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Simplify 'Move'
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Making 'Move' lightweight sounds like a better idea now that I am
looking at it with fresh eyes...
This commit is contained in:
Bruno BELANYI 2024-04-03 23:39:37 +01:00
parent adad4118ae
commit 1c8a101689
4 changed files with 61 additions and 390 deletions
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125
src/board/chess_board/mod.rs
View file

@ -136,21 +136,32 @@ impl ChessBoard {
#[inline(always)]
pub fn do_move(&mut self, chess_move: Move) -> NonReversibleState {
let opponent = !self.current_player();
let is_capture = !(self.combined_occupancy() & chess_move.destination()).is_empty();
let move_piece = Piece::iter()
.find(|&p| !(self.piece_occupancy(p) & chess_move.start()).is_empty())
.unwrap();
let captured_piece = Piece::iter()
.skip(1) // No need to check for the king here
.find(|&p| !(self.occupancy(p, opponent) & chess_move.destination()).is_empty());
let is_double_step = move_piece == Piece::Pawn
&& chess_move.start().rank() == self.current_player().second_rank()
&& chess_move.destination().rank() == self.current_player().fourth_rank();
// Save non-revertible state
let state = NonReversibleState {
castle_rights: self.castle_rights,
en_passant: self.en_passant,
half_move_clock: self.half_move_clock,
captured_piece: chess_move.capture(),
captured_piece,
};
// Non-revertible state modification
if chess_move.capture().is_some() || chess_move.piece() == Piece::Pawn {
if is_capture || move_piece == Piece::Pawn {
self.half_move_clock = 0;
} else {
self.half_move_clock += 1;
}
if chess_move.is_double_step() {
if is_double_step {
let target_square = Square::new(
chess_move.destination().file(),
self.current_player().third_rank(),
@ -159,10 +170,10 @@ impl ChessBoard {
} else {
self.en_passant = None;
}
if chess_move.is_castling() || chess_move.piece() == Piece::King {
if move_piece == Piece::King {
*self.castle_rights_mut(self.current_player()) = CastleRights::NoSide;
}
if chess_move.piece() == Piece::Rook {
if move_piece == Piece::Rook {
let castle_rights = self.castle_rights_mut(self.current_player());
*castle_rights = match chess_move.start().file() {
File::A => castle_rights.without_queen_side(),
@ -170,7 +181,7 @@ impl ChessBoard {
_ => *castle_rights,
}
}
if let Some(piece) = chess_move.capture() {
if let Some(piece) = captured_piece {
*self.piece_occupancy_mut(piece) ^= chess_move.destination();
*self.color_occupancy_mut(opponent) ^= chess_move.destination();
self.combined_occupancy ^= chess_move.destination();
@ -179,7 +190,7 @@ impl ChessBoard {
// Revertible state modification
self.xor(
self.current_player(),
chess_move.piece(),
move_piece,
chess_move.start() | chess_move.destination(),
);
self.total_plies += 1;
@ -196,8 +207,15 @@ impl ChessBoard {
self.castle_rights = previous.castle_rights;
self.en_passant = previous.en_passant;
self.half_move_clock = previous.half_move_clock;
let move_piece = Piece::iter()
// We're looking for the *destination* as this is *undoing* the move
.find(|&p| !(self.piece_occupancy(p) & chess_move.destination()).is_empty())
.unwrap();
if let Some(piece) = previous.captured_piece {
*self.piece_occupancy_mut(piece) ^= chess_move.destination();
// The capture affected the *current* player, from our post-move POV
*self.color_occupancy_mut(self.current_player()) ^= chess_move.destination();
self.combined_occupancy ^= chess_move.destination();
}
@ -206,7 +224,7 @@ impl ChessBoard {
self.xor(
// The move was applied at the turn *before* the current player
!self.current_player(),
chess_move.piece(),
move_piece,
chess_move.start() | chess_move.destination(),
);
self.total_plies -= 1;
@ -435,7 +453,6 @@ impl Default for ChessBoard {
#[cfg(test)]
mod test {
use crate::board::MoveBuilder;
use crate::fen::FromFen;
use super::*;
@ -729,57 +746,21 @@ mod test {
// Start from default position
let mut position = ChessBoard::default();
// Modify it to account for e4 move
position.do_move(
MoveBuilder {
piece: Piece::Pawn,
start: Square::E2,
destination: Square::E4,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::E2, Square::E4, None));
assert_eq!(
position,
ChessBoard::from_fen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1")
.unwrap()
);
// And now c5
position.do_move(
MoveBuilder {
piece: Piece::Pawn,
start: Square::C7,
destination: Square::C5,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::C7, Square::C5, None));
assert_eq!(
position,
ChessBoard::from_fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2")
.unwrap()
);
// Finally, Nf3
position.do_move(
MoveBuilder {
piece: Piece::Knight,
start: Square::G1,
destination: Square::F3,
capture: None,
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::G1, Square::F3, None));
assert_eq!(
position,
ChessBoard::from_fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2 ")
@ -792,43 +773,13 @@ mod test {
// Start from default position
let mut position = ChessBoard::default();
// Modify it to account for e4 move
let move_1 = MoveBuilder {
piece: Piece::Pawn,
start: Square::E2,
destination: Square::E4,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into();
let move_1 = Move::new(Square::E2, Square::E4, None);
let state_1 = position.do_move(move_1);
// And now c5
let move_2 = MoveBuilder {
piece: Piece::Pawn,
start: Square::C7,
destination: Square::C5,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into();
let move_2 = Move::new(Square::C7, Square::C5, None);
let state_2 = position.do_move(move_2);
// Finally, Nf3
let move_3 = MoveBuilder {
piece: Piece::Knight,
start: Square::G1,
destination: Square::F3,
capture: None,
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into();
let move_3 = Move::new(Square::G1, Square::F3, None);
let state_3 = position.do_move(move_3);
// Now revert each move one-by-one
position.undo_move(move_3, state_3);
@ -857,17 +808,7 @@ mod test {
let expected = ChessBoard::from_fen("3Q3k/8/8/8/8/8/8/K7 b - - 0 1").unwrap();
let original = position.clone();
let capture = MoveBuilder {
piece: Piece::Queen,
start: Square::D1,
destination: Square::D8,
capture: Some(Piece::Queen),
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into();
let capture = Move::new(Square::D1, Square::D8, None);
let state = position.do_move(capture);
assert_eq!(position, expected);

