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// This file is part of the shakmaty library. // Copyright (C) 2017 Niklas Fiekas <niklas.fiekas@backscattering.de> // // This program is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program. If not, see <http://www.gnu.org/licenses/>. //! Attack and ray tables. //! //! # Examples //! //! ``` //! # use shakmaty::{Square, Bitboard}; //! use shakmaty::attacks; //! //! let occupied = Bitboard::rank(5); // blocking pieces //! let attacks = attacks::bishop_attacks(Square::C2, occupied); //! // . . . . . . . . //! // . . . . . . . . //! // 0 0 0 0 0 0 1 0 //! // . . . . . 1 . . //! // 1 . . . 1 . . . //! // . 1 . 1 . . . . //! // . . . . . . . . //! // . 1 . 1 . . . . //! //! assert!(attacks.contains(Square::G6)); //! assert!(!attacks.contains(Square::H7)); //! ``` use square::Square; use bitboard::Bitboard; use types::{Color, Role, Piece}; use magics; include!(concat!(env!("OUT_DIR"), "/attacks.rs")); // generated by build.rs /// Looks up attacks for a pawn of `color` on `sq`. #[inline] pub fn pawn_attacks(color: Color, sq: Square) -> Bitboard { // This is safe because properly constructed squares are in bounds. Bitboard(match color { Color::White => WHITE_PAWN_ATTACKS[usize::from(sq)], Color::Black => BLACK_PAWN_ATTACKS[usize::from(sq)], }) } /// Looks up attacks for a knight on `sq`. #[inline] pub fn knight_attacks(sq: Square) -> Bitboard { Bitboard(KNIGHT_ATTACKS[usize::from(sq)]) } /// Looks up attacks for a king on `sq`. #[inline] pub fn king_attacks(sq: Square) -> Bitboard { Bitboard(KING_ATTACKS[usize::from(sq)]) } /// Looks up attacks for a rook on `sq` with `occupied` squares. #[inline] pub fn rook_attacks(sq: Square, occupied: Bitboard) -> Bitboard { // This is safe because properly constructed squares are in bounds. let m = unsafe { magics::ROOK_MAGICS.get_unchecked(usize::from(sq)) }; // This is safe because a sufficient size for the attack tables was // hand-selected. let idx = (m.factor.wrapping_mul(occupied.0 & m.mask) >> (64 - 12)) as usize + m.offset; Bitboard(unsafe { *ATTACKS.get_unchecked(idx) }) } /// Looks up attacks for a bishop on `sq` with `occupied` squares. #[inline] pub fn bishop_attacks(sq: Square, occupied: Bitboard) -> Bitboard { // This is safe because properly constructed squares are in bounds. let m = unsafe { magics::BISHOP_MAGICS.get_unchecked(usize::from(sq)) }; // This is safe because a sufficient size for the attack tables was // hand-selected. let idx = (m.factor.wrapping_mul(occupied.0 & m.mask) >> (64 - 9)) as usize + m.offset; Bitboard(unsafe { *ATTACKS.get_unchecked(idx) }) } /// Looks up attacks for a queen on `sq` with `occupied` squares. #[inline] pub fn queen_attacks(sq: Square, occupied: Bitboard) -> Bitboard { rook_attacks(sq, occupied) ^ bishop_attacks(sq, occupied) } /// Looks up attacks for `piece` on `sq` with `occupied` squares. pub fn attacks(sq: Square, piece: Piece, occupied: Bitboard) -> Bitboard { match piece.role { Role::Pawn => pawn_attacks(piece.color, sq), Role::Knight => knight_attacks(sq), Role::Bishop => bishop_attacks(sq, occupied), Role::Rook => rook_attacks(sq, occupied), Role::Queen => queen_attacks(sq, occupied), Role::King => king_attacks(sq), } } /// The rank, file or diagonal with the two squares (or an empty [`Bitboard`] /// if they are not aligned). /// /// ``` /// # use shakmaty::attacks; /// # use shakmaty::Square; /// /// let ray = attacks::ray(Square::E2, Square::G4); /// // . . . . . . . . /// // . . . . . . . . /// // . . . . . . . . /// // . . . . . . . 1 /// // . . . . . . 1 . /// // . . . . . 1 . . /// // . . . . 1 . . . /// // . . . 1 . . . . /// ``` /// /// [`Bitboard`]: ../struct.Bitboard.html #[inline] pub fn ray(a: Square, b: Square) -> Bitboard { // This is safe because properly constructed squares are in bounds. let idx = usize::from(a) * 64 + usize::from(b); unsafe { Bitboard(*BB_RAYS.get_unchecked(idx)) } } /// The squares between the two squares (bounds not included), or an empty /// [`Bitboard`] if they are not on the same rank, file or diagonal. /// /// ``` /// # use shakmaty::attacks; /// # use shakmaty::Square; /// /// let between = attacks::between(Square::B1, Square::B7); /// // . . . . . . . . /// // . 0 . . . . . . /// // . 1 . . . . . . /// // . 1 . . . . . . /// // . 1 . . . . . . /// // . 1 . . . . . . /// // . 1 . . . . . . /// // . 0 . . . . . . /// /// [`Bitboard`]: ../struct.Bitboard.html #[inline] pub fn between(a: Square, b: Square) -> Bitboard { // This is safe because properly constructed squares are in bounds. let idx = usize::from(a) * 64 + usize::from(b); unsafe { Bitboard(*BB_BETWEEN.get_unchecked(idx)) } } /// Tests if all three squares are aligned on a rank, file or diagonal. /// /// ``` /// # use shakmaty::attacks; /// # use shakmaty::Square; /// /// assert!(attacks::aligned(Square::A1, Square::B2, Square::C3)); /// ``` #[inline] pub fn aligned(a: Square, b: Square, c: Square) -> bool { ray(a, b).contains(c) } #[cfg(test)] mod tests { use super::*; #[test] fn test_rook_attacks() { assert_eq!(rook_attacks(Square::D6, Bitboard(0x3f7f28802826f5b9)), Bitboard(0x8370808000000)); } }