Programming

Hi,

I need to read incoming data from a serial port. I also need the read() to be non-blocking, such that my program can then check for any data to be send via the serial port. I followed some FAQs on the net, set read() to be non-blocking, and got EAGAIN errors popping out.

I realise that under non-blocking mode, it is normal to receive EAGAIN errors. Thus, the next thing I did, is try using select().

Is select() also blocking? How do I use select()?
Can someone provide me some codes or any directions to get started on select()?

Thanks!

Is this what you were looking for?
http://beej.us/guide/bgnet/output/ht....html#blocking

Select lets the system efficiently wait for events on a number of file descriptors or else timeout. Any X application has select as the call that is executed when the application has nothing to do.

There are three sets of filedescriptors, those for reading, those for writing and those for exceptional conditions, a file descriptor may be in multiple sets.

When you get EGAIN or EWOULDBLOCK use select to tell you when the filedescriptor is ready again.

fd_set fds;
FD_ZERO(&fds);
FD_SET(fd,&fds);
i=select(fd+1,&fds,NULL,NULL,NULL);
if (i>0)
{
if (FD_ISSET(fd,&fds)) { do your thing )
}

Hey thanks for the replies.
It really helps