wip: const lookup

src/bitboard.rs

@@ -7,24 +7,25 @@ use std::iter::FusedIterator;
 
 /// A set of squares.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[repr(transparent)]
 pub struct Bitboard(pub(crate) u64);
 
 impl Bitboard {
     /// Returns an empty bitboard.
     #[inline]
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Self(0)
     }
 
     /// Returns `true` if the bitboard is empty.
     #[inline]
-    pub fn is_empty(&self) -> bool {
+    pub const fn is_empty(&self) -> bool {
         self.0 == 0
     }
 
     /// Returns the square in the bitboard with the smallest index.
     #[inline]
-    pub fn first(&self) -> Option<Square> {
+    pub const fn first(&self) -> Option<Square> {
         let mask = self.0;
         match mask {
             0 => None,
@@ -32,10 +33,21 @@ impl Bitboard {
         }
     }
 
+    #[inline]
+    pub(crate) const fn last(&self) -> Option<Square> {
+        let mask = self.0;
+        match mask {
+            0 => None,
+            _ => Some(unsafe {
+                Square::new_unchecked(63_u8.unchecked_sub(mask.leading_zeros() as u8))
+            }),
+        }
+    }
+
     /// Removes the square in the bitboard with the smallest index and returns it, or `None` if the
     /// bitboard is empty.
     #[inline]
-    pub fn pop(&mut self) -> Option<Square> {
+    pub const fn pop(&mut self) -> Option<Square> {
         let Self(ref mut mask) = self;
         let square = match mask {
             0 => None,
@@ -47,13 +59,13 @@ impl Bitboard {
 
     /// Inserts a square in the bitboard.
     #[inline]
-    pub fn insert(&mut self, square: Square) {
+    pub const fn insert(&mut self, square: Square) {
         self.0 |= 1 << square as u8;
     }
 
     /// Returns `true` if the bitboard contains the given square.
     #[inline]
-    pub fn contains(&self, square: Square) -> bool {
+    pub const fn contains(&self, square: Square) -> bool {
         self.0 & (1 << square as u8) != 0
     }
 

src/board.rs

@@ -5,6 +5,7 @@ use crate::bitboard::*;
 macro_rules! container {
     ($v: vis, $a:ident, $b:ident, $n:literal) => {
         #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[repr(transparent)]
         $v struct $b<T>(pub(crate) [T; $n]);
         #[allow(unused)]
         impl<T> $b<T> {
@@ -116,7 +117,7 @@ impl File {
     }
 
     #[inline]
-    pub unsafe fn new_unchecked(index: u8) -> Self {
+    pub const unsafe fn new_unchecked(index: u8) -> Self {
         debug_assert!(index < 8);
         std::mem::transmute(index)
     }
@@ -147,7 +148,7 @@ impl File {
     }
 
     #[inline]
-    pub fn bitboard(self) -> Bitboard {
+    pub const fn bitboard(self) -> Bitboard {
         Bitboard(0x0101010101010101 << (self as u8))
     }
 }
@@ -196,7 +197,7 @@ impl Rank {
     }
 
     #[inline]
-    pub unsafe fn new_unchecked(index: u8) -> Self {
+    pub const unsafe fn new_unchecked(index: u8) -> Self {
         debug_assert!(index < 8);
         std::mem::transmute(index)
     }
@@ -232,7 +233,7 @@ impl Rank {
     }
 
     #[inline]
-    pub fn bitboard(self) -> Bitboard {
+    pub const fn bitboard(self) -> Bitboard {
         Bitboard(0xFF << ((self as u8) << 3))
     }
 }
@@ -278,12 +279,16 @@ impl Square {
     }
 
     #[inline]
-    pub fn new(index: u8) -> Option<Self> {
-        (index < 64).then(|| unsafe { Self::new_unchecked(index) })
+    pub const fn new(index: u8) -> Option<Self> {
+        if index < 64 {
+            Some(unsafe { Self::new_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     #[inline]
-    pub unsafe fn new_unchecked(index: u8) -> Self {
+    pub const unsafe fn new_unchecked(index: u8) -> Self {
         debug_assert!(index < 64);
         std::mem::transmute(index)
     }
@@ -294,12 +299,12 @@ impl Square {
     }
 
     #[inline]
-    pub fn file(self) -> File {
+    pub const fn file(self) -> File {
         unsafe { File::new_unchecked((self as u8) & 7) }
     }
 
     #[inline]
-    pub fn rank(self) -> Rank {
+    pub const fn rank(self) -> Rank {
         unsafe { Rank::new_unchecked((self as u8) >> 3) }
     }
 
@@ -310,7 +315,7 @@ impl Square {
     }
 
     #[inline]
-    pub fn bitboard(self) -> Bitboard {
+    pub const fn bitboard(self) -> Bitboard {
         Bitboard(1 << self as u8)
     }
 
