More of the Same

Yet another month of very light blogging.  And once again, I did actually accomplish a few things that I just simply haven't yet managed to write about.

I was lurking around on the zipit IRC channel lamenting the apparent demise of some zipit sites (and locating the backups on google and in the wayback archives) when beaglebreath mentioned he was looking to move some of his weather monitoring gpio code over to openwrt from z2sid.  Now z2sid comes with a native compiler, but openwrt is where most of the action is these days.  So I thought, hey! openwrt has a package with the PicoC small C interpreter.  Maybe that could handle it.  You only need to read and write some files in sysfs to work the gpios for the weather sensor. Based on my experience with PicoC on IZ2S I figured that'd be easy.  Of course reality gets in the way.  Openwrt had PicoC, but it was on an old version of PicoC, just before the file IO support was added.  Figures. I bumped it up to the latest version on the zipit openwrt github, and then added a tiny patch to convince openwrt to build it.  I had to switch some of beaglebreath's file IO routines to use stdio instead of fcntl.  But with that small change it seems to work for me.  However it's still unclear if it can actually handle the IO for the sensor.

At this point I decided to try a real native compiler instead of the C interpreter in PicoC.  I started with tcc because it's tiny.  It seems to work, sort of.  But I got stuck trying to link anything against uclibc.  Without a libc, file IO would probably be a challenge.  So I revisited the self contained aboriginal linux gcc that worked so well on IZ2S.  Because openwrt is eabi I was able to use the arm5l compiler which is quite reasonable for the arm5tel processor on the zipit.  I built a few hello.c progams, which worked, but the weather sensor program gave the same results as PicoC.  Hmm, maybe we're using the wrong source, or perhaps the sysfs works differently on the openwrt kernel than it does on z2sid.  Since I don't have my own weather sensor I'll have to dig up a logic analyzer someday and watch the IO lines to verify once and for all if PicoC can do it.  I still believe...

Meanwhile, I opted for a real challenging test of the native compiler.  Rockbox!  I got it to build way back in February with the buildroot cross compiler setup from openwrt, but it ran like crap so I gave up on it.

This time I compiled it on the zipit with the native compiler, but wouldn't link against the openwrt SDL shared lib.  Possibly because the libs are stripped?  I don't know.  I gotta swap in the unstripped libs someday and see what happens.  Anyhow, I still had nagging doubts that maybe the previous performance problems could've been fixed with my buffer patched SDL from IZ2S.  So I compiled the IZ2S SDL and salsa code on the openwrt zipit and static linked rockbox against it.  That was a bit of a chore, and the rockbox executable is now about 300K bigger, but it runs nice and smooth.  I had to fetch perl, some perl modules, and coreutils-install packages from the openwrt package repository to work through the rockbox build and install process.  I also created a 32MB swapfile needed to compile a few of the codecs.  Otherwise the build was fairly straightforward, if somewhat tedious.  I even compiled a pile of plugins.  Rockblox, anyone?

I still wonder if the performance problems with the cross-compiled rockbox could be fixed by installing a replacement SDL like I did on IZ2S.  Someday, maybe...

The apps on my openwrt zipit are now looking a whole lot more like my IZ2S zipit apps. 

Here's the goodies.  I updated these from the betas so now all the codecs are included, as well as a gmenu2x icon, and the key bindings on the rockblox and bubbles plugins have been fixed up.
rockbox-wrt-r3.9.1.tgz
rocks-wrt-r3.9.1.tgz

I finally managed to link against the shared libSDL using the unstripped libs from my openwrt staging-area.  So I upxed the smaller rockbox.bin down to just under 280K if you want to try and fit it on the jffs.  But it does sometimes skip when it first starts up.
rockbox-wrt-shared-upxed-r9.1.1.tgz

I also created a rockbox wrapper script with dronz' bass and treble setting settings.

RockboxWrtJffsInst.sh will set you up to use it when you boot from the jffs. This may not be required if you're using the overlay scripts.  I haven't tried them yet.


The updated PicoC is available from the openwrt package repository.

Here are some interesting PicoC links:
PicoC enhanced for a commercial PLC
PicoC robot code documentation

There might be something wrong with the openwrt gdb package so I compiled it on the zipit just in case.

gdb-wrt.tgz