static char* isLegal_test() {
assert(gs.initialized);
printf("Running isLegal_test\n");
char fen[] = "rn1qkbnr/ppp2pp1/3p4/4p2p/4P2P/3P3b/PPP2PP1/RNBQKBNR w KQkq - 0 1";
parseFen(fen);
int numMoves;
MOVE moves[MAX_MOVES];
generateNonCaptures(gs.color, moves, &numMoves, gs.bitboard);
for (int i=0; i < numMoves; i++)
{
MOVE move = moves[i];
//printf("Testing move ");
//printMove(move);
if (!isMoveLegal(move)) {
printf("Not legal ");
printMove(move);
isMoveLegal(move);
}
assert( isMoveLegal(move));
}
return 0;
}
int Board::alphaBeta(int depthLeft, int alpha, int beta, int doNullMove) {
int check = 0;
int oldAlpha = alpha;
int numSearched = 0;
int bestMove = 0;
int hashMove = 0;
int stage;
int i = currentState->firstMove;
int result;
nodes++;
nodesUntilUpdate--;
if(nodesUntilUpdate <= 0) {
switch(game->interfaceUpdate()) {
case OUT_OF_TIME:
abortingSearch = 1;
return 0;
break;
case STOP_SEARCH:
abortingSearch = 1;
return 0;
break;
}
nodesUntilUpdate = nodesPerUpdate;
}
if(isRepetition()) {
returnMove = 0;
return DRAW;
}
HashEntry *e;
e = hash->probe(currentState->hashKey);
if(e!=NULL) {
hashHits++;
//Is it useful for replacing this search - otherwise just find a best move
hashMove = e->bestMove;
returnMove = hashMove;
#ifndef DISABLE_HASH
if(depth > 0 && e->depth >= depthLeft) {
switch(e->flags & 3) {
case HASH_EXACT:
return e->score;
break;
case HASH_LOWER:
if(e->score >= beta) return e->score;
if(e->score > alpha) alpha = e->score;
break;
case HASH_UPPER:
if(e->score <= alpha) return e->score;
if(e->score < beta) beta = e->score;
break;
}
if(e->flags & HASH_NO_NULL) {
doNullMove = 0;
}
}
#endif
}
#ifdef DEBUG_HASH
if(hashMove > 0 && !testLegality(hashMove)) {
print();
cout << "Illegal hash move! ";
printMove(hashMove);
cout << endl;
}
#endif
if(depthLeft == 0) {
int value = quiescence(alpha, beta);
//hash->store(0, value, 0, HASH_EXACT);
return value;
}
check = inCheck();
/*
if(doNullMove && !check && !nullRisk() && depth >= 2) {
int nullDepth = depthLeft - 2;
makeNullMove();
if(nullDepth > 0) {
result = alphaBeta(nullDepth, -beta, -beta+1, NO_NULL_MOVE);
} else {
result = quiescence(-beta, -beta+1);
}
retractNullMove();
if(nullDepth > 0 && result >= beta) {
result = alphaBeta(nullDepth, beta-1, beta, DO_NULL_MOVE);
numMoves = currentState->firstMove;
}
if(result >= beta) {
returnMove = 0;
return beta;
}
}
*/
if(!hashMove && depthLeft >= 3) {
result = alphaBeta(depthLeft - 2, alpha, beta, DO_NULL_MOVE);
numMoves = currentState->firstMove;
//Failed low so have to research with new bounds
if(result <= alpha) result = alphaBeta(depthLeft - 2, -MATE, alpha + 1, DO_NULL_MOVE);
numMoves = currentState->firstMove;
hashMove = returnMove;
}
if(hashMove > 0) {
stage = HASH_MOVE;
} else {
stage = ALL_MOVES;
}
while(stage != FINISHED) {
switch(stage) {
case HASH_MOVE:
moveStack[numMoves++] = hashMove;
stage = ALL_MOVES;
break;
case ALL_MOVES:
if(check) {
generateCheckEvasions();
sortNonCaptures(i, hashMove);
stage = FINISHED;
} else {
generateCaptures();
sortCaptures(i, hashMove);
stage = NON_CAPTURES;
}
break;
case NON_CAPTURES:
generateNonCaptures();
sortNonCaptures(i, hashMove);
stage = FINISHED;
break;
}
for(; i<numMoves; i++) {
int move = moveStack[i];
makeMove(move);
#ifdef DEBUG_BITBOARDS
if(isMessedUp()) {
printMoves();
print();
cout << "Hash move = "; printMove(hashMove); cout << endl;
cout << "MakeMove" << endl;
exit(0);
}
#endif
if(isLegal()) {
numSearched++;
result = -alphaBeta(depthLeft - 1, -beta, -alpha, DO_NULL_MOVE);
retractMove(move);
if(abortingSearch) {
returnMove = bestMove;
return result;
}
if(result > alpha) {
if(result >= beta) {
returnMove = move;
hash->store(move, result, depthLeft, HASH_LOWER);
#ifdef EXTRA_STATS
cutoffs++;
if(i == currentState->firstMove) firstCutoffs++;
#endif
return result;
}
/* if(depth == 0) {
printMove(move);
cout << " ";
printScore(result);
cout << " hashMove: ";
printMove(hashMove);
cout << endl;
}*/
alpha = result;
bestMove = move;
}
} else { //Illegal move
retractMove(move);
}
#ifdef DEBUG_BITBOARDS
if(isMessedUp()) {
printMoves();
print();
cout << "Hash move = "; printMove(hashMove); cout << endl;
cout << "RetractMove" << endl;
exit(0);
}
#endif
}
} //While we have moves
//No legal moves..
if(numSearched ==0) {
returnMove = 0;
if(check) {
return -(MATE - depth);
} else {
return DRAW;
}
}
if(alpha == oldAlpha) {
hash->store(bestMove, alpha, depthLeft, HASH_UPPER);
} else {
hash->store(bestMove, alpha, depthLeft, HASH_EXACT);
}
returnMove = bestMove;
return alpha;
}