diff --git a/include/config.h b/include/config.h
index 51ea4621..391efd28 100644
--- a/include/config.h
+++ b/include/config.h
@@ -163,4 +163,4 @@
 #define likely(expr)    (__builtin_expect(!!(expr), 1))
 #define unlikely(expr)  (__builtin_expect(!!(expr), 0))
 
-#endif // CONFIG_H
\ No newline at end of file
+#endif // CONFIG_H
diff --git a/src/ai/search.cpp b/src/ai/search.cpp
index 097a57a6..af5639fe 100644
--- a/src/ai/search.cpp
+++ b/src/ai/search.cpp
@@ -38,7 +38,7 @@ player_t gSideToMove;
 using namespace CTSL;
 
 // 用于检测重复局面 (Position)
-vector<key_t> moveHistory;
+vector<hash_t> moveHistory;
 
 AIAlgorithm::AIAlgorithm()
 {
@@ -198,7 +198,7 @@ int AIAlgorithm::search(depth_t depth)
     static int nRepetition = 0;
 
     if (state->position->getPhase() == PHASE_MOVING) {
-        key_t key = state->position->getPosKey();
+        hash_t key = state->position->getPosKey();
         
         if (std::find(moveHistory.begin(), moveHistory.end(), key) != moveHistory.end()) {
             nRepetition++;
@@ -343,7 +343,7 @@ value_t AIAlgorithm::search(depth_t depth, value_t alpha, value_t beta)
 
 #if defined (TRANSPOSITION_TABLE_ENABLE) || defined(ENDGAME_LEARNING)
     // 获取哈希值
-    key_t posKey = st->position->getPosKey();
+    hash_t posKey = st->position->getPosKey();
 #endif
 
 #ifdef ENDGAME_LEARNING
diff --git a/src/ai/search.h b/src/ai/search.h
index f377ab2f..e43783ca 100644
--- a/src/ai/search.h
+++ b/src/ai/search.h
@@ -208,7 +208,7 @@ public:
 #include "tt.h"
 
 #ifdef THREEFOLD_REPETITION
-extern vector<key_t> moveHistory;
+extern vector<hash_t> moveHistory;
 #endif
 
 #endif /* SEARCH_H */
diff --git a/src/ai/tt.cpp b/src/ai/tt.cpp
index 4694e174..7ea2865e 100644
--- a/src/ai/tt.cpp
+++ b/src/ai/tt.cpp
@@ -21,13 +21,13 @@
 
 #ifdef TRANSPOSITION_TABLE_ENABLE
 static constexpr int TRANSPOSITION_TABLE_SIZE = 0x2000000; // 8-128M:102s, 4-64M:93s 2-32M:91s 1-16M: 冲突
-HashMap<key_t, TTEntry> TT(TRANSPOSITION_TABLE_SIZE);
+HashMap<hash_t, TTEntry> TT(TRANSPOSITION_TABLE_SIZE);
 
 #ifdef TRANSPOSITION_TABLE_FAKE_CLEAN
 uint8_t transpositionTableAge;
 #endif // TRANSPOSITION_TABLE_FAKE_CLEAN
 
-value_t TranspositionTable::probe(const key_t &key,
+value_t TranspositionTable::probe(const hash_t &key,
                       const depth_t &depth,
                       const value_t &alpha,
                       const value_t &beta,
@@ -88,7 +88,7 @@ out:
     return VALUE_UNKNOWN;
 }
 
-bool TranspositionTable::search(const key_t &key, TTEntry &tte)
+bool TranspositionTable::search(const hash_t &key, TTEntry &tte)
 {
     return TT.find(key, tte);
 
@@ -117,7 +117,7 @@ bool TranspositionTable::search(const key_t &key, TTEntry &tte)
 #endif
 }
 
-void TranspositionTable::prefetch(const key_t &key)
+void TranspositionTable::prefetch(const hash_t &key)
 {
     TT.prefetchValue(key);
 }
@@ -125,7 +125,7 @@ void TranspositionTable::prefetch(const key_t &key)
 int TranspositionTable::save(const value_t &value,
                    const depth_t &depth,
                    const bound_t &type,
-                   const key_t &key
+                   const hash_t &key
 #ifdef TT_MOVE_ENABLE
                    , const move_t &ttMove
 #endif // TT_MOVE_ENABLE
diff --git a/src/ai/tt.h b/src/ai/tt.h
index 2c6f6f48..6d142cf5 100644
--- a/src/ai/tt.h
+++ b/src/ai/tt.h
@@ -30,7 +30,7 @@ using namespace CTSL;
 
 #ifdef TRANSPOSITION_TABLE_ENABLE
 
-extern const key_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT];
+extern const hash_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT];
 
 enum bound_t : uint8_t
 {
@@ -57,8 +57,8 @@ class TranspositionTable
 {
 public:
     // 查找哈希表
-    static bool search(const key_t &key, TTEntry &tte);
-    static value_t probe(const key_t &key,
+    static bool search(const hash_t &key, TTEntry &tte);
+    static value_t probe(const hash_t &key,
                             const depth_t &depth,
                             const value_t &alpha,
                             const value_t &beta,
@@ -72,7 +72,7 @@ public:
     static int save(const value_t &value,
                           const depth_t &depth,
                           const bound_t &type,
-                          const key_t &key
+                          const hash_t &key
 #ifdef TT_MOVE_ENABLE
                           , const move_t &ttMove
 #endif // TT_MOVE_ENABLE
@@ -82,13 +82,13 @@ public:
     static void clear();
 
