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'''[[Main Page|Home]] * [[Engines]] * [[CPW-Engine]] * Eval'''
=Description=
Using this evaluation function CPW-Engine should be aware of the following principles:
# develop the pieces
# castle if possible
# need some minimal level of assistance to disrupt its own castling position
# care for doubled, weak and passed pawns
# know a thing or two about the changes of piece values as pawns dissappear
# try to attack squares around enemy king
For function definitions, see [[CPW-Engine_eval_h]]
=Code=
<pre>
#include "stdafx.h"
#include "0x88_math.h"
#include "eval.h"
#include "transposition.h"
/* adjustements of piece value based on the number of own pawns */
int knight_adj[9] = { -20, -16, -12, -8, -4, 0, 4, 8, 12 };
int rook_adj[9] = { 15, 12, 9, 6, 3, 0, -3, -6, -9 };
static const int SafetyTable[100] = {
0, 0, 1, 2, 3, 5, 7, 9, 12, 15,
18, 22, 26, 30, 35, 39, 44, 50, 56, 62,
68, 75, 82, 85, 89, 97, 105, 113, 122, 131,
140, 150, 169, 180, 191, 202, 213, 225, 237, 248,
260, 272, 283, 295, 307, 319, 330, 342, 354, 366,
377, 389, 401, 412, 424, 436, 448, 459, 471, 483,
494, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500
};
/*******************************************************************
* This struct holds data about certain aspects of evaluation, *
* which allows program to print them if desired. *
*******************************************************************/
struct eval_vector {
int gamePhase;
int mgMob[2];
int egMob[2];
int attCnt[2];
int attWeight[2];
int kingShield[2];
int MaterialAdjustement[2];
int Blockages[2];
int PositionalThemes[2];
} v;
int eval(int alpha, int beta, int use_hash) {
int result = 0, mgScore = 0, egScore = 0;
int stronger, weaker;
/***********************************************************
/ Probe the evaluatinon hashtable, unless we call eval() /
/ only in order to display detailed result /
***********************************************************/
int probeval = tteval_probe();
if (probeval != INVALID && use_hash)
return probeval;
/***********************************************************
/ Clear all eval data /
***********************************************************/
v.gamePhase = 0;
v.mgMob[WHITE] = 0; v.mgMob[BLACK] = 0;
v.egMob[WHITE] = 0; v.egMob[BLACK] = 0;
v.attCnt[WHITE] = 0; v.attCnt[BLACK] = 0;
v.attWeight[WHITE] = 0; v.attWeight[BLACK] = 0;
v.MaterialAdjustement[WHITE] = 0; v.MaterialAdjustement[BLACK] = 0;
v.Blockages[WHITE] = 0; v.Blockages[BLACK] = 0;
v.PositionalThemes[WHITE] = 0; v.PositionalThemes[BLACK] = 0;
v.kingShield[WHITE] = 0; v.kingShield[BLACK] = 0;
/* sum the incrementally counted material and pcsq values */
mgScore = b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] + b.PcsqMg[WHITE]
- b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK] - b.PcsqMg[BLACK];
egScore = b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] + b.PcsqEg[WHITE]
- b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK] - b.PcsqEg[BLACK];
/* add king's pawn shield score and evaluate part of piece blockage score
(the rest of the latter will be done via piece eval) */
v.kingShield[WHITE] = wKingShield();
v.kingShield[BLACK] = bKingShield();
blockedPieces();
mgScore += (v.kingShield[WHITE] - v.kingShield[BLACK]);
/* tempo bonus */
if (b.stm == WHITE) result += e.TEMPO;
else result -= e.TEMPO;
/*******************************************************************
* Adjusting material value for the various combinations of pieces. *
* Currently it scores bishop, knight and rook pairs. The first one *
* gets a bonus, the latter two - a penalty. Please also note that *
* adjustements of knight and rook value based on the number of own *
* pawns on the board are done within the piece-specific routines. *
*******************************************************************/
if (b.PieceCount[WHITE][BISHOP] > 1) result += e.BISHOP_PAIR;
if (b.PieceCount[BLACK][BISHOP] > 1) result -= e.BISHOP_PAIR;
if (b.PieceCount[WHITE][KNIGHT] > 1) result -= e.P_KNIGHT_PAIR;
if (b.PieceCount[BLACK][KNIGHT] > 1) result += e.P_KNIGHT_PAIR;
if (b.PieceCount[WHITE][ROOK] > 1) result -= e.P_ROOK_PAIR;
if (b.PieceCount[BLACK][ROOK] > 1) result += e.P_ROOK_PAIR;
result += getPawnScore();
/*******************************************************************
* Evaluate pieces *
*******************************************************************/
for (U8 row = 0; row < 8; row++)
for (U8 col = 0; col < 8; col++) {
S8 sq = SET_SQ(row, col);
if (b.color[sq] != COLOR_EMPTY) {
switch (b.pieces[sq]) {
case PAWN: // pawns are evaluated separately
break;
case KNIGHT:
EvalKnight(sq, b.color[sq]);
break;
case BISHOP:
EvalBishop(sq, b.color[sq]);
break;
case ROOK:
EvalRook(sq, b.color[sq]);
break;
case QUEEN:
EvalQueen(sq, b.color[sq]);
break;
case KING:
break;
}
}
}
/********************************************************************
* Merge midgame and endgame score. We interpolate between these *
* two values, using a gamePhase value, based on remaining piece *
* material on both sides. With less pieces, endgame score beco- *
* mes more influential. *
********************************************************************/
mgScore += (v.mgMob[WHITE] - v.mgMob[BLACK]);
egScore += (v.egMob[WHITE] - v.egMob[BLACK]);
if (v.gamePhase > 24) v.gamePhase = 24;
int mgWeight = v.gamePhase;
int egWeight = 24 - mgWeight;
result += ((mgScore * mgWeight) + (egScore * egWeight)) / 24;
/********************************************************************
* Add phase-independent score components. *
********************************************************************/
result += (v.Blockages[WHITE] - v.Blockages[BLACK]);
result += (v.PositionalThemes[WHITE] - v.PositionalThemes[BLACK]);
result += (v.MaterialAdjustement[WHITE] - v.MaterialAdjustement[BLACK]);
/********************************************************************
* Merge king attack score. We don't apply this value if there are *
* less than two attackers or if the attacker has no queen. *
*******************************************************************/
if (v.attCnt[WHITE] < 2 || b.PieceCount[WHITE][QUEEN] == 0) v.attWeight[WHITE] = 0;
