inline void do_rjsmc (
vsmc::Sampler<T> &sampler, const std::string &,
std::ostream &zconst_file, const std::string &,
typename MoveType::alpha_type::value_type alpha_config,
typename MoveType::proposal_type::value_type proposal_config,
std::size_t repeat)
{
sampler.move(MoveType(alpha_config, proposal_config), false);
std::vector<double> cn(MaxCompNum);
std::vector<double> w(sampler.size());
for (std::size_t i = 0; i != cn.size(); ++i)
cn[i] = 0;
for (std::size_t i = 0; i != repeat; ++i) {
if (repeat > 1)
std::cout << "Run: " << i + 1 << std::endl;
sampler.initialize();
while (sampler.particle().value().state(0, 0).alpha() < 1)
sampler.iterate();
sampler.particle().weight_set().read_weight(&w[0]);
for (typename vsmc::Sampler<T>::size_type j = 0;
j != sampler.size(); ++j)
cn[sampler.particle().value().state(j, 0).comp_num() - 1] += w[j];
for (std::size_t j = 0; j != cn.size(); ++j)
zconst_file << cn[j] << ' ';
zconst_file << std::endl;
}
}
inline void smc_do (vsmc::Sampler<T> &sampler,
std::ostream &zconst_file, const std::string &schedule_name,
typename MoveType::alpha_type::value_type alpha_config,
std::size_t iter_num)
{
sampler.move(MoveType(alpha_config, &sampler), false);
for (std::size_t i = 0; i != Repeat; ++i) {
if (Repeat > 1)
std::cout << "Run: " << i + 1 << std::endl;
zconst_file << schedule_name << ' ';
zconst_file << alpha_config << ' ';
smc_do(sampler, zconst_file, schedule_name, SM, iter_num);
smc_do(sampler, zconst_file, schedule_name, CM, iter_num);
zconst_file << std::endl;
}
}
void UpdateHistory(POS *p, int last_move, int move, int depth, int ply) {
// Don't update stuff used for move ordering if a move changes material balance
if (p->pc[Tsq(move)] != NO_PC || IsProm(move) || MoveType(move) == EP_CAP)
return;
// Asserts suggested by Ferdinand Mosca because history[] would overflow
// if p->pc[Fsq(move)] == NO_PC. If they ever fire, either move or board
// data are corrupt.
assert(p->pc[Fsq(move)] != NO_PC); // To detect no_pc
assert(p->pc[Fsq(move)] <= NO_PC); // To detect beyond no_pc for deeper examination
// Increment history counter
history[p->pc[Fsq(move)]][Tsq(move)] += 2 * depth * depth;
// Prevent history counters from growing too high
if (history[p->pc[Fsq(move)]][Tsq(move)] > HIST_LIMIT)
TrimHistory();
// Update refutation table, saving new move in the table indexed
// by the coordinates of last move. last_move == 0 is a null move,
// special case of last_move == -1 denotes situations when updating
// refutation table is switched off: at root or in QuiesceFlee()
if (last_move >= 0)
refutation[Fsq(last_move)][Tsq(last_move)] = move;
// Update killer moves, taking care that they are different
if (move != killer[ply][0]) {
killer[ply][1] = killer[ply][0];
killer[ply][0] = move;
}
}
int BadCapture(POS *p, int move) {
int fsq = Fsq(move);
int tsq = Tsq(move);
// Captures that gain material or capture equal piece are good by definition
if (tp_value[TpOnSq(p, tsq)] >= tp_value[TpOnSq(p, fsq)])
return 0;
// Bishop takes knight and knight takes bishop are good irrespectively from
