int GetDrawFactor(POS *p, int sd)
{
int op = Opp(sd);
// Case 1: KPK with edge pawn (else KBPK recognizer would break)
if (PcMatNone(p, sd)
&& PcMatNone(p, op)
&& p->cnt[sd][P] == 1 // TODO: all pawns of a stronger side on a rim
&& p->cnt[op][P] == 0) { // TODO: accept pawns for a weaker side
if (p->Pawns(sd) & FILE_H_BB
&& p->Kings(op) & bbKingBlockH[sd]) return 0;
if (p->Pawns(sd) & FILE_A_BB
&& p->Kings(op) & bbKingBlockA[sd]) return 0;
}
// Case 2: KBPK(P) draws with edge pawn and wrong bishop
if (PcMatB(p, sd)
&& PcMatNone(p, op)
&& p->cnt[sd][P] == 1) { // TODO: all pawns of a stronger side on a rim
if (p->Pawns(sd) & FILE_H_BB
&& NotOnBishColor(p, sd, REL_SQ(H8, sd))
&& p->Kings(op) & bbKingBlockH[sd]) return 0;
if (p->Pawns(sd) & FILE_A_BB
&& NotOnBishColor(p, sd, REL_SQ(A8, sd))
&& p->Kings(op) & bbKingBlockA[sd]) return 0;
}
// Case 3: KBP vs Km
// drawn when defending king stands on pawn's path and can't be driven out
// by a bishop (must be dealt with before opposite bishops ending)
if (PcMatB(p, sd)
&& PcMat1Minor(p, op)
&& p->cnt[sd][P] == 1
&& p->cnt[op][P] == 0
&& (SqBb(p->king_sq[op]) & BB.GetFrontSpan(p->Pawns(sd), sd))
&& NotOnBishColor(p, sd, p->king_sq[op]) )
return 0;
// Case 4: Bishops of opposite color
if (PcMatB(p, sd) && PcMatB(p, op) && DifferentBishops(p)) {
// 4a: single bishop cannot win without pawns
if (p->cnt[sd][P] == 0) return 0;
// 4b: different bishops with a single pawn on the own half of the board
if (p->cnt[sd][P] == 1
&& p->cnt[op][P] == 0) {
if (bbHomeZone[sd] & p->Pawns(sd)) return 0;
// TODO: 4c: distant bishop controls a square on pawn's path
}
// 4d: halve the score for pure BOC endings
return 32;
}
if (p->cnt[sd][P] == 0) {
// Case 5: low and almost equal material with no pawns
if (p->cnt[op][P] == 0) {
if (PcMatRm(p, sd) && PcMatRm(p, op)) return 8;
if (PcMatR (p, sd) && PcMatR (p, op)) return 8;
if (PcMatQ (p, sd) && PcMatQ (p, op)) return 8;
if (PcMat2Minors(p, sd) && PcMatR(p, op)) return 8;
}
// Case 6: two knights
if (PcMatNN(p, sd)) {
if (p->cnt[op][P] == 0) return 0;
else return 4;
}
// Case 7: K(m) vs K(m) or Km vs Kp(p)
if (p->cnt[sd][Q] + p->cnt[sd][R] == 0 && p->cnt[sd][B] + p->cnt[sd][N] < 2 )
return 0;
// Case 8: KR vs Km(p)
if (PcMatR(p, sd) && PcMat1Minor(p, op) ) return 16;
// Case 9: KRm vs KR(p)
if (p->cnt[sd][R] == 1 && p->cnt[sd][Q] == 0 && p->cnt[sd][B] + p->cnt[sd][N] == 1
&& PcMatR(p, op) ) return 16;
// Case 10: KQm vs KQ(p)
if (p->cnt[sd][Q] == 1 && p->cnt[sd][R] == 0 && p->cnt[sd][B] + p->cnt[sd][N] == 1
&& PcMatQ(p, op) ) return 32;
// Case 11: Kmm vs KB(p)
if (PcMat2Minors(p,sd) && PcMatB(p, op) ) return 16;
// Case 12: KBN vs Km(p)
if (PcMatBN(p, sd) && PcMat1Minor(p, op) ) return 16;
// Case 13: KRR vs KRm(p)
if (PcMatRR(p, sd) && PcMatRm(p, op)) return 16;
// Case 14: KRRm vs KRR(p)
if (p->cnt[sd][R] == 2 && p->cnt[sd][Q] == 0 && p->cnt[sd][B] + p->cnt[sd][N] == 1
&& PcMatRR(p, op)) return 16;
}
// Case 15: KRP vs KR
if (PcMatR(p, sd) && PcMatR(p, op) && p->cnt[sd][P] == 1 && p->cnt[op][P] == 0) {
// 15a: good defensive position with a king on pawn's path increases drawing chances
if ((SqBb(p->king_sq[op]) & BB.GetFrontSpan(p->Pawns(sd), sd)))
return 32; // 1/2
// 15b: draw code for rook endgame with edge pawn
if ((RelSqBb(A7, sd) & p->Pawns(sd))
&& ( RelSqBb(A8, sd) & p->Rooks(sd))
&& ( FILE_A_BB & p->Rooks(op))
&& ((RelSqBb(H7, sd) & p->Kings(op)) || (RelSqBb(G7, sd) & p->Kings(op)))
) return 0; // dead draw
if ((RelSqBb(H7, sd) & p->Pawns(sd))
&& ( RelSqBb(H8, sd) & p->Rooks(sd))
&& ( FILE_H_BB & p->Rooks(op))
&& ((RelSqBb(A7, sd) & p->Kings(op)) || (RelSqBb(B7, sd) & p->Kings(op)))
) return 0; // dead draw
}
return 64;
}
void cParam::DynamicInit(void) {
Eval.prog_side = NO_CL;
ResetEngine();
// Init piece/square values together with material value of the pieces.