if (v.attCnt[BLACK] < 2 || b.PieceCount[BLACK][QUEEN] == 0) v.attWeight[BLACK] = 0;
result += SafetyTable[v.attWeight[WHITE]];
result -= SafetyTable[v.attWeight[BLACK]];
/********************************************************************
* Low material correction - guarding against an illusory material *
* advantage. Full blown program should have more such rules, but *
* the current set ought to be useful enough. Please note that our *
* code assumes different material values for bishop and knight. *
* *
* - a single minor piece cannot win *
* - two knights cannot checkmate bare king *
* - bare rook vs minor piece is drawish *
* - rook and minor vs rook is drawish *
********************************************************************/
if (result > 0) { stronger = WHITE; weaker = BLACK; }
else { stronger = BLACK; weaker = WHITE; }
if (b.PawnMaterial[stronger] == 0) {
if (b.PieceMaterial[stronger] < 400) return 0;
if (b.PawnMaterial[weaker] == 0
&& (b.PieceMaterial[stronger] == 2 * e.PIECE_VALUE[KNIGHT]))
return 0;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]
&& b.PieceMaterial[weaker] == e.PIECE_VALUE[BISHOP]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]
&& b.PieceMaterial[weaker] == e.PIECE_VALUE[KNIGHT]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK] + e.PIECE_VALUE[BISHOP]
&& b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK] + e.PIECE_VALUE[KNIGHT]
&& b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]) result /= 2;
}
/*******************************************************************
* Finally return the score relative to the side to move. *
*******************************************************************/
if (b.stm == BLACK) result = -result;
tteval_save(result);
return result;
}
void EvalKnight(S8 sq, S8 side) {
int att = 0;
int mob = 0;
int pos;
v.gamePhase += 1;
if (side == WHITE) {
switch (sq) {
case A8: if (isPiece(BLACK, PAWN, A7) || isPiece(BLACK, PAWN, C7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A8; break;
case H8: if (isPiece(BLACK, PAWN, H7) || isPiece(BLACK, PAWN, F7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A8; break;
case A7: if (isPiece(BLACK, PAWN, A6) && isPiece(BLACK, PAWN, B7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A7; break;
case H7: if (isPiece(BLACK, PAWN, H6) && isPiece(BLACK, PAWN, G7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A7; break;
case C3: if (isPiece(WHITE, PAWN, C2) && isPiece(WHITE, PAWN, D4) && !isPiece(WHITE, PAWN, E4)) v.Blockages[WHITE] -= e.P_C3_KNIGHT; break;
}
}
else
{
switch (sq) {
case A1: if (isPiece(WHITE, PAWN, A2) || isPiece(WHITE, PAWN, C2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A8; break;
case H1: if (isPiece(WHITE, PAWN, H2) || isPiece(WHITE, PAWN, F2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A8; break;
case A2: if (isPiece(WHITE, PAWN, A3) && isPiece(WHITE, PAWN, B2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A7; break;
case H2: if (isPiece(WHITE, PAWN, H3) && isPiece(WHITE, PAWN, G2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A7; break;
case C6: if (isPiece(BLACK, PAWN, C7) && isPiece(BLACK, PAWN, D5) && !isPiece(BLACK, PAWN, E5)) v.Blockages[BLACK] -= e.P_C3_KNIGHT; break;
}
}
/***************************************************************
* Material value adjustement based on the no. of own pawns. *
* Knights lose value as pawns disappear. *
***************************************************************/
v.MaterialAdjustement[side] += knight_adj[b.PieceCount[side][PAWN]];
/****************************************************************
* Collect data about mobility and king attacks. This resembles *
* move generation code, except that we are just incrementing *
* the counters instead of adding actual moves. *
****************************************************************/
for (U8 dir = 0; dir<8; dir++) {
pos = sq + vector[KNIGHT][dir];
if (IS_SQ(pos) && b.color[pos] != side) {
++mob;
if (e.sqNearK[!side][b.KingLoc[!side]][pos])
++att; // this knight is attacking zone around enemy king
}
}
/****************************************************************
* Evaluate mobility. We try to do it in such a way *
* that zero represents average mobility, but our *
* formula of doing so is a puer guess. *
****************************************************************/
v.mgMob[side] += 4 * (mob - 4);
v.egMob[side] += 4 * (mob - 4);
/****************************************************************
* Save data about king attacks *
****************************************************************/
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 2 * att;
}
}
void EvalBishop(S8 sq, S8 side) {
int att = 0;
int mob = 0;
v.gamePhase += 1;
if (side == WHITE) {
switch (sq) {
case A7: if (isPiece(BLACK, PAWN, B6)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case H7: if (isPiece(BLACK, PAWN, G6)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case B8: if (isPiece(BLACK, PAWN, C7)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case G8: if (isPiece(BLACK, PAWN, F7)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case A6: if (isPiece(BLACK, PAWN, B5)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A6; break;
case H6: if (isPiece(BLACK, PAWN, G5)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A6; break;
case F1: if (isPiece(WHITE, KING, G1)) v.PositionalThemes[WHITE] += e.RETURNING_BISHOP; break;
case C1: if (isPiece(WHITE, KING, B1)) v.PositionalThemes[WHITE] += e.RETURNING_BISHOP; break;
}
}
else {
switch (sq) {
case A2: if (isPiece(WHITE, PAWN, B3)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case H2: if (isPiece(WHITE, PAWN, G3)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case B1: if (isPiece(WHITE, PAWN, C2)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case G1: if (isPiece(WHITE, PAWN, F2)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case A3: if (isPiece(WHITE, PAWN, B4)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A6; break;
case H3: if (isPiece(WHITE, PAWN, G4)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A6; break;
case F8: if (isPiece(BLACK, KING, G8)) v.PositionalThemes[BLACK] += e.RETURNING_BISHOP; break;
