array,
// and only shift when we got near the end of the buffer. It really shouldn't matter much though.)
if (size != 0)
{
Buffer.BlockCopy(buffer, count, buffer, 0, size);
}
return(packet);
}
}
