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SEE.cpp
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SEE.cpp
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/*******************************************************************************
Static Exchange Evaluation and Static Table Evaluation.
*******************************************************************************/
#include <iostream>
#include "SEE.h"
#include "macros.h"
#include "bitboards.h"
//int ordering_tables[2][8][64];
/*
void initOrderingTables(short t) {
for (int color = 0; color < 2; color++) {
for (int square = 0; square < 64; square++) {
ordering_tables[color][nPawn][square] = interpolate(nSquareValue[color][nPawn][square], nEndgamePawnValue[color][square], t);
ordering_tables[color][nKing][square] = interpolate(nSquareValue[color][nKing][square], nEndgameKingValue[color][square], t);
ordering_tables[color][nKnight][square] = nSquareValue[color][nKnight][square];
ordering_tables[color][nBishop][square] = nSquareValue[color][nBishop][square];
ordering_tables[color][nRook][square] = nSquareValue[color][nRook][square];
ordering_tables[color][nQueen][square] = nSquareValue[color][nQueen][square];
}
}
}
*/
short STE(CHESSBOARD * b, MOVE m) {
//return 0;
short early_game = nSquareValue[m.color][m.active_piece_id][m.to] - nSquareValue[m.color][m.active_piece_id][m.from];
return early_game;
//return ordering_tables[m.color][m.active_piece_id][m.to] - ordering_tables[m.color][m.active_piece_id][m.from];
}
void findAttackingSquares(bitboard &attackers, CHESSBOARD *b, unsigned char square) {
//identify all of the squares that threaten the square in question.
//Then toggle those bits on in the 'attackers' bitboard
// The idea is to place yourself at the position of the square in question and pretend you are each of the pieces.
// If you end up being able to move to a square containing that piece, then that piece is an attacker.
bitboard pieceDB = 0;
//First check for black attacking pawns:
if(square < 48) {
attackers = ( ((((bitboard)1) << (square+9)) & ~FileMask(h)) | ((((bitboard)1) << (square+7)) & ~FileMask(a)) ) & b->getPieceBB(BLACK,nPawn);
}
//Next check for white attacking pawns:
if(square > 15) {
attackers |= ( ((((bitboard)1) << (square-9)) & ~FileMask(a)) | ((((bitboard)1) << (square-7)) & ~FileMask(h)) ) & b->getPieceBB(WHITE,nPawn);
}
//Store the bits of diagonal attackers to xray through:
bitboard xray = b->getPieceBB(WHITE, nBishop) | b->getPieceBB(WHITE, nQueen)
| b->getPieceBB(BLACK, nBishop) | b->getPieceBB(BLACK, nQueen);
//Diagonal attackers: (Note the double use of 'attackers' in xray|attackers since we want to xray through any attacking pawns.
attackers |= mask::MagicBishopMoves[square][(( ( b->getOccupiedBB(BOTH)^(xray/*|attackers*/) )&mask::MagicBishopMask[square] ) * mask::MagicBishopNumbers[square])>>mask::MagicBishopShift[square]]
& (xray); //In this case, xray also happens to be the pieces we are trying to find.
//Straight sliders to xray through:
xray = b->getPieceBB(WHITE, nRook) | b->getPieceBB(WHITE, nQueen) | b->getPieceBB(BLACK, nRook) | b->getPieceBB(BLACK, nQueen);
//Straight attackers:
attackers |= mask::MagicRookMoves[square][(( (b->getOccupiedBB(BOTH)^xray) & mask::MagicRookMask[square]) * mask::MagicRookNumbers[square])>>mask::MagicRookShift[square]]
& (xray); //In this case, xray also happens to be the pieces we are trying to find.
//Knight attackers:
attackers |= mask::knight_moves[square] & (b->getPieceBB(WHITE, nKnight) | b->getPieceBB(BLACK, nKnight) );
//King Attackers:
attackers |= mask::king_moves[square] & (b->getPieceBB(WHITE, nKing) | b->getPieceBB(BLACK, nKing));
}
short findSmallestAttacker(CHESSBOARD *b, bitboard &attackers, bool color ) {
// _IN_ CHESSBOARD, attackers, color
// _OUT_ attackers
// Returns the value of the attacker (zero in the case that there is not an attacker afterall.
