BPP on a kobo ? 16? is it?

[twobob]

Is the kobo glo a 16 bpp machine under the hood?

The reason I ask is I am looking to implement SDL dithering on the kindles.

I did try just patching the SDL lib I built using a patch that Niluje dug up but it seems to target 16 bpp blit?

So. Is the device 16bpp by default?

is there a place to go ogle some metrics?

thanks!

[KevinShort]

The framebuffer on all Kobo models from the Touch onward is 16 bit. I'd be very interested in SDL dithering, let me know if you get that working!

[twobob]

well... on the kobo its already done...

Let me see if I can find the patch.


EDIT: https://github.com/ifly7charlie/XCSo...kobo-new.patch

You want an armel build of that?

cant do you a Hard float but...
Here's one I smashed together earlier.

unable to test as I dont actually have a kobo.


possibly may need to switch the SDL_MOUSE env_var at runtime to something like /dev/input/event1 but I am totally guessing.

[twobob]

I BEGGED the OP to provide an 8bit target.

Over on the kindle side of the fence we are a bit thin on the ground when it comes to developers... so.. yeah. begging.

https://github.com/ifly7charlie/XCSo...Build/issues/1

Hope the SDL works for you.
if I can tweak it in anyway and rebuild - let me know - happy to help.

[KevinShort]

Awesome, thanks for the download and the link! I'll give it a go as soon as I can.

If that cat picture doesn't get to him, nothing will!

[twobob]

np. if you can run armel bins...

I have a REALLY BIG pile over on the kindle developers corner.

personally I just use dosbox to test this (good as anything else)
can happily provide a bin of that too.. for that purpose

[KevinShort]

I tried your SDL build with sdlgnuboy on my Glo, but I didn't get any dithering. If you've got any suggestions I'm all ears, otherwise I'll try compiling it myself.

I drop by the Kindle dev corner every once in a while, there's a lot of great stuff there. Seems you keep yourself pretty busy with everything you post over there.

[twobob]

To be honest. Just give it a build then. I did a tweak or two (which I obliquely alluded to above) to make it more kindle specific. Perhaps I broke it.

It's way easy:

Git down http://buildroot.uclibc.org/git.html (buildroot)

properly configure. (simple there are a bunch of threads of mine on that but yeah easy)

Drop the patch in the package folder in buildroot under {buildroot}/package/sdl-1.2.5/

make xconfig (shell)

pick SDL as a package.

make

grab from {buildroot}/output/target/usr/lib
That's all I did

Sorry I cant be more help. Without the device it would be crystal ball time.



(OR just cross compile it the old fashioned way )

[KevinShort]

When you compiled SDL, did you set your CFLAGS to "-DKOBO"? I followed the SDL.sh script in the xcsoar github repo.

patch -p0 < $PATCHESDIR/SDL-1.2.15-kobo-new.patch
CFLAGS="-DKOBO" ./configure  --prefix=<whatever> --host=arm-linux --disable-video-x11 --disable-cdrom --disable-audio --disable-opengl --disable-json
make
make install

And I have dithering! I did a hard float compile, but I could easily do a soft float for you if you'd like.

[KevinShort]

I went ahead and did a soft float compile so I could use it in my Debian chroot, so I've attached it below.

If you look at line 569 of the patch file you'll see this:

// this will cause the noise to shift around on the screen, amazingly this
+	// has the effect of causing the pixels to 'refresh' preventing darkening of
+	// the ghosting as dithered areas overlap.
+	uint_fast16_t dither_v = rand() % KOBO_DITHERMATRIX_HEIGHT;

You may or may not want this refreshing. Like it says, it moves the pixels around to prevent ghosting, but it's doing a bunch of tiny black>white refreshes every time the display updates. if you change line 572 to this:

uint_fast16_t dither_v = 0;

then you get more ghosting, but it's overall nicer to look at, IMO. I've attached two version below, one with the random pixel flashing and one without.

[twobob]

Excellent work!

but...

using shadow_fb
SDL: can't set video mode: Using software buffer, but no blitter function is available for 8 bpp.
Signal 11

and..

Can't init SDL SDL not built with audio support...

I'll see what the OP says on his ticket when he gets a chance to have a look.

Glad it worked for you