216
src/board/move.rs
View file

@ -1,232 +1,42 @@
use super::{Piece, Square};
type Bitset = u32;
/// A chess move, containing:
/// * Piece type.
/// * Starting square.
/// * Destination square.
/// * Optional capture type.
/// * Optional promotion type.
/// * Optional captured type.
/// * Whether the move was an en-passant capture.
/// * Whether the move was a double-step.
/// * Whether the move was a castling.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Move(Bitset);
/// A builder for [Move]. This is the prefered and only way of building a [Move].
pub struct MoveBuilder {
pub piece: Piece,
pub start: Square,
pub destination: Square,
pub capture: Option<Piece>,
pub promotion: Option<Piece>,
pub en_passant: bool,
pub double_step: bool,
pub castling: bool,
}
impl From<MoveBuilder> for Move {
#[inline(always)]
fn from(builder: MoveBuilder) -> Self {
Self::new(
builder.piece,
builder.start,
builder.destination,
builder.capture,
builder.promotion,
builder.en_passant,
builder.double_step,
builder.castling,
)
}
}
/// A [Move] is structured as a bitset with the following fields:
/// | Field | Size | Range of values | Note |
/// |-------------|------|-----------------|-------------------------------------------------|
/// | Piece | 3 | 0-6 | Can be interpreted as a [Piece] index |
/// | Start | 6 | 0-63 | Can be interpreted as a [Square] index |
/// | Destination | 6 | 0-63 | Can be interpreted as a [Square] index |
/// | Capture | 3 | 0-7 | Can be interpreted as a [Piece] index if not 7 |
/// | Promotion | 3 | 0-7 | Can be interpreted as a [Piece] index if not 7 |
/// | En-pasant | 1 | 0-1 | Boolean value |
/// | Double-step | 1 | 0-1 | Boolean value |
/// | Castling | 1 | 0-1 | Boolean value |
mod shift {
use super::Bitset;
pub const PIECE: usize = 0;
pub const PIECE_MASK: Bitset = 0b111;
pub const START: usize = 3;
pub const START_MASK: Bitset = 0b11_1111;
pub const DESTINATION: usize = 9;
pub const DESTINATION_MASK: Bitset = 0b11_1111;
pub const CAPTURE: usize = 15;
pub const CAPTURE_MASK: Bitset = 0b111;
pub const PROMOTION: usize = 18;
pub const PROMOTION_MASK: Bitset = 0b111;
pub const EN_PASSANT: usize = 21;
pub const EN_PASSANT_MASK: Bitset = 0b1;
pub const DOUBLE_STEP: usize = 22;
pub const DOUBLE_STEP_MASK: Bitset = 0b1;
pub const CASTLING: usize = 23;
pub const CASTLING_MASK: Bitset = 0b1;
pub struct Move {
start: Square,
destination: Square,
promotion: Option<Piece>,
}
impl Move {
/// Construct a new move.
#[inline(always)]
#[allow(clippy::too_many_arguments)]
fn new(
piece: Piece,
start: Square,
destination: Square,
capture: Option<Piece>,
promotion: Option<Piece>,
en_passant: bool,
double_step: bool,
castling: bool,
) -> Self {
let mut value = 0;
value |= (piece.index() as Bitset) << shift::PIECE;
value |= (start.index() as Bitset) << shift::START;
value |= (destination.index() as Bitset) << shift::DESTINATION;
value |=
(capture.map(Piece::index).unwrap_or(Piece::NUM_VARIANTS) as Bitset) << shift::CAPTURE;
value |= (promotion.map(Piece::index).unwrap_or(Piece::NUM_VARIANTS) as Bitset)
<< shift::PROMOTION;
value |= (en_passant as Bitset) << shift::EN_PASSANT;
value |= (double_step as Bitset) << shift::DOUBLE_STEP;
value |= (castling as Bitset) << shift::CASTLING;
Self(value)
}
/// Get the [Piece] that is being moved.
#[inline(always)]
pub fn piece(self) -> Piece {
