| From: | Jesper Svennevid |
| Date: | 26 Apr 00 at 01:07:14 |
| Subject: | Re: AllocBitmap (was: Re: Minterms) |
> From: Allan Odgaard [Duff@DIKU.DK]
>
> Without having seen the sources for CGX (nor used it for that
> matter ;-) ) I'd say that a bitmap is always allocated in
> graphics memory.
> When there no longer is anything left, the system will start
> to move the bitmaps which aren't BMF_DISPLAYABLE to fast
> ram (based on LRU or similar).
>
> So only bitmaps which doesn't make sense to have in fast ram
> should have the BMF_DISPLAYABLE flag set. E.g. a bitmap for
> a screen can't really be in fast ram, because then it can't
> be displayed. But a logo or similar, which is just used as
> source for blitting, only makes things a little slower to
> have in fast ram, and should naturally be moved when memory
> is low.
On CGX even bitmaps that have BMF_DISPLAYABLE can be swapped
out into fast-ram, as all accesses to the bitmaps are handled
using locks (if you don't lock the bitmap while doing direct-
access, you're in trouble if the bitmap is swapped out :), and
if a bitmap is required to be in gfxboard memory even though
it's full, everything unneeded is swapped out/re-organized
until there is enough room.
It's very noticable for me if I have more than five 1024x768x16
screens open, as the screen-swap time drops from instant
switching to around 1 second per swap.
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