Re: [stella] And now, for my next trick...

Subject: Re: [stella] And now, for my next trick...
From: "Thomas Jentzsch" <tjentzsch@xxxxxx>
Date: Thu, 8 Mar 2001 18:03:25 +0100
Andrew Davie wrote::
> > > b) Life on Mars.   An implementation of John Conway's life (in at least
> Nobody seems to have considered packing the data
> in RAM.  Considering that MOST of the playfield during a life 'game' is 0
> (the theoretical maximum is 50% used), and that large areas of the playfield
> are usually contiguous 0's... and also that non-zero and alternating
> patterns are typically grouped together...  I figure a simple run-length
> packing (speed essential!) would be feasible.
> All the messages I read seem to assume that 1 bit/pixel is the limit that
> can be achieved.  This is not so!  As a simple example, byte-aligned runs of
> 0's only (eight 0's) could be efficiently packed to a single bit, and all
> other data left as-is (plus another bit).  This would be pretty quick to
> unpack, yet save HEAPS of RAM.
> I'm still thinking about the feasibility and operation of the kernal, and
> how I can interleave run-length unpacking into the display kernal, in
> particular.  I'm not saying it CAN be done... I just think it might be
> possible :)

I'm quite sure, that you can pack the playfield very well. And serial unpacking shoudn't be a big problem too. 

But *working* with this packed data, which can't be done just serial, requires a very special algorithm. This *might* be the real problem. 

But I also thought, I couldn't pack the Jammed data that much, and in the end it turned out to be possible. So give it a try!

Have fun!
Thomas Jentzsch         | *** Every bit is sacred ! ***
tjentzsch at web dot de |

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