let index = ((self.0 >> shift::PIECE) & shift::PIECE_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Piece::from_index_unchecked(index) }
pub fn new(start: Square, destination: Square, promotion: Option<Piece>) -> Self {
Self {
start,
destination,
promotion,
}
}
/// Get the [Square] that this move starts from.
#[inline(always)]
pub fn start(self) -> Square {
let index = ((self.0 >> shift::START) & shift::START_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Square::from_index_unchecked(index) }
self.start
}
/// Get the [Square] that this move ends on.
#[inline(always)]
pub fn destination(self) -> Square {
let index = ((self.0 >> shift::DESTINATION) & shift::DESTINATION_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Square::from_index_unchecked(index) }
}
/// Get the [Piece] that this move captures, or `None` if there are no captures.
#[inline(always)]
pub fn capture(self) -> Option<Piece> {
let index = ((self.0 >> shift::CAPTURE) & shift::CAPTURE_MASK) as usize;
if index < Piece::NUM_VARIANTS {
// SAFETY: we know the value is in-bounds
unsafe { Some(Piece::from_index_unchecked(index)) }
} else {
None
}
self.destination
}
/// Get the [Piece] that this move promotes to, or `None` if there are no promotions.
#[inline(always)]
pub fn promotion(self) -> Option<Piece> {
let index = ((self.0 >> shift::PROMOTION) & shift::PROMOTION_MASK) as usize;
if index < Piece::NUM_VARIANTS {
// SAFETY: we know the value is in-bounds
unsafe { Some(Piece::from_index_unchecked(index)) }
} else {
None
}
}
/// Get the whether or not the move is an en-passant capture.
#[inline(always)]
pub fn is_en_passant(self) -> bool {
let index = (self.0 >> shift::EN_PASSANT) & shift::EN_PASSANT_MASK;
index != 0
}
/// Get the whether or not the move is a pawn double step.
#[inline(always)]
pub fn is_double_step(self) -> bool {
let index = (self.0 >> shift::DOUBLE_STEP) & shift::DOUBLE_STEP_MASK;
index != 0
}
/// Get the whether or not the move is a castling.
#[inline(always)]
pub fn is_castling(self) -> bool {
let index = (self.0 >> shift::CASTLING) & shift::CASTLING_MASK;
index != 0
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn builder_simple() {
let chess_move: Move = MoveBuilder {
piece: Piece::Queen,
start: Square::A2,
destination: Square::A3,
capture: None,
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into();
assert_eq!(chess_move.piece(), Piece::Queen);
assert_eq!(chess_move.start(), Square::A2);
assert_eq!(chess_move.destination(), Square::A3);
assert_eq!(chess_move.capture(), None);
assert_eq!(chess_move.promotion(), None);
assert!(!chess_move.is_en_passant());
assert!(!chess_move.is_double_step());
assert!(!chess_move.is_castling());
}
#[test]
fn builder_all_fields() {
let chess_move: Move = MoveBuilder {
piece: Piece::Pawn,
start: Square::A7,
destination: Square::B8,
capture: Some(Piece::Queen),
promotion: Some(Piece::Knight),
en_passant: true,
double_step: true,
castling: true,
}
.into();
assert_eq!(chess_move.piece(), Piece::Pawn);
assert_eq!(chess_move.start(), Square::A7);
assert_eq!(chess_move.destination(), Square::B8);
assert_eq!(chess_move.capture(), Some(Piece::Queen));
assert_eq!(chess_move.promotion(), Some(Piece::Knight));
assert!(chess_move.is_en_passant());
assert!(chess_move.is_double_step());
assert!(chess_move.is_castling());
self.promotion
}
}

