Merge pull request #10 from htamas1210/Engine/legality-checks

Engine/legality checks

engine/src/bitboard.rs

@@ -1,2 +1,6 @@
 mod attackmaps;
 mod utils;
+mod legality;
+mod checkinfo;
+
+pub mod board;

engine/src/bitboard/board.rs

@@ -0,0 +1,182 @@
+use super::utils::try_get_square_number_from_notation;
+
+pub struct Board {
+  pub(in super) bitboards: [u64; 12],     // 0-5 -> white pieces (P, N, B, R, Q, K), 6-11 -> black pieces (p, n, b, r, q, k)
+  pub(in super) piece_board: [u8; 64],    // same as board indexes, 12 -> empty square
+  pub(in super) occupancy: [u64; 3],      // 0 -> white, 1 -> black, 2 -> combined
+  pub(in super) castling_rights: u8,      // 0b0000_KQkq
+  pub(in super) pinned_squares: [u8; 64], // 0 -> E-W, 1 -> NE-SW, 2 -> N-S, 3 -> SE-NW, 4 -> no pin
+  pub(in super) pin_mask: u64,            // 1 -> pin, 0 -> no pin
+  pub(in super) en_passant_square: u64,   // 1 -> ep square, 0 -> no ep square
+  pub(in super) side_to_move: u8          // 0 -> white to play, 1 -> black to play
+}
+
+impl Board {
+
+  pub fn new_clear() -> Self {
+    let mut bit_board: Self = Self {
+      bitboards: [0x0000_0000_0000_0000; 12],
+      piece_board: [12; 64],
+      occupancy: [0x0000_0000_0000_0000; 3],
+      castling_rights: 0b0000_0000,
+      pinned_squares: [4; 64],
+      pin_mask: 0u64,
+      en_passant_square: 0x0000_0000_0000_0000,
+      side_to_move: 0
+    };
+
+    return bit_board;
+  }
+  pub fn new() -> Self {
+    let mut bit_board: Board = Self {
+      bitboards: [0x0000_0000_0000_FF00,
+                0x0000_0000_0000_0042,
+                0x0000_0000_0000_0024,
+                0x0000_0000_0000_0081,
+                0x0000_0000_0000_0008,
+                0x0000_0000_0000_0010,
+                0x00FF_0000_0000_0000,
+                0x4200_0000_0000_0000,
+                0x2400_0000_0000_0000,
+                0x8100_0000_0000_0000,
+                0x0800_0000_0000_0000,
+                0x1000_0000_0000_0000],
+      piece_board: [12; 64],
+      occupancy: [0; 3],
+      castling_rights: 0b0000_1111,
+      pinned_squares: [4; 64],
+      pin_mask: 0u64,
+      en_passant_square: 0x0000_0000_0000_0000,
+      side_to_move: 0
+    };
+    bit_board.calc_occupancy();
+    bit_board.calc_piece_board();
+
+    return bit_board;
+  }
+  pub fn build(fen: &str) -> Self {
+    let mut board: Board = Board::new_clear();
+
+    let mut col: i32 = 0;
+    let mut row: i32 = 7;
+    let pieces: [char; 12] = ['p', 'n', 'b', 'r', 'q', 'k', 'P', 'N', 'B', 'R', 'Q', 'K'];
+    let mut coming_up: &str = fen;
+
+    for (i, c) in coming_up.chars().enumerate() {
+      if pieces.contains(&c) {
+        // board.place_piece(row*8 + col, c);
+        col += 1;
+      }
+      else if ('1'..='8').contains(&c) {
+        col += c.to_string().parse::<i32>().unwrap();
+      }
+      else if c == '/' {
+        row -= 1;
+        col = 0;
+      }
+      else {
+        coming_up = &coming_up[i+1..];
+        break;
+      }
+    }
+    board.calc_occupancy();
+    
+    match coming_up.chars().next().unwrap() {
+      'w' => board.side_to_move = 0,
+      'b' => board.side_to_move = 1,
+       _  => panic!("invalid fen notation / to be handled later")
+    }
+    coming_up = &coming_up[2..];
+
+    for (i, c) in coming_up.chars().enumerate() {
+      match c {
+        'K' => board.castling_rights |= 1 << 3,
+        'Q' => board.castling_rights |= 1 << 2,
+        'k' => board.castling_rights |= 1 << 1,
+        'q' => board.castling_rights |= 1,
+        '-' => {
+          coming_up = &coming_up[i+2..];
+          break;
+        }
+         _  => {
+          coming_up = &coming_up[i+1..];
+          break;
+        }
+      }
+    }
+    match coming_up.chars().next().unwrap() {
+      '-' => {
+          coming_up = &coming_up[1..];
+        }
+       _  => {
+          let notation = coming_up.split(' ').next().unwrap();
+          if let Ok(epsq_index) = try_get_square_number_from_notation(notation) {
+            board.en_passant_square = 1 << epsq_index;
+          }
+       }
+    }
+    board.calc_pinned_squares();
+    board.calc_piece_board();
+
+    return board;
+  }
+
+  #[inline(always)]
+  pub fn bitboards(&self, index: usize) -> u64 {
+    return self.bitboards[index];
+  }
+  #[inline(always)]
+  pub fn piece_board(&self, sq: u8) -> u8 {
+    return self.piece_board[sq as usize];
+  }
+  #[inline(always)]
+  pub fn occupancy(&self, side: usize) -> u64 {
+    return self.occupancy[side];
+  }
+  #[inline(always)]
+  pub fn castling_rights(&self) -> u8 {
+    return self.castling_rights;
+  }
+  #[inline(always)]
+  pub fn pinned_squares(&self, sq: usize) -> u8 {
+    return self.pinned_squares[sq];
+  }
+  #[inline(always)]
+  pub fn pin_mask(&self) -> u64 {
+    return self.pin_mask;
+  }
+  #[inline(always)]
+  pub fn en_passant_square(&self) -> u64 {
+    return self.en_passant_square;
+  }
+  #[inline(always)]
+  pub fn side_to_move(&self) -> u8 {
+    return self.side_to_move;
+  }
+
+  #[inline(always)]
+  pub fn current_king_square(&self) -> u32 {
+    return if self.side_to_move == 0 { self.bitboards[5].trailing_zeros() } else { self.bitboards[11].trailing_zeros() };
+  }
+
+  fn calc_occupancy(&mut self) {
+    self.occupancy = [0u64; 3];
+    for b in 0..6 {
+      self.occupancy[0] |= self.bitboards[b];
+    }
+    for b in 6..12 {
+      self.occupancy[1] |= self.bitboards[b];
+    }
+    self.occupancy[2] = self.occupancy[0] | self.occupancy[1];
+  }
+  fn calc_piece_board(&mut self) {
+    for sq in 0..64 {
+      for b in 0..12 {
+        if (self.bitboards[b as usize] & 1 << sq) != 0 {
+          self.piece_board[sq] = b;
+        }
+      }
+    }
+  }
+
+}

