Small sort_moves() deobfuscation

[stockfish] / src / move.h

diff --git a/src/move.h b/src/move.h
index 56659cd983a0fdc93a7b9d40c16e1c1f2c602534..d70bb81e77b1e4417633994175c896b94e243f11 100644 (file)
--- a/src/move.h
+++ b/src/move.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008 Marco Costalba
+  Copyright (C) 2008-2009 Marco Costalba
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -38,10 +38,22 @@
 
 class Position;
 
+/// A move needs 17 bits to be stored
+///
+/// bit  0- 5: destination square (from 0 to 63)
+/// bit  6-11: origin square (from 0 to 63)
+/// bit 12-14: promotion piece type
+/// bit    15: en passant flag
+/// bit    16: castle flag
+///
+/// Special cases are MOVE_NONE and MOVE_NULL. We can sneak these in
+/// because in any normal move destination square is always different
+/// from origin square while MOVE_NONE and MOVE_NULL have the same
+/// origin and destination square, 0 and 1 respectively.
+
 enum Move {
   MOVE_NONE = 0,
-  MOVE_NULL = 65,
-  MOVE_MAX = 0xFFFFFF
+  MOVE_NULL = 65
 };
 
 
@@ -50,29 +62,81 @@ struct MoveStack {
   int score;
 };
 
+// Note that operator< is set up such that sorting will be in descending order
+inline bool operator<(const MoveStack& f, const MoveStack& s) { return s.score < f.score; }
+
+// Our stable insertion sort in range [firstMove, lastMove), platform independent
+template<typename T>
+inline void sort_moves(T* firstMove, T* lastMove)
+{
+    T value;
+    T *cur, *p, *d;
+
+    if (firstMove != lastMove)
+        for (cur = firstMove + 1; cur != lastMove; cur++)
+        {
+            p = d = cur;
+            value = *p--;
+            if (value < *p)
+            {
+                do *d = *p;
+                while (--d != firstMove && value < *--p);
+                *d = value;
+            }
+        }
+}
+
+// Picks up the best move in range [curMove, lastMove), one per cycle.
+// It is faster then sorting all the moves in advance when moves are few,
+// as normally are the possible captures. Note that is not a stable alghoritm.
+template<typename T>
+inline T pick_best(T* curMove, T* lastMove)
+{
+    T bestMove, tmp;
+
+    bestMove = *curMove;
+    while (++curMove != lastMove)
+    {
+        if (*curMove < bestMove)
+        {
+            tmp = *curMove;
+            *curMove = bestMove;
+            bestMove = tmp;
+        }
+    }
+    return bestMove;
+}
 
 ////
 //// Inline functions
 ////
 
 inline Square move_from(Move m) {
-  return Square((int(m) >> 6) & 077);
+  return Square((int(m) >> 6) & 0x3F);
 }
 
 inline Square move_to(Move m) {
-  return Square(m & 077);
+  return Square(m & 0x3F);
 }
 
-inline PieceType move_promotion(Move m) {
+inline PieceType move_promotion_piece(Move m) {
   return PieceType((int(m) >> 12) & 7);
 }
 
-inline bool move_is_ep(Move m) {
-  return bool((int(m) >> 15) & 1);
+inline int move_is_special(Move m) {
+  return m & (0x1F << 12);
+}
+
+inline int move_is_promotion(Move m) {
+  return m & (7 << 12);
+}
+
+inline int move_is_ep(Move m) {
+  return m & (1 << 15);
 }
 
-inline bool move_is_castle(Move m) {
-  return bool((int(m) >> 16) & 1);
+inline int move_is_castle(Move m) {
+  return m & (1 << 16);
 }
 
 inline bool move_is_short_castle(Move m) {
@@ -104,7 +168,7 @@ inline Move make_ep_move(Square from, Square to) {
 //// Prototypes
 ////
 
-extern std::ostream &operator << (std::ostream &os, Move m);
+extern std::ostream& operator<<(std::ostream &os, Move m);
 extern Move move_from_string(const Position &pos, const std::string &str);
 extern const std::string move_to_string(Move m);
 extern bool move_is_ok(Move m);