Re: [linux-fbdev] Is a FontCache worth implementing ?

[Romain D. <do...@ir...>]

James Simmons wrote:

> If you think about it we already have something like that with teh current
> system execpt instead of it being in card memory it is in system memory.

The idea was to avoid going over the bus : PCI is slow (in particular
the sh*tty implementation in my PM7500)

> Using a image blitter you can translate that data from normal RAM to the
> video card memory. The nice thing about a image blitter is you can do
> depth translations (mono to depth X).

Yes, that was killed my current (test) implementation : 16 colors
mean 16 copies of each glyph. Yuck (8 Mb for 512 glyhs, 16x16 32bpp)

> I though about using a Glyhp
> approach. The voodoo 3 card has a pattern buffer for up to 64 Glyphs which
> can then be very quickly painted on the display. The problem is the
> console system supports alot more characters than that. In the future I
> hope even more.

There's some "glyph" stuff in the pm3, unfortunately, I can only
get nice little rectangle ATM. Not very useful. I haven't managed
to get it to use the glyph data I (try to) send :-(

If only 3DLabs would distribute the doc :-(

> Yes. This is the way the ruby tree handles it. I just got it working in
> the ruby tree. The only problem is their is some bug in take_over_console
> I have to chase down but I do have fbcon running using a voodoo 3 along
> side my MDA. There are 3 functions. One is rectfill which does things like
> clear the margins etc.

That's a more generalized _clear + _clear_margins ?

> Then their is fb_copyarea which copys a area of the
> screen to another area of the screen.

better _bmove ? (if only I could get _that_ one to work
reliably)

> The last function is fb_imageblit
> which transfers data from host memory to screen memory.

Thats seems new to me (I only know 2.2 and 2.4, as I only grep'ped
through Ruby). Could be useful...

> This is used to
> draw the penguin and text. Yes it is simpler to use the accel engine. A
> good example is the new tdfx driver in the ruby CVS.

The idea was to avoid the bus ; maybe I'm biased (or totally wrong),
but the less things go over the bus, the better I feel...

thanks for the answer,

-- 
DOLBEAU Romain               | l'histoire est entierement vraie, puisque
ENS Cachan / Ker Lann        |     je l'ai imaginee d'un bout a l'autre
do...@ir...             |           -- Boris Vian