case C8: if (isPiece(BLACK, KING, B8)) v.PositionalThemes[BLACK] += e.RETURNING_BISHOP; break;
}
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[BISHOP]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[BISHOP][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 3 * (mob - 7);
v.egMob[side] += 3 * (mob - 7);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 2 * att;
}
}
void EvalRook(S8 sq, S8 side) {
int att = 0;
int mob = 0;
int ownBlockingPawns = 0;
int oppBlockingPawns = 0;
int stepFwd;
int nextSq;
v.gamePhase += 2;
/***************************************************************
* Material value adjustement based on the no. of own pawns. *
* Rooks gain value as pawns disappear. *
***************************************************************/
v.MaterialAdjustement[side] += rook_adj[b.PieceCount[side][PAWN]];
/***************************************************************
* This is an ugly hack to detect open files. Merging it with *
* mobility eval would have been better, but less readable, *
* and this is educational program fter all. *
/**************************************************************/
if (side == WHITE) stepFwd = NORTH; else stepFwd = SOUTH;
nextSq = sq + stepFwd;
while (IS_SQ(nextSq)) {
if (b.pieces[nextSq] == PAWN) {
if (b.color[nextSq] == side) {
ownBlockingPawns++;
break;
}
else
oppBlockingPawns++;
}
nextSq += stepFwd;
}
/****************************************************************
* Evaluate open and half-open files. We merge this bonus with *
* mobility score. *
/***************************************************************/
if (!ownBlockingPawns) {
if (!oppBlockingPawns) {
v.mgMob[side] += e.ROOK_OPEN;
v.egMob[side] += e.ROOK_OPEN;
}
else {
v.mgMob[side] += e.ROOK_HALF;
v.egMob[side] += e.ROOK_HALF;
}
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[ROOK]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[ROOK][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 2 * (mob - 7);
v.egMob[side] += 4 * (mob - 7);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 3 * att;
}
}
void EvalQueen(S8 sq, S8 side) {
v.gamePhase += 4;
int att = 0;
int mob = 0;
/****************************************************************
* A queen should not be developed too early *
****************************************************************/
if (side == WHITE && ROW(sq) > ROW_2) {
if (isPiece(WHITE, KNIGHT, B1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, BISHOP, C1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, BISHOP, F1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, KNIGHT, G1)) v.PositionalThemes[WHITE] -= 2;
}
if (side == BLACK && ROW(sq) < ROW_7) {
if (isPiece(BLACK, KNIGHT, B8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, BISHOP, C8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, BISHOP, F8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, KNIGHT, G8)) v.PositionalThemes[BLACK] -= 2;
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[QUEEN]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[QUEEN][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 1 * (mob - 14);
v.egMob[side] += 2 * (mob - 14);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 4 * att;
}
}
int wKingShield() {
int result = 0;
/* king on the kingside */
if (COL(b.KingLoc[WHITE]) > COL_E) {
if (isPiece(WHITE, PAWN, F2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, F3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, G2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, G3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, H2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, H3)) result += e.SHIELD_2;
}
/* king on the queenside */
else if (COL(b.KingLoc[WHITE]) < COL_D) {
if (isPiece(WHITE, PAWN, A2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, A3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, B2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, B3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, C2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, C3)) result += e.SHIELD_2;
}
return result;
}
int bKingShield() {
int result = 0;
/* king on the kingside */
if (COL(b.KingLoc[BLACK]) > COL_E) {
if (isPiece(BLACK, PAWN, F7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, F6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, G7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, G6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, H7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, H6)) result += e.SHIELD_2;
}
/* king on the queenside */
else if (COL(b.KingLoc[BLACK]) < COL_D) {
if (isPiece(BLACK, PAWN, A7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, A6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, B7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, B6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, C7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, C6)) result += e.SHIELD_2;
}
return result;
}
/******************************************************************************
* Pawn structure evaluaton *
******************************************************************************/
int getPawnScore() {
int result;
/**************************************************************************
* This function wraps hashing mechanism around evalPawnStructure(). *
* Please note that since we use the pawn hashtable, evalPawnStructure() *
* must not take into account the piece position. In a more elaborate *
* program, pawn hashtable would contain only the characteristics of pawn *
* structure, and scoring them in conjunction with the piece position *
* would have been done elsewhere. *
**************************************************************************/
int probeval = ttpawn_probe();
if (probeval != INVALID)
return probeval;
result = evalPawnStructure();
ttpawn_save(result);
return result;
}
int evalPawnStructure() {
int result = 0;
for (U8 row = 0; row < 8; row++)
for (U8 col = 0; col < 8; col++) {
S8 sq = SET_SQ(row, col);
if (b.pieces[sq] == PAWN) {
if (b.color[sq] == WHITE) result += EvalPawn(sq, WHITE);
else result -= EvalPawn(sq, BLACK);
}
}
return result;
}
int EvalPawn(S8 sq, S8 side) {
int result = 0;
int flagIsPassed = 1; // we will be trying to disprove that
