From 83d13da85bf089e74ebc7c1996e65e05eeabcd69 Mon Sep 17 00:00:00 2001
From: eug-vs <eugene@eug-vs.xyz>
Date: Wed, 25 Jan 2023 08:12:52 +0300
Subject: feat: enable quiscence in negamax

---
 src/board/engine.rs | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

(limited to 'src/board/engine.rs')

diff --git a/src/board/engine.rs b/src/board/engine.rs
index 75a505e..c6ac512 100644
--- a/src/board/engine.rs
+++ b/src/board/engine.rs
@@ -122,8 +122,6 @@ impl Board {
     }
 
     pub fn negamax_search(&mut self, mut alpha: f32, beta: f32, depth_left: u8) -> (f32, Vec<Move>) {
-        let transposition = self.transposition_table[(self.hash % TTABLE_SIZE) as usize];
-
         let mut principal_variation = Vec::new();
         let color = self.color();
 
@@ -135,20 +133,17 @@ impl Board {
             a_eval.total_cmp(&b_eval)
         });
 
-        if transposition.is_some() {
-            match transposition {
-                Some(item) => {
-                    if item.node_type == NodeType::PV {
-                        // println!("Cache hit at depth {}: {:?}", depth_left, item);
-                        moves.insert(0, item.best_move);
-                    }
+        match self.transposition_table[(self.hash % TTABLE_SIZE) as usize] {
+            Some(item) => {
+                if item.node_type == NodeType::PV {
+                    moves.insert(0, item.best_move);
                 }
-                None => panic!("Unreachable"),
             }
+            None => {},
         }
 
         if depth_left == 0 {
-            return (self.evaluate(Some(moves.len() as f32)), principal_variation);
+            return (self.quiscence(alpha, beta), principal_variation);
         }
 
         for mov in moves {
@@ -190,7 +185,22 @@ impl Board {
 
     pub fn quiscence(&mut self, mut alpha: f32, beta: f32) -> f32 {
         let color = self.color();
-        let moves = self.generate_pseudolegal_moves(color);
+        let mut moves = self.generate_pseudolegal_moves(color);
+
+        moves.sort_unstable_by(|a, b| {
+            let a_eval = self.eval_move(*a);
+            let b_eval = self.eval_move(*b);
+            a_eval.total_cmp(&b_eval)
+        });
+
+        match self.transposition_table[(self.hash % TTABLE_SIZE) as usize] {
+            Some(item) => {
+                if item.node_type == NodeType::PV {
+                    moves.insert(0, item.best_move);
+                }
+            }
+            None => {},
+        }
 
         let stand_pat = self.evaluate(Some(moves.len() as f32));
 
-- 
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