Re: 1.5.18 ( 0.132/4/2 ) - read() - blocks ( serial programming )

[Igor Pechtchanski <pechtcha at cs dot nyu dot edu>]

Ugh, top-posting.  Reformatted...

On Tue, 23 Aug 2005, pppd wrote:

> De: cygwin-owner@XXXXXX.XXX
> Para: "pppd" pppd@XXXXX.XXX.XX
> Cópia: cygwin@XXXXXX.XXX

<http://cygwin.com/acronyms/#PCYMTNQREAIYR>.  Thanks.

> Data: Tue, 23 Aug 2005 15:08:59 -0400 (EDT)
> Assunto: Re: 1.5.18 ( 0.132/4/2 ) - read() - blocks ( serial programming )
>
> > On Tue, 23 Aug 2005, pppd wrote:
> >
> > > Hello guys,
> > >
> > >        I´m working to convert a Linux application to work with
> > > Windows XP under Cygwin 1.5.18 ( 0.132/4/2 ). Ncurses package and
> > > parallel port programming works without changes ( congratulations ).
> > > I have a problem with serial programming.
> > >
> > > First, I did two C files: ( attached )
> > >
> > >        setcmc7.c - Sets serial configuration through Win32 API. (
> > > Linux termios settings/functions doesn't work for me :-( ).
> > >        cmc7.c - Read caracters from serial.
> > >
> > > After setting serial configuration by setcmc7.c I can read serial port
> > > using cmc7.
> > >
> > > My doubt is: Why read() function blocks the terminal (keyboard) until
> > > read a caracter ? At Linux it's work fine ( same code ).
> > >
> > > My application needs to read keyboard at the same time with serial.
> > > I have tried some flags with open ( O_NONBLOCK, O_NDELAY .. )
> > > unfortunately doesn't work too.
> > >
> > > Does anybody can help me please?
>
> Igor,
>
>     Thanks for your advice.
>
> > I doubt the same code works on Linux, since open("COM1") will fail
> > there.
>
> It's work, of course we´ll need change "COM1" for "/dev/ttyS0" and will
> work on Linux.

Then why not use "/dev/ttyS0" on Cygwin?

> > You need to open something that Cygwin knows is a serial port, i.e.,
> > "/dev/ttyS0" (or "/dev/com1", but not "COM1").
>
>     I already tried it with /dev/ttyS0 and /dev/COM1 but doesn't work
> too.

Please post the exact program that doesn't work for you (and that uses the
known Cygwin serial device).

> Unfortunately keeping blocking my keyboard. Do you have an example
> "without block" for serial ?

I don't understand what "without block" means.  What is blocking?

Again, please post *code*, with expected results and actual results.

> BTW, "COM1" works for me like "/dev/com1" and "/dev/ttyS0" on Cygwin.

No it doesn't.  You may think it does, because it still communicates with
the serial port, but as far as Cygwin is concerned, "COM1" is a *file*,
not a serial device, so you won't be able to set any serial parameters,
and the behavior is going to be unpredictable.

> > Plus, you can probably write setcmc7.c using Cygwin calls as well
> > (instead of Win32, that is).
> > 	Igor
>
> Keeping blocking.. :(
> Could you help me ?

When you have posted a small reproducible testcase, people will try it out
on their machines to determine whether this is a general Cygwin issue, or
something with your local configuration.  But until we have the testcase,
it's impossible to debug this problem.
HTH,
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_		pechtcha@cs.nyu.edu
ZZZzz /,`.-'`'    -.  ;-;;,_		igor@watson.ibm.com
     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

If there's any real truth it's that the entire multidimensional infinity
of the Universe is almost certainly being run by a bunch of maniacs. /DA

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/