fix: correctly apply modulo to zobrist hash

1 files changed, 7 insertions, 5 deletions

diff --git a/src/grossmeister/ttable.rs b/src/grossmeister/ttable.rs
index 2f673c9..b6b1a2c 100644
--- a/src/grossmeister/ttable.rs
+++ b/src/grossmeister/ttable.rs
@@ -44,13 +44,14 @@ impl Grossmeister {
     /// Find current position in Transposition Table
     /// This operation is safe from collisions since it compares the *full* hash
     pub fn transposition(&self) -> Option<&TranspositionTableItem> {
-        self.transposition_table.depth_preferred.get(&self.board.hash).and_then(|item| {
+        let hash = self.board.hash % TTABLE_SIZE;
+        self.transposition_table.depth_preferred.get(&hash).and_then(|item| {
             if item.hash == self.board.hash {
                 Some(item)
             } else {
                 None
             }
-        }).or(self.transposition_table.always_replace.get(&self.board.hash).and_then(|item| {
+        }).or(self.transposition_table.always_replace.get(&hash).and_then(|item| {
             if item.hash == self.board.hash {
                 Some(item)
             } else {
@@ -60,12 +61,13 @@ impl Grossmeister {
     }
 
     pub fn store_transposition(&mut self, transposition: TranspositionTableItem) {
-        self.transposition_table.always_replace.insert(self.board.hash, transposition);
-        if match self.transposition_table.depth_preferred.get(&self.board.hash) {
+        let hash = transposition.hash % TTABLE_SIZE;
+        self.transposition_table.always_replace.insert(hash, transposition);
+        if match self.transposition_table.depth_preferred.get(&hash) {
             Some(existing_transposition) => transposition.depth >= existing_transposition.depth,
             None => true,
         } {
-            self.transposition_table.depth_preferred.insert(self.board.hash, transposition);
+            self.transposition_table.depth_preferred.insert(hash, transposition);
         }
     }