/// <summary>
/// Begins an asynchronous write operation.
/// </summary>
/// <param name="buffer">The buffer to write data from.</param>
/// <param name="offset">The byte offset in buffer from which to begin writing.</param>
/// <param name="count">The maximum number of bytes to write.</param>
/// <param name="callback">An optional asynchronous callback, to be called when the write is complete.</param>
/// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests.</param>
/// <returns>An IAsyncResult that represents the asynchronous write, which could still be pending.</returns>
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
WriteCheck(buffer, offset, count);
if (count == 0 || m_SerialPort.SerialPortIo.WaitForWriteEvent(count, m_WriteTimeout)) {
LocalAsync ar = new LocalAsync(state);
if (count > 0) {
InternalWrite(buffer, offset, count);
}
ar.IsCompleted = true;
ar.CompletedSynchronously = true;
if (callback != null) callback(ar);
return ar;
} else {
WriteDelegate write = this.InternalBlockingWrite;
return write.BeginInvoke(buffer, offset, count, callback, state);
}
}
/// <summary>
/// Begins an asynchronous read operation.
/// </summary>
/// <param name="buffer">The buffer to read the data into.</param>
/// <param name="offset">The byte offset in <paramref name="buffer"/> at which to begin writing data read from the stream.</param>
/// <param name="count">The maximum number of bytes to read.</param>
/// <param name="callback">An optional asynchronous callback, to be called when the read is complete.</param>
/// <param name="state">A user-provided object that distinguishes this particular asynchronous read request from other requests.</param>
/// <returns>An <see cref="System.IAsyncResult"/> object to be used with <see cref="EndRead"/>.</returns>
public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
ReadCheck(buffer, offset, count);
if (count == 0 || m_SerialPort.SerialPortIo.WaitForReadEvent(0)) {
// Data in the buffer, we can return immediately
LocalAsync<int> ar = new LocalAsync<int>(state);
if (count > 0) {
ar.Result = InternalRead(buffer, offset, count);
} else {
ar.Result = 0;
}
ar.IsCompleted = true;
ar.CompletedSynchronously = true;
if (callback != null) callback(ar);
return ar;
} else {
// No data in buffer, so we create a thread in the background
ReadDelegate read = this.InternalBlockingRead;
return read.BeginInvoke(buffer, offset, count, callback, state);
}
}
