[openbeos-midi] Re: BMidiPort
- From: Philippe Houdoin <philippe.houdoin@xxxxxxx>
- To: openbeos-midi@xxxxxxxxxxxxx
- Date: Thu, 14 Nov 2002 13:04:07 +0100 (CET)
Matthijs wrote:
> Jerome wrote:
> > For the class BMidiPort I think that just a class that
> > translate BMidi data to BMidiEndpoint data. The hardware
> > midi port are created by the midi_server as BMidiProducer
> > or BMidiConsumer, and BMidiPort just send or receive data.
>
> A BMidiPort represents a hardware MIDI port. It has several
> functions for finding out which hardware ports are available:
> CountDevices(), GetDeviceName(), Open(). How does BMidiPort know
> which hardware ports there are? Does it look through /dev/midi?
> Or does it let the midi_server do that?
Most probably the BMidiPort is responsable for scan all /dev/midi/* it
can support. And the midi_server, thru an internal MidiPort objects,
open each and publish them as a BMidiEndpoint (consumer & producer) ...
However, looking at midi_server internals, it seems he's watching
/dev/midi/* tree, so maybe since Midi2 the BMidiPort class
don't scan devices itself anymore but rely on midi_server to do it.
> What should happen if you
> Open() a port, say /dev/midi/sblive?
As the midi_server should have already open /dev/midi/sblive
it at his startup, I'll bet you will get a "Busy" error on a
BMidiPort::Open("/dev/midi/sblive");
> The BMidiPort now has to ask
> the midi_server for the producer and consumers for that port, but
> how does it do that? Does it simply loop through all endpoints and
> compare their names? These are the issues we should think about ;-)
Well, I guess yes. A quick search at BMidiEndpoint::Name() until it
match device_path passed to BMidiPort::Open(device_path).
-Philippe
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