From e35a4000e4d196f6d0c3689323ba829e44d57ced Mon Sep 17 00:00:00 2001
From: SzilBalazs <szilprogramming@gmail.com>
Date: Tue, 29 Aug 2023 15:22:34 +0200
Subject: [PATCH] Separate history for sides

Bench: 8862183
---
 src/search/history.h       | 18 +++++++++---------
 src/search/move_list.h     |  2 +-
 src/search/search_thread.h |  6 +++---
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/search/history.h b/src/search/history.h
index ebaaaf8..af68523 100644
--- a/src/search/history.h
+++ b/src/search/history.h
@@ -25,7 +25,7 @@ namespace search {
     public:
         chess::Move killer_moves[MAX_PLY + 10][2];
         chess::Move counter_moves[64][64];
-        Score butterfly[64][64];
+        Score main_history[2][64][64];
 
         /**
          * Adds a beta-cutoff to the History.
@@ -35,10 +35,10 @@ namespace search {
          * @param depth Search depth
          * @param ply Distance from root
          */
-        void add_cutoff(chess::Move move, chess::Move last_move, Depth depth, Ply ply) {
+        void add_cutoff(const chess::Board &board, chess::Move move, chess::Move last_move, Depth depth, Ply ply) {
             update_killer_moves(move, ply);
             update_counter_moves(move, last_move);
-            update_butterfly_history(move, depth * 100);
+            update_history(main_history[board.get_stm()][move.get_from()][move.get_to()], depth * 100);
         }
 
         /**
@@ -47,8 +47,8 @@ namespace search {
          * @param move The weak move
          * @param depth Search depth
          */
-        void decrease_history(chess::Move move, Depth depth) {
-            update_butterfly_history(move, -depth * 100);
+        void decrease_history(const chess::Board &board, chess::Move move, Depth depth) {
+            update_history(main_history[board.get_stm()][move.get_from()][move.get_to()], -depth * 100);
         }
 
         /**
@@ -60,7 +60,7 @@ namespace search {
             }
             for (int i = 0; i < 64; i++) {
                 for (int j = 0; j < 64; j++) {
-                    butterfly[i][j] = 0;
+                    main_history[0][i][j] = main_history[1][i][j] = 0;
                     counter_moves[i][j] = chess::NULL_MOVE;
                 }
             }
@@ -76,9 +76,9 @@ namespace search {
             counter_moves[last_move.get_from()][last_move.get_to()] = move;
         }
 
-        void update_butterfly_history(chess::Move move, int bonus) {
-            int scaled = bonus - butterfly[move.get_from()][move.get_to()] * std::abs(bonus) / 32768;
-            butterfly[move.get_from()][move.get_to()] += scaled;
+        static void update_history(Score &entry, int bonus) {
+            int scaled = bonus - entry * std::abs(bonus) / 32768;
+            entry += scaled;
         }
     };
 } // namespace search
\ No newline at end of file
diff --git a/src/search/move_list.h b/src/search/move_list.h
index 325472e..549dcd7 100644
--- a/src/search/move_list.h
+++ b/src/search/move_list.h
@@ -104,7 +104,7 @@ namespace search {
             } else if (move == history.counter_moves[last_move.get_from()][last_move.get_to()]) {
                 return MOVE_SCORE_COUNTER;
             } else {
-                return history.butterfly[move.get_from()][move.get_to()];
+                return history.main_history[board.get_stm()][move.get_from()][move.get_to()];
             }
         }
     };
diff --git a/src/search/search_thread.h b/src/search/search_thread.h
index 11d4a54..96ea625 100644
--- a/src/search/search_thread.h
+++ b/src/search/search_thread.h
@@ -406,7 +406,7 @@ namespace search {
 
                     R -= pv_node;
                     R += !improving;
-                    R -= std::clamp(history.butterfly[move.get_from()][move.get_to()] / 4096, -2, 2);
+                    R -= std::clamp(history.main_history[board.get_stm()][move.get_from()][move.get_to()] / 4096, -2, 2);
 
                     Depth D = std::clamp(new_depth - R, 1, depth - 1);
                     score = -search<NON_PV_NODE>(D, -alpha - 1, -alpha, ss + 1);
@@ -438,9 +438,9 @@ namespace search {
                 if (score >= beta) {
 
                     if (move.is_quiet()) {
-                        history.add_cutoff(move, last_move, depth, ss->ply);
+                        history.add_cutoff(board, move, last_move, depth, ss->ply);
                         for (chess::Move *current_move = quiet_moves; current_move != next_quiet_move; current_move++) {
-                            history.decrease_history(*current_move, depth);
+                            history.decrease_history(board, *current_move, depth);
                         }
                     }