Re: [stella] Collaboration

Subject: Re: [stella] Collaboration
From: Thomas Jentzsch <tjentzsch@xxxxxx>
Date: Mon, 20 Jan 2003 19:13:32 +0100
I wrote:
> There are 6 free cycles in the playfield code, but we would need 8 for
> doing this: 
>   lda RAM1,x
>   and #%01010101
>   sta PF1
>   lda RAM2,x
>   and #%01010101
>   sta PF2
>   lda RAM1,x
>   and #%10101010
>   sta PF1
>   lda RAM2,x
>   and #%10101010
>   sta PF2

After a little bit more thinking about it, I came up with this solution:
   lda RAM1,x
   and #%10101010
   sta PF1
   eor RAM1,x
   sta PF2
   lda RAM2,x
   and #%10101010
   sta PF1
   eor RAM2,x
   sta PF2

This saves 4 cycles.

Currently this still doesn't fit well into the existing kernel, but I
already know how to save 11 bytes and with some compromises we might
even get the whole 22 bytes.

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

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