for (int sq = 0; sq < 64; sq++) {
for (int sd = 0; sd < 2; sd++) {
mg_pst[sd][P][REL_SQ(sq, sd)] = SCALE(pc_value[P], mat_perc) + SCALE(pstPawnMg[pst_style][sq], pst_perc);
eg_pst[sd][P][REL_SQ(sq, sd)] = SCALE(pc_value[P], mat_perc) + SCALE(pstPawnEg[pst_style][sq], pst_perc);
mg_pst[sd][N][REL_SQ(sq, sd)] = SCALE(pc_value[N], mat_perc) + SCALE(pstKnightMg[pst_style][sq], pst_perc);
eg_pst[sd][N][REL_SQ(sq, sd)] = SCALE(pc_value[N], mat_perc) + SCALE(pstKnightEg[pst_style][sq], pst_perc);
mg_pst[sd][B][REL_SQ(sq, sd)] = SCALE(pc_value[B], mat_perc) + SCALE(pstBishopMg[pst_style][sq], pst_perc);
eg_pst[sd][B][REL_SQ(sq, sd)] = SCALE(pc_value[B], mat_perc) + SCALE(pstBishopEg[pst_style][sq], pst_perc);
mg_pst[sd][R][REL_SQ(sq, sd)] = SCALE(pc_value[R], mat_perc) + SCALE(pstRookMg[pst_style][sq], pst_perc);
eg_pst[sd][R][REL_SQ(sq, sd)] = SCALE(pc_value[R], mat_perc) + SCALE(pstRookEg[pst_style][sq], pst_perc);
mg_pst[sd][Q][REL_SQ(sq, sd)] = SCALE(pc_value[Q], mat_perc) + SCALE(pstQueenMg[pst_style][sq], pst_perc);
eg_pst[sd][Q][REL_SQ(sq, sd)] = SCALE(pc_value[Q], mat_perc) + SCALE(pstQueenEg[pst_style][sq], pst_perc);
mg_pst[sd][K][REL_SQ(sq, sd)] = pstKingMg[pst_style][sq];
eg_pst[sd][K][REL_SQ(sq, sd)] = pstKingEg[pst_style][sq];
phalanx[sd][REL_SQ(sq, sd)] = pstPhalanxPawn[sq];
defended[sd][REL_SQ(sq, sd)] = pstDefendedPawn[sq];
sp_pst_data[sd][N][REL_SQ(sq, sd)] = pstKnightOutpost[sq];
sp_pst_data[sd][B][REL_SQ(sq, sd)] = pstBishopOutpost[sq];
}
}
// Init tables for adjusting piece values
// according to the number of own pawns
for (int i = 0; i < 9; i++) {
np_table[i] = adj[i] * np_bonus;
rp_table[i] = adj[i] * rp_malus;
}
// Init backward pawns table, adding file offset to base value
for (int i = 0; i < 8; i++) {
backward_malus_mg[i] = backward_malus_base + file_adj[i];
}
// Init imbalance table, so that we can expose option for exchange delta
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
// insert original values
imbalance[i][j] = imbalance_data[i][j];
// insert value defined by the user
if (imbalance[i][j] == Ex) imbalance[i][j] = exchange_imbalance;
if (imbalance[i][j] == -Ex) imbalance[i][j] = -exchange_imbalance;
}
}
// Init mobility tables
if (mob_style == 0) {
for (int i = 0; i < 9; i++) {
n_mob_mg[i] = 4 * (i-4);
n_mob_eg[i] = 4 * (i-4);
}
for (int i = 0; i < 14; i++) {
b_mob_mg[i] = 5 * (i-7);
b_mob_eg[i] = 5 * (i-7);
}
for (int i = 0; i < 15; i++) {
r_mob_mg[i] = 2 * (i-7);
r_mob_eg[i] = 4 * (i-7);
}
for (int i = 0; i < 28; i++) {
q_mob_mg[i] = 1 * (i-14);
q_mob_eg[i] = 2 * (i-14);
}
}
if (mob_style == 1) {
for (int i = 0; i < 9; i++) {
n_mob_mg[i] = n_mob_mg_decreasing[i];
n_mob_eg[i] = n_mob_eg_decreasing[i];
}
for (int i = 0; i < 14; i++) {
b_mob_mg[i] = b_mob_mg_decreasing[i];
b_mob_eg[i] = b_mob_eg_decreasing[i];
}
for (int i = 0; i < 15; i++) {
r_mob_mg[i] = r_mob_mg_decreasing[i];
r_mob_eg[i] = r_mob_eg_decreasing[i];
}
for (int i = 0; i < 28; i++) {
q_mob_mg[i] = q_mob_mg_decreasing[i];
q_mob_eg[i] = q_mob_eg_decreasing[i];
}
}
// Init king attack table
for (int t = 0, i = 1; i < 512; ++i) {
t = Min(maxAttScore, Min(int(attCurveMult * i * i), t + maxAttStep));
danger[i] = (t * 100) / 256; // rescale to centipawns
// TODO: init separately for Black and White in SetAsymmetricEval() to gain some speed
}
}