Async input from externals, or MIDI input?

[Paul D. DeRocco]

I'm still using Rev 3.5, partly because I've been holding out until LC
includes direct support for MIDI. Has that happened yet?

If not, did LC add (over Rev) any way for a separate thread (or an OS
callback) in an external to cause a message to be sent within LC? One could
never do this in Rev, but if one could, it would allow externals to properly
support MIDI input.

MIDI output is easy in an external, because it's synchronous. But the only
way I was able to do MIDI input in Rev was to stuff it into a FIFO and then
use a timer message to check the FIFO. That's adequate for non-real-time
stuff, but not for receiving musical events. If there were a way for an
external to send a message, or cause a message to be sent, then that would
eliminate the need for polling.

There is already a timer message facility, e.g., 

	send <message> [to <stack>] in <time>

which allows an asynchronous event (ultimately a timer interrupt inside the
kernel) to cause a message to be sent, it would seem to be fairly easy to
extend this to support signals, since Posix guarantees support for at least
eight real-time user-defined signals, and Windows can emulate them easily
enough with semaphores. For instance,

	send <message> [to <stack>] on signal <number>

could express the same concept, but triggered by a signal rather than a
timer interrupt. I could then have my MIDI input callback stuff bytes into a
FIFO and generate a signal, and have LC use the signal to send a message
that reads whatever is in the FIFO.

By the way, combining the two

	send <message> [to <stack>] on signal <number> or in <time>

could express the concept of a time limit, where either the signal or the
timeout would cause the message to be sent, but not both.

But those ideas are predicated on the assumption that LC hasn't dealt with
this issue yet. If it has, I'd like to know about it, and if it solves my
problem, upgrade to the latest version.

-- 

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco at ix.netcom.com