@@ -347,16 +352,17 @@ impl Square {
     }
 
     #[inline]
-    pub(crate) fn trans(self, direction: Direction) -> Option<Self> {
-        self.check_trans(direction).then(|| unsafe {
-            // SAFETY: condition is checked before doing the translation
-            self.trans_unchecked(direction)
-        })
+    pub(crate) const fn trans(self, direction: Direction) -> Option<Self> {
+        if self.check_trans(direction) {
+            Some(unsafe { self.trans_unchecked(direction) })
+        } else {
+            None
+        }
     }
 
     /// SAFETY: the translation must not move the square outside the board
     #[inline]
-    pub(crate) unsafe fn trans_unchecked(self, direction: Direction) -> Self {
+    pub(crate) const unsafe fn trans_unchecked(self, direction: Direction) -> Self {
         debug_assert!(self.check_trans(direction));
         let i = self as u8;
         unsafe {
@@ -375,16 +381,18 @@ impl Square {
 
     /// Returns `false` if the translation would move the square outside the board
     #[inline]
-    fn check_trans(self, direction: Direction) -> bool {
+    const fn check_trans(self, direction: Direction) -> bool {
+        let file = self.file() as u8;
+        let rank = self.rank() as u8;
         match direction {
-            Direction::East => self.file() < File::H,
-            Direction::NorthEast => self.file() < File::H && self.rank() < Rank::Eighth,
-            Direction::North => self.rank() < Rank::Eighth,
-            Direction::NorthWest => self.file() > File::A && self.rank() < Rank::Eighth,
-            Direction::SouthEast => self.file() < File::H && self.rank() > Rank::First,
-            Direction::South => self.rank() > Rank::First,
-            Direction::SouthWest => self.file() > File::A && self.rank() > Rank::First,
-            Direction::West => self.file() > File::A,
+            Direction::East => file < 7,
+            Direction::NorthEast => file < 7 && rank < 7,
+            Direction::North => rank < 7,
+            Direction::NorthWest => file > 0 && rank < 7,
+            Direction::SouthEast => file < 7 && rank > 0,
+            Direction::South => rank > 0,
+            Direction::SouthWest => file > 0 && rank > 0,
+            Direction::West => file > 0,
         }
     }
 }
@@ -525,6 +533,7 @@ impl Role {
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
+#[repr(transparent)]
 pub struct ByRole<T>(pub(crate) [T; 6]);
 #[allow(unused)]
 impl<T> ByRole<T> {
@@ -615,9 +624,18 @@ impl Direction {
     }
 
     #[inline]
-    unsafe fn transmute(value: u8) -> Self {
-        debug_assert!(value < 8);
-        std::mem::transmute(value)
+    pub const fn new(index: u8) -> Option<Self> {
+        if index < 8 {
+            Some(unsafe { Self::new_unchecked(index) })
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    pub const unsafe fn new_unchecked(index: u8) -> Self {
+        debug_assert!(index < 8);
+        std::mem::transmute(index)
     }
 }
 
@@ -625,7 +643,7 @@ impl std::ops::Not for Direction {
     type Output = Self;
     #[inline]
     fn not(self) -> Self::Output {
-        unsafe { Self::transmute(self as u8 ^ 0b111) }
+        unsafe { Self::new_unchecked(self as u8 ^ 0b111) }
     }
 }
 

src/lib.rs

@@ -73,12 +73,11 @@
 //! - etc.
 
 pub(crate) mod array_vec;
+pub(crate) mod lookup;
 pub(crate) mod magics;
-pub(crate) mod rays;
 
 pub mod bitboard;
 pub mod board;
-pub mod lookup;
 pub mod position;
 pub mod san;
 pub mod setup;
@@ -88,3 +87,11 @@ pub mod uci;
 pub mod prelude {
     pub use crate::{position::Position, san::San, setup::Setup, uci::UciMove};
 }
+
+pub fn test() {
+    use crate::bitboard::*;
+    use crate::board::*;
+    let d = &crate::lookup::LOOKUP;
+    let Bitboard(x) = d.pawn_attack(Color::White, Square::F7);
+    println!("{x:016x}");
+}

src/lookup.rs

@@ -1,20 +1,146 @@
-//! Lookup tables initialisation.
-//!
-//! Move generation in eschac requires about 1MB of precomputed lookup tables.
-
 use crate::bitboard::*;
 use crate::board::*;
 use crate::magics::*;
-use crate::rays::*;
 
-pub(crate) use init::InitialisedLookup;
+#[allow(long_running_const_eval)]
+pub(crate) static LOOKUP: Lookup = Lookup::compute();
 
