Subject: Re: [stella] Euchre: a tight fit From: "TwoHeaded Software" <adavie@xxxxxxxxxxxxx> Date: Tue, 4 Sep 2001 13:50:44 +1000 
Every now and then I'll pick up this code (euchre) and have a browse through. Finding spare bytes is quite relaxing when it's not your baby that needs them to survive. Here's another general suggestion for code reduction... Check this code (from Euchre)... PT2 lda NumTrumps cmp #$02 ; Does hand have more than two trumps? bcc PT3 ; No, move on to next check sec sbc #$02 ; Find number of trumps over two... clc ; then increase the likely tricks by that number adc PossibleTricks ; (there are only seven trumps, so if one hand sta PossibleTricks ; has three, no player is likely to have more than two) This code can be improved by paying careful attention to the state of the carry. After the first branch (bcc PT3) we know the carry IS NOT clear (the branch wasn't taken). ie: it is set. So we don't need to set it again. That "sec" can go. Then we subtract 2. But we know that the number we're subtracting from is >= 2, so the subtraction will not change the state of the carry bit (it will be set after the subtraction). So if we went on to add Possibletricks without clearing the carry, we'd have one too many. So instead of subtracting 2, let's just subtract 1. This gives us... PT2 lda NumTrumps cmp #2 bcc PT3 sbc #1 adc PossibleTricks sta PossibleTricks We've saved two bytes :) Cheers A  Andrew Davie, TwoHeaded Software adavie@xxxxxxxxxxxxx  Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
Current Thread 


< Previous  Index  Next > 

Re: [stella] Euchre: a tight fit, TwoHeaded Software  Thread  Re: [stella] Euchre: a tight fit, TwoHeaded Software 
Re: [stella] Stella at 20, Rob  Date  Re: [stella] Stella at 20, nj bloodline 
Month 