Support for 16bpp/32bpp VBE 2.0 modes

[Cacodemon345]

This is probably an extremely niche use case, but since I remember talks about modern OS support in Doomworld:

Can support for 16bpp/32bpp VBE modes be added? AMD GPUs since the GCN era do not support or even list VESA 2.0 8bpp modes properly, so it'd be useful on modern platforms.

[viti95]

Next release will have 15, 16, 24 and 32 bpp support for backbuffered VBE modes, stay tuned 😁

[viti95]

Yep, you're right, AMD GCN cards have very bad VBE implementation. This is my Radeon Pro VII right now (other cards / emulators work fine).

[Cacodemon345]

If it displays Windows XP (or Vista/7's recovery/setup environment) correctly it should also display FastDoom correctly.

[viti95]

FastDoom 1.1.0 is now available 😄

[Cacodemon345]

All modes that are supported work, except 800x600 where it seems to pick a wrong pitch value.

[viti95]

Which video card are you using?

[Cacodemon345]

AMD Radeon RX 460.

[viti95]

Ok, found the issue. Turns out 800x600 in GCN cards use more bytes per line than required. For example, in regular 16bpp modes 2 bytes are required per pixel, so 1600 bytes per line.

But in my Radeon VII, this is the description for the mode:

mode #3 [114]: 800x600x16 bpp, 1 plane(s), 1 bank(s) of 0 KiB, 1664 B/line, wingran=64 KiB, winsize=64 KiB, supported, color, gfx, notvga, lfb winA: reloc read write bnk R 5(11) G 6(5) B 5(0) lin R 5(11) G 6(5) B 5(0) usable

So that's why the image gets scrambled.

[Cacodemon345]

Is this fixable then?

[viti95]

Yes, it is fixable, this fix will be available in the next release

[Cacodemon345]

It works well now, thanks.