Add 'Bitboard' and 'Square' definitions

This commit is contained in:
Bruno BELANYI 2022-07-15 21:33:07 +02:00
parent 2c36ee266d
commit 755e891b17
4 changed files with 415 additions and 0 deletions

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src/board/bitboard.rs Normal file
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use super::Square;
/// Use a 64-bit number to represent a chessboard. Each bit is mapped from to a specific square, so
/// that index 0 -> A1, 1 -> A2, ..., 63 -> H8.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Bitboard(pub(crate) u64);
impl Bitboard {
/// An empty bitboard.
pub const EMPTY: Bitboard = Bitboard(0);
/// Array of bitboards representing the eight ranks, in order from rank 1 to rank 8.
pub const RANKS: [Self; 8] = [
Bitboard(0b00000001_00000001_00000001_00000001_00000001_00000001_00000001_00000001),
Bitboard(0b00000010_00000010_00000010_00000010_00000010_00000010_00000010_00000010),
Bitboard(0b00000100_00000100_00000100_00000100_00000100_00000100_00000100_00000100),
Bitboard(0b00001000_00001000_00001000_00001000_00001000_00001000_00001000_00001000),
Bitboard(0b00010000_00010000_00010000_00010000_00010000_00010000_00010000_00010000),
Bitboard(0b00100000_00100000_00100000_00100000_00100000_00100000_00100000_00100000),
Bitboard(0b01000000_01000000_01000000_01000000_01000000_01000000_01000000_01000000),
Bitboard(0b10000000_10000000_10000000_10000000_10000000_10000000_10000000_10000000),
];
/// Array of bitboards representing the eight files, in order from file A to file H.
pub const FILES: [Self; 8] = [
Bitboard(0b00000000_00000000_00000000_00000000_00000000_00000000_00000000_11111111),
Bitboard(0b00000000_00000000_00000000_00000000_00000000_00000000_11111111_00000000),
Bitboard(0b00000000_00000000_00000000_00000000_00000000_11111111_00000000_00000000),
Bitboard(0b00000000_00000000_00000000_00000000_11111111_00000000_00000000_00000000),
Bitboard(0b00000000_00000000_00000000_11111111_00000000_00000000_00000000_00000000),
Bitboard(0b00000000_00000000_11111111_00000000_00000000_00000000_00000000_00000000),
Bitboard(0b00000000_11111111_00000000_00000000_00000000_00000000_00000000_00000000),
Bitboard(0b11111111_00000000_00000000_00000000_00000000_00000000_00000000_00000000),
];
}
impl Default for Bitboard {
fn default() -> Self {
Self::EMPTY
}
}
/// Treat bitboard as a set of squares, shift each square's index left by the amount given.
impl std::ops::Shl<usize> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn shl(self, rhs: usize) -> Self::Output {
Bitboard(self.0 << rhs)
}
}
/// Treat bitboard as a set of squares, shift each square's index right by the amount given.
impl std::ops::Shr<usize> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn shr(self, rhs: usize) -> Self::Output {
Bitboard(self.0 >> rhs)
}
}
/// Treat bitboard as a set of squares, and invert the set.
impl std::ops::Not for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn not(self) -> Self::Output {
Bitboard(!self.0)
}
}
