bool board_is_mate(const board_t * board) {
attack_t attack[1];
ASSERT(board!=NULL);
attack_set(attack,board);
if (!ATTACK_IN_CHECK(attack)) return false; // not in check => not mate
if (legal_evasion_exist(board,attack)) return false; // legal move => not mate
return true; // in check and no legal move => mate
}
void gen_legal_moves(list_t * list) {
attack_t attack[1];
ASSERT(list!=NULL);
attack_set(attack);
if (ATTACK_IN_CHECK(attack)) {
gen_evasions(list,attack);
} else
{
gen_moves(list);
list_filter(list,&pseudo_is_legal,true);
}
}
void gen_legal_moves(list_t * list, board_t * board) {
attack_t attack[1];
ASSERT(list!=NULL);
ASSERT(board!=NULL);
attack_set(attack,board);
if (ATTACK_IN_CHECK(attack)) {
gen_legal_evasions(list,board,attack);
} else {
gen_moves(list,board);
list_filter(list,board,&pseudo_is_legal,true);
}
// debug
ASSERT(list_is_ok(list));
}
static int full_quiescence(board_t * board, int alpha, int beta, int depth, int height, mv_t pv[]) {
bool in_check;
int old_alpha;
int value, best_value;
int best_move;
int move;
int opt_value;
attack_t attack[1];
sort_t sort[1];
undo_t undo[1];
mv_t new_pv[HeightMax];
int cd;
ASSERT(board!=NULL);
ASSERT(range_is_ok(alpha,beta));
ASSERT(depth_is_ok(depth));
ASSERT(height_is_ok(height));
ASSERT(pv!=NULL);
ASSERT(board_is_legal(board));
ASSERT(depth<=0);
// init
SearchStack[height].best_move = MoveNone;
SearchStack[height].move = MoveNone;
SearchStack[height].threat_move = MoveNone;
SearchStack[height].reduced = false;
SearchCurrent->node_nb++;
SearchInfo->check_nb--;
PV_CLEAR(pv);
if (height > SearchCurrent->max_depth) SearchCurrent->max_depth = height;
if (SearchInfo->check_nb <= 0) {
SearchInfo->check_nb += SearchInfo->check_inc;
search_check();
}
// draw?
if (board_is_repetition(board) || recog_draw(board)) return ValueDraw;
// mate-distance pruning
if (UseDistancePruning) {
// lower bound
value = VALUE_MATE(height+2); // does not work if the current position is mate
if (value > alpha && board_is_mate(board)) value = VALUE_MATE(height);
if (value > alpha) {
alpha = value;
if (value >= beta) return value;
}
// upper bound
value = -VALUE_MATE(height+1);
if (value < beta) {
beta = value;
if (value <= alpha) return value;
}
}
// more init
attack_set(attack,board);
in_check = ATTACK_IN_CHECK(attack);
if (in_check) {
ASSERT(depth<0);
depth++; // in-check extension
}
// height limit
if (height >= HeightMax-1) return eval(board, alpha, beta);
// more init
old_alpha = alpha;
best_value = ValueNone;
best_move = MoveNone;
/* if (UseDelta) */ opt_value = +ValueInf;
if (!in_check) {
// lone-king stalemate?
if (simple_stalemate(board)) return ValueDraw;
// stand pat
value = eval(board, alpha, beta);
ASSERT(value>best_value);
best_value = value;
if (value > alpha) {
alpha = value;
if (value >= beta) goto cut;
}
if (UseDelta) {
opt_value = value + DeltaMargin;
ASSERT(opt_value<+ValueInf);
}
}
// move loop
/* cd = CheckDepth;
if(cd < 0 && board->piece_size[board->turn] <= 5)
cd++; */
sort_init_qs(sort,board,attack, depth>=CheckDepth /* depth>=cd */);
while ((move=sort_next_qs(sort)) != MoveNone) {
SearchStack[height].move = move;
// delta pruning
if (UseDelta && beta == old_alpha+1) {
if (!in_check && !move_is_check(move,board) && !capture_is_dangerous(move,board)) {
ASSERT(move_is_tactical(move,board));
// optimistic evaluation
value = opt_value;
int to = MOVE_TO(move);
int capture = board->square[to];
if (capture != Empty) {
value += VALUE_PIECE(capture);
} else if (MOVE_IS_EN_PASSANT(move)) {
value += ValuePawn;
}
if (MOVE_IS_PROMOTE(move)) value += ValueQueen - ValuePawn;
// pruning
if (value <= alpha) {
if (value > best_value) {
best_value = value;
PV_CLEAR(pv);
}
continue;
}
}
}
move_do(board,move,undo);
