18 int Search(TREE * RESTRICT tree, int ply, int depth, int wtm, int alpha,  in Search()  argument
54         Interrupt(ply);  in Search()
60   if (ply >= MAXPLY - 1)  in Search()
73   if (ply > 1) {  in Search()
74     if ((repeat = Repeat(tree, ply))) {  in Search()
78           SavePV(tree, ply, repeat);  in Search()
80         if (ply <= trace_level)  in Search()
82               (repeat == 3) ? "50-move" : "repetition", ply);  in Search()
98     alpha = Max(alpha, -MATE + ply - 1);  in Search()
99     beta = Min(beta, MATE - ply);  in Search()
128     switch (HashProbe(tree, ply, depth, wtm, alpha, beta, &value)) {  in Search()
178         !Castle(ply, white) && !Castle(ply, black) && Reversible(ply) == 0) {  in Search()
187           Reversible(ply), 0, EnPassant(ply), wtm, HashKey);  in Search()
214           SavePV(tree, ply, 4);  in Search()
259     tree->last[ply] = tree->last[ply - 1];  in Search()
267       tree->curmv[ply] = 0;  in Search()
269       if (ply <= trace_level)  in Search()
270         Trace(tree, ply, depth, wtm, value - 1, value, "SearchNull", serial,  in Search()
273       tree->status[ply + 1] = tree->status[ply];  in Search()
274       Reversible(ply + 1) = 0;  in Search()
276       if (EnPassant(ply + 1)) {  in Search()
277         HashEP(EnPassant(ply + 1));  in Search()
278         EnPassant(ply + 1) = 0;  in Search()
283             -Search(tree, ply + 1, depth - R - 1, Flip(wtm), -beta, -beta + 1,  in Search()
286         value = -Quiesce(tree, ply + 1, Flip(wtm), -beta, -beta + 1, 1);  in Search()
291         HashStore(tree, ply, depth, wtm, LOWER, value, tree->hash_move[ply]);  in Search()
310     tree->next_status[ply].phase = HASH;  in Search()
311     if (!tree->hash_move[ply] && depth >= 6 && do_null && ply > 1 && pv_node) {  in Search()
312       tree->curmv[ply] = 0;  in Search()
315             Search(tree, ply, depth - 2, wtm, alpha, beta, in_check, DO_NULL);  in Search()
317         value = Quiesce(tree, ply, wtm, alpha, beta, 1);  in Search()
322           if ((int) tree->pv[ply - 1].pathl > ply)  in Search()
323             tree->hash_move[ply] = tree->pv[ply - 1].path[ply];  in Search()
325           tree->hash_move[ply] = tree->curmv[ply];  in Search()
326         tree->last[ply] = tree->last[ply - 1];  in Search()
327         tree->next_status[ply].phase = HASH;  in Search()
344       SearchMoveList(tree, ply, depth, wtm, alpha, beta, searched, in_check,  in Search()
379 int SearchMoveList(TREE * RESTRICT tree, int ply, int depth, int wtm,  in SearchMoveList()  argument
406   tree->next_status[ply].phase = HASH;  in SearchMoveList()
433     if (ply == 1 && moves_done == 1 && alpha == original_alpha &&  in SearchMoveList()
438     order = (ply > 1) ? NextMove(current, ply, depth, wtm, in_check)  in SearchMoveList()
441       tree->curmv[ply] = current->curmv[ply];  in SearchMoveList()
447     if (ply <= trace_level)  in SearchMoveList()
448       Trace(tree, ply, depth, wtm, alpha, beta, "SearchMoveList", mode,  in SearchMoveList()
449           current->phase[ply], order);  in SearchMoveList()
451     MakeMove(tree, ply, wtm, tree->curmv[ply]);  in SearchMoveList()
459         searched[searched[0]] = tree->curmv[ply];  in SearchMoveList()
481                   tree->curmv[ply]) - pcval[Captured(tree->curmv[ply])] <=  in SearchMoveList()
533             !(PawnPush(wtm, tree->curmv[ply]))) {  in SearchMoveList()
560               alpha > -MATE + 300 && !CaptureOrPromote(tree->curmv[ply])) {  in SearchMoveList()
600             SearchMove(tree, ply, depth, wtm, alpha, t_beta, beta, extend,  in SearchMoveList()
606           if (mode == parallel && ply == 1)  in SearchMoveList()
610     UnmakeMove(tree, ply, wtm, tree->curmv[ply]);  in SearchMoveList()
643       if (ply == 1) {  in SearchMoveList()
672       HashStore(tree, ply, depth, wtm, LOWER, value, tree->curmv[ply]);  in SearchMoveList()
673       History(tree, ply, depth, wtm, tree->curmv[ply], searched);  in SearchMoveList()
704       if (ply == 1 && mode == serial) {  in SearchMoveList()
834         ThreadSplit(tree, ply, depth, alpha, original_alpha, moves_done))  in SearchMoveList()
840         tree->ply = ply;  in SearchMoveList()
849             if (ply == 1)  in SearchMoveList()
852               HashStore(tree, ply, depth, wtm, LOWER, value, tree->cutmove);  in SearchMoveList()
890     value = (Check(wtm)) ? -(MATE - ply) : DrawScore(wtm);  in SearchMoveList()
892       SavePV(tree, ply, 0);  in SearchMoveList()
894       if (ply <= trace_level)  in SearchMoveList()
895         printf("Search() no moves!  ply=%d\n", ply);  in SearchMoveList()
902         original_alpha) ? tree->hash_move[ply] : tree->pv[ply].path[ply];  in SearchMoveList()
904     if (repeat == 2 && alpha != -(MATE - ply - 1)) {  in SearchMoveList()
907         SavePV(tree, ply, 3);  in SearchMoveList()
909       if (ply <= trace_level)  in SearchMoveList()
910         printf("draw by 50 move rule detected, ply=%d.\n", ply);  in SearchMoveList()
914       tree->pv[ply - 1] = tree->pv[ply];  in SearchMoveList()
915       tree->pv[ply - 1].path[ply - 1] = tree->curmv[ply - 1];  in SearchMoveList()
917     HashStore(tree, ply, depth, wtm, type, alpha, bestmove);  in SearchMoveList()
933 int SearchMove(TREE * RESTRICT tree, int ply, int depth, int wtm, int alpha,  in SearchMove()  argument
956         -Search(tree, ply + 1, depth + extend - reduce - 1, Flip(wtm),  in SearchMove()
960           -Search(tree, ply + 1, depth - 1, Flip(wtm), -t_beta, -alpha, check,  in SearchMove()
964     value = -Quiesce(tree, ply + 1, Flip(wtm), -t_beta, -alpha, 1);  in SearchMove()
981     if (ply == 1)  in SearchMove()
985           -Search(tree, ply + 1, depth + extend - 1, Flip(wtm), -beta, -alpha,  in SearchMove()
988       value = -Quiesce(tree, ply + 1, Flip(wtm), -beta, -alpha, 1);  in SearchMove()