[fpc-pascal] (Unix) serial port handling

Henry Vermaak henry.vermaak at gmail.com
Wed Mar 9 12:47:28 CET 2011

On 09/03/11 11:30, Mark Morgan Lloyd wrote:
> Henry Vermaak wrote:
>> On 08/03/11 10:30, Mark Morgan Lloyd wrote:
>>> Can anybody say whether there is a good reason that serial.pp lacks a
>>> function to read the CD signal?
>>> Is SerFlush, which calls fpfsync, intended to discard input data, output
>>> data or both?
>> fsync just makes sure all the in-kernel caches are written to the
>> device. Flushing input data is just a matter of reading it.
> Thanks for that Henry. Obviously there's scope for confusion here with
> the kernel's tcflush() and tcdrain() functions, where tcflush discards
> input and/or output data.

You're right.  Thinking about it, I don't know what the use of an fsync 
is in SerFlush, since you still don't know if it's been transmitted. 
I'd consider this a bug, SerFlush should use tcdrain.


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