chess-engine/python/python/constants.py

"""Stockfish NNUE Feature Constants"""

# Total feature count: 352 + 60,720 = 61,072
HALF_KA_V2_HM = 352
FULL_THREATS = 60_720
TOTAL_FEATURES = HALF_KA_V2_HM + FULL_THREATS

# Piece Unicode symbol to piece type mapping (0 = pawn, 1 = knight, etc.)
PIECE_TYPE_MAP = {
    "\u265f": 0,  # pawn ♙
    "\u265e": 1,  # knight ♘
    "\u265d": 2,  # bishop ♗
    "\u265c": 3,  # rook ♖
    "\u265b": 4,  # queen ♕
    "\u265a": 5,  # king ♔
    "\u2659": 0,  # pawn ♟
    "\u2658": 1,  # knight ♞
    "\u2657": 2,  # bishop ♝
    "\u2656": 3,  # rook ♜
    "\u2655": 4,  # queen ♛
    "\u2654": 5,  # king ♚
}

# Piece Unicode symbols (Black pieces)
BLACK_PIECES = {
    0: "\u2659",  # pawn ♟
    1: "\u2658",  # knight ♞
    2: "\u2657",  # bishop ♝
    3: "\u2656",  # rook ♜
    4: "\u2655",  # queen ♛
    5: "\u2654",  # king ♚
}

# Piece types (Black pieces)
BLACK_PIECES = {
    0: "P",
    1: "N",
    2: "B",
    3: "R",
    4: "Q",
    5: "K",
}

# Piece-square index tables
# Maps (perspective, piece_type) to square index
PIECE_SQUARE_INDEX = [
    # White perspective
    [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
        23,
        24,
        25,
    ],  # pawns
    [
        2,
        1,
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
        23,
        24,
    ],  # knights
    [
        3,
        2,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
        23,
        24,
        25,
    ],  # bishops
    [
        5,
        4,
        3,
        2,
        1,
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
    ],  # rooks
    [
        4,
        3,
        2,
        1,
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
        23,
    ],  # queens
    [
        5,
        4,
        3,
        2,
        1,
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
    ],  # kings
    # Black perspective
    [
        24,
        23,
        22,
        21,
        20,
        19,
        18,
        17,
        16,
        15,
        14,
        13,
        12,
        11,
        10,
        9,
        8,
        7,
        6,
        5,
        4,
        3,
        2,
        1,
        0,
        5,
    ],  # pawns
    [
        22,
        23,
        24,
        25,
        26,
        27,
        28,
        29,
        30,
        31,
        32,
        33,
        34,
        35,
        36,
        37,
        38,
        39,
        40,
        41,
        42,
        43,
        44,
        45,
        46,
        47,
        48,
    ],  # knights
    [
        24,
        23,
        22,
        21,
        20,
        19,
        18,
        17,
        16,
        15,
        14,
        13,
        12,
        11,
        10,
        9,
        8,
        7,
        6,
        5,
        4,
        3,
        2,
        1,
        0,
        5,
    ],  # bishops
    [
        22,
        21,
        20,
        19,
        18,
        17,
        16,
        15,
        14,
        13,
        12,
        11,
        10,
        9,
        8,
        7,
        6,
        5,
        4,
        3,
        2,
        1,
        0,
        5,
        6,
    ],  # rooks
    [
        23,
        22,
        21,
        20,
        19,
        18,
        17,
        16,
        15,
        14,
        13,
        12,
        11,
        10,
        9,
        8,
        7,
        6,
        5,
        4,
        3,
        2,
        1,
        0,
        5,
        6,
    ],  # queens
    [
        24,
        23,
        22,
        21,
        20,
        19,
        18,
        17,
        16,
        15,
        14,
        13,
        12,
        11,
        10,
        9,
        8,
        7,
        6,
        5,
        4,
        3,
        2,
        1,
        0,
        5,
    ],  # kings
]

# Orientation table for king square
# ORIENT_TBL[ksq] gives the orientation offset based on king position
ORIENT_TBL = [
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
]