Subject: Re: Colour X server for AGA/ECS
To: None <amiga-x@NetBSD.ORG>
From: David Jones <>
List: amiga-x
Date: 01/27/1995 11:00:13
> i)   Is it worth investing any effort in trying to use the blitter or can 68030
>      perform the same area copying/filling operations faster ?

The CPU can do simple things faster since it has 32-bit access to chip ram.
But shifting/masking is slower.

As well, if you can interleave blits with computations then the blitter is
a big win.

> ii)  Does the blotter only operate on a single plane at a time, so to copy
>      an 8 bit deep image around on the screen the blitter copy operation would
>      have to be performed 8 times ?

Plane at a time.  Interleaved bitplanes can be used to save blits (at the
expense of bigger blits).

> iii) Is anyone working on a device driver for the blitter ?

Not yet.  If you write one, try to allow the kernel (floppy driver) to get
independent access as well.

> iv)  Server performance can be boosted somewhat by using a sprite for the mouse
>      pointer rather than using the server's internal software pointer code. Is 

Watch it.  The sprite horizontal resolution is half that of the hi-res mode.
You can't do this completely in X unless you use the ECS Productivity mode
(or AGA).

(Vertical resolution requires interlacing the sprite.  AmigaOS doesn't do
this but there's no reason why you can't play with the copperlist.)

> v)   The X protocol requests GetImage and PutImage might have to convert from
>      chunky to planar or planar to chunky images; does anyone know of a fast
>      software-only alogrithm to convert from one to the other ? I've written one
>      already but its not very fast.

Ask the kool dude demo coderz in comp.sys.amiga.programmer :-)

David Jones, M.A.Sc student, Electronics Group (VLSI), University of Toronto
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