Author: Gerd Isenberg
Date: 15:59:02 03/24/04
Go up one level in this thread
Some minor changes because inOne == inThree is not general enough.
Better to look for no further growing:
if ( (inThree & ~(fromBB|inOne|inTwo)) == 0 && ...
// fixed is subset of tabu (may be equal), the set of all own blocked
// and backward pawns.
// tabu may contain enemy pawn attacks which don't terminate the attack ray
BitBoard getTrappedBishopSquares(BitBoard fixed, BitBoard tabu, int n)
{
BitBoard trappedBishopSquares = 0;
BitBoard potb = ~tabu;
while ( potb ) {
BitBoard fromBB = potb & -potb;
BitBoard inOne = fillBishopAttacks(fromBB, ~fixed) & ~tabu;
BitBoard inTwo = fillBishopAttacks(inOne, ~fixed) & ~tabu;
BitBoard inThree = fillBishopAttacks(inTwo, ~fixed) & ~tabu;
// tag all reachable in up to three moves as done
potb &= ~(fromBB|inOne|inTwo|inThree);
inThree &= ~(fromBB|inOne|inTwo); // growing?
if ( inThree == 0 && popCount(inOne|inTwo) < n )
trappedBishopSquares |= (fromBB|inOne|inTwo);
}
return trappedBishopSquares;
}
popCount > n considers the whole fill area reachable in two moves.
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Last modified: Thu, 15 Apr 21 08:11:13 -0700
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