value = -full_quiescence(board,-beta,-alpha,depth-1,height+1,new_pv);
move_undo(board,move,undo);
if (value > best_value) {
best_value = value;
pv_cat(pv,new_pv,move);
if (value > alpha) {
alpha = value;
best_move = move;
SearchStack[height].best_move = move;
if (value >= beta) goto cut;
}
}
}
// ALL node
if (best_value == ValueNone) { // no legal move
ASSERT(board_is_mate(board));
return VALUE_MATE(height);
}
cut:
ASSERT(value_is_ok(best_value));
return best_value;
}
static int full_no_null(board_t * board, int alpha, int beta, int depth, int height, mv_t pv[], int node_type, int trans_move, int * best_move) {
int value, best_value;
int move;
int new_depth;
attack_t attack[1];
sort_t sort[1];
undo_t undo[1];
mv_t new_pv[HeightMax];
ASSERT(board!=NULL);
ASSERT(range_is_ok(alpha,beta));
ASSERT(depth_is_ok(depth));
ASSERT(height_is_ok(height));
ASSERT(pv!=NULL);
ASSERT(node_type==NodePV||node_type==NodeCut||node_type==NodeAll);
ASSERT(trans_move==MoveNone||move_is_ok(trans_move));
ASSERT(best_move!=NULL);
ASSERT(board_is_legal(board));
ASSERT(!board_is_check(board));
ASSERT(depth>=1);
// init
SearchStack[height].best_move = MoveNone;
SearchStack[height].move = MoveNone;
SearchStack[height].threat_move = MoveNone;
SearchStack[height].reduced = false;
SearchCurrent->node_nb++;
SearchInfo->check_nb--;
PV_CLEAR(pv);
if (height > SearchCurrent->max_depth) SearchCurrent->max_depth = height;
if (SearchInfo->check_nb <= 0) {
SearchInfo->check_nb += SearchInfo->check_inc;
search_check();
}
attack_set(attack,board);
ASSERT(!ATTACK_IN_CHECK(attack));
*best_move = MoveNone;
best_value = ValueNone;
// move loop
sort_init(sort,board,attack,depth,height,trans_move);
while ((move=sort_next(sort)) != MoveNone) {
SearchStack[height].move = move;
new_depth = full_new_depth(depth,move,board,false,false,false,height);
move_do(board,move,undo);
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NODE_OPP(node_type));
move_undo(board,move,undo);
if (value > best_value) {
best_value = value;
pv_cat(pv,new_pv,move);
if (value > alpha) {
alpha = value;
*best_move = move;
SearchStack[height].best_move = move;
if (value >= beta) goto cut;
}
}
}
// ALL node
if (best_value == ValueNone) { // no legal move => stalemate
ASSERT(board_is_stalemate(board));
best_value = ValueDraw;
}
cut:
ASSERT(value_is_ok(best_value));
return best_value;
}
static int full_search(board_t * board, int alpha, int beta, int depth, int height, mv_t pv[], int node_type) {
bool in_check;
bool single_reply;
bool mate_threat;
int trans_move, trans_depth, trans_min_depth, trans_max_depth, trans_min_value, trans_max_value;
int min_value, max_value;
int old_alpha;
int value, best_value;
int move, best_move;
int new_depth;
int played_nb;
int i;
int opt_value;
bool reduced;
int mb;
attack_t attack[1];
sort_t sort[1];
undo_t undo[1];
mv_t new_pv[HeightMax];
mv_t played[256];
int FutilityMargin;
ASSERT(board!=NULL);
ASSERT(range_is_ok(alpha,beta));
ASSERT(depth_is_ok(depth));
ASSERT(height_is_ok(height));
ASSERT(pv!=NULL);
ASSERT(node_type==NodePV||node_type==NodeCut||node_type==NodeAll);
ASSERT(board_is_legal(board));
// horizon?
if (depth <= 0){
if (node_type == NodePV)
CheckDepth = 1 - CheckNb - 1;
else
CheckDepth = 1 - CheckNb;
return full_quiescence(board,alpha,beta,0,height,pv);
}
// init
SearchStack[height].best_move = MoveNone;
SearchStack[height].move = MoveNone;
SearchStack[height].threat_move = MoveNone;
SearchStack[height].reduced = false;
mate_threat = false;
SearchCurrent->node_nb++;
SearchInfo->check_nb--;
PV_CLEAR(pv);
if (height > SearchCurrent->max_depth) SearchCurrent->max_depth = height;
if (SearchInfo->check_nb <= 0) {
SearchInfo->check_nb += SearchInfo->check_inc;
search_check();
}
// draw?