/// Treat each bitboard as a set of squares, keep squares that are in either sets.
impl std::ops::BitOr<Bitboard> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitor(self, rhs: Bitboard) -> Self::Output {
Bitboard(self.0 | rhs.0)
}
}
/// Treat the [Square](crate::board::Square) as a singleton bitboard, and apply the operator.
impl std::ops::BitOr<Square> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitor(self, rhs: Square) -> Self::Output {
self | rhs.into_bitboard()
}
}
/// Treat each bitboard as a set of squares, keep squares that are in both sets.
impl std::ops::BitAnd<Bitboard> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitand(self, rhs: Bitboard) -> Self::Output {
Bitboard(self.0 & rhs.0)
}
}
/// Treat the [Square](crate::board::Square) as a singleton bitboard, and apply the operator.
impl std::ops::BitAnd<Square> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitand(self, rhs: Square) -> Self::Output {
self & rhs.into_bitboard()
}
}
/// Treat each bitboard as a set of squares, keep squares that are in exactly one of either set.
impl std::ops::BitXor<Bitboard> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitxor(self, rhs: Bitboard) -> Self::Output {
Bitboard(self.0 ^ rhs.0)
}
}
/// Treat the [Square](crate::board::Square) as a singleton bitboard, and apply the operator.
impl std::ops::BitXor<Square> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn bitxor(self, rhs: Square) -> Self::Output {
self ^ rhs.into_bitboard()
}
}
/// Treat each bitboard as a set of squares, and substract one set from another.
impl std::ops::Sub<Bitboard> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn sub(self, rhs: Bitboard) -> Self::Output {
Bitboard(self.0 & !rhs.0)
}
}
/// Treat the [Square](crate::board::Square) as a singleton bitboard, and apply the operator.
impl std::ops::Sub<Square> for Bitboard {
type Output = Bitboard;
#[inline(always)]
fn sub(self, rhs: Square) -> Self::Output {
self - rhs.into_bitboard()
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::board::square::*;
#[test]
fn left_shift() {
assert_eq!(Bitboard::RANKS[0] << 1, Bitboard::RANKS[1]);
assert_eq!(Bitboard::FILES[0] << 8, Bitboard::FILES[1]);
}
#[test]
fn right_shift() {
assert_eq!(Bitboard::RANKS[1] >> 1, Bitboard::RANKS[0]);
assert_eq!(Bitboard::FILES[1] >> 8, Bitboard::FILES[0]);
}
#[test]
fn not() {
assert_eq!(!Bitboard::EMPTY, Bitboard(u64::MAX));
}
#[test]
fn or() {
assert_eq!(Bitboard::FILES[0] | Bitboard::FILES[1], Bitboard(0xff_ff));
assert_eq!(Bitboard::FILES[0] | Square::B1, Bitboard(0x1_ff));
}
#[test]
fn and() {
assert_eq!(Bitboard::FILES[0] & Bitboard::FILES[1], Bitboard::EMPTY);
assert_eq!(
Bitboard::FILES[0] & Bitboard::RANKS[0],
Square::A1.into_bitboard()
);
assert_eq!(Bitboard::FILES[0] & Square::A1, Square::A1.into_bitboard());
}
#[test]
fn xor() {
assert_eq!(Bitboard::FILES[0] ^ Square::A1, Bitboard(0xff - 1));
}
#[test]
fn sub() {
assert_eq!(Bitboard::FILES[0] - Bitboard::RANKS[0], Bitboard(0xff - 1));
assert_eq!(Bitboard::FILES[0] - Square::A1, Bitboard(0xff - 1));
}
}

