Original Post
Hi, we are programming a robot in a project at the university, and I thought you might be able to answer a question about boost asio's read function. We are going to communicate from a laptop with the robot, over bluetooth, via a firefly connected to the computers serial port. So long, I think I have managed the outgoing data correctly, using boost::asio::write. However, now I think I need some help with the incoming data (the boost asio documentation is, well ... limited). All messages starts with a header at one byte. The header specifies which message type has been sent. Each message has a unique length which I store in an array called message_lengths. I had imagined the code to loke something like this:
void user_interface::check_for_incoming_messages()
{
boost::asio::streambuf response;
boost::system::error_code error;
std::string s1, s2;
if (boost::asio::read(port, response, boost::asio::transfer_at_least(0), error)) {
convert_streambuf_to_string(response, s1);
int msg_code = s1[0];
if (msg_code < 0 || msg_code >= NUM_MESSAGES) {
// Handle error, invalid message header
}
if (boost::asio::read(port, response, boost::asio::transfer_at_least(message_lengths[msg_code]-s1.length()), error)) {
response >> s2;
// Handle the content of s1 and s2
}
else if (error != boost::asio::error::eof) {
throw boost::system::system_error(error);
}
}
else if (error != boost::asio::error::eof) {
throw boost::system::system_error(error);
}
}
