Well, a good chunky to planar converter does the conversion at copy speed,
i.e. at the speed it takes to copy a block of memory from fast to chip
memory (even faster if it uses cache prefetching..), at least on 040 +.
The limiting factor is the speed of chip mem, which is really slow :(
Cheers,
Gisle
On Mon, 28 Aug 2000 [EMAIL PROTECTED] wrote:
> I think the CD32 had a special chip (HP or ?) which did chunky to
> planar.
> So maybe Rebol runs cool on CD32...I will have to give that a spin and
> see.
>
> Thanks for the explanation,
> Steve Shireman
>
> [EMAIL PROTECTED] wrote:
> >
> > On Fri, Aug 25, 2000 at 08:03:16PM +0200, [EMAIL PROTECTED] wrote:
> > > That's platform dependance. If REBOL/View was designed with the
> > > Amiga chipset in mind, it would probably be quite different and
> > > would be fast on the Amigas, but not really fast on the other
> > > systems. It was instead designed with an abstact system in mind;
> > > probably that was too abstract, and /View is using only a little
> > > of the power of our computers.
> >
> > REBOL internally keeps data in 32-bit chunky format (image!
> > datatype). This is efficient on pretty much every hardware
> > architecture, with the exception of the somewhat obsolete planar
> > bitmap format the Amiga chipset uses.
> >
> > Planar bitmaps were great in the late 80's when it was important
> > to use as few bits as possible per pixel (fewer than 8 typically),
> > in order to achieve high resolutions with little memory. Things have
> > changed since then though, and today everyone is using 8, 16, 24
> > or 32 bits per pixel. For that chunky formats are more efficient, in
> > particular when manipulating individual pixels.
> >
> > What makes REBOL/View relatively slow on Amigas with the native graphics
> > chipset is the necessary chunky-to-planar conversion. We are using
> > optimized Assembler code for that, but it is still a bottleneck. On
> > Amigas with graphics boards REBOL/View is reasonably fast (often
> > faster than under Unix/X running on the same hardware).
> >
> > REBOL/View cannot directly use planar bitmaps for its internal
> > images, not only because that would require some rewrites, but
> > also because the up to 8 planes the Amiga hardware supports would
> > not be sufficient to support the various effects View provides
> > (blending, colorization etc.). Those effects need to operate on
> > 32-bit images throughout, and quantize colors down to the
> > requirements of the display hardware only as the last step. This
> > makes chunky-to-planar conversion inevitable. If REBOL stored
> > all internal bitmaps in 8 or fewer bits then errors would add up
> > when processing effects and the resulting images would look "ugly".
> >
> > --
> > Holger Kruse
> > [EMAIL PROTECTED]
>
>