-/// Forces the initialisation of the lookup tables.
-///
-/// It is not necessary to call this function, as lookup tables are initialised lazily, but it can
-/// be used to ensure that they are initialised before a given time.
-pub fn init() {
-    InitialisedLookup::init();
+macro_rules! loop_bishop_directions {
+    ($d: ident, $body: expr) => {{
+        {
+            let $d = Direction::NorthEast;
+            $body
+        }
+        {
+            let $d = Direction::NorthWest;
+            $body
+        }
+        {
+            let $d = Direction::SouthWest;
+            $body
+        }
+        {
+            let $d = Direction::SouthEast;
+            $body
+        }
+    }};
+}
+
+macro_rules! loop_rook_directions {
+    ($d: ident, $body: expr) => {{
+        {
+            let $d = Direction::East;
+            $body
+        }
+        {
+            let $d = Direction::North;
+            $body
+        }
+        {
+            let $d = Direction::West;
+            $body
+        }
+        {
+            let $d = Direction::South;
+            $body
+        }
+    }};
+}
+
+macro_rules! loop_all_directions {
+    ($d: ident, $body: expr) => {{
+        loop_bishop_directions!($d, $body);
+        loop_rook_directions!($d, $body);
+    }};
+}
+
+macro_rules! by_color {
+    ($c: ident, $body: expr) => {{
+        ByColor([
+            {
+                let $c = Color::White;
+                $body
+            },
+            {
+                let $c = Color::Black;
+                $body
+            },
+        ])
+    }};
+}
+
+macro_rules! by_square {
+    ($sq: ident, $init: expr, $body: expr) => {{
+        let mut res = [$init; 64];
+        let mut $sq: u8 = 0;
+        while $sq < 64 {
+            res[$sq as usize] = {
+                let $sq = Square::new($sq).unwrap();
+                $body
+            };
+            $sq += 1;
+        }
+        BySquare(res)
+    }};
+}
+
+macro_rules! by_direction {
+    ($d: ident, $body: expr) => {{
+        let mut res = [Bitboard(0); 8];
+        let mut $d: u8 = 0;
+        while $d < 8 {
+            res[$d as usize] = {
+                let $d = Direction::new($d).unwrap();
+                $body
+            };
+            $d += 1;
+        }
+        ByDirection(res)
+    }};
+}
+
+pub(crate) struct Rays(BySquare<ByDirection<Bitboard>>);
+
+impl Rays {
+    pub(crate) const fn new() -> Self {
+        Self(by_square!(
+            square,
+            ByDirection([Bitboard(0); 8]),
+            by_direction!(direction, {
+                let mut square = square;
+                let mut res = 0;
+                while let Some(x) = square.trans(direction) {
+                    square = x;
+                    res |= square.bitboard().0;
+                }
+                Bitboard(res)
+            })
+        ))
+    }
+
+    #[inline]
+    pub(crate) const fn ray(&self, square: Square, direction: Direction) -> Bitboard {
+        (self.0).0[square as u8 as usize].0[direction as u8 as usize]
+    }
+
+    pub(crate) const fn blocked(
+        &self,
+        square: Square,
+        direction: Direction,
+        blockers: Bitboard,
+    ) -> Bitboard {
+        let ray = self.ray(square, direction);
+        let blockers = Bitboard(blockers.0 & ray.0);
+        let square = if (direction as u8) < 4 {
+            Bitboard::first(&blockers)
+        } else {
+            Bitboard::last(&blockers)
+        };
+        match square {
+            None => ray,
+            Some(square) => Bitboard(ray.0 & !self.ray(square, direction).0),
+        }
+    }
 }
 
 pub(crate) struct Lookup {
@@ -81,75 +207,97 @@ impl Lookup {
         }
     }
 
-    pub(crate) fn compute() -> Self {
+    const fn compute() -> Self {
         let rays = Rays::new();
 
-        let lines = BySquare::new(|a| {
-            BySquare::new(|b| {
-                for d in Direction::all() {
+        let lines = by_square!(a, BySquare([Bitboard(0); 64]), {
+            by_square!(b, Bitboard(0), {
+                let mut res = Bitboard(0);
+                loop_all_directions!(d, {
                     let r = rays.ray(a, d);
                     if r.contains(b) {
-                        return r;
+                        res = r;
                     }
-                }
-                Bitboard::new()
+                });
+                res
             })
         });
 
-        let segments = BySquare::new(|a| {
-            BySquare::new(|b| {
-                for d in Direction::all() {
+        let segments: BySquare<BySquare<Bitboard>> = by_square!(a, BySquare([Bitboard(0); 64]), {
+            by_square!(b, Bitboard(0), {
+                let mut res = 0;
+                loop_all_directions!(d, {
                     let r = rays.ray(a, d);
                     if r.contains(b) {
-                        return r & !rays.ray(b, d);
+                        res = r.0 & !rays.ray(b, d).0;
                     }
-                }
-                b.bitboard()
+                });
+                Bitboard(res)
             })
         });
 
-        let pawn_attacks = ByColor::new(|color| {
+        let pawn_attacks = by_color!(color, {
             let direction = match color {
                 Color::White => Direction::North,
                 Color::Black => Direction::South,
             };
-            BySquare::new(|square| {
-                let mut res = Bitboard::new();
+            by_square!(square, Bitboard(0), {
+                let mut res = Bitboard(0);
                 if let Some(square) = square.trans(direction) {
-                    square.trans(Direction::East).map(|s| res.insert(s));
-                    square.trans(Direction::West).map(|s| res.insert(s));
+                    if let Some(s) = square.trans(Direction::East) {
+                        res.insert(s)
+                    };
+                    if let Some(s) = square.trans(Direction::West) {
+                        res.insert(s)
+                    };
                 }
                 res
             })
         });
 
