[Xenomai-core] Analogy: A4L_CHAN_AREF_* and AREF_* and other macros

[Daniele Nicolodi <daniele@domain.hid>]

Hello Alexis,

I have noticed that in Analogy headers there are two sets of macros to
define channels references, one with prefix A4L_CHAN_AREF_ and the other
with prefix AREF_. I think keeping both is confusing and dangerous,
because similar symbols are defined with different numerical values!

The later form is the one used in comedi API and drivers, but i think it
is better to prefix all exported symbols and constants with a namespace
like string. I would be for keeping only the former form.

If you agree, I can provide a patch for you to review.

Similarly, I would rename TRIG_ constants to something like A4L_TRIG_,
and while at it I think TRIG_WAKE_EOS should become A4L_CMD_WAKE_EOS, as
it is a command flag and not a trigger source.

Similarly, it would be nice also to rename other macros defined in
command.h, adding at least a common A4L_ prefix. While at it I think
that, maybe after a rename to make their purpose more clear, CR_* macros
should be exposed to user space too.

If you think API breakage should be avoided, even in a so early stage of
development and diffusion, we can keep the old definitions for a while,
issuing deprecation warning (in this case those symbols would have to be
exposed as constant variables where to apply the __deprecated__ gcc
attribute).

Let me know what you think about this proposal.

Cheers,
-- 
Daniele