int flagIsWeak = 1; // we will be trying to disprove that
int flagIsOpposed = 0;
int stepFwd, stepBck;
if (side == WHITE) stepFwd = NORTH; else stepFwd = SOUTH;
if (side == WHITE) stepBck = SOUTH; else stepBck = NORTH;
S8 nextSq = sq + stepFwd;
/*************************************************************************
* We have only very basic data structures that do not update informa- *
* tion about pawns incrementally, so we have to calculate everything *
* here. The loop below detects doubled pawns, passed pawns and sets *
* a flag on finding that our pawn is opposed by enemy pawn. *
*************************************************************************/
while (IS_SQ(nextSq)) {
if (b.pieces[nextSq] == PAWN) { // either opposed by enemy pawn or doubled
flagIsPassed = 0;
if (b.color[nextSq] == side)
result -= 20; // doubled pawn penalty
else
flagIsOpposed = 1; // flag our pawn as opposed
}
if (IS_SQ(nextSq + WEST) && isPiece(!side, PAWN, nextSq + WEST))
flagIsPassed = 0;
if (IS_SQ(nextSq + EAST) && isPiece(!side, PAWN, nextSq + EAST))
flagIsPassed = 0;
nextSq += stepFwd;
}
/*************************************************************************
* Another loop, going backwards and checking whether pawn has support. *
* Here we can at least break out of it for speed optimization. *
*************************************************************************/
nextSq = sq;
while (IS_SQ(nextSq)) {
if (IS_SQ(nextSq + WEST) && isPiece(side, PAWN, nextSq + WEST)) {
flagIsWeak = 0;
break;
}
if (IS_SQ(nextSq + EAST) && isPiece(side, PAWN, nextSq + EAST)) {
flagIsWeak = 0;
break;
}
nextSq += stepBck;
}
/*************************************************************************
* Evaluate passed pawns, scoring them higher if they are protected *
* or if their advance is supported by friendly pawns *
*************************************************************************/
if (flagIsPassed) {
if (isPawnSupported(sq, side)) result += e.protected_passer[side][sq];
else result += e.passed_pawn[side][sq];
}
/*************************************************************************
* Evaluate weak pawns, increasing the penalty if they are situated *
* on a half-open file *
*************************************************************************/
if (flagIsWeak) {
result += e.weak_pawn[side][sq];
if (!flagIsOpposed)
result -= 4;
}
return result;
}
int isPawnSupported(S8 sq, S8 side) {
int step;
if (side == WHITE) step = SOUTH; else step = NORTH;
if (IS_SQ(sq + WEST) && isPiece(side, PAWN, sq + WEST)) return 1;
if (IS_SQ(sq + EAST) && isPiece(side, PAWN, sq + EAST)) return 1;
if (IS_SQ(sq + step + WEST) && isPiece(side, PAWN, sq + step + WEST)) return 1;
if (IS_SQ(sq + step + EAST) && isPiece(side, PAWN, sq + step + EAST)) return 1;
return 0;
}
/******************************************************************************
* Pattern detection *
******************************************************************************/
void blockedPieces() {
// central pawn blocked, bishop hard to develop
if (isPiece(WHITE, BISHOP, C1) && isPiece(WHITE, PAWN, D2) && b.color[D3] != COLOR_EMPTY)
v.Blockages[WHITE] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(WHITE, BISHOP, F1) && isPiece(WHITE, PAWN, E2) && b.color[E3] != COLOR_EMPTY)
v.Blockages[WHITE] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(BLACK, BISHOP, C8) && isPiece(BLACK, PAWN, D7) && b.color[D6] != COLOR_EMPTY)
v.Blockages[BLACK] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(BLACK, BISHOP, F8) && isPiece(BLACK, PAWN, E7) && b.color[E6] != COLOR_EMPTY)
v.Blockages[BLACK] -= e.P_BLOCK_CENTRAL_PAWN;
// uncastled king blocking own rook
if ((isPiece(WHITE, KING, F1) || isPiece(WHITE, KING, G1)) &&
(isPiece(WHITE, ROOK, H1) || isPiece(WHITE, ROOK, G1))
)
v.Blockages[WHITE] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(WHITE, KING, C1) || isPiece(WHITE, KING, B1)) &&
(isPiece(WHITE, ROOK, A1) || isPiece(WHITE, ROOK, B1))
)
v.Blockages[WHITE] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(BLACK, KING, F8) || isPiece(BLACK, KING, G8)) &&
(isPiece(BLACK, ROOK, H8) || isPiece(BLACK, ROOK, G8))
)
v.Blockages[BLACK] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(BLACK, KING, C8) || isPiece(BLACK, KING, B8)) &&
(isPiece(BLACK, ROOK, A8) || isPiece(BLACK, ROOK, B8))
)
v.Blockages[BLACK] -= e.P_KING_BLOCKS_ROOK;
}
int isPiece(U8 color, U8 piece, S8 sq) {
return ((b.pieces[sq] == piece) && (b.color[sq] == color));
}
/***************************************************************************************
* Printing eval results *
***************************************************************************************/
void printEval() {
printf("------------------------------------------\n");
printf("Total value (for side to move): %d \n", eval(-INF, INF, 0));
printf("Material balance : %d \n", b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] - b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK]);
printf("Material adjustement: "); printEvalFactor(v.MaterialAdjustement[WHITE], v.MaterialAdjustement[BLACK]);
printf("Mg Piece/square tables : "); printEvalFactor(b.PcsqMg[WHITE], b.PcsqMg[BLACK]);
printf("Eg Piece/square tables : "); printEvalFactor(b.PcsqEg[WHITE], b.PcsqEg[BLACK]);
printf("Mg Mobility : "); printEvalFactor(v.mgMob[WHITE], v.mgMob[BLACK]);
printf("Eg Mobility : "); printEvalFactor(v.mgMob[WHITE], v.egMob[BLACK]);
printf("Pawn structure : %d \n", evalPawnStructure());
printf("Blockages : "); printEvalFactor(v.Blockages[WHITE], v.Blockages[BLACK]);
printf("Positional themes : "); printEvalFactor(v.PositionalThemes[WHITE], v.PositionalThemes[BLACK]);
printf("King Shield : "); printEvalFactor(v.kingShield[WHITE], v.kingShield[BLACK]);
printf("Tempo: ");
if (b.stm == WHITE) printf("%d", e.TEMPO); else printf("%d", -e.TEMPO);
printf("\n");
printf("------------------------------------------\n");
}
void printEvalFactor(int wh, int bl) {
printf("white %4d, black %4d, total: %4d \n", wh, bl, wh - bl);
}
</pre>
'''[[CPW-Engine|Up one Level]]'''
=Description=
Using this evaluation function CPW-Engine should be aware of the following principles:
