2024-05-27 11:15:18 +00:00
|
|
|
# VGA and SVGA code examples
|
2024-03-22 21:10:14 +00:00
|
|
|
|
|
|
|
|
Some code to exercise the four logic units of the VGA card in
|
|
|
|
|
256 color mode, as well as code that gets SVGA mode
|
|
|
|
|
working. Most of this is in C, but some of it's in assembler
|
|
|
|
|
to help me learn assembler better, as well as get comfortable with
|
|
|
|
|
C/asm interop on x86.
|
2024-05-27 11:15:18 +00:00
|
|
|
|
|
|
|
|
Check out the video I wrote all this code to support:
|
|
|
|
|
https://makertube.net/w/sQSZJcxh8CRuMZWVh8Q6aF
|
|
|
|
|
|
|
|
|
|
Read more about my project The Industrious Rabbit at
|
|
|
|
|
https://theindustriousrabbit.com/
|
|
|
|
|
|
|
|
|
|
## Building
|
|
|
|
|
|
|
|
|
|
You'll need [Open Watcom 2.0](https://open-watcom.github.io/). You can use
|
|
|
|
|
`wmake` on the `makefile` to build some of these, and
|
|
|
|
|
`wcl386 -q -bt=dos -l=dos4g <c or asm files>` for the others. All of these
|
|
|
|
|
run in 32-bit protected mode within a DPMI wrapper and in a flat memory space,
|
|
|
|
|
because I *really don't* want to deal with segment:offset addressing.
|
|
|
|
|
|
|
|
|
|
## What's here
|
|
|
|
|
|
|
|
|
|
### `main.c` and `vga.asm`
|
|
|
|
|
|
|
|
|
|
C code that exercises a bunch of the VGA registers by transforming a colored
|
|
|
|
|
cube of all 256 VGA colors in different ways. The display is set to unchained
|
2024-05-27 12:45:40 +00:00
|
|
|
mode. Lots of latch copies and transforming data with stuff in the latches.
|
2024-05-27 11:15:18 +00:00
|
|
|
The core of the transformation code is in `vga.asm`, which is also where the
|
|
|
|
|
keyboard handler for exiting the program lives.
|
|
|
|
|
|
|
|
|
|
### `svga.c`, `vesa.c`, `dpmi.c`, and `bmp.c`
|
|
|
|
|
|
|
|
|
|
Display a bitmap in a 640x480x256 SVGA mode. Trying to find a fully working
|
|
|
|
|
SVGA, DOS Protected Mode Interface, and VESA example was tough, so hopefully
|
|
|
|
|
this will help you out if you're trying to do the same thing!
|
|
|
|
|
|
|
|
|
|
### `simple.c` and `asmvga.asm`
|
|
|
|
|
|
|
|
|
|
These both draw a single dot on the screen, but in different ways:
|
|
|
|
|
|
|
|
|
|
* `simple.c` draws the dot directly to VGA memory
|
|
|
|
|
* `asmvga.asm` allocates a block of RAM, writes the pixel there, then
|
|
|
|
|
shovels the data from the RAM into the VGA card with `rep movsb`, which
|
|
|
|
|
is the procedure a game would use to draw to a non-VGA RAM buffer and then
|
|
|
|
|
copy when done.
|