if (board_is_repetition(board) || recog_draw(board)) return ValueDraw;
// mate-distance pruning
if (UseDistancePruning) {
// lower bound
value = VALUE_MATE(height+2); // does not work if the current position is mate
if (value > alpha && board_is_mate(board)) value = VALUE_MATE(height);
if (value > alpha) {
alpha = value;
if (value >= beta) return value;
}
// upper bound
value = -VALUE_MATE(height+1);
if (value < beta) {
beta = value;
if (value <= alpha) return value;
}
}
// transposition table
trans_move = MoveNone;
if (UseTrans && depth >= TransDepth) {
if (trans_retrieve(Trans,board->key,&trans_move,&trans_min_depth,&trans_max_depth,&trans_min_value,&trans_max_value)) {
// trans_move is now updated
if (node_type != NodePV) {
if (UseMateValues) {
if (trans_min_value > +ValueEvalInf && trans_min_depth < depth) {
trans_min_depth = depth;
}
if (trans_max_value < -ValueEvalInf && trans_max_depth < depth) {
trans_max_depth = depth;
}
}
min_value = -ValueInf;
if (DEPTH_MATCH(trans_min_depth,depth)) {
min_value = value_from_trans(trans_min_value,height);
if (min_value >= beta) return min_value;
}
max_value = +ValueInf;
if (DEPTH_MATCH(trans_max_depth,depth)) {
max_value = value_from_trans(trans_max_value,height);
if (max_value <= alpha) return max_value;
}
if (min_value == max_value) return min_value; // exact match
}
}
}
// height limit
if (height >= HeightMax-1) return eval(board, alpha, beta);
// more init
old_alpha = alpha;
best_value = ValueNone;
best_move = MoveNone;
played_nb = 0;
attack_set(attack,board);
in_check = ATTACK_IN_CHECK(attack);
// null-move pruning
if (UseNull && depth >= NullDepth && node_type != NodePV) {
if (!in_check
&& !value_is_mate(beta)
&& do_null(board)
&& (!UseNullEval || depth <= NullReduction+1 || eval(board,alpha, beta) >= beta)) {
// null-move search
new_depth = depth - NullReduction - 1;
//new_depth = depth - R_adpt(board->piece_size[board->turn]+board->pawn_size[board->turn],depth,NullReduction) - 1;
move_do_null(board,undo);
value = -full_search(board,-beta,-beta+1,new_depth,height+1,new_pv,NODE_OPP(node_type));
move_undo_null(board,undo);
// verification search
if (UseVer && depth > VerReduction) {
if (value >= beta && (!UseVerEndgame || do_ver(board))) {
new_depth = depth - VerReduction;
ASSERT(new_depth>0);
value = full_no_null(board,alpha,beta,new_depth,height,new_pv,NodeCut,trans_move,&move);
if (value >= beta) {
ASSERT(move==new_pv[0]);
played[played_nb++] = move;
best_move = move;
SearchStack[height].move = move;
SearchStack[height].best_move = move;
best_value = value;
pv_copy(pv,new_pv);
goto cut;
}
}
}
// pruning
if (value >= beta) {
if (value > +ValueEvalInf) value = +ValueEvalInf; // do not return unproven mates
ASSERT(!value_is_mate(value));
// pv_cat(pv,new_pv,MoveNull);
best_move = MoveNone;
best_value = value;
goto cut;
}
SearchStack[height].threat_move = SearchStack[height+1].best_move;
/* if (SearchStack[height-1].reduced){ // Idea by Tord Romstad
if (MOVE_FROM(SearchStack[height+1].best_move) == MOVE_TO(SearchStack[height-1].move))
return alpha-1; */
/* if(((MOVE_TO(SearchStack[height - 2].threat_move) == MOVE_FROM(SearchStack[height - 2].move))
&& (MOVE_TO(SearchStack[height].threat_move) == MOVE_TO(SearchStack[height - 2].move)))
||
((MOVE_TO(SearchStack[height - 2].threat_move) != MOVE_FROM(SearchStack[height - 2].move))
&& (MOVE_TO(SearchStack[height].threat_move) == MOVE_TO(SearchStack[height - 2].threat_move))))
return alpha-1; */
// }
}
}
// mate threat
/* mate_threat = false;
if (value <= VALUE_MATE(height+2)){
mate_threat = true;
} */
// Internal Iterative Deepening
if (UseIID && depth >= IIDDepth && node_type == NodePV && trans_move == MoveNone) {
// new_depth = depth - IIDReduction;
new_depth = MIN(depth - IIDReduction,depth/2);
ASSERT(new_depth>0);
value = full_search(board,alpha,beta,new_depth,height,new_pv,node_type);
if (value <= alpha) value = full_search(board,-ValueInf,beta,new_depth,height,new_pv,node_type);
trans_move = new_pv[0];
}
// move generation
sort_init(sort,board,attack,depth,height,trans_move);
single_reply = false;
if (in_check && LIST_SIZE(sort->list) == 1) single_reply = true; // HACK
// move loop
opt_value = +ValueInf;
while ((move=sort_next(sort)) != MoveNone) {
SearchStack[height].move = move;
// history_tried(move,board);
// extensions
new_depth = full_new_depth(depth,move,board,single_reply,mate_threat,node_type==NodePV, height);
// futility pruning
if (UseFutility && depth <= 2 && node_type != NodePV) {
if (!in_check && new_depth < depth && !move_is_tactical(move,board) && !move_is_dangerous(move,board)) {
ASSERT(!move_is_check(move,board));