engine/src/bitboard/checkinfo.rs

@@ -0,0 +1,21 @@
+
+pub struct CheckInfo {
+  pub check_count: u8,
+  pub move_mask: u64
+}
+
+impl CheckInfo {
+
+  pub fn new() -> Self {
+    return Self {
+      check_count: 0,
+      move_mask: 0xFFFF_FFFF_FFFF_FFFF
+    }
+  }
+
+  #[inline(always)]
+  pub fn add_checker(&mut self, move_mask: u64) {
+    self.move_mask &= move_mask;
+    self.check_count += 1;
+  }
+}

engine/src/bitboard/legality.rs

@@ -0,0 +1,48 @@
+use super::board::Board;
+use super::attackmaps::RAY_TABLE;
+
+impl Board {
+
+  pub(in super) fn calc_pinned_squares(&mut self) {
+    self.pinned_squares = [4; 64];
+    self.pin_mask = 0u64;
+
+    let friendly_pieces: u64 = self.occupancy[self.side_to_move as usize];
+    let offset: usize = 6 * self.side_to_move as usize;
+    let king_board: u64 = self.bitboards[5 + offset];
+    let king_sq: u32 = king_board.trailing_zeros();
+    let opponent_queen_bishop_mask: u64 = self.bitboards[8 - offset] | self.bitboards[10 - offset];
+    let opponent_queen_rook_mask: u64 = self.bitboards[9 - offset] | self.bitboards[10 - offset];
+
+    // Queen-Rook directions
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_rook_mask, 0);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_rook_mask, 2);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_rook_mask, 4);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_rook_mask, 6);
+
+    // Queen-Bishop directions
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_bishop_mask, 1);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_bishop_mask, 3);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_bishop_mask, 5);
+    self.set_pinned_in_ray_direction(king_sq, friendly_pieces, opponent_queen_bishop_mask, 7);
+  }
+
+  pub(in super) fn set_pinned_in_ray_direction(&mut self, king_sq: u32, friendly_pieces: u64, attackers: u64, dir: u8) {
+    let is_up: bool = dir / 4 == 0;
+    let mask: u64 = RAY_TABLE[king_sq as usize][dir as usize];
+    let blockers: u64 = self.occupancy[2] & mask;
+    if blockers == 0 { return; }
+    let first_blocker_sq: u32 = if is_up { blockers.trailing_zeros() } else { 63 - blockers.leading_zeros() };
+    if (friendly_pieces & 1 << first_blocker_sq) != 0 {
+      let blockers: u64 = blockers & !(1 << first_blocker_sq);
+      if blockers == 0 { return; }
+      let second_blocker_sq: u32 = if is_up { blockers.trailing_zeros() } else { 63 - blockers.leading_zeros() };
+
+      if (attackers & 1 << second_blocker_sq) != 0 {
+        self.pinned_squares[first_blocker_sq as usize] = dir % 4;
+        self.pin_mask |= 1 << first_blocker_sq;
+      }
+    }
+  }
+
+}

engine/src/bitboard/utils.rs

@@ -27,6 +27,27 @@ pub fn notation_from_square_number(sq: u8) -> String {
   return notation;
 }
 
+pub fn try_get_square_number_from_notation(notation: &str) -> Result<u8, ()> {
+
+  let file = match notation.chars().nth(0).unwrap() {
+    'a' => 0,
+    'b' => 1,
+    'c' => 2,
+    'd' => 3,
+    'e' => 4,
+    'f' => 5,
+    'g' => 6,
+    'h' => 7,
+     _  => { return Result::Err(()); }
+  };
+  if let Some(rank) = notation.chars().nth(1) {
+    return Result::Ok(file + 8 * (rank.to_digit(10).unwrap() as u8) - 8);
+  }
+  else {
+    return Result::Err(());
+  }
+}
+
 
 // <----- TESTS ----->