-        let king_moves = BySquare::new(|square| {
-            let mut res = Bitboard::new();
-            for direction in Direction::all() {
-                if let Some(x) = square.trans(direction) {
-                    res |= x.bitboard();
+        let king_moves = by_square!(sq, Bitboard(0), {
+            let mut res = 0;
+            loop_all_directions!(d, {
+                if let Some(x) = sq.trans(d) {
+                    res |= x.bitboard().0;
                 }
-            }
-            res
+            });
+            Bitboard(res)
         });
 
-        let knight_moves = BySquare::new(|s| {
+        let knight_moves = by_square!(s, Bitboard(0), {
             let mut res = Bitboard::new();
             if let Some(s) = s.trans(Direction::North) {
-                s.trans(Direction::NorthEast).map(|s| res.insert(s));
-                s.trans(Direction::NorthWest).map(|s| res.insert(s));
+                if let Some(s) = s.trans(Direction::NorthEast) {
+                    res.insert(s);
+                }
+                if let Some(s) = s.trans(Direction::NorthWest) {
+                    res.insert(s)
+                };
             }
             if let Some(s) = s.trans(Direction::West) {
-                s.trans(Direction::NorthWest).map(|s| res.insert(s));
-                s.trans(Direction::SouthWest).map(|s| res.insert(s));
+                if let Some(s) = s.trans(Direction::NorthWest) {
+                    res.insert(s)
+                };
+                if let Some(s) = s.trans(Direction::SouthWest) {
+                    res.insert(s)
+                };
             }
             if let Some(s) = s.trans(Direction::South) {
-                s.trans(Direction::SouthWest).map(|s| res.insert(s));
-                s.trans(Direction::SouthEast).map(|s| res.insert(s));
+                if let Some(s) = s.trans(Direction::SouthWest) {
+                    res.insert(s)
+                };
+                if let Some(s) = s.trans(Direction::SouthEast) {
+                    res.insert(s)
+                };
             }
             if let Some(s) = s.trans(Direction::East) {
-                s.trans(Direction::SouthEast).map(|s| res.insert(s));
-                s.trans(Direction::NorthEast).map(|s| res.insert(s));
+                if let Some(s) = s.trans(Direction::SouthEast) {
+                    res.insert(s)
+                };
+                if let Some(s) = s.trans(Direction::NorthEast) {
+                    res.insert(s)
+                };
             }
             res
         });
@@ -168,35 +316,175 @@ impl Lookup {
     }
 }
 
-mod init {
-    use std::{mem::MaybeUninit, sync::LazyLock};
+// -------- Magics --------
 
-    use super::Lookup;
+const BISHOP_SHR: u8 = 55;
+const ROOK_SHR: u8 = 52;
 
-    static mut LOOKUP: MaybeUninit<Lookup> = MaybeUninit::uninit();
+const TABLE_SIZE: usize = 267_293;
 
-    #[allow(static_mut_refs)]
-    static INIT: LazyLock<()> = LazyLock::new(|| unsafe {
-        LOOKUP.write(Lookup::compute());
+pub(crate) struct Magics {
+    bishop: BySquare<Magic>,
+    rook: BySquare<Magic>,
+    table: [Bitboard; TABLE_SIZE],
+}
+
+#[derive(Clone, Copy)]
+struct Magic {
+    premask: Bitboard,
+    factor: u64,
+    offset: isize,
+}
+
+macro_rules! loop_subsets {
+    ($premask: ident, $subset: ident, $body: expr) => {{
+        let mut $subset: u64 = 0;
+        loop {
+            $subset = $subset.wrapping_sub($premask) & $premask;
+            $body
+            if $subset == 0 {
+                break;
+            }
+        }
+    }};
+}
+
+impl Magics {
+    pub(crate) const fn compute(rays: &Rays) -> Self {
+        let null = Magic {
+            premask: Bitboard(0),
+            factor: 0,
+            offset: 0,
+        };
+
+        let mut table = [Bitboard(0); TABLE_SIZE];
+        let mut len: usize = 0;
+
+        let bishop = by_square!(square, null, {
+            let mut premask = 0;
+            loop_bishop_directions!(direction, {
+                premask |= rays.ray(square, direction).0;
+            });
+            premask &= !Rank::First.bitboard().0;
+            premask &= !Rank::Eighth.bitboard().0;
+            premask &= !File::A.bitboard().0;
+            premask &= !File::H.bitboard().0;
+
+            let factor = bishop_factors(square);
+
+            let mut a = usize::MAX;
+            loop_subsets!(premask, blockers, {
+                let cur = hash(BISHOP_SHR, factor, Bitboard(blockers | !premask));
+                if cur < a {
+                    a = cur;
+                }
+            });
+            let offset = len as isize - a as isize;
+
+            loop_subsets!(premask, blockers, {
+                let index = (offset
+                    + hash(BISHOP_SHR, factor, Bitboard(blockers | !premask)) as isize)
+                    as usize;
+                let mut res = 0;
+                loop_bishop_directions!(direction, {
+                    res |= rays.blocked(square, direction, Bitboard(blockers)).0;
+                });
+                if table[index].0 != 0 && table[index].0 != res {
+                    panic!()
+                }
+                if index >= len {
+                    len = index + 1;
+                }
+                table[index] = Bitboard(res);
             });
 