// optimistic evaluation
if (opt_value == +ValueInf) {
if (depth==2){
FutilityMargin = FutilityMargin2;
}
else{
FutilityMargin = FutilityMargin1;
}
opt_value = eval(board,alpha,beta) + FutilityMargin;
ASSERT(opt_value<+ValueInf);
}
value = opt_value;
// pruning
if (value <= alpha) {
if (value > best_value) {
best_value = value;
PV_CLEAR(pv);
}
continue;
}
}
}
// history pruning
/* reduced = false;
if (UseHistory && depth >= HistoryDepth && node_type != NodePV) {
if (!in_check && played_nb >= HistoryMoveNb && new_depth < depth) {
ASSERT(best_value!=ValueNone);
ASSERT(played_nb>0);
ASSERT(sort->pos>0&&move==LIST_MOVE(sort->list,sort->pos-1));
if (history_reduction(move,board) == true) {
ASSERT(value>=0&&value<16384);
ASSERT(move!=trans_move);
ASSERT(!move_is_tactical(move,board));
ASSERT(!move_is_check(move,board));
new_depth--;
reduced = true;
}
}
} */
// history pruning
reduced = false;
value = sort->value; // history score
if (!in_check && depth < SearchCurrent->max_extensions / 2 && node_type != NodePV && new_depth < depth && value < HistoryValue / depth)
continue;
if (UseHistory && depth >= HistoryDepth && node_type != NodePV) {
if (!in_check && played_nb >= HistoryMoveNb && new_depth < depth) {
ASSERT(best_value!=ValueNone);
ASSERT(played_nb>0);
ASSERT(sort->pos>0&&move==LIST_MOVE(sort->list,sort->pos-1));
value = sort->value; // history score
if (value < HistoryValue) {
ASSERT(value>=0&&value<16384);
ASSERT(move!=trans_move);
ASSERT(!move_is_tactical(move,board));
ASSERT(!move_is_check(move,board));
new_depth--;
reduced = true;
if (UseExtendedHistory && value < HistoryValue / 2 && depth >= 8){
new_depth--;
}
}
}
}
SearchStack[height].reduced = reduced;
// recursive search
move_do(board,move,undo);
if (node_type != NodePV || best_value == ValueNone) { // first move
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NODE_OPP(node_type));
} else { // other moves
value = -full_search(board,-alpha-1,-alpha,new_depth,height+1,new_pv,NodeCut);
if (value > alpha) { // && value < beta
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NodePV);
}
}
// history-pruning re-search
if (HistoryReSearch && reduced && value > alpha /* was >= beta */) {
ASSERT(node_type!=NodePV);
//history_very_bad(move,board);
SearchStack[height].reduced = false;
new_depth++;
ASSERT(new_depth==depth-1);
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NODE_OPP(node_type));
}
move_undo(board,move,undo);
played[played_nb++] = move;
if (value > best_value) {
best_value = value;
pv_cat(pv,new_pv,move);
if (value > alpha) {
alpha = value;
best_move = move;
SearchStack[height].best_move = move;
if (value >= beta){
// history_success(move,board);
goto cut;
}
}
}
if (node_type == NodeCut) node_type = NodeAll;
}
// ALL node
if (best_value == ValueNone) { // no legal move
if (in_check) {
ASSERT(board_is_mate(board));
return VALUE_MATE(height);
} else {
ASSERT(board_is_stalemate(board));
return ValueDraw;
}
}
cut:
ASSERT(value_is_ok(best_value));
// move ordering
if (best_move != MoveNone) {
good_move(best_move,board,depth,height);
if (best_value >= beta && !move_is_tactical(best_move,board)) {
ASSERT(played_nb>0&&played[played_nb-1]==best_move);
for (i = 0; i < played_nb-1; i++) {
move = played[i];
ASSERT(move!=best_move);
history_bad(move,board);
}
history_good(best_move,board);
}
}
// transposition table
if (UseTrans && depth >= TransDepth) {
trans_move = best_move;
trans_depth = depth;
trans_min_value = (best_value > old_alpha) ? value_to_trans(best_value,height) : -ValueInf;
trans_max_value = (best_value < beta) ? value_to_trans(best_value,height) : +ValueInf;
trans_store(Trans,board->key,trans_move,trans_depth,trans_min_value,trans_max_value);
}
return best_value;
}
static int full_quiescence(board_t * board, int alpha, int beta, int depth, int height, mv_t pv[], int ThreadId) {
bool in_check;
int old_alpha;
int value, best_value;
int best_move;
int move;
int opt_value;
attack_t attack[1];
sort_t sort[1];
undo_t undo[1];
mv_t new_pv[HeightMax];
int probe_score, probe_depth;
int trans_move, trans_depth, trans_flags, trans_value;
entry_t * found_entry;
ASSERT(board!=NULL);
ASSERT(range_is_ok(alpha,beta));
ASSERT(depth_is_ok(depth));
ASSERT(height_is_ok(height));
ASSERT(pv!=NULL);
ASSERT(board_is_legal(board));
ASSERT(depth<=0);
// init
SearchCurrent[ThreadId]->node_nb++;
SearchInfo[ThreadId]->check_nb--;
PV_CLEAR(pv);
if (height > SearchCurrent[ThreadId]->max_depth) SearchCurrent[ThreadId]->max_depth = height;
if (SearchInfo[ThreadId]->check_nb <= 0) {
SearchInfo[ThreadId]->check_nb += SearchInfo[ThreadId]->check_inc;
search_check(ThreadId);
}
// draw?
