| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657 |
- Quick Voodoo/Voodoo2 Crash Course (mostly Alan's notes to save looking
- stuff up in the docs all the time)
- Voodoo and Voodoo 2 appear as multimedia devices. They may be on a "dual
- function" board in which case we should not 'borrow' the Voodoo as we will
- blank the main video card. That is reported in the PCI config space.
- Voodoo/Voodoo2 hardware may not always be initialized by the host OS because
- it is not video.
- The voodoo memory is split into two pools. A 1-4Mb pool holds the frame
- buffer, an optional second buffer, zbuffers, and alpha. A second 2-8Mb
- memory area holds all the textures.
- Texture ram is directly writable but not important for the current 2D
- driver. Video RAM is 16bit depth and tiled. The view of the video memory
- area is "magic", it doesn't contain a mapping of the video RAM into PCI
- space but contains pixel poking functionality.
- The frame buffer always appears untiled and 1024 pixels wide. For write
- there are some 16 different write modes including 24/32bit. The hardware
- does not support 24/32bit - these are provided for software rendering
- fallback. Read back is always 16bit. Endian conversion is hardware. Byte
- aligned access is not supported, only word aligned. Also watch how you
- access data - you can't access out of frame buffer space and if you get
- the control bits wrong you also get zbuffered, fogged and other fun.
- LFB writes have depth and alpha if you want.
- The real hardware is RGB565, how it sets stuff up internally is out of
- our hands - which means X memory alloc/pixmap cache is a little
- constrained.
- [IDEA: Should we put the mouse and framebuffer at different Z values so
- that we don't have to erase it to draw under it - less flicker]
- Acceleration:
- All Voodoo
- Fast Fill - Solid 2D rectangle fill
- (Also depth buffer clear for 3D)
- Supports a constant alpha option
- Requires a running 3D engine
- Voodoo2 and later
- Screen to screen blit
- CPU to screen blit
- Ultra fast fill to some alignments
- Monochrome to colour expansion (cpu to screen only)
- (and they finally made the 2D and 3D state independant
- if someone ever gets drunk enough to do DRI...)
- Colour conversion on blit
- Dither
- Chroma testing (src/dst) and selection of op by colour
- raster ops are the usual 16 suspects
- Other bits supported
- CLUT Gamma correction
|