-    #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    pub(crate) struct InitialisedLookup(());
+            Magic {
+                premask: Bitboard(!premask),
+                factor,
+                offset,
+            }
+        });
 
-    impl InitialisedLookup {
-        #[inline]
-        pub(crate) fn init() -> Self {
-            LazyLock::force(&INIT);
-            Self(())
+        let rook = by_square!(square, null, {
+            let mut premask = 0;
+            premask |= rays.ray(square, Direction::East).0 & !File::H.bitboard().0;
+            premask |= rays.ray(square, Direction::North).0 & !Rank::Eighth.bitboard().0;
+            premask |= rays.ray(square, Direction::West).0 & !File::A.bitboard().0;
+            premask |= rays.ray(square, Direction::South).0 & !Rank::First.bitboard().0;
+
+            let factor = rook_factors(square);
+
+            let mut a = usize::MAX;
+            loop_subsets!(premask, blockers, {
+                let cur = hash(ROOK_SHR, factor, Bitboard(blockers | !premask));
+                if cur < a {
+                    a = cur;
+                }
+            });
+            let offset = len as isize - a as isize;
+
+            loop_subsets!(premask, blockers, {
+                let index = (offset
+                    + hash(ROOK_SHR, factor, Bitboard(blockers | !premask)) as isize)
+                    as usize;
+                let mut res = 0;
+                loop_rook_directions!(direction, {
+                    res |= rays.blocked(square, direction, Bitboard(blockers)).0;
+                });
+                if table[index].0 != 0 && table[index].0 != res {
+                    panic!()
+                }
+                if index >= len {
+                    len = index + 1;
+                }
+                table[index] = Bitboard(res);
+            });
+
+            Magic {
+                premask: Bitboard(!premask),
+                factor,
+                offset,
+            }
+        });
+
+        // if len != TABLE_SIZE {
+        //     panic!()
+        // }
+
+        Self {
+            bishop,
+            rook,
+            table,
         }
     }
 
-    impl std::ops::Deref for InitialisedLookup {
-        type Target = Lookup;
-        #[allow(static_mut_refs)]
     #[inline]
-        fn deref(&self) -> &Self::Target {
-            unsafe { LOOKUP.assume_init_ref() }
+    pub(crate) fn bishop(&self, square: Square, blockers: Bitboard) -> Bitboard {
+        unsafe { self.get_unchecked(BISHOP_SHR, *self.bishop.get(square), blockers) }
     }
+
+    #[inline]
+    pub(crate) fn rook(&self, square: Square, blockers: Bitboard) -> Bitboard {
+        unsafe { self.get_unchecked(ROOK_SHR, *self.rook.get(square), blockers) }
+    }
+
+    #[inline]
+    unsafe fn get_unchecked(&self, shr: u8, magic: Magic, blockers: Bitboard) -> Bitboard {
+        let Magic {
+            premask,
+            factor,
+            offset,
+        } = magic;
+        debug_assert!(self
+            .table
+            .get(
+                (hash(shr, factor, blockers | premask) as isize)
+                    .checked_add(offset)
+                    .unwrap() as usize
+            )
+            .is_some());
+        *self.table.get_unchecked(
+            ((hash(shr, factor, blockers | premask) as isize).unchecked_add(offset)) as usize,
+        )
     }
 }

src/magics.rs

@@ -1,193 +1,16 @@
 use crate::bitboard::*;
 use crate::board::*;
-use crate::rays::Rays;
 
-const BISHOP_SHR: u8 = 55;
-const ROOK_SHR: u8 = 52;
+pub(crate) const BISHOP_SHR: u8 = 55;
+pub(crate) const ROOK_SHR: u8 = 52;
 
-pub(crate) struct Magics {
-    bishop: BySquare<Magic>,
-    rook: BySquare<Magic>,
-    table: Box<[Bitboard]>,
-}
+pub(crate) const TABLE_SIZE: usize = 0;
 