// Then turns off the bit in the 'attackers' bitboard.
unsigned char bit;
//pawns:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nPawn))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nPawn];
}
//knights:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nKnight))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nKnight];
}
//bishops:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nBishop))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nBishop];
}
//rooks:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nRook))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nRook];
}
//queens:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nQueen))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nQueen];
}
//king:
if( (bit = bitscan_msb(attackers & b->getPieceBB(color, nKing))) != 64 ) {
//turn off the bit:
attackers ^= (((bitboard)1) << bit);
//Return the piece value:
return nPieceValue[nKing];
}
return 0;
}
inline short max(short a, short b) {
return (a>b)?a:b;
}
short SEE2(CHESSBOARD *b, MOVE m) {
//check to see if this is already a winnin capture first. if so, we dont need to SEE.
if( nPieceValue[m.captured_piece] - nPieceValue[m.active_piece_id] > 0 ) {
return nPieceValue[m.captured_piece];
} else {
short gain[32];
unsigned char d = 0;
//Set the values for the first iteration of the loop.
//short attackers_value = nPieceValue[m.active_piece_id];
gain[d] = nPieceValue[m.captured_piece];
d++;
gain[d] = nPieceValue[m.active_piece_id] - gain[d-1];
//Make the move that we are scoring:
b->quickCapture(m);
bool toMove = !m.color; //since that color just went, it is the other colors turn.
//Find all of the squares that are attacking the square that we just moved too. store them in a bitboard.
bitboard attackers = 0;
findAttackingSquares(attackers, b, m.to);
//loop as long as there are attackers left of the appropriate color:
while(attackers & b->getOccupiedBB(toMove)) {
d++;
gain[d] = findSmallestAttacker(b,attackers,toMove) - gain[d-1];//this will also toggle off the bit of the attacker found.
if( max(-gain[d-1], gain[d]) < 0 ) break; //prune.
//Toggle color:
toMove = !toMove;
}
//unmake the move we are scoring:
b->quickUnCapture(m);
//roll down the total score:
while(--d) {
gain[d-1] = -max(-gain[d-1] , gain[d]);
}
return gain[0];
}
}
short SEE3_Loop(CHESSBOARD * b, bitboard &attackers, short defender, bool toMove) {
//short value = findSmallestAttacker(b,attackers,toMove);
short next_defender = findSmallestAttacker(b,attackers,toMove);
if(attackers & b->getOccupiedBB(!toMove)) {
return max(0, defender - SEE3_Loop(b,attackers, next_defender, !toMove));
} else
return defender;
}
short SEE3(CHESSBOARD *b, MOVE m) {
//check to see if this is already a winnin capture first. if so, we dont need to SEE.
/*
if( nPieceValue[m.captured_piece] - nPieceValue[m.active_piece_id] > 0 ) {
//MVV/LVA: 16000 - (8 * captured_piece_value + capturing_piece_value)
return (16000 - (8 * nPieceValue[m.captured_piece] + nPieceValue[m.active_piece_id]));
}
else {
*/
//Make the move that we are scoring:
b->quickCapture(m);
//Find all of the squares that are attacking the square that we just moved too. store them in a bitboard.
bitboard attackers = 0;
findAttackingSquares(attackers, b, m.to);
short value = nPieceValue[m.captured_piece];
if(attackers & b->getOccupiedBB(!m.color)) {
value = nPieceValue[m.captured_piece] - SEE3_Loop(b, attackers, nPieceValue[m.active_piece_id], !m.color );
}
//unmake the move we are scoring:
b->quickUnCapture(m);
return value;
//}
}
short SEE1(CHESSBOARD * b, MOVE m) {
//short value = nPieceValue[m.captured_piece];
short value = nPieceValue[m.captured_piece] - nPieceValue[m.active_piece_id];
if( value <= 0 ) {
b->quickCapture(m);
value = nPieceValue[m.captured_piece] - SEE1(b,m.to,!m.color);
b->quickUnCapture(m);
}
else {
value = nPieceValue[m.captured_piece];
}
return value;
}
short SEE1(CHESSBOARD * b, unsigned char square, bool toMove) {
//Iterates until there is not an attacker.
short value = 0;
short attackee_value = nPieceValue[b->getBoard(square)];
CAPTURER attacker = getSmallestAttacker(square, !toMove, b);
if(attacker.from != 64) {
//attacker.print();
//std::cout << "->";
b->quickCapture(attacker);
value = std::max(0, attackee_value - SEE1(b, square, !toMove));
b->quickUnCapture(attacker);
}
return value;
}
CAPTURER getSmallestAttacker( unsigned char toSquare, bool toMove, CHESSBOARD * b) {
//TODO: -en passant is not covered here.
