Author: Keith Evans
Date: 12:07:09 02/26/06
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On February 26, 2006 at 07:39:10, Gerd Isenberg wrote: >Hi all, > >First greetings and good luck to all cct8 participants! >Second some thoughts and suggestions for improvements of Dann's switch-approach: > >Dann's approach, to do a switch of a masked row per square and ray-kind with 128 >bitboard cases does almost the same as rotated lookups with rotated occupied >state and square - it may supply appropriate attack bitboards for that ray-kind >and square - and even other precalculated information such as possible covered >xray information. Correct me if i'm wrong, Dann. > >Despite it was interesing to see how the compiler translates a switch with 128 >64-bit cases in a binary search manner, Dann's switch-approach covers a lot of >branch target buffer slots and branch prediction ressources. Also each maked >move inside the search changes almost 7 occupied rays so that some >miss-predictions are likely in the compare/conditional-jump chains of the >switches. One thing that I was wondering about the original thread was is there's any way to approach this the same way for game with boards with more than 64 squares. Even if you don't worry about efficiency, can you even switch on say 128 bits? (e.g. Chinese chess, capablanca chess,...) I wonder if your suggestions would be useful there. I have to admit that it's a bit over my head at the moment...
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