-#[derive(Clone, Copy)]
-struct Magic {
-    premask: Bitboard,
-    factor: u64,
-    offset: isize,
-}
-
-impl Magics {
-    pub(crate) fn compute(rays: &Rays) -> Self {
-        let mut data = Vec::new();
-
-        let mut aux =
-            |shr,
-             factors: fn(Square) -> u64,
-             make_table: fn(&Rays, Square) -> (Bitboard, Vec<(Bitboard, Bitboard)>)| {
-                BySquare::new(|square| {
-                    let (premask, table) = make_table(rays, square);
-                    let factor = factors(square);
-                    let offset = fill_table(&mut data, shr, factor, table);
-                    Magic {
-                        premask,
-                        factor,
-                        offset,
-                    }
-                })
-            };
-
-        let bishop = aux(BISHOP_SHR, bishop_factors, make_bishop_table);
-        let rook = aux(ROOK_SHR, rook_factors, make_rook_table);
-
-        let mut table = Box::new_uninit_slice(data.len());
-        for (i, entry) in data.into_iter().enumerate() {
-            table[i].write(entry);
-        }
-
-        Self {
-            bishop,
-            rook,
-            table: unsafe { table.assume_init() },
-        }
-    }
-
-    #[inline]
-    pub(crate) fn bishop(&self, square: Square, blockers: Bitboard) -> Bitboard {
-        unsafe { self.get_unchecked(BISHOP_SHR, *self.bishop.get(square), blockers) }
-    }
-
-    #[inline]
-    pub(crate) fn rook(&self, square: Square, blockers: Bitboard) -> Bitboard {
-        unsafe { self.get_unchecked(ROOK_SHR, *self.rook.get(square), blockers) }
-    }
-
-    #[inline]
-    unsafe fn get_unchecked(&self, shr: u8, magic: Magic, blockers: Bitboard) -> Bitboard {
-        let Magic {
-            premask,
-            factor,
-            offset,
-        } = magic;
-        *self.table.get_unchecked(
-            ((hash(shr, factor, blockers | premask) as isize).unchecked_add(offset)) as usize,
-        )
-    }
-}
-
-fn fill_table(
-    data: &mut Vec<Bitboard>,
-    shr: u8,
-    factor: u64,
-    table: Vec<(Bitboard, Bitboard)>,
-) -> isize {
-    let offset = data.len() as isize
-        - table
-            .iter()
-            .map(|(x, _)| hash(shr, factor, *x) as isize)
-            .min()
-            .unwrap();
-    for (x, y) in &table {
-        let i = (hash(shr, factor, *x) as isize + offset) as usize;
-        while data.len() <= i {
-            data.push(Bitboard::new());
-        }
-        if data[i] != Bitboard::new() && data[i] != *y {
-            panic!();
-        }
-        data[i] = *y;
-    }
-    offset
-}
-
-fn make_bishop_table(rays: &Rays, square: Square) -> (Bitboard, Vec<(Bitboard, Bitboard)>) {
-    let mut premask = Bitboard::new();
-    for direction in [
-        Direction::NorthWest,
-        Direction::SouthWest,
-        Direction::SouthEast,
-        Direction::NorthEast,
-    ] {
-        premask |= rays.ray(square, direction);
-    }
-    premask &= !Rank::First.bitboard();
-    premask &= !Rank::Eighth.bitboard();
-    premask &= !File::A.bitboard();
-    premask &= !File::H.bitboard();
-
-    let mut table = make_table(premask, |blockers| {
-        let mut res = Bitboard::new();
-        for direction in [
-            Direction::NorthWest,
-            Direction::SouthWest,
-            Direction::SouthEast,
-            Direction::NorthEast,
-        ] {
-            res |= rays.blocked(square, direction, blockers);
-        }
-        res
-    });
-
-    premask = !premask;
-    for (x, _) in &mut table {
-        *x |= premask;
-    }
-
-    (premask, table)
-}
-
-fn make_rook_table(rays: &Rays, square: Square) -> (Bitboard, Vec<(Bitboard, Bitboard)>) {
-    let mut premask = Bitboard::new();
-    premask |= rays.ray(square, Direction::North) & !Rank::Eighth.bitboard();
-    premask |= rays.ray(square, Direction::West) & !File::A.bitboard();
-    premask |= rays.ray(square, Direction::South) & !Rank::First.bitboard();
-    premask |= rays.ray(square, Direction::East) & !File::H.bitboard();
-
-    let mut table = make_table(premask, |blockers| {
-        let mut res = Bitboard::new();
-        for direction in [
-            Direction::North,
-            Direction::West,
-            Direction::South,
-            Direction::East,
-        ] {
-            res |= rays.blocked(square, direction, blockers);
-        }
-        res
-    });
-
-    premask = !premask;
-    for (x, _) in &mut table {
-        *x |= premask;
-    }
-
-    (premask, table)
-}
-
-fn make_table<T, F>(premask: Bitboard, f: F) -> Vec<(Bitboard, T)>
-where
-    F: Fn(Bitboard) -> T,
-{
-    let mut res = Vec::new();
-    let mut subset: u64 = 0;
-    loop {
-        subset = subset.wrapping_sub(premask.0) & premask.0;
-        let x = Bitboard(subset);
-        let y = f(x);
-        res.push((x, y));
-        if subset == 0 {
-            break;
-        }
-    }
-    res
-}
-
-fn hash(shr: u8, factor: u64, x: Bitboard) -> usize {
+pub(crate) const fn hash(shr: u8, factor: u64, x: Bitboard) -> usize {
     (x.0.wrapping_mul(factor) >> shr) as usize
 }
 
