[Oberon] FPGA - Display.Mod 4-bit colour

[Jörg]

Tomas
Do you want it to do yourself from scratch to learn something or just use my code?
Jörg

> Am 10.08.2018 um 13:38 schrieb Tomas Kral <thomas.kral at email.cz>:
> 
> Hi,
> 
> I wish to modify `Display.Mod' to accept 4-bit colour. Standard
> interface currently supports 1-bit colour only.
> 
>  PROCEDURE Dot*(col, x, y, mode: INTEGER);
>  PROCEDURE ReplConst*(col, x, y, w, h, mode: INTEGER);
>  PROCEDURE CopyPattern*(col, patadr, x, y, mode: INTEGER);
>  PROCEDURE CopyBlock*(sx, sy, w, h, dx, dy, mode: INTEGER);
>  PROCEDURE ReplPattern*(col, patadr, x, y, w, h, mode: INTEGER);
> 
> I have a version of VID.v with 4-bit pixels and a 16 entry colour
> lookup table. So `col' parameter in the range {0..15} defines index
> into that table.
> 
> Looking at the code, I realise each display line takes 128 bytes 1-bit.
> 4-bit it must be 4*128. While single word sets 1-bit colour of 32
> pixels, and only 8 pixels of 4-bit colour, correct?
> 
> I am generally seeking advice for the good starting point, also hwoto
> set up a test environment for quick tests turnaround? My idea was to
> make a standalone boot program accepting draw commands over serial.
> 
> I may start with `ReplConst' (font rendering), and `ReplConst' (line
> drawing).
> 
> I wonder how much of the original code I could reuse, just extending
> the loop count, and some 4-bit manipulation?
> 
> Many thanks in advance.
> 
> -- 
> Tomas Kral <thomas.kral at email.cz>
> --
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