[Open-graphics] Designing a CPU

[Philipp Klaus Krause]

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Sorry, I always forget that this list doesn't set reply-to to the list
address.

Timothy Normand Miller schrieb:
> > On 3/16/07, Philipp Klaus Krause <pkk at spth.de> wrote:
>> >> Timothy Normand Miller schrieb:
>> >>
>>> >> >
>>> >> > Here's a few things it'll do:
>>> >> >
>>> >> > - Do translation for VGA text and graphics modes.
>>> >> > - Manage data transfers for copies between host memory and graphics
>>> >> > memory (image up/downloads)
>>> >> > - Unpack GPU command packets into GPU register writes.
>> >>
>> >> How about an accumulation buffer?
> >
> > You're not talking about the accumulation buffer in relation to 3D
> > graphics, are you?  That's not what this subproject is for.  Or do you
> > mean something else?
> >

I'm talking about the OpenGL accumulation buffer. While defined in the
OpenGL spec there's no direct connection to 3D.

You cannot render directly into the accumulation buffer. There's only a
few operations that can be done on it:

ACCUM: Take each pixel from the color buffer, multiply it by a constant,
add it to the accumulation buffer.
LOAD: Take each pixel from the color buffer, multiply it by a constant,
place it in the accumulation buffer.
RETURN: Take each pixel from the accumulation buffer, multiply it by a
constant, place it in the color buffer.
MULT: Take each pixel from the accumulation buffer, multiply it by a
constant, place it in the accumulation buffer.
ADD: Take each pixel from the accumulation buffer, add a constant to it,
place it in the accumulation buffer.

I think that DMA, pixel pack/unpack and accumulation buffer operations
are very similar, so maybe part of their implementation could be shared,
that's why I suggested the accumulation buffer here.

Philipp

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