Author: Ed Schröder
Date: 11:31:10 01/08/03
Go up one level in this thread
On January 08, 2003 at 12:41:39, Gerd Isenberg wrote:
>On January 08, 2003 at 04:43:12, scott farrell wrote:
>
>>My chompster is bit board .... bit boards rule 4ever !!!
>>
>>I really like Ed's code for eval/SEE, call it what you like, by calculating all
>>the attack and defend squares.
>>
>>MSCP does this to a lesser extent.
>>
>>Crafty doesnt seem to do it at all. Robert, am I correct here? do you eval each
>>square in a 64 byte array at all? I couldnt see it.
>>
>>Having used bitboards in chompster I have almost no loops anywhere in my
>>program. 1 or 2 for move generation, and 1 for move ordering and 1 for searching
>>each move, and only a very few in eval but all guarded by a simple bit board &
>>so they dont fire too often.
>>
>>The only way I can think to implement the above, it to iterate over each
>>attackBoard for each piece, which I have available during eval, but I dont
>>really want to iterate over it, yuk ... too sssllloooowwwww.
>>
>>It seems to me, without bit boards, you have to iterate everything, so it seems
>>no problem to be iterating over attack vectors. But for us bit-boarders it seem
>>ugly (too me anyway).
>>
>>All I could think of was to keep each attackVector for each piece. And when
>>traversing each quare on the board, do something like this:
>>
>>for (sq=0; sq<64;sq++){
>> if( (mask[sq] & whiteQueenAttacks) !=0)
>> attackers++;
>> if( (mask[sq] & blackQueenAttacks) !=0)
>> defenders++;
>> ......
>>}
>>if (attackers>defenders)
>> ATTACK_NOW_!!!!!
>>
>>atleast this method I dont have ot itereate the actuall attack vectors, and
>>avoid slow msb/pop type routines.
>>
>>Any help / ideas appreciated.
>>
>>Scott
>
>Hi Scott,
>
>yes, Ed's control structure is really nice to have, specially if they are used
>as indices of a two dimensional 256*256 table, to get a precalculated is enprise
>or hanging information for pieces etc.
>But with attacked bitboards it is probably smarter to use a bitboard based
>approach for hanging or enprise squares or pieces, which may generated in a
>loopless, unconditional way like below (on the fly, hope you get the idea).
Yes Gerd, this is probably most true. I never had the time to put energy in the
bit-boards technique. Do you have any idea about the number of clocks needed to
extract the hanging pieces from a position using bitboards?
>A lot of this stuff may be done in the near future with hammers MMX- or
>XMM-registers.
Or just when 64-bit becomes the standard.
Ed
>Regards,
>Gerd
>
>// several attack bitboards
>pawnAttacks[W] = getPawnAttacksAH(W) | getPawnAttacksHA(W);
>pawnDblAttacks[W] = getPawnAttacksAH(W) & getPawnAttacksHA(W);
>knightAttacks[W] = getKnightAttacks(W);
>knightDblAttacks[W] = getKnightDblAttacks(W);
>bishopAttacks[W] = getBishopAttacks(W);
>rookAttacks[W] = getRookAttacks(W);
>rookDblAttacks[W] = getRookDblAttacks(W);
>queenAttacks[W] = getQueenAttacks(W);
>kingAttacks[W] = getKingAttacks(W);
>xRays[W] = ....;
>
>KnBiAttacks[W] = knightAttacks[W] | bishopAttacks[W];
>KnBiPaAttacks[W] = KnBiAttacks[W] | pawnAttacks[W];
>RKnBiPaAttacks[W] = KnBiPaAttacks[W] | rookAttacks[W];
>QRKnBiPaAttacks[W] = RKnBiPaAttacks[W] | queenAttacks[W];
>allAttacks[W] = QRKnBiPaAttacks[W]| kingAttacks[W];
>
>// single, double and triple attacks
>// (may be exceeded to quad or multiple attacks)
>
>doubleAttacks[W] = pawnDblAttacks[W];
>singleAttacks[W] = pawnAttacks[W];
>
>tripleAttacks[W] = doubleAttacks[W] & knightAttacks[W];
>tripleAttacks[W] |= singleAttacks[W] & knightDblAttacks[W];
>doubleAttacks[W] |= singleAttacks[W] & knightAttacks[W];
>doubleAttacks[W] |= knightDblAttacks[W];
>singleAttacks[W] |= knightAttacks[W];
>
>tripleAttacks[W] |= doubleAttacks[W] & bishopAttacks[W];
>doubleAttacks[W] |= singleAttacks[W] & bishopAttacks[W];
>singleAttacks[W] |= bishopAttacks[W];
>
>tripleAttacks[W] |= doubleAttacks[W] & rookAttacks[W];
>tripleAttacks[W] |= singleAttacks[W] & rookDblAttacks[W];
>doubleAttacks[W] |= singleAttacks[W] & rookAttacks[W];
>doubleAttacks[W] |= rookDblAttacks[W];
>singleAttacks[W] |= rookDblAttacks[W];
>
>tripleAttacks[W] |= doubleAttacks[W] & queenAttacks[W];
>doubleAttacks[W] |= singleAttacks[W] & queenAttacks[W];
>singleAttacks[W] |= queenAttacks[W];
>
>tripleAttacks[W] |= doubleAttacks[W] & xRays[W];
>doubleAttacks[W] |= singleAttacks[W] & xRays[W];
>
>tripleAttacks[W] |= doubleAttacks[W] & kingAttacks[W];
>doubleAttacks[W] |= singleAttacks[W] & kingAttacks[W];
>singleAttacks[W] |= kingAttacks[W];
>
>singleAttacks[W] &= ~doubleAttacks[W];
>doubleAttacks[W] &= ~tripleAttacks[W];
>
>// dominated contols
>valDom[W] = (pawnDblAttacks[W] & ~pawnDblAttacks[B])
> | (pawnAttacks[W] & ~pawnAttacks[B])
> | (KnBiAttacks[W] & ~KnBiPaAttacks[B])
> | (rookAttacks[W] & ~RKnBiPaAttacks[B])
> | (queenAttacks[W] & ~QRKnBiPaAttacks[B])
> | (kingAttacks[W] & ~allAttacks[B]);
>
>valDom[B] = ....
>
>countDom[W] = (tripleAttacks[W] & ~tripleAttacks[B])
> | (doubleAttacks[W] & ~doubleAttacks[B])
> | (singleAttacks[W] & ~singleAttacks[B]);
>
>totalDom[W] = valDom[W] | (countDom[W] & ~valDom[B]);
>...
>
>// hanging pieces (enprise)
>enprise[W] = (queens[W] & RKnBiPaAttacks[B])
> | (rooks[W] & KnBiPaAttacks[B])
> | ((knights[W]|bishops[W])& pawnAttacks[B])
> | (pieces[W] & totalDom[B]);
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.