From: "Matt" <para AT tampabay DOT rr DOT com>
Newsgroups: comp.os.msdos.djgpp
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Subject: Re: DPMI problem
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Date: Wed, 04 Jul 2001 05:01:09 GMT
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To: djgpp AT delorie DOT com
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"Hans-Bernhard Broeker" <broeker AT physik DOT rwth-aachen DOT de> wrote in message
news:9hpbse$bee$1 AT nets3 DOT rz DOT RWTH-Aachen DOT DE...
> Matt <para AT tampabay DOT rr DOT com> wrote:
> [...]
> > I cannot use the movedata functions, which I have already looked into.
The
> > game writes direct to video hardware,
>
> It shouldn't. At least not directly, all the time. Note that access to
> video memory is noticeably slower than to main memory, usually.  This
> is especially true for reading from video memory.  I.e. before you
> even _think_ about reading anything back out of the graphics card's
> memory, switch to an invisible framebuffer in main RAM and
> bitblitting.  And for this blitting operation, movedata() is just
> about perfect --- you'll hardly manage to beat it.
>
> --
> Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
> Even if all the snow were burnt, ashes would remain.

There is a big difference between "shouldn't" and "does", and since I didn't
write this code, "does" is quite operative. It doesn't read vram
fortunately, but it does write directly to vram. The code is poorly
organized, and the only hope I have of fixing it is direct access to some
buffer. I would prefer to back buffer because of the obvious speed
advantages if I have to read it back, however I've yet been unable to figure
out how the entire system works, so that's not a possibility either.