# develop the pieces
# castle if possible
# need some minimal level of assistance to disrupt its own castling position
# care for doubled, weak and passed pawns
# know a thing or two about the changes of piece values as pawns dissappear
# try to attack squares around enemy king
For function definitions, see [[CPW-Engine_eval_h]]
=Code=
<pre>
#include "stdafx.h"
#include "0x88_math.h"
#include "eval.h"
#include "transposition.h"
/* adjustements of piece value based on the number of own pawns */
int knight_adj[9] = { -20, -16, -12, -8, -4, 0, 4, 8, 12 };
int rook_adj[9] = { 15, 12, 9, 6, 3, 0, -3, -6, -9 };
static const int SafetyTable[100] = {
0, 0, 1, 2, 3, 5, 7, 9, 12, 15,
18, 22, 26, 30, 35, 39, 44, 50, 56, 62,
68, 75, 82, 85, 89, 97, 105, 113, 122, 131,
140, 150, 169, 180, 191, 202, 213, 225, 237, 248,
260, 272, 283, 295, 307, 319, 330, 342, 354, 366,
377, 389, 401, 412, 424, 436, 448, 459, 471, 483,
494, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500,
500, 500, 500, 500, 500, 500, 500, 500, 500, 500
};
/*******************************************************************
* This struct holds data about certain aspects of evaluation, *
* which allows program to print them if desired. *
*******************************************************************/
struct eval_vector {
int gamePhase;
int mgMob[2];
int egMob[2];
int attCnt[2];
int attWeight[2];
int kingShield[2];
int MaterialAdjustement[2];
int Blockages[2];
int PositionalThemes[2];
} v;
int eval(int alpha, int beta, int use_hash) {
int result = 0, mgScore = 0, egScore = 0;
int stronger, weaker;
/***********************************************************
/ Probe the evaluatinon hashtable, unless we call eval() /
/ only in order to display detailed result /
***********************************************************/
int probeval = tteval_probe();
if (probeval != INVALID && use_hash)
return probeval;
/***********************************************************
/ Clear all eval data /
***********************************************************/
v.gamePhase = 0;
v.mgMob[WHITE] = 0; v.mgMob[BLACK] = 0;
v.egMob[WHITE] = 0; v.egMob[BLACK] = 0;
v.attCnt[WHITE] = 0; v.attCnt[BLACK] = 0;
v.attWeight[WHITE] = 0; v.attWeight[BLACK] = 0;
v.MaterialAdjustement[WHITE] = 0; v.MaterialAdjustement[BLACK] = 0;
v.Blockages[WHITE] = 0; v.Blockages[BLACK] = 0;
v.PositionalThemes[WHITE] = 0; v.PositionalThemes[BLACK] = 0;
v.kingShield[WHITE] = 0; v.kingShield[BLACK] = 0;
/* sum the incrementally counted material and pcsq values */
mgScore = b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] + b.PcsqMg[WHITE]
- b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK] - b.PcsqMg[BLACK];
egScore = b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] + b.PcsqEg[WHITE]
- b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK] - b.PcsqEg[BLACK];
/* add king's pawn shield score and evaluate part of piece blockage score
(the rest of the latter will be done via piece eval) */
v.kingShield[WHITE] = wKingShield();
v.kingShield[BLACK] = bKingShield();
blockedPieces();
mgScore += (v.kingShield[WHITE] - v.kingShield[BLACK]);
/* tempo bonus */
if (b.stm == WHITE) result += e.TEMPO;
else result -= e.TEMPO;
/*******************************************************************
* Adjusting material value for the various combinations of pieces. *
* Currently it scores bishop, knight and rook pairs. The first one *
* gets a bonus, the latter two - a penalty. Please also note that *
* adjustements of knight and rook value based on the number of own *
* pawns on the board are done within the piece-specific routines. *
*******************************************************************/
if (b.PieceCount[WHITE][BISHOP] > 1) result += e.BISHOP_PAIR;
if (b.PieceCount[BLACK][BISHOP] > 1) result -= e.BISHOP_PAIR;
if (b.PieceCount[WHITE][KNIGHT] > 1) result -= e.P_KNIGHT_PAIR;
if (b.PieceCount[BLACK][KNIGHT] > 1) result += e.P_KNIGHT_PAIR;
if (b.PieceCount[WHITE][ROOK] > 1) result -= e.P_ROOK_PAIR;
if (b.PieceCount[BLACK][ROOK] > 1) result += e.P_ROOK_PAIR;
result += getPawnScore();
/*******************************************************************
* Evaluate pieces *
*******************************************************************/
for (U8 row = 0; row < 8; row++)
for (U8 col = 0; col < 8; col++) {
S8 sq = SET_SQ(row, col);
if (b.color[sq] != COLOR_EMPTY) {
switch (b.pieces[sq]) {
case PAWN: // pawns are evaluated separately
break;
case KNIGHT:
EvalKnight(sq, b.color[sq]);
break;
case BISHOP:
EvalBishop(sq, b.color[sq]);
break;
case ROOK:
EvalRook(sq, b.color[sq]);
break;
case QUEEN:
EvalQueen(sq, b.color[sq]);
break;
case KING:
break;
}
}
}
/********************************************************************
* Merge midgame and endgame score. We interpolate between these *
* two values, using a gamePhase value, based on remaining piece *
* material on both sides. With less pieces, endgame score beco- *
* mes more influential. *
********************************************************************/
mgScore += (v.mgMob[WHITE] - v.mgMob[BLACK]);
egScore += (v.egMob[WHITE] - v.egMob[BLACK]);
if (v.gamePhase > 24) v.gamePhase = 24;
int mgWeight = v.gamePhase;
int egWeight = 24 - mgWeight;
result += ((mgScore * mgWeight) + (egScore * egWeight)) / 24;
/********************************************************************
* Add phase-independent score components. *
********************************************************************/
result += (v.Blockages[WHITE] - v.Blockages[BLACK]);
result += (v.PositionalThemes[WHITE] - v.PositionalThemes[BLACK]);
result += (v.MaterialAdjustement[WHITE] - v.MaterialAdjustement[BLACK]);
/********************************************************************
* Merge king attack score. We don't apply this value if there are *
* less than two attackers or if the attacker has no queen. *
*******************************************************************/
if (v.attCnt[WHITE] < 2 || b.PieceCount[WHITE][QUEEN] == 0) v.attWeight[WHITE] = 0;
if (v.attCnt[BLACK] < 2 || b.PieceCount[BLACK][QUEEN] == 0) v.attWeight[BLACK] = 0;
result += SafetyTable[v.attWeight[WHITE]];
result -= SafetyTable[v.attWeight[BLACK]];
/********************************************************************