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src/board/mod.rs Normal file
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pub mod bitboard;
pub use bitboard::*;
pub mod square;
pub use square::*;

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src/board/square.rs Normal file
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use super::Bitboard;
/// Represent a square on a chessboard. Defined in the same order as the
/// [Bitboard](crate::board::Bitboard) squares.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[rustfmt::skip]
pub enum Square {
A1, A2, A3, A4, A5, A6, A7, A8,
B1, B2, B3, B4, B5, B6, B7, B8,
C1, C2, C3, C4, C5, C6, C7, C8,
D1, D2, D3, D4, D5, D6, D7, D8,
E1, E2, E3, E4, E5, E6, E7, E8,
F1, F2, F3, F4, F5, F6, F7, F8,
G1, G2, G3, G4, G5, G6, G7, G8,
H1, H2, H3, H4, H5, H6, H7, H8,
}
impl std::fmt::Display for Square {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(f, "{}", format!("{:?}", self))
}
}
impl Square {
#[rustfmt::skip]
const ALL: [Self; 64] = [
Self::A1, Self::A2, Self::A3, Self::A4, Self::A5, Self::A6, Self::A7, Self::A8,
Self::B1, Self::B2, Self::B3, Self::B4, Self::B5, Self::B6, Self::B7, Self::B8,
Self::C1, Self::C2, Self::C3, Self::C4, Self::C5, Self::C6, Self::C7, Self::C8,
Self::D1, Self::D2, Self::D3, Self::D4, Self::D5, Self::D6, Self::D7, Self::D8,
Self::E1, Self::E2, Self::E3, Self::E4, Self::E5, Self::E6, Self::E7, Self::E8,
Self::F1, Self::F2, Self::F3, Self::F4, Self::F5, Self::F6, Self::F7, Self::F8,
Self::G1, Self::G2, Self::G3, Self::G4, Self::G5, Self::G6, Self::G7, Self::G8,
Self::H1, Self::H2, Self::H3, Self::H4, Self::H5, Self::H6, Self::H7, Self::H8,
];
/// Iterate over all squares in order.
pub fn iter() -> impl Iterator<Item = Square> {
Self::ALL.iter().cloned()
}
/// Convert from a square index into a [Square] type.
#[inline(always)]
pub fn from_index(index: usize) -> Self {
assert!(index < 64);
// SAFETY: we know the value is in-bounds
unsafe { Self::from_index_unchecked(index) }
}
/// Convert from a square index into a [Square] type, no bounds checking.
#[inline(always)]
pub unsafe fn from_index_unchecked(index: usize) -> Self {
std::mem::transmute(index as u8)
}
/// Return the index of the rank of this square (0 -> rank 1, ..., 7 -> rank 8).
#[inline(always)]
pub fn rank_index(self) -> usize {
(self as usize) % 8
}
/// Return the index of the rank of this square (0 -> file A, ..., 7 -> file H).
#[inline(always)]
pub fn file_index(self) -> usize {
(self as usize) / 8
}
/// Return a bitboard representing the rank of this square.
#[inline(always)]
pub fn rank(self) -> Bitboard {
Bitboard::RANKS[self.rank_index()]
}
/// Return a bitboard representing the rank of this square.
#[inline(always)]
pub fn file(self) -> Bitboard {
Bitboard::FILES[self.file_index()]
}
/// Turn a square into a singleton bitboard.
#[inline(always)]
pub fn into_bitboard(self) -> Bitboard {
Bitboard(1 << (self as usize))
}
}
/// Shift the square's index left by the amount given.
impl std::ops::Shl<usize> for Square {
type Output = Square;
#[inline(always)]
fn shl(self, rhs: usize) -> Self::Output {
Square::from_index(self as usize + rhs)
}
}
/// Shift the square's index right by the amount given.
impl std::ops::Shr<usize> for Square {
type Output = Square;
#[inline(always)]
fn shr(self, rhs: usize) -> Self::Output {
Square::from_index(self as usize - rhs)
}
}
/// Return a board containing all squares but the one given.
impl std::ops::Not for Square {
type Output = Bitboard;
#[inline(always)]
fn not(self) -> Self::Output {
!self.into_bitboard()
}
}
/// Treat the square as a singleton board, and apply the operator.
impl std::ops::BitOr<Square> for Square {
type Output = Bitboard;
#[inline(always)]
fn bitor(self, rhs: Square) -> Self::Output {
self.into_bitboard() | rhs.into_bitboard()
}
}
/// Treat the square as a singleton board, and apply the operator.
impl std::ops::BitOr<Bitboard> for Square {
type Output = Bitboard;
#[inline(always)]
fn bitor(self, rhs: Bitboard) -> Self::Output {
self.into_bitboard() | rhs
}
}
/// Treat the square as a singleton board, and apply the operator.
impl std::ops::BitAnd<Bitboard> for Square {
type Output = Bitboard;
#[inline(always)]
fn bitand(self, rhs: Bitboard) -> Self::Output {
self.into_bitboard() & rhs
}
}
/// Treat the square as a singleton board, and apply the operator.
impl std::ops::BitXor<Bitboard> for Square {
type Output = Bitboard;
#[inline(always)]
fn bitxor(self, rhs: Bitboard) -> Self::Output {
self.into_bitboard() ^ rhs
}
}
/// Treat the square as a singleton board, and apply the operator.
impl std::ops::Sub<Bitboard> for Square {
type Output = Bitboard;
#[inline(always)]
fn sub(self, rhs: Bitboard) -> Self::Output {
self.into_bitboard() - rhs
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::board::bitboard::*;
#[test]
fn left_shift() {
assert_eq!(Square::A1 << 1, Square::A2);
assert_eq!(Square::A1 << 8, Square::B1);
}
#[test]
fn right_shift() {
assert_eq!(Square::A2 >> 1, Square::A1);
assert_eq!(Square::B1 >> 8, Square::A1);
}
#[test]
fn not() {
assert_eq!(!Square::A1, Bitboard(u64::MAX - 1));
}
#[test]
fn or() {
assert_eq!(Square::A1 | Square::A2, Bitboard(0b11));
}
#[test]
fn and() {
assert_eq!(Square::A1 & Bitboard::FILES[0], Square::A1.into_bitboard());
}
#[test]
fn xor() {
assert_eq!(Square::A1 ^ Bitboard::FILES[0], Bitboard(0xff - 1));
}
#[test]
fn sub() {
assert_eq!(Square::A1 - Bitboard::FILES[0], Bitboard::EMPTY);
}
}

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src/lib.rs Normal file
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pub mod board;