Re: low_latency flag

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Fri, 2003-11-21 16:59:50 -0500, Chuck Messenger <chuckm@rochester.rr.com>
wrote in message <bpm18m$73f$1@sea.gmane.org>:
> Luckily, I happened to notice a recent message on this list with the 
> word "low_latency".  This led me to discover the low_latency flag, which 
> you can set with "setserial /dev/ttyS0 low_latency".  This sets a 
> special mode on the port, which defeats some kernel-level buffering.  I 
> don't (yet) know how to set this mode programmatically -- I just call 
> system("...") from my code (yech!).

Looking at setserial's sources, something like this:

struct serial_struct serinfo;
fd = open ("/dev/ttySxx");
ioctl (fd, TIOCGSERIAL, &serinfo);
serinfo.flags |= 0x4000;
ioctl (fd, TIOCSSERIAL, &serinfo);
close (fd);

should do. Of course, not tested and missing all error handling:-(

MfG, JBG

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