-fn bishop_factors(square: Square) -> u64 {
+pub(crate) const fn bishop_factors(square: Square) -> u64 {
     match square {
         Square::A1 => 0x0000404040404040,
         Square::B1 => 0x0040C100081000E8,
@@ -256,7 +79,7 @@ fn bishop_factors(square: Square) -> u64 {
     }
 }
 
-fn rook_factors(square: Square) -> u64 {
+pub(crate) const fn rook_factors(square: Square) -> u64 {
     match square {
         Square::A1 => 0x002000A28110000C,
         Square::B1 => 0x0018000C01060001,

src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    eschac::test();
+}

src/position.rs

@@ -3,7 +3,6 @@
 use crate::array_vec::*;
 use crate::bitboard::*;
 use crate::board::*;
-use crate::lookup::*;
 use crate::san::*;
 use crate::setup::*;
 use crate::uci::*;
@@ -55,10 +54,7 @@ use std::iter::FusedIterator;
 /// requirement is to be efficient while respecting the [`Ord`] trait protocol. It should not be
 /// considered stable.
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
-pub struct Position {
-    setup: Setup,
-    lookup: InitialisedLookup,
-}
+pub struct Position(Setup);
 
 const MAX_LEGAL_MOVES: usize = 218;
 
@@ -76,8 +72,7 @@ impl Position {
     /// i.e. `rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -`
     #[inline]
     pub fn new() -> Self {
-        Self {
-            setup: Setup {
+        Self(Setup {
             w: Bitboard(0x000000000000FFFF),
             p_b_q: Bitboard(0x2CFF00000000FF2C),
             n_b_k: Bitboard(0x7600000000000076),
@@ -85,9 +80,7 @@ impl Position {
             turn: Color::White,
             castling_rights: CastlingRights::full(),
             en_passant: OptionSquare::None,
-            },
-            lookup: InitialisedLookup::init(),
-        }
+        })
     }
 
     /// Tries to read a valid position from a text record.
@@ -182,25 +175,25 @@ impl Position {
     /// responsibility to rule out the legality of en passant before calling this function.
     #[inline]
     pub fn remove_en_passant_target_square(&mut self) {
-        self.setup.en_passant = OptionSquare::None;
+        self.0.en_passant = OptionSquare::None;
     }
 
     /// Returns the occupancy of a square.
     #[inline]
     pub fn get(&self, square: Square) -> Option<Piece> {
-        self.setup.get(square)
+        self.0.get(square)
     }
 
     /// Returns the color whose turn it is to play.
     #[inline]
     pub fn turn(&self) -> Color {
-        self.setup.turn()
+        self.0.turn()
     }
 
     /// Returns `true` if castling is available for the given color and side.
     #[inline]
     pub fn castling_rights(&self, color: Color, side: CastlingSide) -> bool {
-        self.setup.castling_rights(color, side)
+        self.0.castling_rights(color, side)
     }
 
     /// Returns the en passant target square if it exists.
@@ -209,26 +202,26 @@ impl Position {
     /// legal or even pseudo-legal.
     #[inline]
     pub fn en_passant_target_square(&self) -> Option<Square> {
-        self.setup.en_passant_target_square()
+        self.0.en_passant_target_square()
     }
 
     /// Discards the castling rights for the given color and side.
     #[inline]
     pub fn remove_castling_rights(&mut self, color: Color, side: CastlingSide) {
-        self.setup.set_castling_rights(color, side, false);
+        self.0.set_castling_rights(color, side, false);
     }
 
     /// Borrows the position as a [`Setup`].
     #[inline]
     pub fn as_setup(&self) -> &Setup {
-        &self.setup
+        &self.0
     }
 
     /// Converts a position to a [`Setup`], allowing to edit the position without enforcing its
     /// legality.
     #[inline]
     pub fn into_setup(self) -> Setup {
-        self.setup
+        self.0
     }
 
     /// Tries to pass the turn to the other color, failing if it would leave the king in check.
@@ -236,8 +229,8 @@ impl Position {
     /// When possible, this inverts the color to play and removes the en passant square if it
     /// exists.
     pub fn pass(&self) -> Option<Self> {
-        let d = self.lookup;
-        let setup = &self.setup;
+        let d = &crate::lookup::LOOKUP;
+        let setup = &self.0;
         let blockers = setup.p_b_q | setup.n_b_k | setup.r_q_k;
         let k = setup.n_b_k & setup.r_q_k;
         let q = setup.p_b_q & setup.r_q_k;
@@ -255,23 +248,19 @@ impl Position {
                 | d.knight(king_square) & n
                 | d.bishop(king_square, blockers) & (q | b)
                 | d.rook(king_square, blockers) & (q | r));
-        checkers.is_empty().then(|| Self {
-            setup: Setup {
+        checkers.is_empty().then(|| {
+            Self(Setup {
                 turn: !setup.turn,
                 en_passant: OptionSquare::None,
                 ..setup.clone()
-            },
-            lookup: d,
+            })
         })
     }
 