// the way minor pieces' values are tuned
if ((TpOnSq(p, fsq) == B) && (TpOnSq(p, tsq) == N)) return 0;
if ((TpOnSq(p, fsq) == N) && (TpOnSq(p, tsq) == B)) return 0;
// En passant captures are good by definition
if (MoveType(move) == EP_CAP) return 0;
// We have to evaluate this capture using expensive Static Exchange Evaluation
return Swap(p, fsq, tsq) < 0;
}
int sHistory::MoveChangesMaterialBalance(sPosition *p, int move)
{
if (p->pc[Tsq(move)] != NO_PC || IsProm(move) || MoveType(move) == EP_CAP) return 1;
return 0;
}
void POS::UndoMove(int move, UNDO *u) {
int sd = Opp(side);
int op = side;
int fsq = Fsq(move);
int tsq = Tsq(move);
int ftp = Tp(pc[tsq]); // moving piece
int ttp = u->ttp;
castle_flags = u->castle_flags;
ep_sq = u->ep_sq;
rev_moves = u->rev_moves;
pawn_key = u->pawn_key;
hash_key = u->hash_key;
head--;
pc[fsq] = Pc(sd, ftp);
pc[tsq] = NO_PC;
cl_bb[sd] ^= SqBb(fsq) | SqBb(tsq);
tp_bb[ftp] ^= SqBb(fsq) | SqBb(tsq);
#ifndef LEAF_PST
mg_pst[sd] += Param.mg_pst_data[sd][ftp][fsq] - Param.mg_pst_data[sd][ftp][tsq];
eg_pst[sd] += Param.eg_pst_data[sd][ftp][fsq] - Param.eg_pst_data[sd][ftp][tsq];
#endif
// Update king location
if (ftp == K) king_sq[sd] = fsq;
// Undo capture
if (ttp != NO_TP) {
pc[tsq] = Pc(op, ttp);
cl_bb[op] ^= SqBb(tsq);
tp_bb[ttp] ^= SqBb(tsq);
phase += phase_value[ttp];
#ifndef LEAF_PST
mg_pst[op] += Param.mg_pst_data[op][ttp][tsq];
eg_pst[op] += Param.eg_pst_data[op][ttp][tsq];
#endif
cnt[op][ttp]++;
}
switch (MoveType(move)) {
case NORMAL:
break;
case CASTLE:
// define complementary rook move
switch (tsq) {
case C1: { fsq = A1; tsq = D1; break; }
case G1: { fsq = H1; tsq = F1; break; }
case C8: { fsq = A8; tsq = D8; break; }
case G8: { fsq = H8; tsq = F8; break; }
}
pc[tsq] = NO_PC;
pc[fsq] = Pc(sd, R);
cl_bb[sd] ^= SqBb(fsq) | SqBb(tsq);
tp_bb[R] ^= SqBb(fsq) | SqBb(tsq);
#ifndef LEAF_PST
mg_pst[sd] += Param.mg_pst_data[sd][R][fsq] - Param.mg_pst_data[sd][R][tsq];
eg_pst[sd] += Param.eg_pst_data[sd][R][fsq] - Param.eg_pst_data[sd][R][tsq];
#endif
break;
case EP_CAP:
tsq ^= 8;
pc[tsq] = Pc(op, P);
cl_bb[op] ^= SqBb(tsq);
tp_bb[P] ^= SqBb(tsq);
phase += phase_value[P];
#ifndef LEAF_PST
mg_pst[op] += Param.mg_pst_data[op][P][tsq];
eg_pst[op] += Param.eg_pst_data[op][P][tsq];
#endif
cnt[op][P]++;
break;
case EP_SET:
break;
case N_PROM: case B_PROM: case R_PROM: case Q_PROM:
pc[fsq] = Pc(sd, P);
tp_bb[P] ^= SqBb(fsq);
tp_bb[ftp] ^= SqBb(fsq);
phase += phase_value[P] - phase_value[ftp];
#ifndef LEAF_PST
mg_pst[sd] += Param.mg_pst_data[sd][P][fsq] - Param.mg_pst_data[sd][ftp][fsq];
eg_pst[sd] += Param.eg_pst_data[sd][P][fsq] - Param.eg_pst_data[sd][ftp][fsq];
#endif
cnt[sd][P]++;
cnt[sd][ftp]--;
break;
}
side ^= 1;
}
/*-----------------------------------------------------------------------------*/
bool Notation::AddMove(const MoveKif& move)
{
const MoveKif* prev_move = this->getPrevMove();
const MoveKif& move_current = this->current_moves_->back();
if (move.number() != 0 && move.number() != (this->move_current_->number() + 1))
{
// 番号が違う
return false;
}
if (move_current.number() != this->number())
{
// 指し手の末尾と番号が違う場合 ブランチとして作成する
this->current_moves_ = this->move_current_->MakeBranch(this->current_moves_);
}
int number = this->move_current_->number();
// 要素追加
this->current_moves_->emplace_back(move);
this->move_current_ = &this->current_moves_->back();
MoveKif& move_kif = this->current_moves_->back();
if (move_kif.number() == 0)
{
move_kif.set_number(number + 1);
}
move_kif.set_side(this->position_.side_to_move());
if ((move_kif.move_type() & MOVE_FLAG))
{
if (move_kif.to() == move_current.to())
{
// 同ほげをたてる
move_kif.set_move_type(MoveType(move_kif.move_type() | MoveType::SAME_FLAG));
}
Piece capture_piece = position_.GetPiece(move_kif.to());
if (capture_piece != NO_PIECE)
{
// 捕獲する場合 captureフラグを建てる
move_kif.set_capture_piece(capture_piece);
move_kif.set_move_type(MoveType(move_kif.move_type() | MoveType::CAPTURE_FLAG));
}
}
else if (is_result(move_kif.move_type()))
{
this->result_ = move_kif.move_type();
this->winner_ = this->getWinPlayer(move_kif);
}
if (move_kif.totalTime == 0)
{
// トータル時間の計算
move_kif.totalTime = ((prev_move != nullptr) ? prev_move->totalTime : 0) + move_kif.time;
}
if (is_move(move_kif.move_type()))
{
// 盤面をすすめる
this->position_.DoMove(move_kif);
}
return true;
}
void sManipulator::DoMove(sPosition *p, int move, UNDO *u)
{
int side = p->side; // moving side
int fsq = Fsq(move); // start square
int tsq = Tsq(move); // target square
int ftp = TpOnSq(p, fsq); // moving piece
int ttp = TpOnSq(p, tsq); // captured piece
U64 bbMove = SqBb(fsq) | SqBb(tsq); // optimization from Stockfish
// save data for undoing a move
u->ttp = ttp;
u->castleFlags = p->castleFlags;
u->epSquare = p->epSquare;
u->reversibleMoves = p->reversibleMoves;
u->hashKey = p->hashKey;
u->pawnKey = p->pawnKey;
p->repetitionList[p->head++] = p->hashKey;
// update reversible move counter (zeroing is done on captures and pawn moves)
p->reversibleMoves++;
p->hashKey ^= zobCastle[p->castleFlags];
p->castleFlags &= castleMask[fsq] & castleMask[tsq];
p->hashKey ^= zobCastle[p->castleFlags];
// clear en passant square
if (p->epSquare != NO_SQ) {
p->hashKey ^= zobEp[File(p->epSquare)];
p->epSquare = NO_SQ;
}
// move a piece from start square
p->pc[fsq] = NO_PC;
p->pc[tsq] = Pc(side, ftp);
p->hashKey ^= zobPiece[Pc(side, ftp)][fsq] ^ zobPiece[Pc(side, ftp)][tsq];
if (ftp == P) {
p->reversibleMoves = 0;
p->pawnKey ^= zobPiece[Pc(side, ftp)][fsq] ^ zobPiece[Pc(side, ftp)][tsq];
}
p->bbCl[side] ^= bbMove;
p->bbTp[ftp] ^= bbMove;
p->pstMg[side] += Data.pstMg[side][ftp][tsq] - Data.pstMg[side][ftp][fsq];
p->pstEg[side] += Data.pstEg[side][ftp][tsq] - Data.pstEg[side][ftp][fsq];
// on a king move update king location data
if (ftp == K) p->kingSquare[side] = tsq;
// capture
if (ttp != NO_TP) {
p->reversibleMoves = 0;
p->hashKey ^= zobPiece[Pc(Opp(side), ttp)][tsq];
if (ttp == P)
p->pawnKey ^= zobPiece[Pc(Opp(side), ttp)][tsq];
p->bbCl[Opp(side)] ^= SqBb(tsq);
p->bbTp[ttp] ^= SqBb(tsq);
p->pcCount[Opp(side)][ttp]--;
p->pieceMat[Opp(side)] -= Data.matValue[ttp];
