[Oberon] FPGA - Bitmaps.Mod

[Tomas Kral]

Hi,

I have completed early version of `Bitmaps.Mod' for FPGA Oberon.
Surely it is far from perfect, but I wish to share now for comments and
improvement.

https://github.com/tcat-qldom/Oberon-bitmaps

Being a result of my studying PO2013, also reading source code, I
borrowed this code pattern from `Display.Mod'

SYSTEM.GET(dst, pix);
SYSTEM.PUT(dst, SYSTEM.VAL(SET, LSL(wd, x MOD 32)) + pix);

IF x MOD 32 > 0 THEN
  SYSTEM.GET(dst+4, pix); wd := ASR(wd, -(x MOD 32));
  SYSTEM.PUT(dst+4, SYSTEM.VAL(SET, wd)*{0..x MOD 32-1} + pix)
END

As I use it very frequently in my code, it makes room for some
optimisation.

I wish to use it in `Pict.Mod' to display those legacy pictures
`Grapes.Pict' and `Esher.Pict' from Ceres.

When I learn more about colours, it would be interesting to add 3, or
4 bit colour to FPGA. I have some `VID.v' mods already available. 

-- 
Tomas Kral <thomas.kral at email.cz>