From 2e0e0623360fc6d68004f14780bc674d2703136d Mon Sep 17 00:00:00 2001
From: Terje <tkirstihagen@gmail.com>
Date: Sat, 30 Dec 2023 18:14:40 +0100
Subject: [PATCH] Bench: 26879122

---
 src/history.h |  8 ++++++++
 src/search.c  | 11 +++++++++++
 src/threads.c |  1 +
 src/threads.h |  7 +++++++
 4 files changed, 27 insertions(+)

diff --git a/src/history.h b/src/history.h
index 9bf81ead..d1789395 100644
--- a/src/history.h
+++ b/src/history.h
@@ -28,11 +28,13 @@
 
 #define QuietEntry(move)        (&thread->history[thread->pos.stm][fromSq(move)][toSq(move)])
 #define PawnEntry(move)         (&thread->pawnHistory[PawnStructure(&thread->pos)][piece(move)][toSq(move)])
+#define CorrEntry()             (&thread->corrHistory[thread->pos.stm][CorrectionStructure(&thread->pos)])
 #define NoisyEntry(move)        (&thread->captureHistory[piece(move)][toSq(move)][PieceTypeOf(capturing(move))])
 #define ContEntry(offset, move) (&(*(ss-offset)->continuation)[piece(move)][toSq(move)])
 
 #define QuietHistoryUpdate(move, bonus)        (HistoryBonus(QuietEntry(move),        bonus,  6880))
 #define PawnHistoryUpdate(move, bonus)         (HistoryBonus(PawnEntry(move),         bonus,  8192))
+#define CorrHistoryUpdate(bonus)               (HistoryBonus(CorrEntry(),             bonus,   512))
 #define NoisyHistoryUpdate(move, bonus)        (HistoryBonus(NoisyEntry(move),        bonus, 16384))
 #define ContHistoryUpdate(offset, move, bonus) (HistoryBonus(ContEntry(offset, move), bonus, 30000))
 
@@ -55,6 +57,12 @@ INLINE void UpdateContHistories(Stack *ss, Move move, int bonus) {
     ContHistoryUpdate(4, move, bonus);
 }
 
+INLINE void UpdateCorrHistory(Thread *thread, int score, int staticEval) {
+    int correction = score - staticEval;
+    CorrHistoryUpdate(CLAMP(correction, -512, 512));
+    if (*CorrEntry() > 512) puts("CorrEntry() > 512");
+}
+
 // Updates history heuristics when a quiet move is the best move
 INLINE void UpdateQuietHistory(Thread *thread, Stack *ss, Move bestMove, Depth depth, Move quiets[], int qCount) {
 
diff --git a/src/search.c b/src/search.c
index 174b0409..d39e7311 100644
--- a/src/search.c
+++ b/src/search.c
@@ -107,6 +107,8 @@ static int Quiescence(Thread *thread, Stack *ss, int alpha, const int beta) {
          : ttEval != NOSCORE          ? ttEval
                                       : EvalPosition(pos, thread->pawnCache);
 
+    eval += *CorrEntry();
+
     // If we are at max depth, return static eval
     if (ss->ply >= MAX_PLY)
         return eval;
@@ -295,6 +297,8 @@ static int AlphaBeta(Thread *thread, Stack *ss, int alpha, int beta, Depth depth
     if (ttScore != NOSCORE && TTScoreIsMoreInformative(ttBound, ttScore, eval))
         eval = ttScore;
 
+    eval += *CorrEntry();
+
     // Improving if not in check, and current eval is higher than 2 plies ago
     bool improving = !inCheck && eval > (ss-2)->staticEval;
 
@@ -567,6 +571,13 @@ static int AlphaBeta(Thread *thread, Stack *ss, int alpha, int beta, Depth depth
                      : pvNode && bestMove ? BOUND_EXACT
                                           : BOUND_UPPER);
 
+    // Update correction history
+    if (   !inCheck
+        &&  (!bestMove || moveIsQuiet(bestMove))
+        && !(bestScore >= beta && bestScore <= ss->staticEval)
+        && !(!bestMove && bestScore >= ss->staticEval))
+        UpdateCorrHistory(thread, bestScore, ss->staticEval);
+
     return bestScore;
 }
 
diff --git a/src/threads.c b/src/threads.c
index 335e13dd..6fd2eb1a 100644
--- a/src/threads.c
+++ b/src/threads.c
@@ -127,6 +127,7 @@ void ResetThreads() {
         memset(threads[i].pawnCache,      0, sizeof(PawnCache)),
         memset(threads[i].history,        0, sizeof(threads[i].history)),
         memset(threads[i].pawnHistory,    0, sizeof(threads[i].pawnHistory)),
+        memset(threads[i].corrHistory,    0, sizeof(threads[i].corrHistory)),
         memset(threads[i].captureHistory, 0, sizeof(threads[i].captureHistory)),
         memset(threads[i].continuation,   0, sizeof(threads[i].continuation));
 }
diff --git a/src/threads.h b/src/threads.h
index bab7ff35..620321d7 100644
--- a/src/threads.h
+++ b/src/threads.h
@@ -28,13 +28,19 @@
 #define SS_OFFSET 10
 #define MULTI_PV_MAX 64
 #define PAWN_HISTORY_SIZE 512
+#define CORRECTION_HISTORY_SIZE 131072
 
 INLINE int PawnStructure(const Position *pos) {
     return pos->pawnKey & (PAWN_HISTORY_SIZE - 1);
 }
 
+INLINE int CorrectionStructure(const Position *pos) {
+    return pos->pawnKey & (CORRECTION_HISTORY_SIZE - 1);
+}
+
 typedef int16_t ButterflyHistory[COLOR_NB][64][64];
 typedef int16_t PawnHistory[PAWN_HISTORY_SIZE][PIECE_NB][64];
+typedef int16_t CorrectionHistory[COLOR_NB][CORRECTION_HISTORY_SIZE];
 typedef int16_t CaptureToHistory[PIECE_NB][64][TYPE_NB];
 typedef int16_t PieceToHistory[PIECE_NB][64];
 typedef PieceToHistory ContinuationHistory[PIECE_NB][64];
@@ -74,6 +80,7 @@ typedef struct Thread {
     PawnCache pawnCache;
     ButterflyHistory history;
     PawnHistory pawnHistory;
+    CorrectionHistory corrHistory;
     CaptureToHistory captureHistory;
     ContinuationHistory continuation[2][2];