     // 预读取
-    static void prefetch(const key_t &key);
+    static void prefetch(const hash_t &key);
 
 private:
     friend struct TTEntry;
 };
 
-extern HashMap<key_t, TTEntry> TT;
+extern HashMap<hash_t, TTEntry> TT;
 
 #ifdef TRANSPOSITION_TABLE_FAKE_CLEAN
 extern uint8_t transpositionTableAge;
diff --git a/src/base/hashmap.h b/src/base/hashmap.h
index 219295ff..102ccc0c 100644
--- a/src/base/hashmap.h
+++ b/src/base/hashmap.h
@@ -26,7 +26,7 @@ namespace CTSL //Concurrent Thread Safe Library
     //during the creation of the bucket. All the key buckets are created during the construction of the map.
     //Locks are taken per bucket, hence multiple threads can write simultaneously in different buckets in the key map
 #ifdef HASH_KEY_DISABLE
-    #define hashFn key_t
+    #define hashFn hash_t
     template <typename K, typename V>
 #else
     template <typename K, typename V, typename F = std::key<K> >
@@ -34,7 +34,7 @@ namespace CTSL //Concurrent Thread Safe Library
     class HashMap
     {
         public:
-            HashMap(key_t hashSize_ = HASH_SIZE_DEFAULT) : hashSize(hashSize_)
+            HashMap(hash_t hashSize_ = HASH_SIZE_DEFAULT) : hashSize(hashSize_)
             {
 #ifdef DISABLE_HASHBUCKET
                 hashTable = new HashNode<K, V>[hashSize]; //create the key table as an array of key nodes
@@ -230,7 +230,7 @@ namespace CTSL //Concurrent Thread Safe Library
 #else
             F hashFn;
 #endif
-            const key_t hashSize;
+            const hash_t hashSize;
 #ifdef DISABLE_HASHBUCKET
 #ifndef HASHMAP_NOLOCK
             mutable std::shared_timed_mutex mutex_;
diff --git a/src/base/zobrist.cpp b/src/base/zobrist.cpp
index 0992896f..262d1a1a 100644
--- a/src/base/zobrist.cpp
+++ b/src/base/zobrist.cpp
@@ -19,7 +19,7 @@
 
 #include "zobrist.h"
 
-const key_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT] = {
+const hash_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT] = {
 #ifdef TRANSPOSITION_TABLE_CUTDOWN
     {0x4E421A, 0x3962FF, 0x6DB6EE, 0x219AE1},
     {0x1F3DE2, 0xD9AACB, 0xD51733, 0xD3F9EA},
diff --git a/src/base/zobrist.h b/src/base/zobrist.h
index cb6131ae..492cb95d 100644
--- a/src/base/zobrist.h
+++ b/src/base/zobrist.h
@@ -22,4 +22,4 @@
 #include "config.h"
 #include "position.h"
 
-extern const key_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT];
+extern const hash_t zobrist[SQ_EXPANDED_COUNT][PIECETYPE_COUNT];
diff --git a/src/game/position.cpp b/src/game/position.cpp
index a0986247..ef18822a 100644
--- a/src/game/position.cpp
+++ b/src/game/position.cpp
@@ -352,7 +352,7 @@ bool Position::start()
     // 如果游戏处于未开始状态
     case PHASE_READY:
         // 启动计时器
-        startTime = time(NULL);
+        startTime = time(nullptr);
         // 进入开局状态
         phase = PHASE_PLACING;
         return true;
@@ -363,6 +363,20 @@ bool Position::start()
 
 bool Position::placePiece(square_t square, bool updateCmdlist)
 {
+    ring_t r;
+    seat_t s;
+    int i;
+    // 时间的临时变量
+    int seconds = -1;
+
+    // 对于开局落子
+    int piece = '\x00';
+    int n = 0;
+
+    int playerId = Player::toId(sideToMove);
+
+    bitboard_t fromTo;
+
     // 如果局面为“结局”，返回false
     if (phase == PHASE_GAMEOVER)
         return false;
@@ -380,19 +394,8 @@ bool Position::placePiece(square_t square, bool updateCmdlist)
         return false;
 
     // 格式转换
-    ring_t r;
-    seat_t s;
     Board::squareToPolar(square, r, s);
 