44
src/fen.rs
View file

@ -202,7 +202,7 @@ impl FromFen for ChessBoard {
#[cfg(test)]
mod test {
use crate::board::MoveBuilder;
use crate::board::Move;
use super::*;
@ -220,57 +220,21 @@ mod test {
fn en_passant() {
// Start from default position
let mut position = ChessBoard::default();
position.do_move(
MoveBuilder {
piece: Piece::Pawn,
start: Square::E2,
destination: Square::E4,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::E2, Square::E4, None));
assert_eq!(
ChessBoard::from_fen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1")
.unwrap(),
position
);
// And now c5
position.do_move(
MoveBuilder {
piece: Piece::Pawn,
start: Square::C7,
destination: Square::C5,
capture: None,
promotion: None,
en_passant: false,
double_step: true,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::C7, Square::C5, None));
assert_eq!(
ChessBoard::from_fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2")
.unwrap(),
position
);
// Finally, Nf3
position.do_move(
MoveBuilder {
piece: Piece::Knight,
start: Square::G1,
destination: Square::F3,
capture: None,
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into(),
);
position.do_move(Move::new(Square::G1, Square::F3, None));
assert_eq!(
ChessBoard::from_fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2 ")
.unwrap(),

66
utils/gdb/seer_pretty_printers.py
View file

@ -186,79 +186,35 @@ class Move(object):
in memory.
"""
# Should be kept in sync with the values in `move.rs`
PIECE_SHIFT = 0
PIECE_MASK = 0b111
START_SHIFT = 3
START_MASK = 0b11_1111
DESTINATION_SHIFT = 9
DESTINATION_MASK = 0b11_1111
CAPTURE_SHIFT = 15
CAPTURE_MASK = 0b111
PROMOTION_SHIFT = 18
PROMOTION_MASK = 0b111
EN_PASSANT_SHIFT = 21
EN_PASSANT_MASK = 0b1
DOUBLE_STEP_SHIFT = 22
DOUBLE_STEP_MASK = 0b1
CASTLING_SHIFT = 23
CASTLING_MASK = 0b1
def __init__(self, val):
self._val = val
def __init__(self, start, destination, promotion):
self._start = Square(start)
self._destination = Square(destination)
self._promotion = Piece(promotion)
@classmethod
def from_gdb(cls, val):
return cls(int(val))
@property
def piece(self):
return Piece(self._val >> self.PIECE_SHIFT & self.PIECE_MASK)
start = Square(int(val["start"]))
destination = Square(int(val["destination"]))
promotion = optional(Piece.from_gdb, val["promotion"])
cls(start, destination, promotion)
@property
def start(self):
return Square(self._val >> self.START_SHIFT & self.START_MASK)
return self._start
@property
def destination(self):
return Square(self._val >> self.DESTINATION_SHIFT & self.DESTINATION_MASK)
@property
def capture(self):
index = self._val >> self.CAPTURE_SHIFT & self.CAPTURE_MASK
if index == 7:
return None
return Piece(index)
return self._destination
@property
def promotion(self):
index = self._val >> self.PROMOTION_SHIFT & self.PROMOTION_MASK
if index == 7:
return None
return Piece(index)
@property
def en_passant(self):
return bool(self._val >> self.EN_PASSANT_SHIFT & self.EN_PASSANT_MASK)
@property
def double_step(self):
return bool(self._val >> self.DOUBLE_STEP_SHIFT & self.DOUBLE_STEP_MASK)
@property
def castling(self):
return bool(self._val >> self.CASTLING_SHIFT & self.CASTLING_MASK)
return self._promotion
def __str__(self):
KEYS = [
"piece",
"start",
"destination",
"capture",
"promotion",
"en_passant",
"double_step",
"castling",
]
indent = lambda s: " " + s