Babys-First-Chess-Engine/evaluate.cpp at main · francoNovoa08/Babys-First-Chess-Engine · GitHub

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#include "evaluate.h"
#include <bit>

static const int PAWN_TABLE[64] = {
     0,  0,  0,  0,  0,  0,  0,  0,
    50, 50, 50, 50, 50, 50, 50, 50,
    10, 10, 20, 30, 30, 20, 10, 10,
     5,  5, 10, 25, 25, 10,  5,  5,
     0,  0,  0, 20, 20,  0,  0,  0,
     5, -5,-10,  0,  0,-10, -5,  5,
     5, 10, 10,-20,-20, 10, 10,  5,
     0,  0,  0,  0,  0,  0,  0,  0
};

static const int KNIGHT_TABLE[64] = {
    -50,-40,-30,-30,-30,-30,-40,-50,
    -40,-20,  0,  0,  0,  0,-20,-40,
    -30,  0, 10, 15, 15, 10,  0,-30,
    -30,  5, 15, 20, 20, 15,  5,-30,
    -30,  0, 15, 20, 20, 15,  0,-30,
    -30,  5, 10, 15, 15, 10,  5,-30,
    -40,-20,  0,  5,  5,  0,-20,-40,
    -50,-40,-30,-30,-30,-30,-40,-50
};

static const int BISHOP_TABLE[64] = {
    -20,-10,-10,-10,-10,-10,-10,-20,
    -10,  0,  0,  0,  0,  0,  0,-10,
    -10,  0,  5, 10, 10,  5,  0,-10,
    -10,  5,  5, 10, 10,  5,  5,-10,
    -10,  0, 10, 10, 10, 10,  0,-10,
    -10, 10, 10, 10, 10, 10, 10,-10,
    -10,  5,  0,  0,  0,  0,  5,-10,
    -20,-10,-10,-10,-10,-10,-10,-20
};

static const int ROOK_TABLE[64] = {
     0,  0,  0,  0,  0,  0,  0,  0,
     5, 10, 10, 10, 10, 10, 10,  5,
    -5,  0,  0,  0,  0,  0,  0, -5,
    -5,  0,  0,  0,  0,  0,  0, -5,
    -5,  0,  0,  0,  0,  0,  0, -5,
    -5,  0,  0,  0,  0,  0,  0, -5,
    -5,  0,  0,  0,  0,  0,  0, -5,
     0,  0,  0,  5,  5,  0,  0,  0
};

static const int QUEEN_TABLE[64] = {
    -20,-10,-10, -5, -5,-10,-10,-20,
    -10,  0,  0,  0,  0,  0,  0,-10,
    -10,  0,  5,  5,  5,  5,  0,-10,
     -5,  0,  5,  5,  5,  5,  0, -5,
      0,  0,  5,  5,  5,  5,  0, -5,
    -10,  5,  5,  5,  5,  5,  0,-10,
    -10,  0,  5,  0,  0,  0,  0,-10,
    -20,-10,-10, -5, -5,-10,-10,-20
};

static const int KING_MIDDLE_TABLE[64] = {
    -30,-40,-40,-50,-50,-40,-40,-30,
    -30,-40,-40,-50,-50,-40,-40,-30,
    -30,-40,-40,-50,-50,-40,-40,-30,
    -30,-40,-40,-50,-50,-40,-40,-30,
    -20,-30,-30,-40,-40,-30,-30,-20,
    -10,-20,-20,-20,-20,-20,-20,-10,
     20, 20,  0,  0,  0,  0, 20, 20,
     20, 30, 10,  0,  0, 10, 30, 20
};

// Mirror for black
static constexpr int mirror(int sq) {
    return sq ^ 56; // Flips rank
}

static int pieceSquareBonus(PieceType pt, Colour c, Square sq) {
    int idx = (c == Colour::White) ? sq : mirror(sq);
    switch (pt) {
    case PieceType::Pawn:   return PAWN_TABLE[idx];
    case PieceType::Knight: return KNIGHT_TABLE[idx];
    case PieceType::Bishop: return BISHOP_TABLE[idx];
    case PieceType::Rook:   return ROOK_TABLE[idx];
    case PieceType::Queen:  return QUEEN_TABLE[idx];
    case PieceType::King:   return KING_MIDDLE_TABLE[idx];
    default:                return 0;
    }
}

static constexpr int PIECE_VALUES[6] = {
    PAWN_VALUE, KNIGHT_VALUE, BISHOP_VALUE,
    ROOK_VALUE, QUEEN_VALUE,  KING_VALUE
};

int evaluate(const Position& pos) {
    int score = 0;

    for (int c = 0; c < 2; c++) {
        int sign = (c == static_cast<int>(pos.sideToMove)) ? 1 : -1;
        Colour colour = static_cast<Colour>(c);

        for (int pt = 0; pt < 6; pt++) {
            Bitboard bb = pos.getPieces(colour, static_cast<PieceType>(pt));
            while (bb) {
                Square sq = popLsb(bb);
                score += sign * (PIECE_VALUES[pt] +
                    pieceSquareBonus(static_cast<PieceType>(pt),
                        colour, sq));
            }
        }
    }

    return score;
}