From 6ceaca4c7b2cc1fa87617b1b9e83d38d8e880924 Mon Sep 17 00:00:00 2001
From: mstembera <m_stembera@yahoo.com>
Date: Thu, 20 Mar 2025 12:40:27 -0700
Subject: [PATCH] Change layout of CorrectionHistory<NonPawn>

https://tests.stockfishchess.org/tests/view/67da5b158c7f315cc372a9d2
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 150368 W: 38874 L: 38401 D: 73093
Ptnml(0-2): 424, 16821, 40262, 17212, 465

Make CorrectionHistory\<NonPawn\> handle both black and white
internally. A follow up to
https://github.com/official-stockfish/Stockfish/pull/5816

closes https://github.com/official-stockfish/Stockfish/pull/5934

No functional change
---
 src/history.h  |  6 ++++++
 src/search.cpp | 11 +++++------
 src/search.h   |  2 +-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/history.h b/src/history.h
index fd9b98b9..ec245230 100644
--- a/src/history.h
+++ b/src/history.h
@@ -155,6 +155,12 @@ struct CorrHistTypedef<Continuation> {
     using type = MultiArray<CorrHistTypedef<PieceTo>::type, PIECE_NB, SQUARE_NB>;
 };
 
+template<>
+struct CorrHistTypedef<NonPawn> {
+    using type =
+      Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, CORRECTION_HISTORY_SIZE, COLOR_NB, COLOR_NB>;
+};
+
 }
 
 template<CorrHistType T>
diff --git a/src/search.cpp b/src/search.cpp
index 2da19f32..0c543c30 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -87,8 +87,8 @@ int correction_value(const Worker& w, const Position& pos, const Stack* const ss
     const auto  m     = (ss - 1)->currentMove;
     const auto  pcv   = w.pawnCorrectionHistory[pawn_structure_index<Correction>(pos)][us];
     const auto  micv  = w.minorPieceCorrectionHistory[minor_piece_index(pos)][us];
-    const auto  wnpcv = w.nonPawnCorrectionHistory[WHITE][non_pawn_index<WHITE>(pos)][us];
-    const auto  bnpcv = w.nonPawnCorrectionHistory[BLACK][non_pawn_index<BLACK>(pos)][us];
+    const auto  wnpcv = w.nonPawnCorrectionHistory[non_pawn_index<WHITE>(pos)][WHITE][us];
+    const auto  bnpcv = w.nonPawnCorrectionHistory[non_pawn_index<BLACK>(pos)][BLACK][us];
     const auto  cntcv =
       m.is_ok() ? (*(ss - 2)->continuationCorrectionHistory)[pos.piece_on(m.to_sq())][m.to_sq()]
                  : 0;
@@ -141,9 +141,9 @@ void update_correction_history(const Position& pos,
     workerThread.pawnCorrectionHistory[pawn_structure_index<Correction>(pos)][us]
       << bonus * 111 / 128;
     workerThread.minorPieceCorrectionHistory[minor_piece_index(pos)][us] << bonus * 146 / 128;
-    workerThread.nonPawnCorrectionHistory[WHITE][non_pawn_index<WHITE>(pos)][us]
+    workerThread.nonPawnCorrectionHistory[non_pawn_index<WHITE>(pos)][WHITE][us]
       << bonus * nonPawnWeight / 128;
-    workerThread.nonPawnCorrectionHistory[BLACK][non_pawn_index<BLACK>(pos)][us]
+    workerThread.nonPawnCorrectionHistory[non_pawn_index<BLACK>(pos)][BLACK][us]
       << bonus * nonPawnWeight / 128;
 
     if (m.is_ok())
@@ -581,8 +581,7 @@ void Search::Worker::clear() {
     pawnHistory.fill(-1262);
     pawnCorrectionHistory.fill(6);
     minorPieceCorrectionHistory.fill(0);
-    nonPawnCorrectionHistory[WHITE].fill(0);
-    nonPawnCorrectionHistory[BLACK].fill(0);
+    nonPawnCorrectionHistory.fill(0);
 
     for (auto& to : continuationCorrectionHistory)
         for (auto& h : to)
diff --git a/src/search.h b/src/search.h
index cd3b6ad9..071773f8 100644
--- a/src/search.h
+++ b/src/search.h
@@ -289,7 +289,7 @@ class Worker {
 
     CorrectionHistory<Pawn>         pawnCorrectionHistory;
     CorrectionHistory<Minor>        minorPieceCorrectionHistory;
-    CorrectionHistory<NonPawn>      nonPawnCorrectionHistory[COLOR_NB];
+    CorrectionHistory<NonPawn>      nonPawnCorrectionHistory;
     CorrectionHistory<Continuation> continuationCorrectionHistory;
 
    private: