void SortRoot (void)
/*****************************************************************************
*
* Sort the moves at the root. The heuristic is simple. Try captures/
* promotions first. Other moves are ordered based on their swapoff values.
*
*****************************************************************************/
{
leaf *p;
int f, t ;
int side, xside;
BitBoard enemyP;
side = board.side;
xside = 1^side;
enemyP = board.b[xside][pawn];
for (p = TreePtr[1]; p < TreePtr[2]; p++)
{
f = Value[cboard[FROMSQ(p->move)]];
if (cboard[TOSQ(p->move)] != 0 || (p->move & PROMOTION))
{
t = Value[cboard[TOSQ(p->move)]];
if (f < t)
p->score = -1000 + t - f;
else
p->score = -1000 + SwapOff (p->move);
}
else
p->score = -3000 + SwapOff (p->move);
p->score += taxicab[FROMSQ(p->move)][D5] - taxicab[TOSQ(p->move)][E4];
if ( f == ValueP ) {
/* Look at pushing Passed pawns first */
if ( (enemyP & PassedPawnMask[side][TOSQ(p->move)]) == NULLBITBOARD )
p->score +=50;
}
}
}
void ShowMoveList (int ply)
/**************************************************************************
*
* Print out the move list.
*
**************************************************************************/
{
leaf *node;
int i = 0;
for (node = TreePtr[ply]; node < TreePtr[ply+1]; node++)
{
SANMove (node->move, ply);
printf ("%5s %3d\t", SANmv, SwapOff(node->move));
if (++i == 5)
{
printf ("\n");
i = 0;
}
}
printf ("\n");
}
int PhasePick (leaf **p1, int ply)
/***************************************************************************
*
* A phase style routine which returns the next move to the search.
* Hash move is first returned. If it doesn't fail high, captures are
* generated, sorted and tried. If no fail high still occur, the rest of
* the moves are generated and tried.
* The idea behind all this is to save time generating moves which might
* not be needed.
* CAVEAT: To implement this, the way that genmoves & friends are called
* have to be modified. In particular, TreePtr[ply+1] = TreePtr[ply] must
* be set before the calls can be made.
* If the board ever gets corrupted during the search, then there is a bug
* in IsLegalMove() which has to be fixed.
*
***************************************************************************/
{
static leaf* p[MAXPLYDEPTH];
leaf *p2;
int mv;
int side;
side = board.side;
switch (pickphase[ply])
{
case PICKHASH:
TreePtr[ply+1] = TreePtr[ply];
pickphase[ply] = PICKGEN1;
if (Hashmv[ply] && IsLegalMove (Hashmv[ply]))
{
TreePtr[ply+1]->move = Hashmv[ply];
*p1 = TreePtr[ply+1]++;
return (true);
}
case PICKGEN1:
pickphase[ply] = PICKCAPT;
p[ply] = TreePtr[ply+1];
GenCaptures (ply);
for (p2 = p[ply]; p2 < TreePtr[ply+1]; p2++)
p2->score = SwapOff(p2->move) * WEIGHT +
Value[cboard[TOSQ(p2->move)]];
case PICKCAPT:
while (p[ply] < TreePtr[ply+1])
{
pick (p[ply], ply);
if ((p[ply]->move & MOVEMASK) == Hashmv[ply])
{
p[ply]++;
continue;
}
*p1 = p[ply]++;
return (true);
}
case PICKKILL1:
pickphase[ply] = PICKKILL2;
if (killer1[ply] && killer1[ply] != Hashmv[ply] &&
IsLegalMove (killer1[ply]))
{
TreePtr[ply+1]->move = killer1[ply];
*p1 = TreePtr[ply+1];
TreePtr[ply+1]++;
return (true);
}
case PICKKILL2:
pickphase[ply] = PICKGEN2;
if (killer2[ply] && killer2[ply] != Hashmv[ply] &&
IsLegalMove (killer2[ply]))
{
TreePtr[ply+1]->move = killer2[ply];
*p1 = TreePtr[ply+1];
TreePtr[ply+1]++;
return (true);
}
case PICKGEN2:
pickphase[ply] = PICKREST;
p[ply] = TreePtr[ply+1];
GenNonCaptures (ply);
for (p2 = p[ply]; p2 < TreePtr[ply+1]; p2++)
{
p2->score = history[side][(p2->move & 0x0FFF)] +
taxicab[FROMSQ(p2->move)][D5] - taxicab[TOSQ(p2->move)][E4];
if (p2->move & CASTLING)
p2->score += CASTLINGSCORE;
}
case PICKREST:
while (p[ply] < TreePtr[ply+1])
{
pick (p[ply], ply);
mv = p[ply]->move & MOVEMASK;
if (mv == Hashmv[ply] || mv == killer1[ply] ||
mv == killer2[ply])
{
p[ply]++;
continue;
}
*p1 = p[ply]++;
return (true);
}
}
return (false);
}
static int negascout(struct SearchData *sd,
int alpha,
int beta,
const int depth,
int node_type
#if MP
,int exclusiveP
#endif /* MP */
) {
struct Position *p = sd->position;
struct SearchStatus *st;
int best = -INF;
int bestm = M_NONE;
int tmp;
int talpha;
int incheck;
int lmove;
int move;
int extend = 0;
int threat = FALSE;
int reduce_extensions;
int next_type;
int was_futile = FALSE;
#if FUTILITY
int is_futile;
int optimistic = 0;
#endif
#if MP
int deferred_cnt = 0;
int deferred_list[MAX_DEFERRED];
int deferred_depth[MAX_DEFERRED];
#endif
EnterNode(sd);
Nodes++;
/* check for search termination */
if (sd->master && TerminateSearch(sd)) {
AbortSearch = TRUE;
goto EXIT;
}
/* max search depth reached */
if (sd->ply >= MaxDepth) goto EXIT;
/*
* Check for insufficent material or theoretical draw.
*/
if ( /* InsufMat(p) || CheckDraw(p) || */ Repeated(p, FALSE)) {
best = 0;
goto EXIT;
}
/*
* check extension
*/
incheck = InCheck(p, p->turn);
if (incheck && p->material[p->turn] > 0) {
extend += CheckExtend(p);
ChkExt++;
}
/*
* Check the hashtable
*/
st = sd->current;
HTry++;
#if MP
switch (ProbeHT(p->hkey, &tmp, depth, &(st->st_hashmove), &threat, sd->ply,
exclusiveP, sd->localHashTable))
#else
switch (ProbeHT(p->hkey, &tmp, depth, &(st->st_hashmove), &threat, sd->ply))
#endif /* MP */
{
case ExactScore:
HHit++;
best = tmp;
goto EXIT;
case UpperBound:
if (tmp <= alpha) {
HHit++;
best = tmp;
goto EXIT;
}
break;
case LowerBound:
if (tmp >= beta) {
HHit++;
best = tmp;
goto EXIT;
}
break;
case Useless:
threat = !incheck && MateThreat(p, OPP(p->turn));
break;
#if MP
case OnEvaluation:
best = -ON_EVALUATION;
goto EXIT;
#endif
}
/*
* Probe EGTB
*/
if (depth > EGTBDepth && ProbeEGTB(p, &tmp, sd->ply)) {
best = tmp;
goto EXIT;
}
/*
* Probe recognizers
*/
switch (ProbeRecognizer(p, &tmp)) {
case ExactScore:
best = tmp;
goto EXIT;
case LowerBound:
if (tmp >= beta) {
best = tmp;
goto EXIT;
}
break;
case UpperBound:
if (tmp <= alpha) {
best = tmp;
goto EXIT;
}
break;
}
#if NULLMOVE
/*
* Null move search.
* See Christian Donninger, "Null Move and Deep Search"
* ICCA Journal Volume 16, No. 3, pp. 137-143
*/
if (!incheck && node_type == CutNode && !threat) {
int next_depth;
int nms;
next_depth = depth - ReduceNullMove;
if (next_depth > 0) {
next_depth = depth - ReduceNullMoveDeep;
}
DoNull(p);
if (next_depth < 0) {
nms = -quies(sd, -beta, -beta+1, 0);
} else {
#if MP
nms = -negascout(sd, -beta, -beta+1, next_depth, AllNode, 0);
#else
nms = -negascout(sd, -beta, -beta+1, next_depth, AllNode);
#endif
}
UndoNull(p);
if (AbortSearch) goto EXIT;
if (nms >= beta) {
if (p->nonPawn[p->turn] >= Value[Queen]) {
best = nms;
goto EXIT;
} else {
if (next_depth < 0) {
nms = quies(sd, beta-1, beta, 0);
} else {
#if MP
nms = negascout(sd, beta-1, beta, next_depth, CutNodeNoNull,
0);
#else
nms = negascout(sd, beta-1, beta, next_depth,
CutNodeNoNull);
#endif
}
if (nms >= beta) {
best = nms;
goto EXIT;
} else {
extend += ExtendZugzwang;
ZZExt++;
}
}
} else if (nms <= -CMLIMIT) {
threat = TRUE;
}
}
#endif /* NULLMOVE */
lmove = (p->actLog-1)->gl_Move;
reduce_extensions = (sd->ply > 2*sd->depth);
talpha = alpha;
switch (node_type) {
case AllNode:
next_type = CutNode;
break;
case CutNode:
case CutNodeNoNull:
next_type = AllNode;
break;
default:
next_type = PVNode;
break;
}
#if FUTILITY
is_futile = !incheck && !threat && alpha < CMLIMIT && alpha > -CMLIMIT;
if (is_futile) {
if (p->turn == White) {
optimistic = MaterialBalance(p) + MaxPos;
} else {
optimistic = -MaterialBalance(p) + MaxPos;
}
}
#endif /* FUTILITY */
/*
* Internal iterative deepening. If we do not have a move, we try
* a shallow search to find a good candidate.
*/
if (depth > 2*OnePly && ((alpha + 1) != beta) && !LegalMove(p, st->st_hashmove)) {
int useless;
#if MP
useless = negascout(sd, alpha, beta, depth-2*OnePly, PVNode, 0);
#else
useless = negascout(sd, alpha, beta, depth-2*OnePly, PVNode);
#endif
st->st_hashmove = sd->pv_save[sd->ply+1];
}
/*
* Search all legal moves
*/
while ((move = incheck ? NextEvasion(sd) : NextMove(sd)) != M_NONE) {
int next_depth = extend;
if (move & M_CANY && !MayCastle(p, move)) continue;
/*
* recapture extension
*/
if ((move & M_CAPTURE) && (lmove & M_CAPTURE) &&
M_TO(move) == M_TO(lmove) &&
IsRecapture(p->piece[M_TO(move)], (p->actLog-1)->gl_Piece)) {
RCExt += 1;
next_depth += ExtendRecapture[TYPE(p->piece[M_TO(move)])];
}
/*
* passed pawn push extension
*/
if (TYPE(p->piece[M_FROM(move)]) == Pawn &&
p->nonPawn[OPP(p->turn)] <= Value[Queen]) {
int to = M_TO(move);
if (((p->turn == White && to >= a7)
|| (p->turn == Black && to <= h2))
&& IsPassed(p, to, p->turn) && SwapOff(p, move) >= 0) {
next_depth += ExtendPassedPawn;
PPExt += 1;
}
}
/*
* limit extensions to sensible range.
*/
if (reduce_extensions) next_depth /= 2;
next_depth += depth - OnePly;
#if FUTILITY
/*
* Futility cutoffs
*/
if (is_futile) {
if (next_depth < 0 && !IsCheckingMove(p, move)) {
tmp = optimistic + ScoreMove(p, move);
if (tmp <= alpha) {
if (tmp > best) {
best = tmp;
bestm = move;
was_futile = TRUE;
}
continue;
}
}
#if EXTENDED_FUTILITY
/*
* Extended futility cutoffs and limited razoring.
* See Ernst A. Heinz, "Extended Futility Pruning"
* ICCA Journal Volume 21, No. 2, pp 75-83
*/
else if (next_depth >= 0 && next_depth < OnePly
&& !IsCheckingMove(p, move)) {
tmp = optimistic + ScoreMove(p, move) + (3*Value[Pawn]);
if (tmp <= alpha) {
if (tmp > best) {
best = tmp;
bestm = move;
was_futile = TRUE;
}
continue;
}
}
#if RAZORING
else if (next_depth >= OnePly && next_depth < 2*OnePly
&& !IsCheckingMove(p, move)) {
tmp = optimistic + ScoreMove(p, move) + (6*Value[Pawn]);
if (tmp <= alpha) {
next_depth -= OnePly;
}
}
#endif /* RAZORING */
#endif /* EXTENDED_FUTILITY */
}
#endif /* FUTILITY */
DoMove(p, move);
if (InCheck(p, OPP(p->turn))) {
UndoMove(p, move);
} else {
/*
* Check extension
*/
if (p->material[p->turn] > 0 && InCheck(p, p->turn)) {
next_depth += (reduce_extensions) ?
ExtendInCheck>>1 : ExtendInCheck;
}
/*
* Recursively search this position. If depth is exhausted, use
* quies, otherwise use negascout.
*/
if (next_depth < 0) {
tmp = -quies(sd, -beta, -talpha, 0);
} else if (bestm != M_NONE && !was_futile) {
#if MP
tmp = -negascout(sd, -talpha-1, -talpha, next_depth, next_type,
bestm != M_NONE);
if (tmp != ON_EVALUATION && tmp > talpha && tmp < beta) {
tmp = -negascout(sd, -beta, -tmp, next_depth,
node_type == PVNode ? PVNode : AllNode,
bestm != M_NONE);
}
#else
tmp = -negascout(sd, -talpha-1, -talpha, next_depth, next_type);
if (tmp > talpha && tmp < beta) {
tmp = -negascout(sd, -beta, -tmp, next_depth,
node_type == PVNode ? PVNode : AllNode);
}
#endif /* MP */
} else {
#if MP
tmp = -negascout(sd, -beta, -talpha, next_depth, next_type,
bestm != M_NONE);
#else
tmp = -negascout(sd, -beta, -talpha, next_depth, next_type);
#endif /* MP */
}
UndoMove(p, move);
if (AbortSearch) goto EXIT;
#if MP
if (tmp == ON_EVALUATION) {
/*
* This child is ON_EVALUATION. Remember move and
* depth.
*/
deferred_list[deferred_cnt] = move;
deferred_depth[deferred_cnt] = next_depth;
deferred_cnt++;
} else {
#endif /* MP */
/*
* beta cutoff, enter move in Killer/Countermove table
*/
if (tmp >= beta) {
if (!(move & M_TACTICAL)) {
PutKiller(sd, move);
sd->counterTab[p->turn][lmove & 4095] = move;
}
StoreResult(sd, tmp, alpha, beta, move, depth, threat);
best = tmp;
goto EXIT;
}
/*
* Improvement on best move to date
*/
if (tmp > best) {
best = tmp;
bestm = move;
was_futile = FALSE;
if (best > talpha) {
talpha = best;
}
}
next_type = CutNode;
#if MP
}
#endif /* MP */
}
}
int Quiesce (uint8_t ply, int alpha, int beta)
/**************************************************************************
*
* Our quiescent search. This quiescent search is able to recognize
* mates.
*
**************************************************************************/
{
uint8_t side, xside;
int best, delta, score, savealpha;
leaf *p, *pbest;
if (EvaluateDraw ())
return (DRAWSCORE);
side = board.side;
xside = 1^side;
InChk[ply] = SqAtakd (board.king[side], xside);
best = Evaluate (alpha, beta);
if (best >= beta && !InChk[ply])
return (best);
TreePtr[ply+1] = TreePtr[ply];
if (InChk[ply])
{
GenCheckEscapes (ply);
if (TreePtr[ply] == TreePtr[ply+1])
return (-MATE+ply-2);
if (best >= beta)
return (best);
SortMoves (ply);
}
else
{
GenCaptures (ply);
if (TreePtr[ply] == TreePtr[ply+1])
return (best);
SortCaptures (ply);
}
savealpha = alpha;
pbest = NULL;
alpha = MAX(best, alpha);
delta = MAX (alpha - 150 - best, 0);
for (p = TreePtr[ply]; p < TreePtr[ply+1]; p++)
{
pick (p, ply);
/* We are in check or capture cannot bring score near alpha, give up */
if (!InChk[ply] && SwapOff (p->move) < delta)
continue;
/* If capture cannot bring score near alpha, give up */
if (p->score == -INFINITY)
continue;
#ifdef THREATEXT
/* See search.c for an explanation of the code below */
if (threatply+1 == ply)
{
if ((TOSQ(p->move) == FROMSQ(threatmv)) ||
(FROMSQ(p->move) == TOSQ(threatmv)))
continue;
}
if (threatply && threatply+3 == ply && FROMSQ(p->move) == TOSQ(threatmv))
continue;
#endif
MakeMove (side, &p->move);
QuiesCnt++;
if (SqAtakd (board.king[side], xside))
{
UnmakeMove (xside, &p->move);
continue;
}
score = -Quiesce (ply+1, -beta, -alpha);
UnmakeMove (xside, &p->move);
if (score > best)
{
best = score;
pbest = p;
if (best >= beta)
goto done;
alpha = MAX (alpha, best);
}
}
done:
if (flags & USEHASH && pbest != NULL)
TTPut (side, 0, ply, savealpha, beta, best, pbest->move);
return (best);
}
