Author: Vincent Diepeveen
Date: 07:13:42 07/07/03
Go up one level in this thread
On July 07, 2003 at 09:55:26, Gerd Isenberg wrote: >On July 07, 2003 at 09:21:17, Jarkko Pesonen wrote: > >>In Crafty bitboard function FirstOne gives 12 and LastOne gives 53. >>Is there fast implementation for LeftOne and RightOne, which >>would give in below case 33 and 38. >>C implementation would ne appriciated. >> >>---+---+---+---+---+---+---+---+ >> | | | | | | | | >>---+---+---+---+---+---+---+---+ >> | | | | | *P| | | >>---+---+---+---+---+---+---+---+ >> | | | | | | | | >>---+---+---+---+---+---+---+---+ >> | *P| *P| | | | *P| | >>---+---+---+---+---+---+---+---+ 0x0080000062000400 >> | | | | | | | | >>---+---+---+---+---+---+---+---+ >> | | | | | | | | >>---+---+---+---+---+---+---+---+ >> | | | |*P | | | | >>---+---+---+---+---+---+---+---+ >> | | | | | | | | >>---+---+---+---+---+---+---+---+ >> >>thanks in advance >> >>Jarkko > >Hi Jarkko, > >i fear there is no fast LeftOne or RightOne with this bit mapping >a1=0,h1=7,a2=8,h8=63. Rotating eg. Mirroring files with ranks is a rather time >comsuming algorithm - unless you use several rotated bitboards with incremental >update during make/unmake move. 1 is enough, and further only need is 1 convert and 1 invert array of 64 squares. >Regards, >Gerd
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