* Low material correction - guarding against an illusory material *
* advantage. Full blown program should have more such rules, but *
* the current set ought to be useful enough. Please note that our *
* code assumes different material values for bishop and knight. *
* *
* - a single minor piece cannot win *
* - two knights cannot checkmate bare king *
* - bare rook vs minor piece is drawish *
* - rook and minor vs rook is drawish *
********************************************************************/
if (result > 0) { stronger = WHITE; weaker = BLACK; }
else { stronger = BLACK; weaker = WHITE; }
if (b.PawnMaterial[stronger] == 0) {
if (b.PieceMaterial[stronger] < 400) return 0;
if (b.PawnMaterial[weaker] == 0
&& (b.PieceMaterial[stronger] == 2 * e.PIECE_VALUE[KNIGHT]))
return 0;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]
&& b.PieceMaterial[weaker] == e.PIECE_VALUE[BISHOP]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]
&& b.PieceMaterial[weaker] == e.PIECE_VALUE[KNIGHT]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK] + e.PIECE_VALUE[BISHOP]
&& b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]) result /= 2;
if (b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK] + e.PIECE_VALUE[KNIGHT]
&& b.PieceMaterial[stronger] == e.PIECE_VALUE[ROOK]) result /= 2;
}
/*******************************************************************
* Finally return the score relative to the side to move. *
*******************************************************************/
if (b.stm == BLACK) result = -result;
tteval_save(result);
return result;
}
void EvalKnight(S8 sq, S8 side) {
int att = 0;
int mob = 0;
int pos;
v.gamePhase += 1;
if (side == WHITE) {
switch (sq) {
case A8: if (isPiece(BLACK, PAWN, A7) || isPiece(BLACK, PAWN, C7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A8; break;
case H8: if (isPiece(BLACK, PAWN, H7) || isPiece(BLACK, PAWN, F7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A8; break;
case A7: if (isPiece(BLACK, PAWN, A6) && isPiece(BLACK, PAWN, B7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A7; break;
case H7: if (isPiece(BLACK, PAWN, H6) && isPiece(BLACK, PAWN, G7)) v.Blockages[WHITE] -= e.P_KNIGHT_TRAPPED_A7; break;
case C3: if (isPiece(WHITE, PAWN, C2) && isPiece(WHITE, PAWN, D4) && !isPiece(WHITE, PAWN, E4)) v.Blockages[WHITE] -= e.P_C3_KNIGHT; break;
}
}
else
{
switch (sq) {
case A1: if (isPiece(WHITE, PAWN, A2) || isPiece(WHITE, PAWN, C2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A8; break;
case H1: if (isPiece(WHITE, PAWN, H2) || isPiece(WHITE, PAWN, F2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A8; break;
case A2: if (isPiece(WHITE, PAWN, A3) && isPiece(WHITE, PAWN, B2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A7; break;
case H2: if (isPiece(WHITE, PAWN, H3) && isPiece(WHITE, PAWN, G2)) v.Blockages[BLACK] -= e.P_KNIGHT_TRAPPED_A7; break;
case C6: if (isPiece(BLACK, PAWN, C7) && isPiece(BLACK, PAWN, D5) && !isPiece(BLACK, PAWN, E5)) v.Blockages[BLACK] -= e.P_C3_KNIGHT; break;
}
}
/***************************************************************
* Material value adjustement based on the no. of own pawns. *
* Knights lose value as pawns disappear. *
***************************************************************/
v.MaterialAdjustement[side] += knight_adj[b.PieceCount[side][PAWN]];
/****************************************************************
* Collect data about mobility and king attacks. This resembles *
* move generation code, except that we are just incrementing *
* the counters instead of adding actual moves. *
****************************************************************/
for (U8 dir = 0; dir<8; dir++) {
pos = sq + vector[KNIGHT][dir];
if (IS_SQ(pos) && b.color[pos] != side) {
++mob;
if (e.sqNearK[!side][b.KingLoc[!side]][pos])
++att; // this knight is attacking zone around enemy king
}
}
/****************************************************************
* Evaluate mobility. We try to do it in such a way *
* that zero represents average mobility, but our *
* formula of doing so is a puer guess. *
****************************************************************/
v.mgMob[side] += 4 * (mob - 4);
v.egMob[side] += 4 * (mob - 4);
/****************************************************************
* Save data about king attacks *
****************************************************************/
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 2 * att;
}
}
void EvalBishop(S8 sq, S8 side) {
int att = 0;
int mob = 0;
v.gamePhase += 1;
if (side == WHITE) {
switch (sq) {
case A7: if (isPiece(BLACK, PAWN, B6)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case H7: if (isPiece(BLACK, PAWN, G6)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case B8: if (isPiece(BLACK, PAWN, C7)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case G8: if (isPiece(BLACK, PAWN, F7)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A7; break;
case A6: if (isPiece(BLACK, PAWN, B5)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A6; break;
case H6: if (isPiece(BLACK, PAWN, G5)) v.Blockages[WHITE] -= e.P_BISHOP_TRAPPED_A6; break;
case F1: if (isPiece(WHITE, KING, G1)) v.PositionalThemes[WHITE] += e.RETURNING_BISHOP; break;
case C1: if (isPiece(WHITE, KING, B1)) v.PositionalThemes[WHITE] += e.RETURNING_BISHOP; break;
}
}
else {
switch (sq) {
case A2: if (isPiece(WHITE, PAWN, B3)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case H2: if (isPiece(WHITE, PAWN, G3)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case B1: if (isPiece(WHITE, PAWN, C2)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case G1: if (isPiece(WHITE, PAWN, F2)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A7; break;
case A3: if (isPiece(WHITE, PAWN, B4)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A6; break;
case H3: if (isPiece(WHITE, PAWN, G4)) v.Blockages[BLACK] -= e.P_BISHOP_TRAPPED_A6; break;
case F8: if (isPiece(BLACK, KING, G8)) v.PositionalThemes[BLACK] += e.RETURNING_BISHOP; break;
case C8: if (isPiece(BLACK, KING, B8)) v.PositionalThemes[BLACK] += e.RETURNING_BISHOP; break;
}
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[BISHOP]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[BISHOP][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 3 * (mob - 7);
