[Merkaartor] Refactoring GPS/ directory

[Chris Browet]

>
> The run method of QGPSComDevice is a huge do-while loop that basically
> never goes to sleep. It is constantly polling for either a change of
> stopLoop or data available on the serial io-device.
>
> As a consequence the thread is constantly 'active' using resources like
> CPU time and consequently battery power. It is better to set up signals
> that will wake up your event loop on serial data available (readyRead
> signal on a QIODevice). Then you can have the run method enter the
> thread eventloop with exec(). Qt will be smart and put the thread to
> sleep and will get a kernel signal when there is something to read on
> the serial port filedescriptor.


Ok. I get you now. You can use signals if you want, but at the bottom of the
chain, there will always be a thread waiting for bytes coming in on the
serial line, it's just the way it is, so I'm not convinced this will save
CPU cycles or battery.
But, as I said, if you think it's better, go on.

>
> Not all GPS'es use RS-232 as the datatransport layer. For example
> bluetooth gps-es obviously use bluetooth.


Not everything serial uses a RS232 port (RS232 is an electronic standard,
defining voltage levels and so).
Every bluetooth GPS uses a virtual serial port to communicate. AFAIK, there
is no GPS specific service.
My GPS is an external plain bluetooth one and it's the only way I can
communicate with it.

>From the gpsd main page:
"gpsd is a service daemon that monitors one or more GPSes attached to a host
computer through serial or USB ports"

So, unless you use a usb GPS (an even usb is a serial protocol), there is
simply no added value that I can think of to use gpsd (besides the fact that
it is a Linux standard and that it is network enabled).

But I maybe miss something...

>
> gpsd is certainly something unix-y. And yes, we most definitly want to
> keep serial port access working :) Please verify that I didn't already
> break something inadvertently! I could easily have! BTW. Can you send me a
> gps-replay file so that at least I can keep checking that part?
>
>
Sending you a NMEA file directly to your adress.

- Chris -
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