// -Avoid king captures king sort of stuff.
bitboard pieceDB =0;
//Pawn check:
if(toMove == WHITE && toSquare < 48) {
pieceDB = (((bitboard)1) << (toSquare+9)) & ~FileMask(h); //~mask::file[h];
pieceDB|= (((bitboard)1) << (toSquare+7)) & ~FileMask(a); //~mask::file[a];
pieceDB &= b->getPieceBB(!toMove,nPawn);
if(pieceDB) {
return(CAPTURER(nPawn, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(toMove == BLACK && toSquare > 15) {
pieceDB = (((bitboard)1) << (toSquare-9)) & ~FileMask(a); //~mask::file[h];
pieceDB|= (((bitboard)1) << (toSquare-7)) & ~FileMask(h); //~mask::file[a];
pieceDB &= b->getPieceBB(!toMove,nPawn);
if(pieceDB) {
return(CAPTURER(nPawn, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
//Knight Check:
pieceDB = mask::knight_moves[toSquare] & b->getPieceBB(!toMove, nKnight);
if(pieceDB) {
return(CAPTURER(nKnight, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
//Bishop attacks:
if(pieceDB = (mask::MagicBishopMoves[toSquare][((b->getOccupiedBB(BOTH)&mask::MagicBishopMask[toSquare]) * mask::MagicBishopNumbers[toSquare])>>mask::MagicBishopShift[toSquare]]
& (b->getPieceBB(!toMove,nBishop))) ) {
return (CAPTURER(nBishop, b->getBoard(toSquare), bitscan_msb(pieceDB),toSquare, !toMove));
}
// Rook attacks:
if(pieceDB = (mask::MagicRookMoves[toSquare][((b->getOccupiedBB(BOTH) & mask::MagicRookMask[toSquare]) * mask::MagicRookNumbers[toSquare])>>mask::MagicRookShift[toSquare]]
& (b->getPieceBB(!toMove,nRook))) ) {
return (CAPTURER(nRook, b->getBoard(toSquare), bitscan_msb(pieceDB),toSquare, !toMove));
}
//Queen attacks:
if(pieceDB = (mask::MagicBishopMoves[toSquare][((b->getOccupiedBB(BOTH)&mask::MagicBishopMask[toSquare]) * mask::MagicBishopNumbers[toSquare])>>mask::MagicBishopShift[toSquare]]
& (b->getPieceBB(!toMove,nQueen))) ) {
return (CAPTURER(nQueen, b->getBoard(toSquare), bitscan_msb(pieceDB),toSquare, !toMove));
}
if(pieceDB = (mask::MagicRookMoves[toSquare][((b->getOccupiedBB(BOTH) & mask::MagicRookMask[toSquare]) * mask::MagicRookNumbers[toSquare])>>mask::MagicRookShift[toSquare]]
& (b->getPieceBB(!toMove,nQueen)))) {
return (CAPTURER(nQueen, b->getBoard(toSquare),bitscan_msb(pieceDB),toSquare, !toMove));
}
//King Check:
if(pieceDB = mask::king_moves[toSquare] & b->getPieceBB(!toMove, nKing)) {
return(CAPTURER(nKing, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
//Bishop Check:
/*
if(pieceDB = mask::ne[toSquare] & b->getPieceBB(!toMove, nBishop)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::ne[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nBishop, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::nw[toSquare] & b->getPieceBB(!toMove, nBishop)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::nw[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nBishop, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::se[toSquare] & b->getPieceBB(!toMove, nBishop)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::se[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nBishop, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::sw[toSquare] & b->getPieceBB(!toMove, nBishop)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::sw[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nBishop, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
//Rook Check:
if(pieceDB = mask::north[toSquare] & b->getPieceBB(!toMove, nRook)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::north[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nRook, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::west[toSquare] & b->getPieceBB(!toMove, nRook)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::west[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nRook, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::south[toSquare] & b->getPieceBB(!toMove, nRook)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::south[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nRook, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::east[toSquare] & b->getPieceBB(!toMove, nRook)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::east[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nRook, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
//Queen Check:
if(pieceDB = mask::ne[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::ne[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::nw[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::nw[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::se[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::se[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::sw[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::sw[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::north[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::north[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::west[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_lsb(pieceDB) == bitscan_lsb( mask::west[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_lsb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::south[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::south[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
if(pieceDB = mask::east[toSquare] & b->getPieceBB(!toMove, nQueen)) {
if(bitscan_msb(pieceDB) == bitscan_msb( mask::east[toSquare] & b->getOccupiedBB(BOTH) ) ) {
return(CAPTURER(nQueen, b->getBoard(toSquare), bitscan_msb(pieceDB), toSquare, !toMove));
}
}
*/
return(CAPTURER(0,0,64,64,0));
}