if (board_is_repetition(board)) return ValueDraw;
/*
Interior node recognizer from scorpio by Daniel Shawul
-> dont probe at the leaves as this will slow down search
For 4/3 pieces probe there also.
-> After captures and pawn moves assume exact score and cutoff tree,
because we are making progress. Note this is not done only for speed.
-> if we are far from root (depth / 2), assume exact score and cutoff tree
*/
/* if (egbb_is_loaded && board->piece_nb <= 4){
if (probe_bitbases(board, probe_score)){
probe_score = value_from_trans(probe_score,height);
return probe_score;
}
}*/
if (recog_draw(board,ThreadId)) return ValueDraw;
// mate-distance pruning
if (UseDistancePruning) {
// lower bound
value = VALUE_MATE(height+2); // does not work if the current position is mate
if (value > alpha && board_is_mate(board)) value = VALUE_MATE(height);
if (value > alpha) {
alpha = value;
if (value >= beta) return value;
}
// upper bound
value = -VALUE_MATE(height+1);
if (value < beta) {
beta = value;
if (value <= alpha) return value;
}
}
// transposition table: added by Jerry Donald, about +20 elo self-play
// new in Toga II 4.0: accept hash hits in PV ~ +3 elo
trans_move = MoveNone;
if (UseTrans) {
if (trans_retrieve(Trans,&found_entry,board->key,&trans_move,&trans_depth,&trans_flags,&trans_value)) {
trans_value = value_from_trans(trans_value,height);
if ((UseExact && trans_value != ValueNone && TRANS_IS_EXACT(trans_flags))
|| (TRANS_IS_LOWER(trans_flags) && trans_value >= beta)
|| (TRANS_IS_UPPER(trans_flags) && trans_value <= alpha)) {
return trans_value;
}
}
}
// more init
attack_set(attack,board);
in_check = ATTACK_IN_CHECK(attack);
if (in_check) {
ASSERT(depth<0);
depth++; // in-check extension
}
// height limit
if (height >= HeightMax-1) return eval(board, alpha, beta, ThreadId);
// more init
old_alpha = alpha;
best_value = ValueNone;
best_move = MoveNone;
/* if (UseDelta) */ opt_value = +ValueInf;
if (!in_check) {
// lone-king stalemate?
if (simple_stalemate(board)) return ValueDraw;
// stand pat
value = eval(board, alpha, beta, ThreadId);
ASSERT(value>best_value);
best_value = value;
if (value > alpha) {
alpha = value;
if (value >= beta) goto cut;
}
if (UseDelta) {
opt_value = value + DeltaMargin;
ASSERT(opt_value<+ValueInf);
}
}
// move loop
/* cd = CheckDepth;
if(cd < 0 && board->piece_size[board->turn] <= 5)
cd++; */
sort_init_qs(sort,board,attack, depth>=SearchCurrent[ThreadId]->CheckDepth /* depth>=cd */);
while ((move=sort_next_qs(sort)) != MoveNone) {
// delta pruning
if (UseDelta && beta == old_alpha+1) { // i.e. non-PV
if (!in_check && !move_is_check(move,board) && !capture_is_dangerous(move,board)) {
ASSERT(move_is_tactical(move,board));
// optimistic evaluation
value = opt_value;
int to = MOVE_TO(move);
int capture = board->square[to];
if (capture != Empty) {
value += VALUE_PIECE(capture);
} else if (MOVE_IS_EN_PASSANT(move)) {
value += ValuePawn;
}
if (MOVE_IS_PROMOTE(move)) value += ValueQueen - ValuePawn;
// pruning
if (value <= alpha) {
if (value > best_value) {
best_value = value;
PV_CLEAR(pv);
}
continue;
}
}
}
move_do(board,move,undo);
value = -full_quiescence(board,-beta,-alpha,depth-1,height+1,new_pv,ThreadId);
move_undo(board,move,undo);
if (value > best_value) {
best_value = value;
pv_cat(pv,new_pv,move);
if (value > alpha) {
alpha = value;
best_move = move;
if (value >= beta) goto cut;
}
}
}
// ALL node
if (best_value == ValueNone) { // no legal move
ASSERT(board_is_mate(board));
return VALUE_MATE(height);
}
cut:
// store result in hash table (JD)
if (UseTrans) {
trans_move = best_move;
trans_depth = 0;
trans_flags = TransUnknown;
if (best_value > old_alpha) trans_flags |= TransLower;
if (best_value < beta) trans_flags |= TransUpper;
trans_value = value_to_trans(best_value,height);
trans_store(Trans,board->key,trans_move,trans_depth,trans_flags,trans_value);
}
ASSERT(value_is_ok(best_value));
return best_value;
}
