Re: Serial port buffering?


Grant Edwards wrote:
On 2006-10-28, Charles Sullivan <cwsulliv@xxxxxxxxxxxx> wrote:

Do the standard RS232 serial port drivers in Linux/Unix
provide any buffering of received characters other than
whatever hardware buffers are in the UART?

Yes. The last time I looked, they provde 1 page buffers for
both rx and tx (on an IA32 machine, that's 4KB).

I'm wondering how to handle the situation where a burst
of perhaps several hundred characters arrives at the
serial port (with no flow control) and a process can't
wait for them all to arrive before starting what may be
a relatively time-consuming analysis. (Assuming that
the analysis can be completed before another burst
arrives.)

It should be fine unless you let more than 4K of unread bytes
get queued up -- then data gets dropped.

The flip buffer is only 512 bytes, the N_TTY buffer is 4K, so I think
its better to rely on flip buffer which is 512 byte.

--
Grant Edwards grante Yow! Is this an out-take
at from the "BRADY BUNCH"?
visi.com

.

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