New kernel modes (including 800x600@56Hz !)

Since a recent commit, developers now have a better way to set modes.

The kconf.h kernel configuration file allows now several modes, selectable through your project Makefile config options.

Current defined timings include  :

- 640x480, 60Hz @ 168MHz clock (default one), 7 clocks per pixel
- 320x480, 60Hz @ 168MHz clock (repeat each line twice to use as 320x240 display)
- 640x480, 60Hz, overclocked at 192 MHZ,  7 clocks per pixel (longer vsync time)
- 800x600, 56Hz ! overclocked a bit at 180MHz. Yes the bitbox can do 800x600, 56fps.
You only have 5 clocks per pixels here however, so you'd better optimize that blit loop.

other modes can be created by adding config lines to the kconf.h file, all timing computation is based on number of pixels for Porch begin/end/sync and display sizes in pixels ; however be sure to get the right clock ratios to run USB/SDIO clocks at 48MHz !

yes, testkernel can work at 800x600 (sorry bad pic)

Playing TitanFall and Super Mario 3D World on the bitbox

 Well, playing a video of Titanfall on a Bitbox, of course playing a demanding PC / nextgen console videogame is out of reach :) But OK, then, can we have video on the bitbox ?

Full motion video on a very small hardware like the bitbox poses some interesting optimization issues and challenges. That's the kind of challenges you're faced with when you've got a few k on RAM - too few to store the image you're showing entirely- and 180MHz to generate the content and synthetise you VGA signal by software ...

Can we made nice cinematic cutscenes for the game, i.e. full motion video on the bitbox ? Can we make it 4K 3D video ? Well, no (What did you think ? 1080p50 with an Arduino ?)

But ... how far can we go ?