static int full_search(board_t * board, int alpha, int beta, int depth, int height, mv_t pv[], int node_type, bool extended, int ThreadId) {
bool in_check;
bool single_reply;
bool good_cap;
int trans_move, trans_depth, trans_flags, trans_value;
int old_alpha;
int value, best_value;
int move, best_move;
int new_depth;
int played_nb;
int i;
int opt_value;
bool reduced, cap_extended;
attack_t attack[1];
sort_t sort[1];
undo_t undo[1];
mv_t new_pv[HeightMax];
mv_t played[256];
int FutilityMargin;
int probe_score, probe_depth;
int newHistoryValue;
int threshold;
int reduction;
int last_move;
int quiet_move_count;
entry_t * found_entry;
ASSERT(board!=NULL);
ASSERT(range_is_ok(alpha,beta));
ASSERT(depth_is_ok(depth));
ASSERT(height_is_ok(height));
ASSERT(pv!=NULL);
ASSERT(node_type==NodePV||node_type==NodeCut||node_type==NodeAll);
ASSERT(board_is_legal(board));
// horizon?
if (depth <= 0){
if (node_type == NodePV)
SearchCurrent[ThreadId]->CheckDepth = 1 - SearchCurrent[ThreadId]->CheckNb - 1;
else
SearchCurrent[ThreadId]->CheckDepth = 1 - SearchCurrent[ThreadId]->CheckNb;
return full_quiescence(board,alpha,beta,0,height,pv,ThreadId);
}
// init
SearchCurrent[ThreadId]->node_nb++;
SearchInfo[ThreadId]->check_nb--;
PV_CLEAR(pv);
if (height > SearchCurrent[ThreadId]->max_depth) SearchCurrent[ThreadId]->max_depth = height;
if (SearchInfo[ThreadId]->check_nb <= 0) {
SearchInfo[ThreadId]->check_nb += SearchInfo[ThreadId]->check_inc;
search_check(ThreadId);
}
// draw?
if (board_is_repetition(board)) return ValueDraw;
/*
Interior node recognizer from scorpio by Daniel Shawul
-> dont probe at the leaves as this will slow down search
For 4/3 pieces probe there also.
-> After captures and pawn moves assume exact score and cutoff tree,
because we are making progress. Note this is not done only for speed.
-> if we are far from root (depth / 2), assume exact score and cutoff tree
*/
// if (egbb_is_loaded && board->piece_nb <= 5){
// probe_depth = (2 * SearchCurrent[ThreadId]->act_iteration) / 3;
// if ((board->piece_nb <=4 || height <= probe_depth)
// && (height >= probe_depth
// || board->cap_sq != SquareNone || PIECE_IS_PAWN(board->moving_piece))
// ) {
//
// if (probe_bitbases(board, probe_score)){
// if (probe_score < 0 && board_is_mate(board)) return VALUE_MATE(height);
// probe_score = value_from_trans(probe_score,height);
// /* trans_move = MoveNone;
// trans_depth = depth;
// trans_flags = TransUnknown;
// if (probe_score > alpha) trans_flags |= TransLower;
// if (probe_score < beta) trans_flags |= TransUpper;
// trans_store(Trans,board->key,trans_move,trans_depth,trans_flags,probe_score);*/
// return probe_score;
// }
// }
// }
if (recog_draw(board,ThreadId)) return ValueDraw;
// mate-distance pruning
if (UseDistancePruning) {
// lower bound
value = VALUE_MATE(height+2); // does not work if the current position is mate
if (value > alpha && board_is_mate(board)) value = VALUE_MATE(height);
if (value > alpha) {
alpha = value;
if (value >= beta) return value;
}
// upper bound
value = -VALUE_MATE(height+1);
if (value < beta) {
beta = value;
if (value <= alpha) return value;
}
}
// transposition table
trans_move = MoveNone;
if (UseTrans && depth >= TransDepth) {
if (trans_retrieve(Trans,&found_entry,board->key,&trans_move,&trans_depth,&trans_flags,&trans_value)) {
// trans_move is now updated
/* if (found_entry->depth != trans_depth){
found_entry->depth = trans_depth;
}*/
if (node_type != NodePV /*|| ThreadId > 0*/) {
if (UseMateValues) {
if (trans_depth < depth) {
if (trans_value < -ValueEvalInf && TRANS_IS_UPPER(trans_flags)) {
trans_depth = depth;
trans_flags = TransUpper;
} else if (trans_value > +ValueEvalInf && TRANS_IS_LOWER(trans_flags)) {
trans_depth = depth;
trans_flags = TransLower;
}
}
if (trans_depth >= depth) {
trans_value = value_from_trans(trans_value,height);
if ((UseExact && TRANS_IS_EXACT(trans_flags))
|| (TRANS_IS_LOWER(trans_flags) && trans_value >= beta)
