/// <summary>
/// Send command to Lego RCX brick and read reply.
/// </summary>
///
/// <param name="command">Command to send.</param>
/// <param name="reply">Buffer to receive reply into.</param>
/// <param name="expectedReplyLen">Expected reply length.</param>
///
/// <returns>Returns <b>true</b> if the command was sent successfully and reply was
/// received, otherwise <b>false</b>.</returns>
///
/// <exception cref="NullReferenceException">Communication can not be performed, because connection with
/// RCX brick was not established yet.</exception>
/// <exception cref="ArgumentException">Reply buffer size is smaller than the reply data size.</exception>
/// <exception cref="ApplicationException">Reply does not correspond to command (first byte of reply
/// should be complement (bitwise NOT) to the first byte of command orred with 0x08).</exception>
///
protected bool SendCommand(byte[] command, byte[] reply, int expectedReplyLen)
{
bool result = false;
uint status;
IntPtr queue;
lock ( sync )
{
// check if GhostAPI stack was created (if device is connected)
if (stack == IntPtr.Zero)
{
throw new NullReferenceException("Not connected to RCX brick");
}
// create command queue
status = GhostAPI.GhCreateCommandQueue(out queue);
if (!GhostAPI.PBK_SUCCEEDED(status))
{
return(false);
}
// append command to the queue
status = GhostAPI.GhAppendCommand(queue, command, command.Length, expectedReplyLen);
if (GhostAPI.PBK_SUCCEEDED(status))
{
// execute command
status = GhostAPI.GhExecute(stack, queue);
if (GhostAPI.PBK_SUCCEEDED(status))
{
IntPtr commandHandle;
uint replyLen;
// get first command and its reply data lenght
if (
(GhostAPI.PBK_SUCCEEDED(GhostAPI.GhGetFirstCommand(queue, out commandHandle))) &&
(GhostAPI.PBK_SUCCEEDED(GhostAPI.GhGetCommandReplyLen(commandHandle, out replyLen)))
)
{
// check provided reply buffer size
if (reply.Length < replyLen)
{
throw new ArgumentException("Reply buffer is too small");
}
// get reply data
status = GhostAPI.GhGetCommandReply(commandHandle, reply, replyLen);
if (GhostAPI.PBK_SUCCEEDED(status))
{
// check that reply corresponds to command
if ((command[0] | 0x08) != (byte)~reply[0])
{
throw new ApplicationException("Reply does not correspond to command");
}
result = true;
}
}
}
}
// destroy command queue
GhostAPI.GhDestroyCommandQueue(queue);
}
return(result);
}