Determine Opposite Colors Mathematically #2498
Conversation
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It would be more code, this would be much clearer with a square_color() method. Then opposite_colors would just check it square_color(s1) != square_color(s2); |
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This could also be added now that we have a method that quickly determines square color: http://tests.stockfishchess.org/tests/view/5e28b69ec3b97aa0d75bc2aa |
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Merged via f3c83ed, thanks! |
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@protonspring Sorry to necro an older patch, but I was looking at the current KXK endgame and I came across these lines: |
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I don't think so. If you did opposite_colors you would first have to check
if there were in fact two bishops first, then do opposite_colors on
pos.square<BISHOP>(strongSide)[0], etc. That doesn't seem as clean as what
is there.
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@protonspring Cool that makes sense, I forgot that we would have to first check for the existence of both bishops before we could call opposite_colors. Thanks. |
2 participants
This is a non-functional speed-up. Master has to access SquareBB twice while this patch determines opposite_colors just using the values of the squares. It doesn't seem to change the overall speed of bench, but calling opposite_colors(...) 10Million times:
master: 39.4 seconds
patch: 11.4 seconds.
The only data point I have (other than my own tests), is a quite old failed STC test:
LLR: -2.93 (-2.94,2.94) [-1.50,4.50]
Total: 24308 W: 5331 L: 5330 D: 13647
Ptnml(0-2): 315, 2577, 6326, 2623, 289
http://tests.stockfishchess.org/tests/view/5e010256c13ac2425c4a9a67