Thank for answer.
I replace tcflush(fd,TCIFLUSH) by
do {
err = read(fd,iobuffer,1000)
} while(err>0)
and it work OK on Win98.
I still have problem on Windows2000Sp2.
It seem that it hangs in functions:
tcsetattr(fd,TCSANOW,&newtio);
read(fd,iobuffer,1000);
write(fd,iobuffer,10);
Strange thing is, that it hangs from my point of view randomly.
Becase sometimes is operation successfully and other times it hangs (Windows:program
is not responding).
thank for help
Marty
> Cygwin's current tcflush implimentation is rather crude. Although, it may
> not be possible to do any better. PTC.
>
> if (queue == TCIFLUSH || queue == TCIOFLUSH)
> /* Input flushing by polling until nothing turns up
> (we stop after 1000 chars anyway) */
> for (int max = 1000; max > 0; max--)
> {
> COMSTAT st;
> if (!PurgeComm (get_handle (), PURGE_RXABORT | PURGE_RXCLEAR))
> break;
> low_priority_sleep (100);
> if (!ClearCommError (get_handle (), &ev, &st) || !st.cbInQue)
> break;
> }
>
> So, your not really hung. Just stuck for a long time.
>
> As a work around, tell the device to shut up first, then flush.
>
> On Mon, 13 Oct 2003, Martin Farnik wrote:
>
> > Hi.
> > I use CYGWIN_98-4.10 mine 1.5.5(0.94/3/2) 2003-09-20 16:31 i686 uknown
> > unknown Cygwin
> >
> > First i try to describe a situation:
> > I have a device which is connected with computer thru serial line.
> > Device is still sending data.These data isn't for my program.I have
> > open com port and let them go into buffer . When a want to talk with
> > device i flush input buffer, send it a command paket and device stop
> > sending data and wait for my next command.
> > Problem is when I want to flush INPUT buffer before I send a command. In
> > this point it hangs, maybe for buffer full.
> > Here is piece of code:
> >
> > -----I open port when i start program -----
> >
> > fd = open(PORT0, O_RDWR | O_NOCTTY );
> > tcgetattr(fd,&oldtio); /* save current port settings */
> >
> > bzero(&newtio, sizeof(newtio));
> > newtio.c_cflag = CS8 | CLOCAL | CREAD | CSTOPB;
> > newtio.c_iflag = 0;
> > newtio.c_oflag &= ~OPOST;
> > newtio.c_lflag = 0;
> >
> > newtio.c_cc[VTIME] = 1;
> > newtio.c_cc[VMIN] = 0;
> >
> > cfsetispeed(&newtio,B19200);
> > cfsetospeed(&newtio,B19200);
> > tcflush(fd, TCIFLUSH);
> > tcsetattr(fd,TCSANOW,&newtio);
> > -------------------------------------------------
> > --this code is execute when a want to talk with device----
> >
> > tcflush(fd, TCIFLUSH); <--------- in this point where it hangs
> > err = write (fd,iobuffer,10);
> >
>
> --
> Brian Ford
> Senior Realtime Software Engineer
> VITAL - Visual Simulation Systems
> FlightSafety International
> Phone: 314-551-8460
> Fax: 314-551-8444
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