Am 16.05.2010 16:06, schrieb Dave Chapman:
Thomas Martitz wrote:
My understanding of the purpose of RaaA is that it would use less
and less of the Rockbox firmware code as time went on. Development
of the sim should go in the opposite direction - using more and more
Rockbox code.
No, I don't think RaaA aims to use less and less Rockbox code. It's a
port of Rockbox afterall.
I said "Rockbox firmware code". So what _is_ RaaA if it's not about
using less Rockbox code than a "real" Rockbox ?
I sad it, it's a rockbox port. It will use as much of the (entirely,
including firmware) Rockbox code as possible. Exactly in the same way
how the other ports do it. That's why it was moved into the target tree.
Only the target specific code is there, the rest is re-use of Rockbox code.
I'm also not convinced that changing some #ifdef SIMULATOR lines to
use things like HAVE_SDL or HAVE_SDL_AUDIO makes the code for the
simulator better. IMO it makes it harder to see the places where
the sim differs from the target it's simulating (it still differs in
the same way, it's just obfuscated more).
Can you respond to this?
Frank Gevaerts described it well. We have a single place, sim.h, where
you look for defines which differ from the target. It's no more or less
obfuscated.
As an example of the different purposes of the sim and RaaA, the SDL
button driver for RaaA should expose all buttons to the apps/ part
of Rockbox (especially if there is a full keyboard on the device).
The SDL button code for the sim should (although it doesn't
currently) provide simulation of the hardware buttons (and/or
touchscreen and remote) on the real device, including things like
mechanical and electrical limitations. Other buttons are used for
events such as USB insertion/removal.
That's not going to change. The parts that are simulating a target
override the SDL app parts, e.g. by including a different
button-target.h. We never simulated mechanical and electrical
limitations and that's not going to change.
Why is that not going to change? Who decided that wasn't a desirable
feature of the sim?
Anyway, I don't see how target-tree'ifying would prevent doing that.
We want to run code which
compiles for a target on a more convinient system (simulate), not
emulate the target itself.
Are you talking about RaaA or the UI simulator? IMO, the ideal UI
simulator would be a close simulation of the target. I know that
isn't always true now, but that is the direction the UI sim has always
been moving.
It's not only not true, it's impossible too. We can maybe move it closer
but it'll never be close. Use qemu if you want to do that. Either way,
and as above, I don't see how target-tree'ifying would prevent anything.
Similarly, the LCD code for the sim presents the main LCD, the
remote LCD (if present on the target), a backdrop image, simulation
of backlights, simulation of charcell etc. For RaaA, none of those
complications are needed, but different complications may be - such
as possible window resizing, or run-time detection of LCD size (if
we go all the way with RaaA), or other things we haven't thought of
yet.
I don't see any problem here. These complications won't touch the SDL
app, because it will not define SIMULATOR.
I don't understand your answer. My suggestion is that the
LCD-simulating SDL code for the sim will be very different to the SDL
code needed for RaaA, so it shouldn't be assumed that unifying it is a
good idea - just because they are both using SDL.
But it isn't different. It's not like SDL offers you an incredibly
versatile API, it is very simple in fact. Even with SDL you're limited
to very few ways of doing it. There's no different way of doing it
differently *within* SDL happening. Other platforms may offer different
ways, but that's not an issue for SDL and not for the sim or the SDL-RaaA.
Am I missing something obvious? Why is putting the sim code in
target tree a good idea?
I think you mix up sim-specific code and sdl specific. The former
will stay specific for the simulator, the latter will be reused for
the sdl application because code duplication is bad.
Code duplication is not _always_ bad. My point with all this is that
you may want to do things in fundamentally different ways in an
SDL-based RaaA to the sim, and it's too early to say you won't.
It's not too early to claim that I think. I think I've looked into it
enough to confidently claim that things are not going to happen
fundamentally different.
I would have preferred to have seen a new SDL target being added to
the target tree, with none of the sim code in it - i.e. a shiny new
SDL target without the baggage of the sim, and leaving the sim free
to be developed and improved independently of RaaA (and in the
opposite direction).
That doesn't make sense to me. The difference between the sims and an
SDL app boil down to the button and lcd handling. There need to be
very few #ifdef SIMULATOR to separate the SDL app from the sim.
That may be the case now, but I would argue that it won't be the case
for very long.
I would have wanted to keep an open mind about the possibility that
the sim SDL code and RaaA SDL code would differ, and work on RaaA
without worrying about the sim.
If, much later during the development of RaaA, there is still a
significant amount of the sim's SDL code left in RaaA, then that would
be the time to consider merging the two, not now, before you've
explored the possibilities.
Merging later is a much bigger pain that doing it from the beginning.
If the RaaA app does something different than the sim later, then it
won't in the target tree area. It will be at higher levels. Remember
that the target tree only holds the *drivers*, it doesn't make up an app
on its own. And the drivers are specific to SDL, not specific to whether
it's an app or a sim.
Best regads.