     /// Returns the mirror image of the position (see [`Setup::mirror`]).
     #[inline]
     pub fn mirror(&self) -> Self {
-        Self {
-            setup: self.setup.mirror(),
-            lookup: self.lookup,
-        }
+        Self(self.0.mirror())
     }
 
     /// Returns the number of possible chess games for a given number of moves.
@@ -351,7 +340,7 @@ impl Position {
             to,
             promotion,
         } = uci;
-        let role = self.setup.get_role(from).ok_or(InvalidUciMove::Illegal)?;
+        let role = self.0.get_role(from).ok_or(InvalidUciMove::Illegal)?;
         #[inline]
         fn aux<'l, const ROLE: u8>(
             position: &'l Position,
@@ -550,9 +539,7 @@ impl<'l> Move<'l> {
     #[inline]
     pub fn is_capture(self) -> bool {
         self.raw.kind == MoveType::EnPassant
-            || !((self.position.setup.p_b_q
-                | self.position.setup.n_b_k
-                | self.position.setup.r_q_k)
+            || !((self.position.0.p_b_q | self.position.0.n_b_k | self.position.0.r_q_k)
                 & self.to().bitboard())
             .is_empty()
     }
@@ -562,7 +549,7 @@ impl<'l> Move<'l> {
     pub fn captured(self) -> Option<Role> {
         match self.raw.kind {
             MoveType::EnPassant => Some(Role::Pawn),
-            _ => self.position.setup.get_role(self.raw.to),
+            _ => self.position.0.get_role(self.raw.to),
         }
     }
 
@@ -932,10 +919,7 @@ impl<'l> Visitor for Moves<'l> {
 impl Position {
     /// SAFETY: The position must be valid.
     pub(crate) unsafe fn from_setup(setup: Setup) -> Self {
-        Self {
-            setup,
-            lookup: InitialisedLookup::init(),
-        }
+        Self(setup)
     }
 
     fn generate_moves<T>(&self, visitor: &mut T)
@@ -953,8 +937,8 @@ impl Position {
             turn,
             en_passant,
             castling_rights,
-        } = self.setup;
-        let d = self.lookup;
+        } = self.0;
+        let d = &crate::lookup::LOOKUP;
 
         let blockers = p_b_q | n_b_k | r_q_k;
         let (us, them) = match turn {
@@ -1267,7 +1251,7 @@ impl Position {
 
     #[inline]
     unsafe fn play_unchecked(&mut self, m: RawMove) {
-        let Self { setup, .. } = self;
+        let Self(setup) = self;
 
         setup.en_passant = OptionSquare::None;
 

src/rays.rs

@@ -1,44 +1,2 @@
 use crate::bitboard::*;
 use crate::board::*;
-
-pub(crate) struct Rays(BySquare<ByDirection<Bitboard>>);
-
-impl Rays {
-    pub(crate) fn new() -> Self {
-        Self(BySquare::new(|square| {
-            ByDirection::new(|direction| {
-                let mut square = square;
-                let mut res = Bitboard::new();
-                while let Some(x) = square.trans(direction) {
-                    square = x;
-                    res |= square.bitboard();
-                }
-                res
-            })
-        }))
-    }
-
-    #[inline]
-    pub(crate) fn ray(&self, square: Square, direction: Direction) -> Bitboard {
-        *self.0.get(square).get(direction)
-    }
-
-    pub(crate) fn blocked(
-        &self,
-        square: Square,
-        direction: Direction,
-        blockers: Bitboard,
-    ) -> Bitboard {
-        let blockers = blockers & *self.0.get(square).get(direction);
-        let square2 = if (direction as u8) < 4 {
-            blockers.first()
-        } else {
-            blockers.last()
-        };
-        *self.0.get(square).get(direction)
-            & !match square2 {
-                Some(square2) => *self.0.get(square2).get(direction),
-                None => Bitboard::new(),
-            }
-    }
-}

src/setup.rs

@@ -4,7 +4,6 @@
 
 use crate::bitboard::*;
 use crate::board::*;
-use crate::lookup::*;
 use crate::position::*;
 
 /// **A builder type for chess positions.**
@@ -347,7 +346,7 @@ impl Setup {
         debug_assert!((self.p_b_q & self.n_b_k & self.r_q_k).is_empty());
 
         let mut reasons = IllegalPositionReasons::new();
-        let d = InitialisedLookup::init();
+        let d = &crate::lookup::LOOKUP;
 
         let blockers = self.p_b_q | self.n_b_k | self.r_q_k;
         let pieces = self.pieces();