|| (TRANS_IS_UPPER(trans_flags) && trans_value <= alpha)) {
return trans_value;
}
/* if (TRANS_IS_EXACT(trans_flags))
return trans_value;
if (TRANS_IS_LOWER(trans_flags)) {
if (trans_value >= beta)
return trans_value;
if (trans_value > alpha)
alpha = trans_value;
}
if (TRANS_IS_UPPER(trans_flags)) {
if (trans_value <= alpha)
return trans_value;
if (trans_value < beta)
beta = trans_value;
} */
}
}
}
}
}
// height limit
if (height >= HeightMax-1) return eval(board, alpha, beta, ThreadId);
// more init
old_alpha = alpha;
best_value = ValueNone;
best_move = MoveNone;
played_nb = 0;
last_move = SearchCurrent[ThreadId]->last_move;
attack_set(attack,board);
in_check = ATTACK_IN_CHECK(attack);
// null-move pruning
if (UseNull && depth >= NullDepth && node_type != NodePV
&& !(trans_move != MoveNone && TRANS_IS_UPPER(trans_flags) && trans_depth >= depth - NullReduction - depth/4 && trans_value < beta)) {
// if hash table tells us we are < beta, the null move search probably wastes time
// bugfix 25-3-2013 (trans_move condition added) was LOS ~90%, + 10 elo. Probably not nearly that good but it's a bugfix...)
if (!in_check
&& !value_is_mate(beta)
&& do_null(board)
&& (!UseNullEval || depth <= NullReduction+1 || eval(board,alpha, beta, ThreadId) >= beta)) {
// null-move search
// if (depth < 11)
new_depth = depth - NullReduction - depth/4; // JD: from Stockfish, 10 elo better
// else
// new_depth = depth - NullReduction - 2;
//new_depth = depth - R_adpt(board->piece_size[board->turn]+board->pawn_size[board->turn],depth,NullReduction) - 1;
move_do_null(board,undo);
SearchCurrent[ThreadId]->last_move = MoveNone; // refutation table
value = -full_search(board,-beta,-beta+1,new_depth,height+1,new_pv,NODE_OPP(node_type),false,ThreadId);
move_undo_null(board,undo);
// pruning
if (value >= beta) {
if (value > +ValueEvalInf) value = +ValueEvalInf; // do not return unproven mates
ASSERT(!value_is_mate(value));
// pv_cat(pv,new_pv,MoveNull);
best_move = MoveNone;
best_value = value;
goto cut;
}
}
}
// Razoring: idea by Tord Romstad (Glaurung), fixed by Jerry Donald
if (node_type != NodePV && !in_check && trans_move == MoveNone && depth <= 3){
threshold = beta - RazorMargin - (depth-1)*39; // Values from Protector (Raimund Heid)
if (eval(board,threshold-1, threshold, ThreadId) < threshold){
value = full_quiescence(board,threshold-1,threshold,0,height,pv,ThreadId);
if (value < threshold) // corrected - was < beta which is too risky at depth > 1
return value;
}
}
// Internal Iterative Deepening
if (UseIID && depth >= IIDDepth && node_type == NodePV && trans_move == MoveNone) {
new_depth = MIN(depth - IIDReduction,depth/2);
ASSERT(new_depth>0);
value = full_search(board,alpha,beta,new_depth,height,new_pv,node_type,false,ThreadId);
if (value <= alpha) value = full_search(board,-ValueInf,beta,new_depth,height,new_pv,node_type,false,ThreadId);
trans_move = new_pv[0];
}
// move generation
sort_init(sort,board,attack,depth,height,trans_move,last_move,ThreadId);
single_reply = false;
if (in_check && LIST_SIZE(sort->list) == 1) single_reply = true; // HACK
// move loop
opt_value = +ValueInf;
good_cap = true;
quiet_move_count = 0;
while ((move=sort_next(sort,ThreadId)) != MoveNone) {
// extensions
new_depth = full_new_depth(depth,move,board,single_reply,node_type==NodePV, height, extended, &cap_extended, ThreadId);
// history pruning
value = sort->value; // history score
if (!in_check && depth <= 6 && node_type != NodePV
&& new_depth < depth && value < 2 * HistoryValue / (depth + depth % 2) /*2*/
&& played_nb >= 1+depth && !move_is_dangerous(move,board)){
continue;
}
// futility pruning
if (UseFutility && node_type != NodePV && depth <= 5) {
if (!in_check && new_depth < depth&& !move_is_tactical(move,board) && !move_is_dangerous(move,board)) {
ASSERT(!move_is_check(move,board));
// move count based pruning (added by Jerry Donald: ~+20 elo!)
