refactor: separate zobrist module

1 files changed, 6 insertions, 37 deletions

diff --git a/src/board/mod.rs b/src/board/mod.rs
index f7016d3..854ce0e 100644
--- a/src/board/mod.rs
+++ b/src/board/mod.rs
@@ -1,10 +1,12 @@
 use crate::{bitboard::{Bitboard, BitboardFns}, moves::{Move, MoveKind}, attacks::Attacks, square::Square, board::io::IO};
 
-use self::ttable::{TranspositionTable, TTABLE_SIZE};
+use self::{ttable::{TranspositionTable, TTABLE_SIZE}, zobrist::ZobristSeed};
 pub mod io;
+mod zobrist;
 mod engine;
 mod ttable;
 
+#[derive(Debug, Clone, Copy)]
 pub enum CastlingSide {
     King,
     Queen,
@@ -26,7 +28,7 @@ pub struct Board {
 
     // TODO: remove
     transposition_table: TranspositionTable,
-    zobrist_seed: [u64; 781],
+    zobrist_seed: ZobristSeed,
     attacks: Attacks,
 }
 
@@ -99,39 +101,6 @@ impl Board {
         self.pieces_by_color(color).iter().fold(0, |acc, bitboard| acc | bitboard)
     }
 
-    /// Compute and store zobrist hash of the current position
-    /// https://www.chessprogramming.org/Zobrist_Hashing
-    fn update_zobrist_hash(&mut self) {
-        self.hash = 0;
-
-        if self.color() == Color::Black {
-            self.hash ^= match self.zobrist_seed.last() {
-                Some(x) => x,
-                None => panic!("Something is wrong with zobrist seed list"),
-            };
-        }
-
-        for (piece_id, bitboard) in self.piece_sets.iter().enumerate() {
-            for square in bitboard.serialize() {
-                self.hash ^= self.zobrist_seed[piece_id * 64 + square as usize];
-            }
-        }
-
-        for color in 0..2 {
-            for castle_side in 0..2 {
-                if self.castling_rights[color][castle_side] {
-                    self.hash ^= self.zobrist_seed[(12 * 64) + color * 2 + castle_side];
-                }
-            }
-        }
-
-        match self.ep_target {
-            Some(square) => {
-                self.hash ^= self.zobrist_seed[(12 * 64 + 4) + square.file() as usize];
-            },
-            None => {},
-        }
-    }
 
 
     fn ep_bitboard(&self) -> Bitboard {
@@ -731,7 +700,7 @@ impl Color {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{bitboard::BitboardFns, square::Square};
+    use crate::{bitboard::BitboardFns, square::Square, board::zobrist::Zobrist};
 
     #[test]
     fn square_enum() {
@@ -813,7 +782,7 @@ mod tests {
         board.print();
 
         let hash = board.hash;
-        board.update_zobrist_hash();
+        board.compute_hash();
         assert_eq!(hash, board.hash, "Hash should be correctly updated after move");
 
         assert!(board.piece_sets[PieceType::PawnBlack as usize] & Square::F7.to_bitboard() == 0);