p->phase -= Data.phaseValue[ttp];
p->pstMg[Opp(side)] -= Data.pstMg[Opp(side)][ttp][tsq];
p->pstEg[Opp(side)] -= Data.pstEg[Opp(side)][ttp][tsq];
}
switch (MoveType(move)) {
case NORMAL:
break;
case CASTLE:
if (tsq > fsq) {
fsq += 3;
tsq -= 1;
} else {
fsq -= 4;
tsq += 1;
}
p->pc[fsq] = NO_PC;
p->pc[tsq] = Pc(side, R);
p->hashKey ^= zobPiece[Pc(side, R)][fsq] ^ zobPiece[Pc(side, R)][tsq];
p->bbCl[side] ^= SqBb(fsq) | SqBb(tsq);
p->bbTp[R] ^= SqBb(fsq) | SqBb(tsq);
p->pstMg[side] += Data.pstMg[side][R][tsq] - Data.pstMg[side][R][fsq];
p->pstEg[side] += Data.pstEg[side][R][tsq] - Data.pstEg[side][R][fsq];
break;
case EP_CAP:
tsq ^= 8;
p->pc[tsq] = NO_PC;
p->hashKey ^= zobPiece[Pc(Opp(side), P)][tsq];
p->pawnKey ^= zobPiece[Pc(Opp(side), P)][tsq];
p->bbCl[Opp(side)] ^= SqBb(tsq);
p->bbTp[P] ^= SqBb(tsq);
p->pcCount[Opp(side)][P]--;
p->phase -= Data.phaseValue[P];
p->pstMg[Opp(side)] -= Data.pstMg[Opp(side)][P][tsq];
p->pstEg[Opp(side)] -= Data.pstEg[Opp(side)][P][tsq];
break;
case EP_SET:
tsq ^= 8;
if (bbPawnAttacks[side][tsq] & bbPc(p, Opp(side), P)) {
p->epSquare = tsq;
p->hashKey ^= zobEp[File(tsq)];
}
break;
// promotion: (1) add promoted piece and add values associated with it
case N_PROM: // (2) remove promoted pawn and substract values associated with it
case B_PROM:
case R_PROM:
case Q_PROM:
ftp = PromType(move);
p->pc[tsq] = Pc(side, ftp);
p->hashKey ^= zobPiece[Pc(side, P)][tsq] ^ zobPiece[Pc(side, ftp)][tsq];
p->pawnKey ^= zobPiece[Pc(side, P)][tsq];
p->bbTp[P] ^= SqBb(tsq);
p->bbTp[ftp]^= SqBb(tsq);
p->pcCount[side][ftp]++;
p->pcCount[side][P]--;
p->pieceMat[side] += Data.matValue[ftp];
p->phase += Data.phaseValue[ftp] - Data.phaseValue[P];
p->pstMg[side] += Data.pstMg[side][ftp][tsq] - Data.pstMg[side][P][tsq];
p->pstEg[side] += Data.pstEg[side][ftp][tsq] - Data.pstEg[side][P][tsq];
break;
}
p->side ^= 1;
p->hashKey ^= SIDE_RANDOM;
}
int Search(POS *p, int ply, int alpha, int beta, int depth, int was_null, int last_move, int last_capt_sq, int *pv) {
int best, score, null_score, move, new_depth, new_pv[MAX_PLY];
int fl_check, fl_prunable_node, fl_prunable_move, mv_type, reduction;
int is_pv = (beta > alpha + 1);
int mv_tried = 0, quiet_tried = 0, fl_futility = 0;
int mv_played[MAX_MOVES];
int mv_hist_score;
int victim, last_capt;
MOVES m[1];
UNDO u[1];
assert(ply > 0);
// Quiescence search entry point
if (depth <= 0)
return QuiesceChecks(p, ply, alpha, beta, pv);
// Periodically check for timeout, ponderhit or stop command
nodes++;
CheckTimeout();
// Quick exit on a timeout or on a statically detected draw
if (abort_search) return 0;
if (ply) *pv = 0;
if (IsDraw(p)) return DrawScore(p);
// Mate distance pruning
int checkmatingScore = MATE - ply;
if (checkmatingScore < beta) {
beta = checkmatingScore;
if (alpha >= checkmatingScore)
return alpha;
}
int checkmatedScore = -MATE + ply;
if (checkmatedScore > alpha) {
alpha = checkmatedScore;
if (beta <= checkmatedScore)
return beta;
}
// Retrieving data from transposition table. We hope for a cutoff
// or at least for a move to improve move ordering.
