From 0e54688853e1be9f6da11bde17e1820252b69f97 Mon Sep 17 00:00:00 2001
From: Calcitem <calcitem@outlook.com>
Date: Thu, 1 Oct 2020 11:04:15 +0800
Subject: [PATCH] =?UTF-8?q?Zobrist:=20=E6=AF=8F=E6=AC=A1=E6=8D=A2=E8=BE=B9?=
 =?UTF-8?q?=E6=97=B6=E5=BC=82=E6=88=96=20side=20=E8=80=8C=E4=B8=8D?=
 =?UTF-8?q?=E7=94=A8=20Key=20=E7=9A=84=E7=89=B9=E5=AE=9A=E4=BD=8D=E6=A0=87?=
 =?UTF-8?q?=E8=AE=B0=E8=BD=AE=E5=88=B0=E8=B0=81=E8=B5=B0?=
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自对弈棋谱不变。
---
 src/position.cpp | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/position.cpp b/src/position.cpp
index 5c1ab5b0..7b7ca5e3 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -39,6 +39,7 @@ using std::string;
 namespace Zobrist
 {
 Key psq[PIECE_TYPE_NB][SQUARE_NB];
+Key side;
 }
 
 namespace
@@ -153,6 +154,8 @@ void Position::init()
         for (Square s = SQ_0; s < SQUARE_NB; ++s)
             Zobrist::psq[pt][s] = rng.rand<Key>();
 
+    Zobrist::side = rng.rand<Key>();
+
     // Prepare the cuckoo tables
     std::memset(cuckoo, 0, sizeof(cuckoo));
     std::memset(cuckooMove, 0, sizeof(cuckooMove));
@@ -1226,6 +1229,7 @@ inline void Position::set_side_to_move(Color c)
 inline void Position::change_side_to_move()
 {
     set_side_to_move(~sideToMove);
+    st->key ^= Zobrist::side;
 }
 
 inline Key Position::update_key(Square s)
@@ -1255,9 +1259,11 @@ Key Position::update_key_misc()
     st->key = st->key << KEY_MISC_BIT >> KEY_MISC_BIT;
     Key hi = 0;
 
+#if 0
     if (sideToMove == WHITE) {
         hi |= 1U;
     }
+#endif
 
     if (action == ACTION_REMOVE) {
         hi |= 1U << 1;
@@ -1278,23 +1284,25 @@ Key Position::next_primary_key(Move m)
     MoveType mt = type_of(m);
 
     if (mt == MOVETYPE_REMOVE) {
-        int pieceType = ~sideToMove;
-        npKey ^= Zobrist::psq[pieceType][s];
+        npKey ^= Zobrist::psq[~sideToMove][s];
 
         if (rule.hasBannedLocations && phase == PHASE_PLACING) {
             npKey ^= Zobrist::psq[BAN][s];
         }
 
-        return npKey;
+        goto out;
     }
 
-    int pieceType = sideToMove;
-    npKey ^= Zobrist::psq[pieceType][s];
+    npKey ^= Zobrist::psq[sideToMove][s];
 
     if (mt == MOVETYPE_MOVE) {
-        npKey ^= Zobrist::psq[pieceType][from_sq(m)];
+        npKey ^= Zobrist::psq[sideToMove][from_sq(m)];
     }
 
+out:
+    // Note: Guess only, maybe side is not changed actually
+    npKey ^= Zobrist::side;
+
     return npKey;
 }