Author: James Robertson
Date: 01:48:05 06/20/00
Go up one level in this thread
On June 20, 2000 at 04:44:57, Tony Werten wrote:
>On June 20, 2000 at 03:50:36, James Robertson wrote:
>
>>On June 20, 2000 at 03:09:49, Tony Werten wrote:
>>
>>>On June 19, 2000 at 19:54:39, James Robertson wrote:
>>>
>>>>On June 19, 2000 at 19:48:36, Larry Griffiths wrote:
>>>>
>>>>>I have found bitboards to be an even trade-off on my Pentium system. I have to
>>>>>update about 6 bitboards when a piece moves and this generates a lot of
>>>>>instructions. I get it back in my IsKingInCheck code so it evens out.
>>>>
>>>>While detecting check is faster with bitboards if you have many pieces on the
>>>>board, I think it is actually slower in endgame positions. :(
>>>
>>>I don't understand this. I have written it before but here it is again. You only
>>>have to look at the to and from square of the last move.
>>
>>I do not understand.... could you please elaborate?
>
>Sure,
>
>If you exclude a rochade, a check can only occur in 2 ways.
>
>1) The piece last moved is giving check ( on the to-square )
>2) The piece just moved revealed a slider which is giving check. ( behind the
>from square )
>
>The code should look something likes this. ( there might be some mistakes)
>
>if (last_move==rochade)
>{
> square=king_square;
> if (possible to attack square from rook_square)
> {
> repeat
> square+=dir_of_rook;
> until (square!=empty)
> }
> return (square==rook_square)
>}
>
>if (possible for moved_piece to attack king_square from to_square)
>{
> if moved_piece==KING,KNIGHT or PAWN then return (true)
> square=king_square;
> repeat
> square+=dir_of_to_square;
> until (square!=empty)
> if (square==to_square return) (true)
>}
>
>if (possible for BISHOP or ROOK to attack king_square from from_square)
>{
> square=king_square;
> repeat
> square+=dir_of_from_square;
> if (square!=empty) then return (piece_on_square can attack king_square)
> until (square is not on board)
>}
>
>return false;
>
>cheers,
This idea looks nice. I think I can use it to improve my existing code....
Thanks!
James
>
>Tony
>
>PS If you are looking for a selfcheck, you only have to do the from_square. ( If
>you didn't start of in check )
>
>>
>>Thanks,
>>James
>>
>>>
>>>It has nothing to do with the number of pieces.
>>>
>>>Tony
>>>
>>>>
>>>>James
>>>>
>>>>> I like
>>>>>to have fast move generation code, but most of my gains have been through
>>>>>alpha-beta, hash-table, killer-move and movelist ordering etc.
>>>>>
>>>>>Larry.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.