move = 0;
if (TransRetrieve(p->hash_key, &move, &score, alpha, beta, depth, ply)) {
// For move ordering purposes, a cutoff from hash is treated
// exactly like a cutoff from search
if (score >= beta) UpdateHistory(p, last_move, move, depth, ply);
// In pv nodes only exact scores are returned. This is done because
// there is much more pruning and reductions in zero-window nodes,
// so retrieving such scores in pv nodes works like retrieving scores
// from slightly lower depth.
if (!is_pv || (score > alpha && score < beta))
return score;
}
// Safeguard against exceeding ply limit
if (ply >= MAX_PLY - 1)
return Eval.Return(p, 1);
// Are we in check? Knowing that is useful when it comes
// to pruning/reduction decisions
fl_check = InCheck(p);
// INTERNAL ITERATIVE DEEPENING - we try to get a hash move to improve move ordering
if (!move && is_pv && depth >= 6 && !fl_check) {
Search(p, ply, alpha, beta, depth - 2, 0, 0, -1, new_pv);
if (abort_search) return 0;
TransRetrieve(p->hash_key, &move, &score, alpha, beta, depth, ply);
}
// Can we prune this node?
fl_prunable_node = !fl_check
&& !is_pv
&& alpha > -MAX_EVAL
&& beta < MAX_EVAL;
// Beta pruning / static null move
if (use_beta_pruning
&& fl_prunable_node
&& depth <= 3
&& !was_null) {
int sc = Eval.Return(p, 1) - 120 * depth; // TODO: Tune me!
if (sc > beta) return sc;
}
// Null move
if (use_nullmove
&& fl_prunable_node
&& depth > 1
&& !was_null
&& MayNull(p)
) {
int eval = Eval.Return(p, 1);
if (eval > beta) {
new_depth = depth - ((823 + 67 * depth) / 256); // simplified Stockfish formula
// omit null move search if normal search to the same depth wouldn't exceed beta
// (sometimes we can check it for free via hash table)
if (TransRetrieve(p->hash_key, &move, &null_score, alpha, beta, new_depth, ply)) {
if (null_score < beta) goto avoid_null;
}
p->DoNull(u);
if (new_depth > 0) score = -Search(p, ply + 1, -beta, -beta + 1, new_depth, 1, 0, -1, new_pv);
else score = -QuiesceChecks(p, ply + 1, -beta, -beta + 1, new_pv);
p->UndoNull(u);
// Verification search (nb. immediate null move within it is prohibited)
if (new_depth > 6 && score >= beta && use_null_verification)
score = Search(p, ply, alpha, beta, new_depth - 5, 1, move, -1, new_pv);
if (abort_search ) return 0;
if (score >= beta) return score;
}
}
avoid_null:
// end of null move code
// Razoring based on Toga II 3.0
if (use_razoring
&& fl_prunable_node
&& !move
&& !was_null
&& !(p->Pawns(p->side) & bbRelRank[p->side][RANK_7]) // no pawns to promote in one move
&& depth <= 3) {
int threshold = beta - razor_margin[depth];
int eval = Eval.Return(p, 1);
if (eval < threshold) {
score = QuiesceChecks(p, ply, alpha, beta, pv);
if (score < threshold) return score;
}
}
// end of razoring code
// Init moves and variables before entering main loop
best = -INF;
InitMoves(p, m, move, Refutation(last_move), ply);
// Main loop
while ((move = NextMove(m, &mv_type))) {
// Gather data about the move
mv_hist_score = history[p->pc[Fsq(move)]][Tsq(move)];
victim = TpOnSq(p, Tsq(move));
if (victim != NO_TP) last_capt = Tsq(move);
else last_capt = -1;
// Set futility pruning flag before the first applicable move is tried
if (mv_type == MV_NORMAL && quiet_tried == 0) {
if (use_futility
&& fl_prunable_node
&& depth <= 6) {
if (Eval.Return(p, 1) + fut_margin[depth] < beta) fl_futility = 1;
}
}
p->DoMove(move, u);
if (Illegal(p)) { p->UndoMove(move, u); continue; }
// Update move statistics
// (needed for reduction/pruning decisions and for updating history score)
mv_played[mv_tried] = move;
mv_tried++;
if (mv_type == MV_NORMAL) quiet_tried++;
// Can we prune this move?
