Help with extending highres VGA text driver

heapdump

Hi all,

I tried to extend the 1024x768 / 8x12 px font graphics driver from Chip Gracey with the following changes:

+ use 8x16 font instead of 8x12 which results in 128x48 tiles
+ use full character set 0-255 instead of 0-127
+ use independent color for each tile (graphics memory contains 2 bytes per tile, char + color)

I know it will take a lot of memory, but for me that will be OK as I am using a dedicated Propeller chip for my GPU.
(Should result in about 12k for graphics mem + rom font + code)

I am new to this and decoding / adapting PASM code is a bit hard for me, so it would be nice if somebody is willing to help me out here :-)

Thanks in advance!

Patrick

Electrodude

Chip Gracey has 16x16 tile 4 color drivers that do various resolutions. I've attached a possibly half-broken modification I made to his 1280x1024 16x16 tile driver that makes it do 8x8 tiles at 1024x768 resolution. You might try modifying it to do 8x16 tiles. I've also attached an 8x8 font that works with it.

I'm pretty sure my 1024x768 8x8 driver is mostly based off of Chip Gracey's 1280x1024 driver, but I probably took parts of it from Chip Gracey's 1024x768 16x16 or 16x32 tile driver, which I've also attached. I had to base my driver off of the 1280x1024 driver because I needed more cogs to process the smaller tiles.

My 8x8 version might be half broken - I don't remember, as it's been a long time since I last used it. I might have gone back and fixed it at some point. If it is half br oken, it's because because colors are for every 2 tiles, which isn't what I wanted. I was going to modify it so that the first tile would use colors 0 and 1 and the second would use 2 and 3, to effectively give 2 colors/tile but that never happened, I think because I ran out of time to run the extra instructions.

Later today, I'll try to post a demo for my driver and see what its current status is.

You might use a diff utility to see what I've changed in my 8x8 driver. If you have git installed on your computer:

git diff --no-index vga_1280x1024_tile_driver_with_cursor.spin vga_1024x768_8x8_tile_driver_with_cursor.spin

or, if you have some sort of Unix and somehow only have plain diff:

diff -U3 vga_1280x1024_tile_driver_with_cursor.spin vga_1024x768_8x8_tile_driver_with_cursor.spin

EDIT: What happened to my attachments?!?

Electrodude

Here are the attachments.

I also attached Chip Gracey's 1280x1024 driver for comparison, in case you don't have it.

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Electrodude wrote: »

Here are the attachments.

I also attached Chip Gracey's 1280x1024 driver for comparison, in case you don't have it.

@Electrodude:
Thank you very much! This looks like a very good base to start
I will try it tomorrow and see if it works for me...

Cheers

heapdump

@Electrodude:

as I took a closer look this morning to the adapted driver I first was happy when I realised that it is using a address for tiles instead of an char index, but then I wondered how 10bit can archive this; it results in a fragmented memory by 64 bytes (2 longs, 16x32). I only need 2 bytes per character so the 10bit address resolution is too rough - 3/4 of the memory would be wasted. :-/
I am not sure if I understand how you did it with the 8x8 version... did you change addressing oder so?

It comes very close to what I wished to have - so after a few modifications I hope it works

Thanks so far!

Patrick

heapdump

Hi all,

finally with the help of kuroneko I neary reached all my goals
Atteached you can find the current version of the driver which supports:

+ 1024x768 with: 64 colours for foreground and 4 palatted colours for background
+ it uses a 8x12 full full range character font set from zx81vga (Thanks for the permission!)
+ added support for compiling with bstc (formerly I was unable to handle constructs like '+4' etc. in PASM sections

It is still memory hungry und needs ~20k for RAM buffer + extra memory for code :-/

If anybody have so great idea to modify it to run with 8x16 it would be very nice!

Cheers,

Patrick