From 6211e5be8963411a88196f0e4778647c55d13616 Mon Sep 17 00:00:00 2001
From: stefiosif <stef8iosif@gmail.com>
Date: Fri, 28 Mar 2025 23:35:02 +0200
Subject: [PATCH] Add history maluses

---
 src/board/game.rs           | 14 ++++++++++++++
 src/search/mod.rs           |  2 +-
 src/search/move_ordering.rs |  4 ++--
 src/search/negamax.rs       | 13 ++++++-------
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/src/board/game.rs b/src/board/game.rs
index a57c727..e28f091 100644
--- a/src/board/game.rs
+++ b/src/board/game.rs
@@ -320,6 +320,20 @@ impl Game {
             .step_by(2)
             .any(|mp| mp.zobrist_hash.expect("State without hash.") == self.hash)
     }
+
+    pub fn update_history(&mut self, color: Color, mv: Move, depth: u8, punish: bool) {
+        const MAX_HISTORY: i32 = 8192;
+        let bonus = if punish {
+            -(depth as i32 * depth as i32)
+        } else {
+            depth as i32 * depth as i32
+        };
+
+        let clamped_bonus = bonus.clamp(-MAX_HISTORY, MAX_HISTORY);
+        let history_value = self.history_heuristic[color][mv.src()][mv.dst()];
+        self.history_heuristic[color][mv.src()][mv.dst()] +=
+            clamped_bonus - history_value * clamped_bonus.abs() / MAX_HISTORY;
+    }
 }
 
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
diff --git a/src/search/mod.rs b/src/search/mod.rs
index 95c2884..00f1ef8 100644
--- a/src/search/mod.rs
+++ b/src/search/mod.rs
@@ -12,7 +12,7 @@ pub const INC: u128 = 80;
 pub const HARD_LIMIT_DIVISION: u128 = 3;
 pub const SOFT_LIMIT_DIVISION: u128 = 20;
 pub const TT_SIZE_IN_MB: usize = 64;
-pub const MAX_HISTORY: i16 = 8192;
+pub const MAX_HISTORY: i32 = 8192;
 pub const ASPIRATION_WINDOW_INITIAL: i16 = 20;
 pub const ASPIRATION_WINDOW_DEPTH_THRESHOLD: u8 = 4;
 pub const ASPIRATION_WINDOW_EXPANSION: i16 = 2;
diff --git a/src/search/move_ordering.rs b/src/search/move_ordering.rs
index 2361f71..9eb7daa 100644
--- a/src/search/move_ordering.rs
+++ b/src/search/move_ordering.rs
@@ -11,9 +11,9 @@ pub fn score_move(
     mv: Move,
     killer_move: Option<Move>,
     color: Color,
-    history_heuristic: &[[[i16; 64]; 64]; 2],
+    history_heuristic: &[[[i32; 64]; 64]; 2],
     tt_move: Option<Move>,
-) -> i16 {
+) -> i32 {
     if Some(mv) == tt_move {
         return -100;
     }
diff --git a/src/search/negamax.rs b/src/search/negamax.rs
index 30fcda2..477b866 100644
--- a/src/search/negamax.rs
+++ b/src/search/negamax.rs
@@ -109,6 +109,7 @@ pub fn negamax(
     let mut legal_moves = 0;
     let mut best_move = entry.and_then(|entry| entry.mv);
     let mut best_score = MIN_SCORE;
+    let mut quiets_tried: Vec<Move> = Vec::new();
 
     for mv in moves {
         game.make_move(&mv);
@@ -166,16 +167,14 @@ pub fn negamax(
         if score >= beta {
             if !mv.is_capture() {
                 game.killer[plies as usize] = Some(mv);
-
-                let current_score = game.history_heuristic[color][mv.src()][mv.dst()];
-                let bonus = (depth * depth) as i16;
-                let clamped_bonus = bonus.clamp(-MAX_HISTORY, MAX_HISTORY);
-                game.history_heuristic[color][mv.src()][mv.dst()] +=
-                    clamped_bonus - current_score * clamped_bonus.abs() / MAX_HISTORY;
+                game.update_history(color, mv, depth, false);
+                for q in quiets_tried {
+                    game.update_history(color, q, depth, true);
+                }
             }
             break;
         } else if !mv.is_capture() {
-            game.history_heuristic[color][mv.src()][mv.dst()] -= 1;
+            quiets_tried.push(mv);
         }
     }