fl_prunable_move = !InCheck(p)
&& (mv_type == MV_NORMAL)
&& (mv_hist_score < hist_limit);
// Set new search depth
new_depth = depth - 1;
// Check extension (pv node or low depth)
if (is_pv || depth < 9) {
new_depth += InCheck(p);
if (is_pv && Tsq(move) == last_capt_sq) new_depth += 1;
}
// Futility pruning
if (fl_futility
&& fl_prunable_move
&& mv_tried > 1) {
p->UndoMove(move, u); continue;
}
// Late move pruning
if (use_lmp
&& fl_prunable_node
&& fl_prunable_move
&& quiet_tried > lmp_limit[depth]
&& depth <= 3
&& MoveType(move) != CASTLE ) {
p->UndoMove(move, u); continue;
}
// Late move reduction
reduction = 0;
if (use_lmr
&& depth >= 2
&& mv_tried > 3
&& alpha > -MAX_EVAL && beta < MAX_EVAL
&& !fl_check
&& fl_prunable_move
&& lmr_size[is_pv][depth][mv_tried] > 0
&& MoveType(move) != CASTLE ) {
// read reduction size from the table
reduction = lmr_size[is_pv][depth][mv_tried];
// increase reduction on bad history score
if (mv_hist_score < 0
&& new_depth - reduction > 2
&& lmr_hist_adjustement)
reduction++;
// reduce search depth
new_depth -= reduction;
}
// a place to come back if reduction looks suspect
re_search:
// PVS
if (best == -INF)
score = -Search(p, ply + 1, -beta, -alpha, new_depth, 0, move, last_capt, new_pv);
else {
score = -Search(p, ply + 1, -alpha - 1, -alpha, new_depth, 0, move, last_capt, new_pv);
if (!abort_search && score > alpha && score < beta)
score = -Search(p, ply + 1, -beta, -alpha, new_depth, 0, move, last_capt, new_pv);
}
// Reduced move scored above alpha - we need to re-search it
if (reduction
&& score > alpha) {
new_depth += reduction;
reduction = 0;
goto re_search;
}
// Undo move
p->UndoMove(move, u);
if (abort_search) return 0;
// Beta cutoff
if (score >= beta) {
if (!fl_check) {
UpdateHistory(p, last_move, move, depth, ply);
for (int mv = 0; mv < mv_tried; mv++)
DecreaseHistory(p, mv_played[mv], depth);
}
TransStore(p->hash_key, move, score, LOWER, depth, ply);
return score;
}
// Updating score and alpha
if (score > best) {
best = score;
if (score > alpha) {
alpha = score;
BuildPv(pv, new_pv, move);
}
}
} // end of the main loop
// Return correct checkmate/stalemate score
if (best == -INF)
return InCheck(p) ? -MATE + ply : DrawScore(p);
// Save score in the transposition table
if (*pv) {
if (!fl_check) {
UpdateHistory(p, last_move, *pv, depth, ply);
for (int mv = 0; mv < mv_tried; mv++)
DecreaseHistory(p, mv_played[mv], depth);
}
TransStore(p->hash_key, *pv, best, EXACT, depth, ply);
} else
TransStore(p->hash_key, 0, best, UPPER, depth, ply);
return best;
}
int SearchRoot(POS *p, int ply, int alpha, int beta, int depth, int *pv) {
int best, score, move, new_depth, new_pv[MAX_PLY];
int fl_check, fl_prunable_move, mv_type, reduction;
int mv_tried = 0, quiet_tried = 0;
int mv_played[MAX_MOVES];
int mv_hist_score;
int victim, last_capt;
int move_change = 0;
fl_has_choice = 0;
MOVES m[1];
UNDO u[1];
// Periodically check for timeout, ponderhit or stop command
nodes++;
CheckTimeout();
// Quick exit
if (abort_search) return 0;
// Retrieving data from transposition table. We hope for a cutoff
// or at least for a move to improve move ordering.