-    // 时间的临时变量
-    int seconds = -1;
-
-    // 对于开局落子
-    int piece = '\x00';
-    int n = 0;
-
-    int playerId = Player::toId(sideToMove);
-
     if (phase == PHASE_PLACING) {
         piece = (0x01 | sideToMove) + rule.nTotalPiecesEachSide - nPiecesInHand[playerId];
         nPiecesInHand[playerId]--;
@@ -479,7 +482,6 @@ bool Position::placePiece(square_t square, bool updateCmdlist)
     // 如果落子不合法
     if (nPiecesOnBoard[sideId] > rule.nPiecesAtLeast ||
         !rule.allowFlyWhenRemainThreePieces) {
-        int i;
         for (i = 0; i < 4; i++) {
             if (square == MoveList::moveTable[currentSquare][i])
                 break;
@@ -503,7 +505,7 @@ bool Position::placePiece(square_t square, bool updateCmdlist)
         moveStep++;
     }
 
-    bitboard_t fromTo = square_bb(currentSquare) | square_bb(square);
+    fromTo = square_bb(currentSquare) | square_bb(square);
     board.byTypeBB[ALL_PIECES] ^= fromTo;
     board.byTypeBB[playerId] ^= fromTo;
 
@@ -852,6 +854,7 @@ bool Position::doMove(move_t m)
         if (selectPiece(from_sq(m))) {
             return placePiece(to_sq(m));
         }
+        break;
     case MOVETYPE_PLACE:
         return placePiece(to_sq(m));
     default:
@@ -1174,13 +1177,13 @@ void Position::constructKey()
     key = 0;
 }
 
-key_t Position::getPosKey()
+hash_t Position::getPosKey()
 {
     // TODO: 每次获取哈希值时更新 key 值剩余8位，放在此处调用不优雅
     return updateKeyMisc();
 }
 
-key_t Position::updateKey(square_t square)
+hash_t Position::updateKey(square_t square)
 {
     // PieceType is board.locations[square] 
 
@@ -1196,18 +1199,18 @@ key_t Position::updateKey(square_t square)
     return key;
 }
 
-key_t Position::revertKey(square_t square)
+hash_t Position::revertKey(square_t square)
 {
     return updateKey(square);
 }
 
-key_t Position::updateKeyMisc()
+hash_t Position::updateKeyMisc()
 {
     const int KEY_MISC_BIT = 8;
 
     // 清除标记位
     key = key << KEY_MISC_BIT >> KEY_MISC_BIT;
-    key_t hi = 0;
+    hash_t hi = 0;
 
     // 置位
 
@@ -1219,17 +1222,17 @@ key_t Position::updateKeyMisc()
         hi |= 1U << 1;
     }
 
-    hi |= static_cast<key_t>(nPiecesNeedRemove) << 2;
-    hi |= static_cast<key_t>(nPiecesInHand[BLACK]) << 4;     // TODO: 或许换 phase 也可以？
+    hi |= static_cast<hash_t>(nPiecesNeedRemove) << 2;
+    hi |= static_cast<hash_t>(nPiecesInHand[BLACK]) << 4;     // TODO: 或许换 phase 也可以？
 
-    key = key | (hi << (CHAR_BIT * sizeof(key_t) - KEY_MISC_BIT));
+    key = key | (hi << (CHAR_BIT * sizeof(hash_t) - KEY_MISC_BIT));
 
     return key;
 }
 
-key_t Position::getNextPrimaryKey(move_t m)
+hash_t Position::getNextPrimaryKey(move_t m)
 {
-    key_t npKey = key /* << 8 >> 8 */;
+    hash_t npKey = key /* << 8 >> 8 */;
     square_t sq = static_cast<square_t>(to_sq(m));;
     movetype_t mt = type_of(m);
 
diff --git a/src/game/position.h b/src/game/position.h
index 1fe05ed0..09333899 100644
--- a/src/game/position.h
+++ b/src/game/position.h
@@ -56,7 +56,7 @@ public:
     Board board;
 
     // 局面的哈希值
-    key_t key {0};
+    hash_t key {0};
 
     // 局面阶段标识
     enum phase_t phase {PHASE_NONE};
@@ -238,11 +238,11 @@ public:
     bool removePiece(square_t square, bool updateCmdlist = false);
 
     // key 相关
-    key_t getPosKey();
-    key_t revertKey(square_t square);
-    key_t updateKey(square_t square);
-    key_t updateKeyMisc();
-    key_t getNextPrimaryKey(move_t m);
+    hash_t getPosKey();
+    hash_t revertKey(square_t square);
+    hash_t updateKey(square_t square);
+    hash_t updateKeyMisc();
+    hash_t getNextPrimaryKey(move_t m);
 
     // 赢盘数
     int score[COLOR_COUNT] = { 0 };
diff --git a/src/game/types.h b/src/game/types.h
index 4ed55a1a..47ad926f 100644
--- a/src/game/types.h
+++ b/src/game/types.h
@@ -30,9 +30,9 @@ using score_t = uint32_t;
 typedef uint32_t bitboard_t;
 
 #ifdef TRANSPOSITION_TABLE_CUTDOWN
-using key_t = uint32_t;
+using hash_t = uint32_t;
 #else
-using key_t = uint64_t;
+using hash_t = uint64_t;
 #endif /* TRANSPOSITION_TABLE_CUTDOWN */
 
 enum move_t : int32_t