[openbeos-midi] Re: Update (and SBLive midi tester wanted!)
- From: Crain Greg <greg.crain@xxxxxxxxxxx>
- To: "'openbeos-midi@xxxxxxxxxxxxx'" <openbeos-midi@xxxxxxxxxxxxx>
- Date: Fri, 12 Sep 2003 12:54:48 -0400
>> There's still a few things that I am not 100% sure about.
>The undocumented workarounds flag in the generic_mpu401_module
>create_device() call, maybe
>:-\
Yup, thats one of them! But I have a suspicion what it is. Some soundcards do
not implement a UART command port, only a data port, so that it is always in
UART mode. The generic module should not try to reset, or enter UART mode on
these cards. With no command port, I think the data port is slightly different
too. I haven't seen a soundcard that does this, but they supposedly exist.
>> Is the module copied for each sound card, or is the module only
>> loaded once and all cards share it
>> I'm not that familiar how modules are used.
>Kernel modules are load on demand, and when more than one driver or
>other module call get_module() on it, he's shared between us, yes.
>However, each generic_mpu401_module "client" should call
>create_device() first, and pass in void **out_storage argument a place
>to keep
>an "handle" to client specific data. That way the MPU401 module attach,
>with client help, each specific module "client" (aka sound card driver)
>data...
Okay, that makes sense. Thats something that would still need to be added.
>> Is the midi parser even used
>Good question!
>I guess his purpose is to help midi driver coders to implement in their
>driver a read() hook that return full, valid, MIDI event bytes, as the
>midi server expect to get at least one event per read() call.
One thing that I saw was that if I ever returned anything other than a single
byte at a time from the read_hook, the thread would die and the read_hook
wasn't called again. This makes sense if num_bytes=0, but I would think that
if I had 4 bytes in the buffer, they should all be returned. Maybe I'm doing
something wrong still.
I will try to clean-up, debug my code over the weekend and post it monday,
working or not. More eyes looking at it would only help.
Greg Crain
gsc70@xxxxxxxxxxx
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