79 lines
2.9 KiB
Nim
79 lines
2.9 KiB
Nim
# Copyright 2024 Mattia Giambirtone & All Contributors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import bitboards
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import magics
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import pieces
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type
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Position* = object
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## A chess position
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# Castling availability. This just keeps track
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# of whether the king or the rooks on either side
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# moved, the actual checks for the legality of castling
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# are done elsewhere
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castlingAvailability*: tuple[white, black: tuple[queen, king: bool]]
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# Number of half-moves that were performed
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# to reach this position starting from the
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# root of the tree
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plyFromRoot*: int8
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# Number of half moves since
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# last piece capture or pawn movement.
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# Used for the 50-move rule
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halfMoveClock*: int8
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# Full move counter. Increments
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# every 2 ply (half-moves)
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fullMoveCount*: int8
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# En passant target square (see https://en.wikipedia.org/wiki/En_passant)
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enPassantSquare*: Square
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# The side to move
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sideToMove*: PieceColor
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# Positional bitboards for all pieces
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pieces*: array[2, array[6, Bitboard]]
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# Pieces pinned for the current side to move
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diagonalPins*: Bitboard # Pinned diagonally (by a queen or bishop)
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orthogonalPins*: Bitboard # Pinned orthogonally (by a queen or rook)
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# Pieces checking the current side to move
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checkers*: Bitboard
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func getKingStartingSquare*(color: PieceColor): Square {.inline.} =
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## Retrieves the starting square of the king
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## for the given color
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case color:
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of White:
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return "e1".toSquare()
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of Black:
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return "e8".toSquare()
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else:
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discard
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func `[]`*(self: array[2, array[6, Bitboard]], color: PieceColor): ptr array[6, Bitboard] {.inline.} = addr self[color.int]
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func `[]`*(self: array[6, Bitboard], kind: PieceKind): ptr Bitboard {.inline.} = addr self[kind.int]
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func `[]=`*(self: var array[6, Bitboard], kind: PieceKind, bitboard: Bitboard) {.inline.} = self[kind.int] = bitboard
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func getBitboard*(self: Position, kind: PieceKind, color: PieceColor): Bitboard =
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## Returns the positional bitboard for the given piece kind and color
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return self.pieces[color.int][kind.int]
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func getBitboard*(self: Position, piece: Piece): Bitboard =
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## Returns the positional bitboard for the given piece type
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return self.getBitboard(piece.kind, piece.color) |