if (quiet_move_count >= MoveCountLimit[depth])continue;
quiet_move_count++;
// optimistic evaluation (Chris Formula)
if (opt_value == +ValueInf) {
if (depth>=2){
FutilityMargin = FutilityMargin2 + (depth % 2) * 100;
}
else{
FutilityMargin = FutilityMargin1;
}
opt_value = eval(board,alpha-FutilityMargin,alpha,ThreadId) + FutilityMargin;
ASSERT(opt_value<+ValueInf);
}
value = opt_value;
// pruning
if (value <= alpha) {
if (value > best_value) {
best_value = value;
PV_CLEAR(pv);
}
continue;
}
}
}
// Late Move Reductions
// init
reduced = false;
reduction = 0;
// lookup reduction
if (UseHistory) {
if (!in_check && new_depth < depth && played_nb >= HistoryMoveNb
&& depth >= HistoryDepth && !move_is_dangerous(move,board)) {
if (good_cap && !move_is_tactical(move,board)){
good_cap = false;
}
if (!good_cap){
reduction = (node_type == NodePV ? quietPvMoveReduction[depth<64 ? depth: 63][played_nb<64? played_nb: 63]:
quietMoveReduction[depth<64 ? depth: 63][played_nb<64? played_nb: 63]);
// reduced bad captures less
if (move_is_tactical(move,board)) reduction = reduction / 2; // bad captures
// set reduction flag
if (reduction > 0) reduced = true;
}
}
}
// recursive search
move_do(board,move,undo);
SearchCurrent[ThreadId]->last_move = move;
if (node_type != NodePV || best_value == ValueNone) { // first move or non-pv
value = -full_search(board,-beta,-alpha,new_depth-reduction,height+1,new_pv,NODE_OPP(node_type),cap_extended,ThreadId);
// The move was reduced and fails high; so we research with full depth
if (reduced && value >= beta){
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NODE_OPP(node_type),cap_extended,ThreadId);
}
} else { // other moves (all PV children)
value = -full_search(board,-alpha-1,-alpha,new_depth-reduction,height+1,new_pv,NodeCut,cap_extended,ThreadId);
// In case of fail high:
// If reduced then we try a research with node_type = NodePV
if (value > alpha && reduced){ // && value < beta
value = -full_search(board,-beta,-alpha,new_depth-reduction,height+1,new_pv,NodePV,cap_extended,ThreadId);
// Still fails high! We research to full depth
if (reduced && value >= beta){
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NodePV,cap_extended,ThreadId);
}
// If not reduced we research as a PV node
} else if (value > alpha){
value = -full_search(board,-beta,-alpha,new_depth,height+1,new_pv,NodePV,cap_extended,ThreadId);
}
}
move_undo(board,move,undo);
played[played_nb++] = move;
if (value > best_value) {
best_value = value;
pv_cat(pv,new_pv,move);
if (value > alpha) {
alpha = value;
best_move = move;
if (value >= beta){
goto cut;
}
}
}
if (node_type == NodeCut) node_type = NodeAll;
}
// ALL node
if (best_value == ValueNone) { // no legal move
if (in_check) {
ASSERT(board_is_mate(board));
return VALUE_MATE(height);
} else {
ASSERT(board_is_stalemate(board));
return ValueDraw;
}
}
cut:
ASSERT(value_is_ok(best_value));
// move ordering
if (best_move != MoveNone) {
good_move(best_move,board,depth,height,ThreadId);
if (best_value >= beta && !move_is_tactical(best_move,board)) { // check is 204b and d, e
// refutation table ~5 elo
if (last_move != MoveNull && last_move != MoveNone)refutation_update(best_move, last_move, board, ThreadId);
ASSERT(played_nb>0&&played[played_nb-1]==best_move);
for (i = 0; i < played_nb-1; i++) {
move = played[i];
ASSERT(move!=best_move);
history_bad(move,board,ThreadId);
bad_move(move,board,depth,height,ThreadId); // added JD ~ 5 elo
}
history_good(best_move,board,ThreadId);
}
}
// transposition table
if (UseTrans && depth >= TransDepth) {
trans_move = best_move;
trans_depth = depth;
trans_flags = TransUnknown;
if (best_value > old_alpha) trans_flags |= TransLower;
if (best_value < beta) trans_flags |= TransUpper;
trans_value = value_to_trans(best_value,height);
trans_store(Trans,board->key,trans_move,trans_depth,trans_flags,trans_value);
}
return best_value;
}