v.egMob[side] += 3 * (mob - 7);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 2 * att;
}
}
void EvalRook(S8 sq, S8 side) {
int att = 0;
int mob = 0;
int ownBlockingPawns = 0;
int oppBlockingPawns = 0;
int stepFwd;
int nextSq;
v.gamePhase += 2;
/***************************************************************
* Material value adjustement based on the no. of own pawns. *
* Rooks gain value as pawns disappear. *
***************************************************************/
v.MaterialAdjustement[side] += rook_adj[b.PieceCount[side][PAWN]];
/***************************************************************
* This is an ugly hack to detect open files. Merging it with *
* mobility eval would have been better, but less readable, *
* and this is educational program fter all. *
/**************************************************************/
if (side == WHITE) stepFwd = NORTH; else stepFwd = SOUTH;
nextSq = sq + stepFwd;
while (IS_SQ(nextSq)) {
if (b.pieces[nextSq] == PAWN) {
if (b.color[nextSq] == side) {
ownBlockingPawns++;
break;
}
else
oppBlockingPawns++;
}
nextSq += stepFwd;
}
/****************************************************************
* Evaluate open and half-open files. We merge this bonus with *
* mobility score. *
/***************************************************************/
if (!ownBlockingPawns) {
if (!oppBlockingPawns) {
v.mgMob[side] += e.ROOK_OPEN;
v.egMob[side] += e.ROOK_OPEN;
}
else {
v.mgMob[side] += e.ROOK_HALF;
v.egMob[side] += e.ROOK_HALF;
}
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[ROOK]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[ROOK][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 2 * (mob - 7);
v.egMob[side] += 4 * (mob - 7);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 3 * att;
}
}
void EvalQueen(S8 sq, S8 side) {
v.gamePhase += 4;
int att = 0;
int mob = 0;
/****************************************************************
* A queen should not be developed too early *
****************************************************************/
if (side == WHITE && ROW(sq) > ROW_2) {
if (isPiece(WHITE, KNIGHT, B1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, BISHOP, C1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, BISHOP, F1)) v.PositionalThemes[WHITE] -= 2;
if (isPiece(WHITE, KNIGHT, G1)) v.PositionalThemes[WHITE] -= 2;
}
if (side == BLACK && ROW(sq) < ROW_7) {
if (isPiece(BLACK, KNIGHT, B8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, BISHOP, C8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, BISHOP, F8)) v.PositionalThemes[BLACK] -= 2;
if (isPiece(BLACK, KNIGHT, G8)) v.PositionalThemes[BLACK] -= 2;
}
/****************************************************************
* Collect data about mobility and king attacks *
****************************************************************/
for (char dir = 0; dir<vectors[QUEEN]; dir++) {
for (char pos = sq;;) {
pos = pos + vector[QUEEN][dir];
if (!IS_SQ(pos)) break;
if (b.pieces[pos] == PIECE_EMPTY) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
}
else if (b.color[pos] != side) {
mob++;
if (e.sqNearK[!side][b.KingLoc[!side]][pos]) ++att;
break;
}
else {
break;
}
}
}
v.mgMob[side] += 1 * (mob - 14);
v.egMob[side] += 2 * (mob - 14);
if (att) {
v.attCnt[side]++;
v.attWeight[side] += 4 * att;
}
}
int wKingShield() {
int result = 0;
/* king on the kingside */
if (COL(b.KingLoc[WHITE]) > COL_E) {
if (isPiece(WHITE, PAWN, F2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, F3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, G2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, G3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, H2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, H3)) result += e.SHIELD_2;
}
/* king on the queenside */
else if (COL(b.KingLoc[WHITE]) < COL_D) {
if (isPiece(WHITE, PAWN, A2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, A3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, B2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, B3)) result += e.SHIELD_2;
if (isPiece(WHITE, PAWN, C2)) result += e.SHIELD_1;
else if (isPiece(WHITE, PAWN, C3)) result += e.SHIELD_2;
}
return result;
}
int bKingShield() {
int result = 0;
/* king on the kingside */
if (COL(b.KingLoc[BLACK]) > COL_E) {
if (isPiece(BLACK, PAWN, F7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, F6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, G7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, G6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, H7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, H6)) result += e.SHIELD_2;
}
/* king on the queenside */
else if (COL(b.KingLoc[BLACK]) < COL_D) {
if (isPiece(BLACK, PAWN, A7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, A6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, B7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, B6)) result += e.SHIELD_2;
if (isPiece(BLACK, PAWN, C7)) result += e.SHIELD_1;
else if (isPiece(BLACK, PAWN, C6)) result += e.SHIELD_2;
}
return result;
}
/******************************************************************************
* Pawn structure evaluaton *
******************************************************************************/
int getPawnScore() {
int result;
/**************************************************************************
* This function wraps hashing mechanism around evalPawnStructure(). *
* Please note that since we use the pawn hashtable, evalPawnStructure() *
* must not take into account the piece position. In a more elaborate *
* program, pawn hashtable would contain only the characteristics of pawn *
* structure, and scoring them in conjunction with the piece position *
* would have been done elsewhere. *
**************************************************************************/
int probeval = ttpawn_probe();
if (probeval != INVALID)
return probeval;
result = evalPawnStructure();
ttpawn_save(result);
return result;
}
int evalPawnStructure() {
int result = 0;
for (U8 row = 0; row < 8; row++)
for (U8 col = 0; col < 8; col++) {
S8 sq = SET_SQ(row, col);
if (b.pieces[sq] == PAWN) {