move = 0;
if (TransRetrieve(p->hash_key, &move, &score, alpha, beta, depth, ply)) {
// For move ordering purposes, a cutoff from hash is treated
// exactly like a cutoff from search
if (score >= beta) UpdateHistory(p, -1, move, depth, ply);
// Root node is a pv node, so we return only exact scores
if (score > alpha && score < beta)
return score;
}
// Are we in check? Knowing that is useful when it comes
// to pruning/reduction decisions
fl_check = InCheck(p);
// Init moves and variables before entering main loop
best = -INF;
InitMoves(p, m, move, Refutation(-1), ply);
// Main loop
while ((move = NextMove(m, &mv_type))) {
mv_hist_score = history[p->pc[Fsq(move)]][Tsq(move)];
victim = TpOnSq(p, Tsq(move));
if (victim != NO_TP) last_capt = Tsq(move);
else last_capt = -1;
p->DoMove(move, u);
if (Illegal(p)) { p->UndoMove(move, u); continue; }
// Update move statistics (needed for reduction/pruning decisions)
mv_played[mv_tried] = move;
mv_tried++;
if (mv_tried > 1) fl_has_choice = 1; // we have a choice between at least two root moves
if (depth > 16 && verbose) DisplayCurrmove(move, mv_tried);
if (mv_type == MV_NORMAL) quiet_tried++;
fl_prunable_move = !InCheck(p) && (mv_type == MV_NORMAL);
// Set new search depth
new_depth = depth - 1 + InCheck(p);
// Late move reduction
reduction = 0;
if (use_lmr
&& depth >= 2
&& mv_tried > 3
&& mv_hist_score < hist_limit
&& alpha > -MAX_EVAL && beta < MAX_EVAL
&& !fl_check
&& fl_prunable_move
&& lmr_size[1][depth][mv_tried] > 0
&& MoveType(move) != CASTLE ) {
reduction = lmr_size[1][depth][mv_tried];
// increase reduction on bad history score
if (mv_hist_score < 0
&& new_depth - reduction > 2
&& lmr_hist_adjustement)
reduction++;
new_depth -= reduction;
}
re_search:
// PVS
if (best == -INF)
score = -Search(p, ply + 1, -beta, -alpha, new_depth, 0, move, last_capt, new_pv);
else {
score = -Search(p, ply + 1, -alpha - 1, -alpha, new_depth, 0, move, last_capt, new_pv);
if (!abort_search && score > alpha && score < beta)
score = -Search(p, ply + 1, -beta, -alpha, new_depth, 0, move, last_capt, new_pv);
}
// Reduced move scored above alpha - we need to re-search it
if (reduction && score > alpha) {
new_depth += reduction;
reduction = 0;
goto re_search;
}
p->UndoMove(move, u);
if (abort_search) return 0;
// Beta cutoff
if (score >= beta) {
if (!fl_check) {
UpdateHistory(p, -1, move, depth, ply);
for (int mv = 0; mv < mv_tried; mv++)
DecreaseHistory(p, mv_played[mv], depth);
}
TransStore(p->hash_key, move, score, LOWER, depth, ply);
// Update search time depending on whether the first move has changed
if (depth > 4) {
if (pv[0] != move) Timer.OnNewRootMove();
else Timer.OnOldRootMove();
}
// Change the best move and show the new pv
BuildPv(pv, new_pv, move);
DisplayPv(score, pv);
return score;
}
// Updating score and alpha
if (score > best) {
best = score;
if (score > alpha) {
alpha = score;
// Update search time depending on whether the first move has changed
if (depth > 4) {
if (pv[0] != move) Timer.OnNewRootMove();
else Timer.OnOldRootMove();
}
// Change the best move and show the new pv
BuildPv(pv, new_pv, move);
DisplayPv(score, pv);
}
}
} // end of the main loop
// Return correct checkmate/stalemate score
if (best == -INF)
return InCheck(p) ? -MATE + ply : DrawScore(p);
// Save score in the transposition table
if (*pv) {
if (!fl_check) {
UpdateHistory(p, -1, *pv, depth, ply);
for (int mv = 0; mv < mv_tried; mv++)
DecreaseHistory(p, mv_played[mv], depth);
}
TransStore(p->hash_key, *pv, best, EXACT, depth, ply);
} else
TransStore(p->hash_key, 0, best, UPPER, depth, ply);
return best;
}
