[LAD] alsa sequencer and sysex editing

rdxesy at yahoo.de rdxesy at yahoo.de
Mon Jun 2 16:13:26 UTC 2008

hello ")

Ok, I am writing a remote and SysEx-editor for e-mu 
synthesizers (http://ppcontrol.sf.net). I am asking for 
help on how to use the alsa sequencer the way it was 
intended to be used for this kind of application. You know, 
there are so many options and flags and stuff to be used 
and I feel a little lost.

Basically I send a lot of SysEx messages and need to make 
sure to catch all the answers. My current implementation is 
as following:

I have a single sequencer (duplex, nonblocking), a queue 
and two ports: one with read and one with write caps. To 
send a SysEx command I just queue an event with that 
message. (So far so good?).
Now I just wait for an constant time (usleep) before I 
check the input queue. Problem: if the time is too short, i 
would have missed the answer, if I wait to long I waste 

My question is: how would I make sure to catch all answers 
from the device without using a thread and without just 
waiting for an constant time before I check if there is an 
answer( which is alo not very fail save, a message might 
take a little longer if there is traffic on the midibus)?

Thank you.


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