if (b.color[sq] == WHITE) result += EvalPawn(sq, WHITE);
else result -= EvalPawn(sq, BLACK);
}
}
return result;
}
int EvalPawn(S8 sq, S8 side) {
int result = 0;
int flagIsPassed = 1; // we will be trying to disprove that
int flagIsWeak = 1; // we will be trying to disprove that
int flagIsOpposed = 0;
int stepFwd, stepBck;
if (side == WHITE) stepFwd = NORTH; else stepFwd = SOUTH;
if (side == WHITE) stepBck = SOUTH; else stepBck = NORTH;
S8 nextSq = sq + stepFwd;
/*************************************************************************
* We have only very basic data structures that do not update informa- *
* tion about pawns incrementally, so we have to calculate everything *
* here. The loop below detects doubled pawns, passed pawns and sets *
* a flag on finding that our pawn is opposed by enemy pawn. *
*************************************************************************/
while (IS_SQ(nextSq)) {
if (b.pieces[nextSq] == PAWN) { // either opposed by enemy pawn or doubled
flagIsPassed = 0;
if (b.color[nextSq] == side)
result -= 20; // doubled pawn penalty
else
flagIsOpposed = 1; // flag our pawn as opposed
}
if (IS_SQ(nextSq + WEST) && isPiece(!side, PAWN, nextSq + WEST))
flagIsPassed = 0;
if (IS_SQ(nextSq + EAST) && isPiece(!side, PAWN, nextSq + EAST))
flagIsPassed = 0;
nextSq += stepFwd;
}
/*************************************************************************
* Another loop, going backwards and checking whether pawn has support. *
* Here we can at least break out of it for speed optimization. *
*************************************************************************/
nextSq = sq;
while (IS_SQ(nextSq)) {
if (IS_SQ(nextSq + WEST) && isPiece(side, PAWN, nextSq + WEST)) {
flagIsWeak = 0;
break;
}
if (IS_SQ(nextSq + EAST) && isPiece(side, PAWN, nextSq + EAST)) {
flagIsWeak = 0;
break;
}
nextSq += stepBck;
}
/*************************************************************************
* Evaluate passed pawns, scoring them higher if they are protected *
* or if their advance is supported by friendly pawns *
*************************************************************************/
if (flagIsPassed) {
if (isPawnSupported(sq, side)) result += e.protected_passer[side][sq];
else result += e.passed_pawn[side][sq];
}
/*************************************************************************
* Evaluate weak pawns, increasing the penalty if they are situated *
* on a half-open file *
*************************************************************************/
if (flagIsWeak) {
result += e.weak_pawn[side][sq];
if (!flagIsOpposed)
result -= 4;
}
return result;
}
int isPawnSupported(S8 sq, S8 side) {
int step;
if (side == WHITE) step = SOUTH; else step = NORTH;
if (IS_SQ(sq + WEST) && isPiece(side, PAWN, sq + WEST)) return 1;
if (IS_SQ(sq + EAST) && isPiece(side, PAWN, sq + EAST)) return 1;
if (IS_SQ(sq + step + WEST) && isPiece(side, PAWN, sq + step + WEST)) return 1;
if (IS_SQ(sq + step + EAST) && isPiece(side, PAWN, sq + step + EAST)) return 1;
return 0;
}
/******************************************************************************
* Pattern detection *
******************************************************************************/
void blockedPieces() {
// central pawn blocked, bishop hard to develop
if (isPiece(WHITE, BISHOP, C1) && isPiece(WHITE, PAWN, D2) && b.color[D3] != COLOR_EMPTY)
v.Blockages[WHITE] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(WHITE, BISHOP, F1) && isPiece(WHITE, PAWN, E2) && b.color[E3] != COLOR_EMPTY)
v.Blockages[WHITE] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(BLACK, BISHOP, C8) && isPiece(BLACK, PAWN, D7) && b.color[D6] != COLOR_EMPTY)
v.Blockages[BLACK] -= e.P_BLOCK_CENTRAL_PAWN;
if (isPiece(BLACK, BISHOP, F8) && isPiece(BLACK, PAWN, E7) && b.color[E6] != COLOR_EMPTY)
v.Blockages[BLACK] -= e.P_BLOCK_CENTRAL_PAWN;
// uncastled king blocking own rook
if ((isPiece(WHITE, KING, F1) || isPiece(WHITE, KING, G1)) &&
(isPiece(WHITE, ROOK, H1) || isPiece(WHITE, ROOK, G1))
)
v.Blockages[WHITE] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(WHITE, KING, C1) || isPiece(WHITE, KING, B1)) &&
(isPiece(WHITE, ROOK, A1) || isPiece(WHITE, ROOK, B1))
)
v.Blockages[WHITE] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(BLACK, KING, F8) || isPiece(BLACK, KING, G8)) &&
(isPiece(BLACK, ROOK, H8) || isPiece(BLACK, ROOK, G8))
)
v.Blockages[BLACK] -= e.P_KING_BLOCKS_ROOK;
if ((isPiece(BLACK, KING, C8) || isPiece(BLACK, KING, B8)) &&
(isPiece(BLACK, ROOK, A8) || isPiece(BLACK, ROOK, B8))
)
v.Blockages[BLACK] -= e.P_KING_BLOCKS_ROOK;
}
int isPiece(U8 color, U8 piece, S8 sq) {
return ((b.pieces[sq] == piece) && (b.color[sq] == color));
}
/***************************************************************************************
* Printing eval results *
***************************************************************************************/
void printEval() {
printf("------------------------------------------\n");
printf("Total value (for side to move): %d \n", eval(-INF, INF, 0));
printf("Material balance : %d \n", b.PieceMaterial[WHITE] + b.PawnMaterial[WHITE] - b.PieceMaterial[BLACK] - b.PawnMaterial[BLACK]);
printf("Material adjustement: "); printEvalFactor(v.MaterialAdjustement[WHITE], v.MaterialAdjustement[BLACK]);
printf("Mg Piece/square tables : "); printEvalFactor(b.PcsqMg[WHITE], b.PcsqMg[BLACK]);
printf("Eg Piece/square tables : "); printEvalFactor(b.PcsqEg[WHITE], b.PcsqEg[BLACK]);
printf("Mg Mobility : "); printEvalFactor(v.mgMob[WHITE], v.mgMob[BLACK]);
printf("Eg Mobility : "); printEvalFactor(v.mgMob[WHITE], v.egMob[BLACK]);
printf("Pawn structure : %d \n", evalPawnStructure());
printf("Blockages : "); printEvalFactor(v.Blockages[WHITE], v.Blockages[BLACK]);
printf("Positional themes : "); printEvalFactor(v.PositionalThemes[WHITE], v.PositionalThemes[BLACK]);
printf("King Shield : "); printEvalFactor(v.kingShield[WHITE], v.kingShield[BLACK]);
printf("Tempo: ");
if (b.stm == WHITE) printf("%d", e.TEMPO); else printf("%d", -e.TEMPO);
printf("\n");
printf("------------------------------------------\n");
}
void printEvalFactor(int wh, int bl) {
printf("white %4d, black %4d, total: %4d \n", wh, bl, wh - bl);
}
</pre>
'''[[CPW-Engine|Up one Level]]'''
