Hi all.

I am stuck porting a windows app to linux. In windows we have a waitforcommevent which keeps looking for RXCHAR event and I can use that condition to do a read on the serial port.

A similar approach in linux would be to use SIGIO interrupt and set a signal handler function to alter a global variable based on which I do a read port.

Is there a cleaner approach than this? The reason being that, I have blocked SIGIO when I am doing a "read", but while doing that I also do a IOCTL for FIONREAD, to get the number of chars in the comport. Probably this generates a SIGIO(which as told before I am blocking, till I complete "read". ), and I am getting wront character counts and my program crashes.

Well, you might say I could have blocked SIGIO after IOCTL and before 'read', but read is inside a big function and I don't want SIGIO happening when this function is going on.

Could any of you signal experts tell me what is the best approach to know that a character has arrived to be read in the serial port. I am requesting an approach very similar to what we have in windows.

Thanks
KD

the question is 'what is your aim ?'.
there is a seriel-programming-howto explaining all stuff. what to use depends on your exact problem. seriell devices are special since they are deeply connected with terminal servers.
but this can be an advantage if you know what you want.

This is one of the very best serial port programming guides for Linux:
http://www.easysw.com/~mike/serial/

grumpf:

I have clearly explained the aim. Not sure how elaborate can I get. But probably it was confusing. In any case, I meddled around a little and resolved he issue. IOCTL for FIONREAD does not raise SIGIO. I was stuck somewhere else. so no issues.

jim mcnamara:

thanks. but i used the guide earlier and its very very limited. serial comm is much much much more than what he has explained in simple terms. but for starters yes, there is nothing better than this guide. but it fails misreably in the "read" department.