Rockbox mail archiveSubject: Re: development questions
Re: development questions
From: Linus Nielsen Feltzing <linus_at_haxx.se>
Date: Mon, 17 Jan 2005 08:53:14 +0100
Ray Lambert wrote:
> I'm not sure what you mean by "off-screen" icons.
I had a hard time finding a good name for it. :-)
> Are you saying there are two different display areas on these
> devices; one that uses fonts and one which doesn't, or something like
It's a two-line text display surrounded by fixed icons. The font can't
be changed, but the LCD can redefine up to 8 custom characters. We use
that to simulate a latin-8 character set.
> In any case, I guess it sounds like there's nothing I can do. :(
> Since my post, I've found a new way to do from mpeg.c which was
> pretty easy and seems to be more accurate. I put the check in
> playback_tick() (since that's where id3->elapsed gets updated). This
> seems to work very well but I'm not sure if it's a good design
> decision to put my code there.
That's where I would put it.
> The main question is whether it's safe. playback_tick() is called
> from a timer interrupt. Everything in my code seems to be safe to
> touch in an interrupt (atomic and read-only); the only question is
> whether the calls back to mpeg.c are safe. They all end-up doing a
> queue_post(), which is safe so long as the queuing operation is safe.
Yup. The queue_post() function is interrupt safe, and is intended to be
called from interrupts.
> There's also a question of using too much CPU in the interrupt. But
> there's really only a few integer comparisons taking place and the
> queue_post() call. So I think that's okay. I haven't noticed any
> problems in my testing so far.
I think it sounds perfectly OK.
Bring on the patch! :-)
Received on 2005-01-17