feat: use transposition table in negamax

1 files changed, 25 insertions, 0 deletions

diff --git a/src/board/ttable.rs b/src/board/ttable.rs
new file mode 100644
index 0000000..3a103da
--- /dev/null
+++ b/src/board/ttable.rs
@@ -0,0 +1,25 @@
+use crate::moves::Move;
+
+/// https://www.chessprogramming.org/Node_Types
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum NodeType {
+    /// Principal variation node - exact score
+    PV,
+    /// Fail-high
+    Cut,
+    /// Fail-low
+    All,
+}
+
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub struct TranspositionTableItem {
+    /// Zobrist hash of this position
+    pub hash: u64,
+    pub best_move: Move,
+    pub depth: u8,
+    pub score: f32,
+    pub node_type: NodeType,
+}
+
+pub const TTABLE_SIZE: u64 = 2u64.pow(24);
+pub type TranspositionTable = Vec<Option<TranspositionTableItem>>;