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If you are doing embedded development, you have to learn C -
there's no way round it. Use C for the low-level stuff and the
time-critical stuff. Lua can make sense for higher level coding,
especially for code that might change often.
Mixing C and Lua is not hard - I suppose that's one of the
main points about using Lua in the first place.
mvh.,
David
----- Original Message -----
Sent: Thursday, May 18, 2006 8:12
PM
Subject: Re: lua on ARM7
Hi Asko, all,
Sorry, I've been out of the office for a
few days and not keeping up with this thread.
Anyway, I'm definately
interested in that SDL_mixer example.. might help clear up some stuff.
I was thinking of using LUA to process samples from the ARM's on-board
analog-to-digital converter, but it looks like that would be asking too much.
So my next question is.. how hard is it to compile LUA to ARM7
assembly :-)
maybe Thumb mode ...
I realize it would be very
complicated, since you would need the garbage collector. but what if I limit
it to compiling a LUA function like this :
function
process(input1, input2)
return input1 *
input2
end
I guess that wouldn't be too hard? I'm
not sure if there exists a lua scanner/parser in LUA itself...
what if
it gets more complicated:
lut = [0, 0, 0, 0, ...
0] --- say, 256 values in lut
function process(input)
return lut [ input ]
end
or what
about this :
function
process(input)
local t = [math.random(),
math.random(), math.random()]
return input
* t[math.random(3)]
end
I know these functions
don't make a lot of sense but I'm trying to get a general idea of how to go
about this.
I'd like to have some function in LUA that does something
like this
funBinaryCode = compileARM(function
(input1, input2) return input1*input2 end)
--- funBinaryCode now holds
a table of bytes which can be cast to a function pointer on the ARM7 and
called
Any comments highly
appreciated.
Bert
Asko Kauppi
<askok@dnainternet.net> wrote:
Ah, yeah.
Your flag thing is a "one entry queue"
but I was expecting Bert not
to want to lose a single interrupt (and
them to be different, like
having some data values attached, that Lua
would care about).
Anyways, already this is getting speculative,
since we don't know
what Bert does. Bert: if you want an event dispatch
queue, I can send
code I've used in LuaX/SDL_mixer, to catch played
music samples at
real time (and show the graphs by Lua). Don't remember
about memory
allocation, but yes, most likely one alloc per interrupt is
needed
there.
-asko
David Given kirjoitti 15.5.2006
kello 20.00:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash:
SHA1
>
> Asko Kauppi wrote:
> [...]
>> I would
consider doing an "event dispatch" interrupt handler (in
>> C)
that
>> would sit in the other end of a FIFO queue, the other end
being
>> polled
>> by Lua (can you run one instance, as
the main loop?) to take in
>> "commands".
>
[...]
>
> A common technique is to have the interrupt handler
set a bit to say
> 'this interrupt has happened'. Your userspace code
then polls all the
> various bits, does its work, and then clears them
again. Getting the
> logic right to ensure that all interrupts are
properly serviced is
> a bit
> challenging, and of course you
lose any kind of real-time-ness, but it
> does allow you to avoid
having to allocate memory during your
> interrupt
>
handler.
>
> - --
> +- David Given --McQ-+ "Preacher,
don't the Bible have some pretty
> | dg@cowlark.com | specific things
to say about killing?" "Quite
> | (dg@tao-group.com) | specific. It
is, however, somewhat fuzzier
> on the
> +- www.cowlark.com --+
subject of kneecaps." --- Firefly, _War
> Stories_
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