Re: [stella] optimization : sneaky fractional bit representation

Subject: Re: [stella] optimization : sneaky fractional bit representation
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Wed, 03 Jun 1998 18:07:58 GMT
>1) Figure what information you need to save - each will have a numeric
>range.
>2) repeat steps 3 thru 5 for all the items
>3) adjust the item's range so it's 0 to n (doesn't have to be a power of 2)
>4) add the item value to be encoded to your bitstream
>5) multiply your bitstream by n  (goto step 3 if there's more items)
>6) now we have a long bitstream which has the encoded bits.
>7) segment the bitstream into, say, 5 bit segments and convert each into a
>letter/digit by table lookup
>8) bob's your uncle.
>
>The decode is, of course, the reverse.
>1) combine all letters in password to a long bitstream (by reverse lookup of
>the letter values in the table)
>2) to get the next item, MOD your bitstream by items range => encoded info
>for this item
>3) divide bitstream by items range and repeat at step 2
>
>Thats how it was done.
>Hope that's what you were after, because buggered if I could remember ACTUAL
>passwords and information encoded.  I can hardly remember the games... sort
>of a selective memory loss to dull the pain.

That was definitely interesting, and could be implemented on the 2600 for a
password game.  Problem is the lack of memory and the multiplications...
the 2600 would have a heck of a time multiplying a 40-bit stream by, say,
11.

I was after a method to generate passwords containing whatever data I
wanted for a specific game :)  Didn't think it would work :) I can hack
quite a bit of stuff using the Nesticle emulator's save and load memory
state capabilities anyway (I completely figured out the character data for
Final Fantasy in those files - if anyone wants the format for that, let me
know... i think it'd be kinda off-topic here though)

--
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/stella.html

Current Thread