Re: Fwd: Re: [Jsynthlib-devel] Method to pack/unpack 7-bit bytes to/from 8-bit bytes?

[Jeff W. <jww...@ya...>]

--- Joe Emenaker <jo...@em...> wrote:

> This is what I was concerned about in my original
> post.... that it's 
> common enough that people have implemented it
> several times in various 
> synthdrivers.
> 
> We should see if the FCB1010 does it the same way as
> the Alesis and/or 
> the XML driver and, if they're the same, move them
> into the general 
> synthdriver utils. I can only think of *two*
> different ways of doing the 
> conversion that aren't completely insane... and one
> of them makes a lot 
> more sense than the other. So, it's very likely that
> they're all the 
> same and we can have a global
> deNibbilize/reNibbilize.
> 
> - Joe
> 

For each group of seven bytes the FCB1010 takes bit 8
from each byte and creates and 8th byte at the end of
the group. The representation of the 8th byte is:
0, msb byte 6, msb byte 5, msb byte 4...msb byte 0

Make sense?

I just took a quick look at the Aleses sysex spec and
I suspect that they might be putting the eighth byte
at the beginning of the sequence (although I did not
read deep enough into it to tell for sure). You would
also have to know if they're storing the bits of the
eighth byte in the same order or the opposite order as
the FCB1010.

Jeff



		
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